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Eugenol-inhibited root growth in Avena fatua involves ROS-mediated oxidative damage

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  • Amity University Punjab Mohali
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... Eugenol (4), the most potent phytotoxin in clove oil has been demonstrated to be phytotoxic, affecting the germination and seedling growth, chlorophyll content and cellular respiration in several weeds. [10][11][12] It induced the generation of ROS in plant cells causing oxidative stress and disrupting membrane integrity. 10,12 In fact, clove (Syzygium aromaticum) oil has been used in several herbicidal formulations for organic farming. ...
... [10][11][12] It induced the generation of ROS in plant cells causing oxidative stress and disrupting membrane integrity. 10,12 In fact, clove (Syzygium aromaticum) oil has been used in several herbicidal formulations for organic farming. [11][12][13][14] However, other propenylbenzene-rich essential oils such as anise (Pimpinella anisum), bay (Cinnamomum sp.), basil (Ocimum tenuiflorum) and betel (Piper betle) have not been investigated in great detail. ...
... Chavibetol (1) and 11 of its structural analogues (2,(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) were chosen for the SAR study. All of these propenylbenzene analogues varied in the position and structure of the aromatic substitutions. ...
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BACKGROUND Many essential oils and their constituent volatile organic compounds are known to be phytotoxic and potential bioherbicides. This study aims to investigate the phytotoxicity of propenylbenzene‐rich essential oils and identify active molecule(s) therein. RESULTS Five commercially available propenylbenzene‐rich oils were screened, of which betel (Piper betle L.) oil was identified as a potent natural phytotoxin. It dose‐dependently inhibited wheatgrass (Triticum aestivum) seed germination and growth in water and agar medium with half maximal inhibitory concentration (IC50) in the range 23.2–122.7 μg mL⁻¹. Phytotoxicity‐guided fractionation and purification revealed chavibetol as the major and most potent phytotoxic constituent of betel oil, followed by chavibetol acetate. A structure–activity relationship study involving 12 propenylbenzenes indicated the structural and positional importance of aromatic substitutions for the activity. Furthermore, the phytotoxic efficacy of chavibetol was established against wheatgrass germination and growth in water (IC50 15.8–53.4 μg mL⁻¹), agar (IC50 34.4–53.6 μg mL⁻¹) and aerial (IC50 1.7–4.5 mg L⁻¹) media with a more pronounced effect on the radicle. Also, in open phytojars, chavibetol efficiently inhibited the growth of 3–7‐day‐old bermudagrass (Cynodon dactylon) seedlings when sprayed directly (IC50 2.3–3.4 mg jar⁻¹) or supplemented in agar (IC50 116.6–139.1 μg mL⁻¹). The growth of pre‐germinated green amaranth (Amaranthus viridis) was inhibited more effectively in both application modes (1.2–1.4 mg jar⁻¹ and IC50 26.8–31.4 μg mL⁻¹ respectively). CONCLUSION The study concluded betel oil as a potent phytotoxic herbal extract and its major constituent chavibetol as a promising volatile phytotoxin for the future management of weeds in their early phase of emergence. © 2023 Society of Chemical Industry.
... (clove essential oil) are β-caryophyllene, eugenol, and eugenol acetate [128][129][130][131]. For example, eugenol inhibited the root growth of Avena fatua [132], Abutilon theophrasti, Amaranthus spp., broccoli (Brassica oleracea), Chenopodium album [133,134], Portulaca oleracea, and Urtica urens [134]. Additionally, it inhibited the seedling growth of Chenopodium album, Melilotus indicus, Raphanus raphanistrum, Sisymbrium irio [131], Amaranthus retroflexus, and Brassica oleracea [133]. ...
... The main bioactive substances of cinnamon essential oil are eugenol and trans-cinnamic aldehyde [137,138,141]. Cinnamon exhibited herbicidal effects on Ageratum conyziodes, Amarantus retroflexus, Ambrosia artemisiifolia, Bidens pilosa, Cassia occidentalis, Chenopodium album, Commelina benghalensis, Echinochloa crus-galli, Leptochloa chinensis, Lolium spp., Phalaris minor, Sinapis arvensis, Sorghum halepense, and Taraxacum officinale [132,[142][143][144]. Cinnamon essential oil also inhibited the seed germination of Amaranthus tricolor and Echinochloa crus-galli [137,145]. ...
... Eugenol: The phenylpropanoid eugenol is known to elicit the generation of active oxygen species in plants, which leads to cell membrane damage and inhibition of photosynthesis. The enhanced activity of ROS-scavenging enzymes inhibits further metabolic pathways [131][132][133]137,143,144]. ...
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Concerning human and environmental health, safe alternatives to synthetic pesticides are urgently needed. Many of the currently used synthetic pesticides are not authorized for application in organic agriculture. In addition, the developed resistances of various pests against classical pesticides necessitate the urgent demand for efficient and safe products with novel modes of action. Botanical pesticides are assumed to be effective against various crop pests, and they are easily biodegradable and available in high quantities and at a reasonable cost. Many of them may act by diverse yet unexplored mechanisms of action. It is therefore surprising that only few plant species have been developed for commercial usage as biopesticides. This article reviews the status of botanical pesticides, especially in Europe and Mediterranean countries, deepening their active principles and mechanisms of action. Moreover, some constraints and challenges in the development of novel biopesticides are highlighted.
... Whenever ROS generation overpowers its scavenging by the antioxidants, cell comes under oxidative stress (Garg and Manchanda 2009;Gill and Tuteja 2010). Further, excessive production of ROS leads to peroxidation of lipid membrane, inhibition of enzymatic machinery, damage to DNA and ultimately causes cell death by initiating PCD pathway (Apel and Hirt 2004;Hsiung et al. 2013;Ahuja et al. 2015;Dmitrović et al. 2015). ...
... The decrement in chlorophyll content might be due to degradation of photosynthetic pigment chl a and chl b or inhibition of chlorophyll synthesis in target plant (Romagni et al. 2000;Poonpaiboonpipat et al. 2013). Retardation in the seedling growth of the test weeds as observed in the present study is in harmony with many earlier studies (Ahuja et al. 2015;Dmitrović et al. 2015;Fagodia et al. 2017). The growth inhibitory effect of PO could be due to the presence of its major components or the synergy among major and minor components. ...
... They also enhanced transpiration by interfering with the cuticular waxes and damaging stomata (Schulz et al. 2007) and caused various physiological alterations (Dudai et al. 2000). EOs/components also induced oxidative stress in test plant via generating the ROS (Kaur et al. 2011;Chowhan et al. 2013;Ahuja et al. 2015) and altering the plant water balance (Graña et al. 2016;Araniti et al. 2017a). Despite numerous reports on the phytotoxicity of essential oils and their constituents, their primary target point still remains unclear. ...
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The present study was conducted to evaluate the phytotoxic potential of Pogostemon oil in terms of oxidative stress on two weeds, viz. Avena fatua L. and Phalaris minor Retz. GC–MS analysis revealed that Pogostemon oil is rich in sesquiterpenes with azulen-2-ol, 1,4-dimethyl-7-(1-methyl ethyl)-as the major component of the oil with maximum % area (28.2%). For the laboratory bioassay, oil emulsion of different concentrations, ranging from 0.25 to 2.5 mg mL−1, was prepared. The effect of oil treatment was studied on per cent germination, seedling length, chlorophyll content and dry weight of the test plants. The inhibitory effect of Pogostemon oil was much pronounced on Avena fatua as compared to Phalaris minor. Roots were adversely affected due to oxidative damage. Consequently, oxidative damage, IC30, IC50 and IC70 values for A. fatua were calculated. Pogostemon oil treatment induced excessive generation of ROS leading to oxidative stress in test plant. ROS further disintegrated membrane integrity as evident from the increased level of MDA, REL and decreased level of CDs. Further exposure to Pogostemon oil enhanced the activities of antioxidant enzymes, thus indicating the activation of ROS scavenging mechanism. Thus, Pogostemon oil inhibits the growth of test plant via inducing oxidative stress and therefore shows potential towards weed management.
... Root elongation was more inhibited by NE than shoot growth in both weeds. Ahuja et al. (2015) reported that root growth was more inhibited than shoot growth in Avena fatua by eugenol treatment. The higher inhibitory effect on roots can be caused by the higher penetrance of monoterpenes into the roots than into the shoots due to the lack of cuticle cover in the roots allowing free penetration of monoterpenes (Yoshimura et al., 2011). ...
... The greatest reduction (53%) in chlorophyll content was observed in C. album by 3000 μL.L −1 NE. Our findings are in agreement with previous reports regarding the negative effect of EO and monoterpenes on chlorophyll content (Arora et al., 2015;Ahuja et al., 2014Ahuja et al., , 2015Singh et al., 2002;Zhou and Yu, 2006;Kaur et al., 2011). Furthermore, EOs and their individual components might affect the photosynthetic performance of plants. ...
... The correlations between the electrolyte leakage and some factors such as EO concentration, EO component and plant species have previously been confirmed (Amri et al., 2013;Kaur et al., 2010). Ahuja et al. (2015) reported that overproduction of ROS could be a possible reason for the induction of oxidative stress leading to membrane damage, and hence, enhancing electrolyte leakage. The mode of action of most EOs depends on their roles in relative electrolyte leakage, inhibition of photosynthesis process and enzymatic inactivation (Macias et al., 2000). ...
Article
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The aim of the present study was to obtain an oil/water (O/W) nanoemulsion (NE) containing garden savory (Satureja hortensis) essential oil (EO) and evaluating its herbicidal activity against Amaranthus retroflexus and Chenopodium album. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were employed to determine the chemical composition of the EO. Carvacrol (55.6%) and γ-terpinene (31.9%) were the major EO components. Low energy method was applied, allowing achievement of EO nanodroplets. The NE also presented low polydispersity, and the mean droplet was below 130 nm even after storage for 30 d. Laboratory tests showed that the NE at different concentrations (100, 200, 400, 800, and 1000 ) significantly (P≤0.05) reduced the germination indices and the seedling's growth in dose-response. The inhibitory effect was the greatest at 800 NE. Overall, root length was more inhibited as compared to shoot length. Post-emergence application of NE at different concentrations (1000, 2000, 3000, 4000 and 5000 of EO) on 2–4 true leaves' stage of the weeds caused significant (P≤0.05) decrease in the growth factors in dose-dependent manner. Complete lethality was observed by 4000 NE sprayed on the weeds. Spraying of NE significantly (P≤0.05) reduced chlorophyll content in the tested weeds. Increasing in relative electrolyte leakage (REL) 1 and 5 d after treatment represented significant cell membrane disruption and increased cell membrane permeability. Transmission electron microscope (TEM) pictures confirmed NE droplet size and demonstrated membrane destruction. The study approved that the NE of S. hortensis EO has herbicidal properties as it has high phytotoxic effect, and interferes with the germination, growth and physiological processes of the weeds. The production of NE from S. hortensis EO is a low energy method that offers a promising practical natural herbicide for weed control in organic agricultural systems.
... Under unfavorable environments, ROS act as crucial cellular signaling molecules in the regulation of stress tolerance at low levels, but ROS in excess would cause detrimental effects (ROS stress) on various molecular processes, which in turn adversely affect plant growth and provoke cell death (Mittler, 2017;Tognetti et al., 2017). Several studies have recorded that exposure to individual VOC chemicals could induce oxidative stress through ROS production and ROS scavenging systems in plants (Ahuja et al., 2015;Chowhan et al., 2014). According to Ditengou et al. (2015), α-thujopsene -the volatile fungal sesquiterpene could stimulate the production of superoxide anion radicals (O 2 ...
... Results shown above demonstrated that 2MB and 3MB loading in rice roots led to an overaccumulation of ROS in a time-dependent manner. Similar to our observation, Ahuja et al. (2015) reported that exposure to (100-1000 µM) eugenol, a plant volatile compound, led to an increase in ROS generation (O 2 -, H 2 O 2 , • OH) in Avena fatua. ...
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2-Methyl-1-butanol (2MB) and 3-Methyl-1-butanol (3MB) are microbial volatile organic compounds (VOCs) and found in indoor air. Here, we applied rice as a bioindicator to investigate the effects of these indoor microbial volatile pollutants. A remarkable decrease in germination percentage, shoot and root elongation, as well as lateral root numbers were observed in 3MB. Furthermore, ROS production increased by 2MB and 3MB, suggesting that pentanol isomers could induce cytotoxicity in rice seedlings. The enhancement of peroxidase (POD) and catalase (CAT) activity provided evidence that pentanol isomers activated the enzymatic antioxidant scavenging systems, with a more significant effect observed in 3MB. Furthermore, 3MB induced higher activity levels of glutathione (GSH), oxidized glutathione (GSSG), and the GSH/GSSG ratio in rice compared to the levels induced by 2MB. Additionally, qRT-PCR analysis showed more up-regulation in the expression of glutaredoxins (GRXs), peroxiredoxins (PRXs), thioredoxins (TRXs), and glutathione S-transferases (GSTUs) genes in 3MB. Taking the impacts of pentanol isomers together, the present study suggests that 3MB exhibits more cytotoxic than 2MB, as such has critical effects on germination and the early seedling stage of rice. Our results provide molecular insights into how isomeric indoor microbial volatile pollutants affect plant growth through airborne signals.
... It can easily permeate the lipopolysaccharide layer of cell membranes, penetrate cytoplasmic membrane and cytoplasm of gram-negative bacteria, causing intracellular component leakage (da Silva et al., 2018). Additionally, eugenol has been shown to be highly phytotoxic to several plant species, including amaranth, ryegrass, quinoa, and barnyard grass (Evans et al., 2009), which inhibits the germination and early growth of wild oats, reduces plant photosynthetic efficiency and chlorophyll content, and induces the accumulation of excess ROS (Ahuja et al., 2015). ...
... The ability of these BCP and eugenol to target multiple genes through allelopathy allowed them to overcome tolerance to chemical herbicides and could serve as excellent candidates for natural biological herbicides Natural herbicides derived from the allelopathy of compounds can provide effective alternatives to chemical herbicides for sustainable agricultural practices (Ahuja et al., 2015). In this study, we discovered that BCP and eugenol inhibited the growth of A. thaliana seedlings by affecting the expression of various genes involved in different metabolic pathways. ...
Article
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Weeds present a significant challenge to high crop yield and quality. In our study, we investigated the phytotoxic activity of β-caryophyllene (BCP) and eugenol, which are natural allelopathic chemical compounds, on Arabidopsis seedlings. We found that these compounds inhibited the growth of Arabidopsis thaliana plants. When either BCP or eugenol was applied, it led to decrease in the content of cell wall components such as lignin, cellulose, hemicellulose, and pectin; and increase in the levels of endogenous hormones like ETH, ABA, SA, and JA in the seedlings. Through transcriptome profiling, we identified 7181 differentially expressed genes (DEGs) in the roots and shoots that were induced by BCP or eugenol. The genes involved in the synthesis of lignin, cellulose, hemicellulose, and pectin were down-regulated, whereas genes related to synthesis and signal transduction of ABA, ETH, SA, and JA were up-regulated. However, genes related to IAA synthesis and signal transduction were found to be down-regulated. Furthermore, we characterized 24 hub genes using Weighted Correlation Network Analysis (WGCNA). Among them, the identified 16 genes in response to BCP was primarily associated with hypoxia stress, while 8 genes induced by eugenol were linked to inhibition of cell division. Our results suggested that BCP and eugenol had ability to target multiple genes to inhibit growth and development of Arabidopsis plants. Therefore, they can serve as excellent candidates for natural biological herbicides.
... Eugenol (C 10 H 12 O 2 ), a natural monoterpene, was also found to inhibit seed germination in wheat (Darabi et al. 2011), Avena fatua (Ahuja et al. 2015) and rice (Hu et al. 2017). Eugenol is commonly observed in the essential oils of several plant families, such as Lamiaceae, Lauraceae, Myrtaceae and Myristicaceae, and is the most important active ingredient of clove oil. ...
... The mechanism of eugenol-inhibited seed germination in different plants remains controversial. In Avena fatua, eugenol induced the accumulation of ROS, but several antioxidant enzyme activities were paradoxically activated, including CAT, SOD and APX (Ahuja et al. 2015). In rice, eugenol effectively inhibited rice germination by increasing the expression of the ABA biosynthetic gene OsNCED2 and suppressing the expression of the ABA catabolic gene OsABA8ox2, thereby elevating the levels of ABA (Hu et al. 2017). ...
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Key message The inhibitory effect of eugenol on rice germination is mediated by a two-step modulatory process: Eugenol first regulates the antagonism of GA and ABA, followed by activation of catalase activity. Abstract The natural monoterpene eugenol has been reported to inhibit preharvest sprouting in rice. However, the inhibitory mechanism remains obscure. In this study, simultaneous monitoring of GA and ABA responses by the in vivo GA and ABA-responsive dual-luciferase reporter system showed that eugenol strongly inhibited the GA response after 6 h of imbibition, whereas eugenol significantly enhanced the ABA response after 12 h of imbibition. Gene expression analysis revealed that eugenol significantly induced the ABA biosynthetic genes OsNCED2, OsNCED3, and OsNCED5, but notably suppressed the ABA catabolic genes OsABA8ox1 and OsABA8ox2. Conversely, eugenol inhibited the GA biosynthetic genes OsGA3ox2 and OsGA20ox4 but significantly induced the GA catabolic genes OsGA2ox1 and OsGA2ox3 during imbibition. OsABI4, the key signaling regulator of ABA and GA antagonism, was notably induced before 12 h and suppressed after 24 h by eugenol. Moreover, eugenol markedly reduced the accumulation of H2O2 in seeds after 36 h of imbibition. Further analysis showed that eugenol strongly induced catalase activity, protein accumulation, and the expression of three catalase genes. Most importantly, mitigation of eugenol-inhibited seed germination was found in the catc mutant. These findings indicate that catalase associated with antagonistic changes of ABA and GA is involved in the sequential regulation of eugenol-inhibited seed germination in rice.
... However, it is not clear how the allelopathic activity of chavicol changes among these isoforms. For the allelopathic study in this work, eugenol was chosen as the comparative allelochemical compound to the BE because of the studies of allelopathic activity and the mode of action of eugenol or isoeugenol in several reports [20,24,30]. Nevertheless, the most abundant phenylpropanoid in BE was allyl-pyrocatechol diacetate (4-allyl-1,2-diacetoxybenzene), and the allelopathic action of BE might be from this compound. ...
... However, allyl-pyrocatechol and other unreported compounds including terpenoid and alkaloid volatiles were not excluded for the molecular action of BE. Ahuja et al. reported that eugenol inhibited root development through the tissue damaging mechanism by ROS [24]. The mechanism of eugenol action involved ROS-mediated oxidative stress to the roots. ...
Article
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Natural herbicide is considered as a sustainable approach for weed management in agriculture. Here, allelopathic activities of Piper betle L. extract (BE) and known allelochemical eugenol (EU) were studied against rice and associated weeds in terms of germination and seedling growth. Five plant species including a rice crop (Oryza sativa L.); a dicot weed, false daisy (Eclipta prostrata (L.) L.); and three monocot weeds, barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), swollen fingergrass (Chloris barbata Sw.), and weedy rice (Oryza sativa f. spontanea Roshev.) were studied. The paper-based results demonstrated that BE and EU had inhibitory effects on seed germination and seedling growth. The IC50 values of BE and EU for seed germination were ranked from swollen fingergrass, to false daisy, barnyard grass, rice, and weedy rice, respectively. The ratio of root to shoot length of the seedlings indicated that the roots were more affected by the treatments than the shoots. In addition, the gel-based results showed the reduction of the rice seedling root system, especially on lateral root length and the numbers upon the treatments. Taken together, BE had an allelopathic activity similar to that of EU. Interestingly, the major paddy weed, barnyard grass, was more sensitive to BE than rice, underlining BE as a natural herbicide in rice agriculture.
... Allelopathic potential of plant species can be exploited in many ways, use of aqueous extracts of plants is one. Different plant species contain allelochemicals in different concentrations (2). Weeds may be better controlled by using the plants that are rich in allelochemicals (13). ...
... Our results are in agreement with previous work of varios authors. The leaves and stem extracts of Erythroxylum monogynum significantly decreased the germination and growth of tomato (2). The Cassia tora L exracts inhibited the germination, growth and metabolism of Parthenium hysterophorus (11). ...
... Some studies carried out in recent years relate the herbicidal activity of plant extracts or EOs to their composition in monoterpenes, and these substances are postulated as the future of natural herbicide components [32][33][34][35]. For example, eugenol, a monoterpene that can be found in many EOs as the major compound, like in Syzygium aromaticum EO, has shown strong phytotoxic potential against A. retroflexus [30] and A. fatua [31]. In A. fatua, eugenol inhibited its seedling growth, affecting more the roots than the coleoptiles. ...
... The natural products studied on this work for their potential as bioherbicides were pelargonic acid, trans-cinnamaldehyde and carvacrol. Pelargonic acid (PA) (CH3(CH2)7CO2H, n-nonanoic acid), which is present as esters in the EO of Pelargonium spp., is a saturated fatty acid with nine carbons in its structure [28][29][30][31][32][33][34][35][36][37][38][39][40]. PA and its salts are used like active ingredients in bioherbicide formulations for garden and professional uses worldwide. ...
Article
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Weeds and herbicides are important stress factors for crops. Weeds are responsible for great losses in crop yields, more than 50% in some crops if left uncontrolled. Herbicides have been used as the main method for weed control since their development after the Second World War. It is necessary to find alternatives to synthetic herbicides that can be incorporated in an Integrated Weed Management Program, to produce crops subjected to less stress in a more sustainable way. In this work, three natural products: pelargonic acid (PA), carvacrol (CV), and cinnamic aldehyde (CA) were evaluated, under greenhouse conditions in postemergence assays, against problematic weeds in Mediterranean crops Amaranthus retroflexus, Avena fatua, Portulaca oleracea, and Erigeron bonariensis, to determine their phytotoxic potential. The three products showed a potent herbicidal activity, reaching high efficacy (plant death) and damage level in all species, being PA the most effective at all doses applied, followed by CA and CV. These products could be good candidates for bioherbicides formulations.
... resulted in the generation of ROS in the roots of 5-day wheat seedlings, increased lipid peroxidation, loss of membrane permeability, and death of root cells. Activation of antioxidant mechanisms was found to be under the influence of phenolic compounds and flavonoids (Pergo and Ishii-Iwamoto 2011;Mahmood et al. 2013;Ahuja et al. 2015). ...
... It is widely believed that allelochemicals influence the level of non-enzymatic antioxidants and increase the activity of enzymes (Ding et al. 2007;Pergo and Ishii-Iwamoto 2011;García-Sánchez et al. 2012;Ahuja et al. 2015). The major group of non-enzymatic antioxidants are polyphenolic compounds whose role is the removal of reactive oxygen species which affects many metabolic processes in cells (Cruz-Ortega et al. 2007). ...
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This study was conducted to determine if common buckwheat (Fagopyrum esculentum Moench) root residues (BRR) in soil are effective in limiting the growth and metabolic responses of barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), wind grass (Apera spica-venti L.), cleavers (Galium aparine L.), and tiny vetch (Vicia hirsuta L.). After removal of above ground parts, BRR of 14-day-old buckwheat plants remained in soil for an additional 7 days when the weeds were seeded. After 30 days of growth, biomass of above ground parts of the weeds as well as free and bound phenolic acids and flavonoids were determined. Antioxidant capacity and peroxidase activity were measured in barnyard grass and cleavers. The biomass of 30-day-old plants of barnyard grass and cleavers grown in bare soil was approximately 5- and 3.5-fold higher, respectively, than in plants grown in the presence of BRR. BRR did not affect the biomass of wind grass and tiny vetch plants, but activate the antioxidant response, increase in peroxidase activity, and the content of phenolic compounds in weed tissues, which indicates an adaptation to the stressful environmental conditions.
... Furthermore, it has been reported that the potential anti-germination and herbicidal activities possessed by some essential oils may also be related to the pro-oxidant activity that these natural compounds exert on germinating seeds and seedlings [12,13]. Therefore, another goal of our work was to show if the essential oil of M. didyma, and perhaps its major constituent (thymol), are able to induce oxidative stress in the germinating seeds used by us. ...
... The mechanism of the inhibitory action of essential oils remains unclear, although it has been reported that volatile oils, particularly monoterpenes, inhibit the cell division of apical meristems. Probably, the main cause of this action is the generation of Reactive Oxygen Species (ROS)-induced oxidative stress and the inhibition of DNA synthesis or disruption of the membranes [12]. ...
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The chemical composition of the essential oil of the flowering aerial parts of Monarda didyma L. cultivated in central Italy was analyzed by Gas Chromatography/Mass Spectrometry (GC/MS). The major compounds of the oil were thymol (59.3%), p-cymene (10.3%), terpinolene (9.2%), δ-3-carene (4.4%), myrcene (3.7%), and camphene (3.4%). The essential oil was tested in vitro for its anti-germination activity against Papaver rhoeas L., Taraxacum officinale F. H. Wigg., Avena fatua L., Raphanus sativus L. and Lepidium sativum L. seeds, demonstrating good inhibitory activity in a dose-dependent way. The exposure of the employed weed seeds to M. didyma essential oil and thymol solution (59.3%) increased the level of hydrogen peroxide (H2O2) and malondialdehyde (MDA), markers of oxidative stress, in emerging 5-day-old rootlets.
... In this context, the essential oils of five species of sage and twenty-seven monoterpenes have been tested against the germination of Raphanus sativus L. and Lepidium sativum L. by De Martino et al. [8,9] furthermore Marandino et al. [10] have evaluated the essential oils of three Hypericum species for the potential in vitro phytotoxic activity against the same plants. Recently it has been reported that eugenol, a monoterpenoid alcohol, one of the major constituents in the essential oil of Ocimum basilicum L., Cinnamomum verum J. Presl and other plants, inhibits the root growth of Avena fatua L. (an infesting plant) inducing the generation of reactive oxygen species (ROS) and leading to oxidative stress and membrane damage in the root tissues [11]. ...
... The mechanism of the inhibitory action of EOs remains unclear, although it has been reported that volatile oils, and particularly the monoterpenes, inhibit cell division of apical meristems. Probably the main cause of this action may be the generation of ROS-induced oxidative stress and inhibition of DNA synthesis or disruption of the membranes [11]. ...
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The chemical composition of an Italian oil of tarragon (Artemisia dracunculus L.) was analyzed by GC/EIMS. The major compound of the oil was estragole (73.3%), followed by limonene (5.4%), (E)-β-ocimene (5.3%), β-pinene (3.4%) and (Z)-β-ocimene (3.0%). The essential oil was tested "in vitro" for its antigermination activity against Raphanus sativus L., Lepidium sativum L, Papaver rhoeas L. and Avena fatua L. seeds and demonstrating a good inhibitory activity in a dose-dependent way.
... In our study, the imbalance between production and scavenging of ROS after stress in the two plants, resulting in different levels of oxidative stress in the cells, may be the key to the relative safety of the crops. Further, under stress conditions, primarily, plasma membrane reflected by accumulation of MDA after lipid peroxidation [43]. SAEO induced excessive generation of ROS suggests a similar mechanism of action leading to oxidative stress and ultimately tissue damage in E. crus-galli. ...
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Echinochloa crus-galli is a serious weed species in rice paddies. To obtain a new potential bioherbicide, we evaluated the inhibitory activities of 13 essential oils and their active substances against E. crus-galli. Essential oil from Syzygium aromaticum (L.) Merr. & L. M. Perry (SAEO) exhibited the highest herbicidal activity (EC50 = 3.87 mg mL⁻¹) among the 13 essential oils evaluated. The SAEO was isolated at six different temperatures by vacuum fractional distillation, including 164°C, 165°C (SAEO—165), 169°C, 170°C 175°C and 180°C. The SAEO—165 had the highest inhibitory rate against E. crus-galli. Gas chromatography-mass spectrometry and high phase liquid chromatography identified eugenol (EC50 = 4.07 mg mL⁻¹), α-caryophyllene (EC50 = 17.34 mg mL⁻¹) and β-caryophyllene (EC50 = 96.66 mg mL⁻¹) as the three compounds in SAEO. Results from a safety bioassay showed that the tolerance of rice seedling (~ 20% inhibition) was higher than that of E. crus-galli (~ 70% inhibition) under SAEO stress. SAEO induced excessive generation of reactive oxygen species leading to oxidative stress and ultimately tissue damage in E. crus-galli. Our results indicate that SAEO has a potential for development into a new selective bio-herbicide. They also provide an example of a sustainable management strategy for E. crus-galli in rice paddies.
... It was completely inhibited by the application of eugenol at a concentration of 640 nL mL -1 [34] . It also inhibited germination (60%) of Avena fatua at a concentration of 1000 µM [35] . These show that SAEO has the potential to be developed as a herbicide against E. crus-galli in elds. ...
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Echinochloa crus-galli is a serious weed species in rice paddies. To obtain a new potential bioherbicide, we evaluated the inhibitory activities of 13 essential oils and their active substances against E. crus-galli . Essential oil from Syzygium aromaticum (L.) Merr. & L. M. Perry (SAEO) exhibited the highest herbicidal activity (EC 50 = 3.87 mg mL ⁻¹ ) among the 13 essential oils evaluated. The SAEO was isolated at six different temperatures by vacuum fractional distillation, including 164 ℃, 165 ℃ (SAEO − 165), 169 ℃, 170 ℃ 175 ℃ and 180 ℃. The SAEO − 165 had the highest inhibitory rate against E. crus-galli . Gas chromatography-mass spectrometry and high phase liquid chromatography identified Eugenol (EC 50 = 4.07 mg mL ⁻¹ ), α-caryophyllene (EC 50 = 17.34 mg mL ⁻¹ ) and β-caryophyllene (EC 50 = 96.66 mg mL ⁻¹ ) as the three compounds in SAEO. Results from a safety bioassay showed that the tolerance of rice seedling (~ 20% inhibition) was higher than that of E. crus-galli (~ 70% inhibition) under SAEO stress. Additionally, defense enzymes in E. crus-galli and rice seedling showed decreased activities, but only CAT levels were affected under SAEO treatment. Our results indicate that SAEO has a potential for development into a new selective bio-herbicide. They also provide an example of a sustainable management strategy for E. crus-galli in rice paddies.
... Although the inhibitory reaction mechanism of EOs remains unclear, there are reports of a hindrance to apical meristems' cell division. Reactive Oxygen Species (ROS) production causing membrane disruption or DNA synthesis inhibition is probably responsible [35]. ...
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Essential oils are volatile constituents that give aromatic plants their characteristic odour. The application of these plant actives in food, agriculture, pharmaceutics, and cosmetics has been widely studied. Aromatherapy, a complementary therapy involving the use of essential oils to treat several diseases ranging from microbial infections to metabolic dysfunctions, has been utilised for centuries. Anticancer, antimicrobial, and anti-inflammatory activities are well-established among other pharmacological properties of these aromatic oils. The oils, which are composed mainly of terpene-based compounds, have also been explored as nutraceuticals, alternative green preservatives, and functional additives in foods. However, due to their physicochemical properties, viz high volatility and low aqueous solubility, essential oil delivery to target receptors were challenging when administered as chemotherapeutics. Hence, formulating essential oils with suitable excipients to enhance their delivery and bioavailability, invariably improving their bioactivity and therapeutic efficacy becomes expedient. Nanotechnology presents a unique strategy to develop a particulate delivery system for the controlled, sustained, and extended release of essential oils. In this review, we examine and summarize the trends and developments in the formulation of essential oils using polymeric nanoparticles.
... e peroxidation byproducts of lipids are used for the estimation of RoS [40]. Also, the polyunsaturated fatty acids are peroxidized by MDA which acts as a stabilizing agent in the cellular membrane. ...
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Background: Diabetes is considered one of the most encyclopedic metabolic disorders owing to an alarming rise in the number of patients, which is increasing at an exponential rate. With the current therapeutics, which only aims to provide symptomatic and momentary relief, the scientists are shifting gears to explore alternative therapies which not only can target diabetes but can also help in limiting the progression of diabetic complications including diabetic neuropathy (DN). Methods: Tecoma stans leaf methanolic extract was prepared using the Soxhlet method. A streptozotocin (STZ; 45 mg/kg)-induced diabetic animal model was used and treatment with oral dosing of T. stans leaf extract at the different doses of 200 mg/kg, 300 mg/kg, and highest dose, i.e., 400 mg/kg, was initiated on day 3 after STZ administration. The pharmacological response for general and biochemical (angiogenic, inflammatory, and oxidative) parameters and behavioral parameters were compared using Gabapentin as a standard drug with the results from the test drug. Results: Parameters associated with the pathogenesis of diabetic neuropathy were evaluated. For general parameters, different doses of T. stans extract (TSE) on blood sugar showed significant effects as compared to the diabetic group. Also, the results from biochemical analysis and behavioral parameters showed significant positive effects in line with general parameters. The combination therapy of TSE at 400 mg/kg with a standard drug produced nonsignificant effects in comparison with the normal group. Conclusion: The leaves of T. stans possess antidiabetic effects along with promising effects in the management of DN by producing significant effects by exhibiting antioxidative, antiangiogenic, and anti-inflammatory properties, which are prognostic markers for DN, and thus, T. stans can be considered as an emerging therapeutic option for DN.
... ROS accumulation induces several adverse effects, including lipid peroxidation, and the associated membrane damage and electrolyte leakage 9,10 . Typical oxidative stress symptoms span from growth retardation and tissue discoloration to necrosis [11][12][13][14][15][16] . Besides, evolutionary events have provided alternative strategies in plants to cope with unfavorable conditions. ...
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γ-Aminobutyric acid (GABA) is a non-protein amino acid with multifunctional roles in dynamic plant responses. To determine the effects of exogenous GABA application (0, 25 and 50 µM) on drought response, two chickpea cultivars with contrasting tolerance to water deficit were examined. Plants were exposed to four irrigation levels (irrigation to 100, 60, 40 and 20% field capacity). Water deficit decreased growth, chlorophyll content, and photosynthetic efficiency. It increased electrolyte leakage and lipid peroxidation owing to both higher ROS accumulation and lower antioxidant enzyme activity. These negative effects of water deficit and the alleviating role of GABA application were more prominent in the sensitive, as compared to the tolerant cultivar. Water deficit also increased proline and GABA contents more in the tolerant cultivar, whereas their content was more enhanced by GABA application in the sensitive one. This may confer an additional level of regulation that results in better alleviation of drought damage in tolerant chickpea cultivars. In conclusion, the stimulatory effect of GABA on growth and physiological modulation depends on both the water stress severity and the cultivar sensitivity to it, implying a probable unknown GABA-related mechanism established by tolerant chickpea cultivars; a lost or not gained mechanism in susceptible ones.
... These natural materials are good candidates as a source of potential biocontrol products [4][5][6][7][8] . Regarding herbicidal effects in particular, EOs have variously been reported to cause oxidative damage, ion leakage, decreased cellular respiration, waxy cuticular layer removal, and mitosis inhibition 9,10 . Herbicides based on plant EOs have been demonstrated effective against a wide range of weeds, and have promise as natural alternatives to nonselective herbicides 11 . ...
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Essential oil-based bioherbicides are a promising avenue for the development of eco-friendly pesticides. This study formulated nanoemulsions containing citronella ( Cymbopogon nardus ) essential oil (CEO) as an herbicidal product using a high-pressure homogenization method with hydrophilic-lipophilic balance (HLB) values ranging 9-14.9 for the surfactant mixture (Tween 60 and Span 60). The CEO was high in monoterpene compounds (36.333% geraniol, 17.881% trans-citral, 15.276% cis-citral, 8.991% citronellal, and 4.991% β-citronellol). The nanoemulsion at HLB 14 was selected as optimal due to having the smallest particle size (78.8 nm, PI 0.286), confirmed by transmission electron microscopy. After 28 days of storage, particle size in the selected formulation changed to 57.9 and 139.8 nm under 4°C and 25°C, respectively. Germination and seedling growth assays with Echinochloa crus-galli showed that the nanoemulsion exerted a significant dose-dependent inhibitory effect at all tested HLBs (9-14.9) and concentrations (100–800 µL/L). The inhibitory effect was greatest at HLB 14. Treatment of E. cruss-galli seed with the HLB 14 nanoemulsion significantly reduced seed imbibition and α-amylase activity. Our findings support that CEO nanoemulsions have a phytotoxic effect and hence herbicidal properties for controlling E. cruss-galli . Accordingly, this nanoemulsion may have potential as a bioherbicide resource.
... Activity of antioxidant enzymes were clearly elevated in this group, resulting in deactivation of ROS and reduction in injuries, due to oxidative stress by this antioxidant property. In this regard, several studies exhibited minocycline, as an antioxidant agent which can prevent lipid peroxidation, increase SOD and GPx levels (28,29). ...
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Background: The aim of this study is the investigation of apoptotic related gens in ovary of the rat model of torsion/detorsion treated by Minocycline. Materials and Methods: This experimental study performed on 32 female Wistar rat which classified into 4 group;1 sham; 2 TD: torsion/detorsion group received normal saline; 3 TDM: torsion/detorsion group treated with 40mg/kg Minocycline; 4 MC: healthy group received 40mg/kg Minocycline. After the therapy period (7days), histoplogical parameters, the oxidative stress markers in serum and the expression of apoptotic related genes were measured in the ovary of rats. Results: The level of SOD, GPX was decreased in the TD group. And also the level of MDA increased in the TD group and decreased in treated groups (p<0.001). The expression of Bax was elevated in the TD group although in treated groups their expression ratio was attenuated. Conclusion: Our result shows that the administration of Minocycline can replace the oxidative damage in ovarian tissue and regulate the apoptotic related genes expression.
... Essential oils (EOs) are volatile secondary metabolites of many higher plants, which were recognized as an important natural source of green pesticides. Their constituents are generally small amphiphilic compounds capable to cross the cell wall and directly interact with the plant plasma membrane (Lins et al., 2019), induce generation of reactive oxygen species (ROS) resulting in oxidative stress accompanied with membrane damage and electrolyte leakage (Ahuja et al., 2015) or cause alterations in normal structure of nuclei and chromosome (Aragao et al., 2015). A review paper focused on the phytotoxic effects of EOs and their components, which could be used in weed management, was presented by Amiri et al. (2013). ...
Chapter
With a changing climate and cultivation of vast agricultural monocultures, the abundance of various pests shows an increase and their activity is shifting, expanding and intensifying. To avoid losses on crops, a variety of synthetic pesticides are increasingly being used to control harmful pests. This trend leads to overuse of pesticides, which has environmental consequences because these toxic chemicals enter the soil and water, can exhibit toxic effects on non-target organisms and could also eventually enter the food chain resulting in adverse impact on human health. Consequently, rapid development of nanotechnologies enabled the reformulation of pesticides into nanosystems, characterized by controlled release, targeted distribution, increased efficiency and reduced dose-dependent toxicity. In addition, so-called biopesticides, i.e. pesticides based on natural compounds, are toxic to specific pests and relatively harmless to non-target organisms and the ecosystem and could be easily formulated also in various types of nanoscale preparations. This chapter gives a comprehensive overview of recent findings related to the activity and mechanisms of action of biopesticides including plant extracts and essential oils or their constituents, biopesticides produced by microorganisms, peptides obtained in spider venoms and Cry proteins produced by Bacillus thuringiensis in their bulk as well as nanoscale form against noxious weeds and harmful arthropods causing losses of economically important crops. Special attention is paid also to insecticidal activity of green synthesized metal nanoparticles against mosquitoes which are important vectors of many diseases causing annually more than a million deaths in tropical regions. Keywords: arthropods, biopesticides, essential oils, bioherbicides, bioinsecticides, metals/metal oxides, microbial pesticides, nanoformulations, toxins, weeds
... It has recently been reported that eugenol inhibits the radical elongation of Avena fatua L., promoting the formation of reactive oxygen species (ROS), capable of provoking oxidative stress and membrane damage in the root tissues (Ahuja et al., 2015). ...
Article
The goal of this paper is to study the seasonal influence on the phytochemical composition and bioactivity of Ocimum basilicum L. cv ’Aroma 2’ essential oils (EOs), due to considerable interest of this cultivar for the preparation of sauces. By GC-MS analysis, the chemical profiles of EOs from plants harvested in May and in October, were characterized and biological activities were determined. The phytotoxicity on radish (Raphanus sativus L.), lettuce (Lactuca sativa L.), tomato (Solanum lycopersicum L.), and garden cress (Lepidium sativum L.), the antioxidant and the antibacterial properties (towards Gram-positive and Gram-negative strains) as well as the antibiofilm capability, were evaluated. In addition, the total phenolic content was determined. The chemical composition of the oils was influenced by the season, so that the essential oil from plants harvested in May was mainly composed of linalool (48.1 %), while in the October sample eugenol (76.8 %) was the main constituent. Essential oils did not show significant activity against the germination of tested seeds; instead, the radicle growth was inhibited. Both EOs showed good antioxidant activity with an half maximal inhibitory concentration (IC50) ’Aroma 2’ May = 6.1 μg/mL, IC50 ’Aroma 2’ October = 6.6 μg/mL), comparable to vitamin C (IC50 = 3.0 μg/mL). The total phenolic content, with a value of 484.9 mg/g gallic acid equivalent (GAE), confirmed a high antioxidant activity of ’Aroma 2’ October essential oil. The EOs and their major compounds, linalool and eugenol, showed a variable degree activity on the tested bacterial strains, in some cases comparable to tetracycline. Both EOs, at the highest dose tested , demonstrated good inhibitory activity of the biofilm produced by all testedstrains, with inhibitory percentages not inferior than 58 %. The test of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was employed to evaluate the effect of the oils on cellular metabolism: Pseudomonas aeruginosa was found to be the most sensitive strain.
... They also disrupt microtubules in interphase and thus, inhibit the cell growth (Chaimovitsh et al. 2010). EO s and their constituents have been reported to induce the generation of ROS (reactive oxygen species), thus, causing the oxidative damage to cells (Ahuja et al. 2014;Abrahim et al. 2000). Abrahim et al (2000) reported that monoterpenes inhibit the germination and growth by altering the mitochondrial respiration by acting as uncouplers of oxidative phosphorylation, thus inhibiting the electron transport chain. ...
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The present study was conducted with an aim to assess the phytotoxicity of foliar volatiles and essential oil (EO) extracted from the aerial parts of Pogostemon benghalensis (Lamiaceae) against coffee weed (Cassia occidentalis) and barnyard grass (Echinochloa crus-galli). A foliar volatile bioassay was conducted using freshly chopped leaves of barnyard grass and coffee weed, and the results exhibited a significant growth retarding effect on both the weeds. GC–MS analysis of the EO revealed that the major compound present in the oil was Azulen-2-ol, 1,4 dimethyl-7-(1-methylethyl). In comparison to the control, a significant inhibition in the seedling growth and rate of germination was observed in response to EO (0.25–2.5 mg mL−1). Moreover, a significant decrease in the chlorophyll content of both the weeds was also evident upon application of foliar volatiles and EO of P. benghalensis. Present study concludes that the EO of P. benghalensis is phytotoxic towards the growth of weeds and can prove to be a potential candidate for use as an environment-friendly bioherbicide.
... Essential oils (EO) and their constituents are allowed in organic food processing as additives and flavors as they are generally recognized as safe (GRAS, US FDA; Wieczyńska & Cavoski, 2018). Eugenol (4-allyl-2-methoxyphenol) is a major part of clove EO, and is a promising food additive owing to its antibacterial (Devi et al., 2013;M et al., 2014;Ma et al., 2016;Zhang et al., 2017), antiviral (Dai et al., 2013;Sun et al., 2016;Wang & Fan, 2014), antioxidant, i.e., using the phenolics to inhibit the polymerization of free radicals (Ahuja et al., 2015;Tao et al., 2005) and anticancer properties (Bezerra et al., 2017;Nam & Kim, 2013). Furthermore, eugenol is an approved food additive with the U.S. Food and Drug Administration, with an LD 50 of 3000 mg/kg based on mouse data (Gong et al., 2016). ...
Article
The browning inhibition and preservation properties of eugenol emulsions (EUG) on fresh-cut Chinese water chestnut (CWC), and the associated mechanisms of browning inhibition were studied in relation to enzymatic activities and polyphenol substrates. Fresh-cut CWC was treated with different concentrations of EUG, resulting in the maintenance of quality, inhibition of the microbial index which decreased by 1.20 log CFU/g after storage and enzymatic activities of different enzymes such as polyphenol oxidase, peroxidase, and phenylalanine ammonia lyase (PAL). Correlation analysis between enzymatic activities and degree of browning suggested that PAL was the main enzyme that led to browning in fresh-cut CWC. The enzymatic activity of PAL was decreased by 57% with the 1.5% EUG treatment after 12 d of storage. HPLC analysis showed that EUG-treated fresh-cut CWC (1.5%) slightly changed 5 phenolics during storage and the EUG content decreased from 32.8 to 13.0 mg/kg in treated groups. The potential mechanism is that EUG could inhibit the browning of CWC by reducing the enzymatic activities especially PAL, and decreasing the changes in phenolic content.
... Hazrati et al. (2017) reported that root elongation can be more inhibited than shoot growth. Ahuja et al. (2015) also reported that root growth is more inhibited than shoot growth in A. fatua L. by eugenol treatment. The greater inhibitory effect on roots is probably caused by a stronger penetrative action of monoterpenes on roots than on shoots, due to a lack of cuticle cover in the roots that makes monoterpenes penetrate the roots more freely (Yoshimura et al., 2011). ...
Article
In the present study, variations were examined in the content and compositions of Vitex-pseudo-negundo leaf essential oil (EO). These evaluations were carried out at 2 different ontogenetic stages, i.e. before and during flowering. Fresh leaves of vitex were harvested and analyzed at these two stages. The EOs of air-dried samples were extracted by hydrodistillation. The yield of EOs (w/W%) significantly increased (P ≤ 0.05) in the leaves at the flowering stage (0.43%), compared to the stage before it (0.25%). The EOs were analyzed by gas chromatography (GC) and by GC–mass spectrometry (GC–MS). The main EO components in the leaves at these 2 stages were α-pinene (25.4–30.2%), limonene (11.9–12.5%), α-terpinyl acetate (22.6–29.5%) and (E)-caryophyllene (7.6–11.6%). Moreover, α-terpinyl acetate had its strongest presence at the flowering stage (29.5%), while α-pinene, limonene and (E)-caryophyllene showed their highest contents before the flowering stage (30.2, 12.5 and 11.6%, respectively). The phytotoxic activities of EOs were examined at the full flowering stage. These EOs were employed in concentrations of 0, 400, 800, 1200, 1600, 2000 and 2400 μL/L and were used on a crop, Lepidium sativum, and on two weeds, Amaranthus retroflexus and Taraxacum officinale. The EOs of vitex showed inhibitory effects on these species. The efficiency of inhibition depended on the type of species being treated with EO and on the concentration of EO being used.
... Many experiments showed that one of the main effects of EOs is the inhibition of photosynthesis, resulting from a decrease in the chlorophyll content (Hazrati et al., 2017) and alterations of the light phase of photosynthesis (Synowiec et al., 2015). In some cases, EOs lead to the production of uncontrolled level of reactive oxygen species, thereby promoting oxidative stress and oxidative burst (Ahuja et al., 2015) as well as loss of the efficiency of cellular respiration (Kaur et al., 2010). Recently, Araniti et al. (2018), through a physiological and metabolomic approach, described in detail the physiological response of Arabidopsis thaliana seedlings to the EO of oregano. ...
... Up regulation of antioxidant enzymes activities was reported due to the generation of reactive oxygen species (ROS) in response to the EOs dose. Elevation in antioxidant enzyme activities suggested the induction of oxidative stress in tissues 20 . ...
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Experimental studies were carried out under invitro conditions to examine the effect of Callistemon viminalis essential oil (EO) against the Echinochloa crus-galli L., Amaranthus viridis and Phalaris minor. EO composition was analysed by gas chromatography/mass spectrometry, revealing that EO was rich in monoterpenes and sesquiterpenes like eucalyptol, D-limonene, α-terpineol and caryophyllene oxide. EO applied in the concentration range of 0.5, 1, 2 and 4 μl against Amaranthus viridis, Echinochloa crus-galli L. and Phalaris minor drastically affected the germination of all test plants and inhibited root and shoot development. Not only seedling growth, even the chlorophyll content also reduced appreciably. This led to the demonstration that Callistemon viminalis EO was negatively affecting the photosynthetic process. Upregulation of antioxidant enzymes activities indicated that these enzymes were providing protection against Callistemon viminalis EO induced stress. Amaranthus viridis was reported to be more sensitive in comparison to Echinochloa crus-galli L. and Phalaris minor.
... The growth retardatory effects of Melaleuca oil on the test plants is in agreement with earlier studies reporting inhibitory effect of volatile oils from aromatic plants on the seedling growth of weeds ( Singh et al., 2009;Rolli et al., 2014, Arora et al., 2016Ricci et al., 2017). The reduction in early growth of weeds could be due to the inhibitory effect of plant volatiles on the cell division and lowered root mitotic activity, DNA synthesis of growing root tips and disruption of the membranes ( Nishida et al., 2005;Ahuja et al., 2015). The effect might be attributed either to high percent of main constituent or to synergy among different oil constituents. ...
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The work was undertaken to investigate the phytotoxic potential of essential oil from Melaleuca leucadendra against three weed species, viz., Echinochloa crus-galli, Cyperus rotundus and Leptochloa chinensis. It was observed that volatile oil (0.25-1.5 mg ml-1) of Melaleuca retarded the germination and growth of all the test weeds in a dose-response bioassay conducted under laboratory conditions. Generally, both root and shoot length showed an inhibitory effect in a concentration dependent manner and the maximum effect was observed in C. rotundus, followed by E. crus-galli and L. chinensis. The Melaleuca oil not only affected the germination and seedling growth of the test weeds, but also inhibited the chlorophyll content and dry weight. At the highest dose of Melaleuca oil treatment (1.5 mg ml-1), the chlorophyll content declined by nearly 50% in E. crus-galli and 90% in L. chinensis over the control. Thus, it is concluded that volatile oil possesses phytotoxic potential towards other plants and could be further explored for weed management.
... Essential oils as herbicides disrupt both the germination process and the growth of seedlings of treated plants. In seedlings, essential oils, or their main compounds, cause oxidative damage mediated by reactive oxygen species (Amri et al. 2013;Ahuja et al. 2015). Foliar-applied essential oils cause visible leaf wilting within only a few hours of their application, as a result of membrane disruption (Poonpaiboonpipat et al. 2013), a decrease in the chlorophyll content and a decline in cellular respiration (Kaur et al. 2010). ...
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This work aimed to assess the phytotoxic potential of 12 essential oils (EOs) collected from plants growing in natural or cultivated stands in a temperate climate, i.e., Achillea millefolium, Acorus calamus, Carum carvi, Chamomilla recutita, Foeniculum vulgare, Lavandula angustifolia, Melissa officinalis, Mentha × piperita, Salvia officinalis, Solidago canadensis, Tanacetum vulgare and Thymus vulgaris. The germination of four weed species, i.e., Amaranthus retroflexus, Avena fatua, Bromus secalinus and Centaurea cyanus, was tested against all 12 EOs, and the germination of three crops, i.e., Avena sativa, Brassica napus and Zea mays, was tested in the presence of six EOs. The influence of five doses of each EO against the germination of the tested species was assessed in a petri dish experiment. The results were analyzed using dose-response non-linear analysis, the effective dose (ED50) and multivariate analysis. As a result, four groups of EOs of contrasting phytotoxicity were distinguished. The most phytotoxic group consisted of four EOs, namely C. carvi, T. vulgaris, M. × piperita and S. officinalis. These EOs were composed mainly of oxygenated monoterpenes in a range of 64.1–93.3 %. The least phytotoxic group consisted of S. canadensis EO, composed mainly of mono- and sesquiterpene hydrocarbons (92.3 %). In addition, principal component analysis indicated that the phytotoxic effect of the EOs also depended on the sensitivity of the plant species. Crops are more tolerant than weeds to the majority of EOs. Small-seeded species, namely A. retroflexus and C. cyanus, were the most sensitive to the EOs, while the kernels of Z. mays and the seeds of A. fatua were the most tolerant.
... The absorbance of the supernatant was read at 532 nm and corrected for nonspecific absorbance at 600 nm. The content of • OH was determined using ε = 155 mM −1 cm −1 and expressed as nmol g −1 DW ( Ahuja et al. 2015). ...
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This study sought to contribute to the understanding of the detrimental effect of the mistletoe (Viscum album L.), a hemiparasitic plant, on the mortality of the Scots pine (Pinus sylvestris L.). Fieldwork was conducted in the town of Kelkit (Gumushane province, Turkey) from April to October in 2013. Pine needles of similar ages were removed from the branches of mistletoe-infested and noninfested Scots pine plants, then transported to the laboratory and used as research materials. The effects of the mistletoe on the Scots pine during infestation were evaluated by determining the levels of water, electrolyte leakage (EL), malondialdehyde (MDA, being a product of lipid peroxidation) and reactive oxygen species (ROS) such as superoxide anion (O2−•), hydrogen peroxide (H2O2) and hydroxyl radical (•OH). In addition, the activities of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were measured in the same samples. The highest level of drought stress was found in summer (especially in August) as a result of the lowest water content in the soil and the highest average temperature occurring in these months. The drought stress induced by mistletoe infestation caused a regular decrease in water content, while it increased the levels of EL, MDA and ROS (H2O2, O2−• and •OH). The infestation also stimulated the activities of CAT and POX, with the exception of SOD. On the other hand, in August, when the drought conditions were the harshest, the levels of EL and MDA, which are two of the most important indicator parameters for oxidative stress, as well as the levels of H2O2 and •OH, which are two of the ROS leading to oxidative stress, reached the highest values in both infested and noninfested needles, whereas the O2−• level decreased. For the same period and needles, CAT activity increased, while SOD activity decreased. Peroxidase activity, however, did not exhibit a significant change. Our findings indicate that the increased mortality of the Scots pine may result from the mistletoe-induced very severe drought stress, and that the increase in the capacity of antioxidative enzyme system does not protect the plant against oxidative stress in dry summer seasons.
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Echinochloa colona, a highly invasive weed, poses significant challenges to rice cultivation globally and is usually managed effectively through chemical herbicides. Conventional chemical herbicides have contributed to environmental degradation and increased herbicide resistance. This study explores the potential of natural herbicides derived from plant extracts as eco-friendly alternatives for sustainable weed management. Ten plant samples, including Calotropis gigantea, Ocimum tenuiflorum and Prosopis juliflora, were collected and their allelochemicals were extracted using Soxhlet extractor with methanol and hexane solvents. The efficacy of these extracts in inhibiting E. colona germination was tested through pot culture and laboratory assays. GC-MS analysis identified key allelochemicals responsible for the phytotoxic effects, leading to the formulation of natural herbicides in the form of Emulsifiable Concentrates (EC). Field experiments were conducted to assess the performance of these formulations in rice ecosystems. Results indicated that pre-emergence application of 50% EC formulation of 10% methanolic extract of Ocimum tenuiflorum + one hand weeding at 25 DAS showed significant reduction in weed density, dry weight, weed index and increase in weed control efficiency, crop yield and highest benefit cost ratio though further optimization is required to improve formulation stability. This study demonstrates the potential of natural herbicides as effective and sustainable tools for managing E. colona in rice fields, providing an alternative to synthetic chemicals. The findings underscore the need for continued research into the development of durable and efficient natural herbicide formulations
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ZEIN/PVA NANOPARTICLES LOADED WITH EUGENOL AND CLOVE ESSENTIAL OIL: OPTIMIZATION OF SYNTHESIS AND ANALYTICAL VALIDATION FOR EUGENOL QUANTIFICATION. Nanoparticles of zein (NPZ) stabilized with surfactant polyvinyl alcohol (PVA), and nanoparticles of zein/PVA loaded with eugenol (NPZ-Eug) and the essential oil extracted from the clove (Syzygium aromaticum) (NPZ-OC) were produced by nanoprecipitation method. The extraction method of essential oil of the clove was carried out by the hydrodistillation technique, obtaining a content of 81.5% (m/m) of eugenol. The nanoparticle preparation method was optimized using a one-factor-at-a-time design of experiments, where different levels of variables (zein concentration, PVA concentration, and eugenol concentration) were explored. The best condition of synthesis was obtained with 0.3% (m/v) zein, 0.6% (m/v) PVA and 1.5 mg L-1 eugenol or essential oil of the clove, reaching NPs with acceptable propriety for stable nanoparticulate systems: size particles (NPZ = 113, NPZ-Eug = 229 and NPZ-OC = 279 nm), polydispersity index (PDI < 0.26), and zeta potential (≈ −30 mV). Loaded NPs showed encapsulation efficiency and drug-loading of 52 and 20% (NPZ-Eug), and 62, 27% (NPZ-OC), respectively. The quantification method of eugenol was validated by analytical parameters. Finally, all NPs produced exhibited good colloidal stability, confirming the effectiveness of PVA as a stabilizing agent, which had not been previously reported for these systems. The results obtained provide promising prospects for further investigations into its potential application as a bioinsecticide agent.
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A natural herbicide nanoemulsion was fabricated from citronella (Cymbopogon nardus L.) essential oil (CEO) and a nonionic surfactant Tween 60 mixed with Span 60 at hydrophilic-lipophilic balance 14 using a microfluidization method. The main constituents of CEO were citronellol (35.244%), geraniol (21.906%), and citronellal (13.632%). CEO nanoemulsion droplet size and polydispersity index (PI) were evaluated by dynamic light scattering (DLS). The smallest droplet size (33.2 nm, PI 0.135) was obtained from a microfluidizer at 20,000 psi, 7 cycles. Nanoemulsion droplet in transmission electron microscopy correlated with DLS confirmed CEO to successfully produce nanoemulsion. The herbicidal activity of the nanoemulsion as a foliar spray was evaluated against Echinochloa cruss-galli and Amaranthus tricolor as representative narrow- and broadleaf weed plants, both of which presented visual toxicity symptoms. The modes of action of the nanoemulsion were then determined in terms of membrane integrity (relative electrolyte leakage; REL), malondialdehyde (MDA), and photosynthetic pigment contents. The results showed increase in REL and MDA which indicated the destruction of the treated plants; additionally, chlorophylls and carotenoid contents were decreased. Consequently, CEO nanoemulsion may have the possibility to act as a natural herbicide resource, and natural herbicides from citronella nanoemulsions could be good alternatives for use in sustainable agriculture.
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p -Phenylenediamine (PPD) is an aromatic amine commonly used in hair dyes which has high toxicity including carcinogenicity and mutagenicity. It is crucial to eliminate its danger to public health and...
Chapter
Eugenol (CAS number: 97-53-0), a naturally occurring aromatic compound, is present mainly in essential oils. It has been used in variety of industries, including pharmaceutical, food, cosmetics, and agriculture; it has versatile pharmacological actions on almost all systems and is classified as carcinogenic risk to humans as Group 3: not classifiable as to its carcinogenicity to humans.
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Essential oil-based bioherbicides are a promising avenue for the development of eco-friendly pesticides. This study formulated nanoemulsions containing citronella (Cymbopogon nardus) essential oil (CEO) as an herbicidal product using a high-pressure homogenization method with hydrophilic-lipophilic balance (HLB) values ranging 9–14.9 for the surfactant mixture (Tween 60 and Span 60). The CEO was high in monoterpene compounds (36.333% geraniol, 17.881% trans-citral, 15.276% cis-citral, 8.991% citronellal, and 4.991% β-citronellol). The nanoemulsion at HLB 14 was selected as optimal due to having the smallest particle size (79 nm, PI 0.286), confirmed by transmission electron microscopy. After 28 days of storage, particle size in the selected formulation changed to 58 and 140 nm under 4 °C and 25 °C, respectively. Germination and seedling growth assays with Echinochloa crus-galli showed that the nanoemulsion exerted a significant dose-dependent inhibitory effect at all tested HLBs (9–14.9) and concentrations (100–800 µL/L). The inhibitory effect was greatest at HLB 14. Treatment of E. cruss-galli seed with the HLB 14 nanoemulsion significantly reduced seed imbibition and α-amylase activity. Our findings support that CEO nanoemulsions have a phytotoxic effect and hence herbicidal properties for controlling E. cruss-galli. Accordingly, this nanoemulsion may have potential as a bioherbicide resource.
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Endophytic fungi isolated from the insectivorous plant Drosera burmannii were tested for their antioxidant potential. The isolate Dro2 was found to have superlative antioxidant activity of the culture broth, scavenging 57.6 ± 0.2% of 2,2-diphenyl-1-picrylhydrazyl free radical. 5.8S rDNA homology led to identification of the isolate as a new strain and it has been named Mucor irregularis isolate Dro2. Optimization studies revealed ethyl acetate to be optimum for extraction of the antioxidant compounds. The crude solvent extract showed 89.6% 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging activity with respect to 86.1% ABTS radical reducing antioxidant power of ascorbic acid. The sample exhibited 824.0 ± 25.5 μM reducing ability in assay, compared to 1204.0 ± 17.8 μM for ascorbic acid. The sample extract displayed IC50DPPH of 53.6 μg/mL. The crude extract was further purified through various chromatography techniques and GC-MS was performed on the purified active fractions to ascertain the nature and identify compounds conferring antioxidant potential to the endophytic fungal isolate. The active fractions were found to comprise multitudinous compounds with varied biological activity. Antioxidant compounds, such as 2,4-di-tert-butylphenol, myristic acid, pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methyl propyl), palmitic acid, were found in significant abundance. This study substantiates the candidature of the endophytic fungus Mucor irregularis isolate Dro2 as an industrially capable source for obtaining bioactive compounds, particularly antioxidant compounds.
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Herbicides are agrochemicals applied in the control of weeds. With the frequent and repetitive use of these substances, serious problems have been reported. Compounds of natural origin and their derivatives are attractive options to obtain new compounds with herbicidal properties. By aiming to develop compounds with potentiated herbicidal activity, phenoxyacetic acids were synthesized from eugenol and guaiacol. The synthesized compounds were characterized and the herbicidal potential of phenoxyacetic acids and precursors was evaluated through bioassays regarding the germination and initial development of Lactuca sativa and Sorghum bicolor seedlings, with the induction of DNA damage. The induction of changes in the mitotic cycle of meristematic cells of roots of L. sativa was also analyzed. At the concentration of 3 mmol L-1, phenols and their respective phenoxyacetic acids presented phytotoxic and cytotoxic activities in L. sativa and S. bicolor. Eugenol and guaiacol also presented genotoxic action in L. sativa. The toxic effect of eugenoxyacetic acid was more pronounced in L. sativa than in S. bicolor, similar to the commercial 2,4-D herbicide. Molecular properties of the phenols and their derivatives phenoxyacetic acids were compared with the ones obtained for the herbicide 2,4-D, where it was found a correlation between their molecular properties and bioactivity.
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Essential oil based bioherbicides are topic of interest for the new era agriculture because of growing concern worldwide to develop herbicide with low environmental impact. In the present study, oil in water nanoemulsions of fennel (Foeniculum vulgare Mill.) essential oil were formulated by ultrasonic emulsification method and evaluated for herbicidal potential against Phalaris minor Retz., Avena ludoviciana Durieu, Rumex dentatus L. and Medicago denticulata Willd through Petri dish bioassay. The germination of P. minor, A. ludoviciana, R. dentatus and M. denticulata was totally inhibited at concentrations 0.4, 0.3, 0.3 and 0.05 wt%. Major constituents of F. vulgare essential oil, estragole, anethole and binary mixture did not completely inhibit the germination of the tested weed species even at highest concentrations. Nanoemulsions having 0.05 and 0.01 wt% F. vulgare essential oil were spherical in nature with average size below 130 nm and have good stability to centrifugation and dilution. The formulated nanoemulsions were clear and transparent even after 30 days of storage at ambient temperature. Nanoemulsions were more effective and completely inhibited the germination of P. minor, A. ludoviciana, R. dentatus and M. denticulata even at low dose of 0.05 wt% by adversely affecting the physiological processes like membrane leakage and reactive oxygen species mediated cellular damage. Nanoemulsions of F. vulgare essential oil have bioherbicidal properties and can contribute to the development of alternative tool for sustainable management of weeds.
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In the present study, aqueous extracts were obtained from the leaves and flowers of Vitex pseudo-negundo. The effects of these extracts were examined on the germination percentage and several developmental factors of three plant species, namely, Lepidium sativum, Amaranthus retroflexus and Taraxacum officinale. The major phenolic compounds of the leaf extract were Trans-ferulic acid (913.71 mg/L), Chloregenic acid (235 mg/L) and Hesperedin (115.68 mg/L), while those of the flower were Chloregenic acid (333 mg/L), p-Coumaric acid (256.04 mg/L) and Hesperedin (185.72 mg/L), as recognized by HPLC. The stock extract had a concentration of 10% (w/v) and was made from dried powders of the Vitex flower and leaf. The extract at 2.5% had a stimulatory effect on the seed germination of Lepidium sativum. A substantial increase (P ≤ 0.05) was observed in the germination percentage (98.3 and 96.6%, when using flower and leaf extract, respectively). The 7.5% extract (either leaf or flower) reduced root length to zero in A. retroflexus and T. officinale. However, in Lepidium sativum, there was a significant difference between leaf and flower extracts. At the same concentration (2.5%), leaf extract reduced fresh weight (0.43 g) more than the flower extract did (0.68 g). Taraxacum officinale and Amaranthus retroflexus showed a significant increase in the fresh weight of seedlings (0.2 g and 0.06 g, respectively) in response to the leaf extract (2.5%), compared to the control treatment, which indicates a stimulatory effect. In contrast, the highest concentration (7.5%) caused a significant inhibition (P ≤ 0.05%).
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Essential oils (EOs) are naturally occurring substances that have shown great prospect in the field of antimicrobial, antioxidant and pest control by nontoxic mechanisms. In this regard, EOs are considered the promising and eco-friendly approach for controlling harmful algae. In this study, the anti-cyanobacterial activity of EOs eugenol against Microcystis aeruginosa are evaluated from the perspective of photosynthetic efficiency, the behavior of extracellular organic matter (EOM), endogenous plant hormone synthesis, and nitric oxide signaling pathway. Results showed that the photosynthetic activity of M. aeruginosa decreased significantly after eugenol treatments. Eugenol treatment resulted in cells rupture and the release of EOM. Levels of endogenous plant hormones salicylic acid (SA) and jasmonic acid (JA) were enhanced separately by 2.32 and 2.01 times after 4 d of exposure to eugenol. And the inhibition of SA and JA biosynthesis further promotes the inhibitory effects of eugenol on algae. Additionally, the signaling molecule nitric oxide (NO) increased significantly by 3.78-fold. Furthermore, the influence of NO on microalgae exposed to eugenol was also determined, suggesting that the inhibitory effect of eugenol stress might be associated with NO generation in M. aeruginosa. These findings will be helpful for the understanding of the fate and potential of eugenol in harmful algae control.
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Gumilar RA, Wijayanto N, Wulandari AS. 2017. Effect of Azadirachta excelsa and Melia azedarach extracts on soybean germination. Nusantara Bioscience 9: 346-351. Azadirachta excelsa and Melia azedarach are potential tree species developed in agroforestry system. Both plants are fast growing species and good for timber use. However, there is an inadequacy on both species due to their allelopathic compound contents. Allelopathic compounds in the plants are distributed from root, stem, leaf, and fruit; which at certain concentrations could inhibit germination, growth, and development of other plants. The objective of this study was to analyze the effects of root, leaf, and twig extracts of M. azedarach and A. excelsa on the germination of soybean. Result of this study showed that the root, leaf, and twig extracts of M. azedarach and A. excelsa were able to inhibit the development of soybean. 5 % twig extract of M. azedarach significantly inhibited the germination by 77.75%. Leaf and twig extracts of A. excelsa at 1.25% concentration has shown to provide stimulant effect on the germination of soybean.
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Mufidah L, Sugiyatno A, Ratule MT. 2017. Short Communication: Cost-benefit analysis of rehabilitation and opening new cultivation land for tangerine cv Madu impacted by volcanic ash fallout of Mount Sinabung, North Sumatra, Indonesia. Nusantara Bioscience 9: 339-345. Indonesian tangerine plants which have diverse varieties possess the adaptability from lowlands to highlands in the tropical region. Some of the tangerine production centers in Indonesia, such as Karo, Mandailing Natal, Dairi, Malang, Batu, and Bali are located in the volcano path which is prone to eruption. The eruption of Mount Sinabung in 2013 and 2014 had caused damage to the local tangerine cv Madu cultivation which was estimated to reach more than 476 billion rupiahs. The eruption affected a cultivation area of 7.202,89 ha and has been predicted to be one of the factors that caused the decline of North Sumatra’s contribution to tangerine production. Therefore, this paper has tried: (i) to analyze the financial feasibility of rehabilitating tangerine cv Madu cultivation located in between 7-10 km radius of the eruption center (zone 1) and in between 5-7 km radius of the eruption center (zone 2), and (ii) to consider the option of opening up a new tangerine cultivation land.The results showed that the BCR for the immediate rehabilitation of zones 1 and 2 were 3.33 and 2, respectively. Thus, the rehabilitation scheme was feasible to be implemented and can reduce the damage and losses suffered by farmers. On the other hand, the opening of new land still takes approximately three years to be productive. The BCRof the option of opening new land within that period of time was 0.47, which is lower compared with that of the rehabilitation of zones 1 and 2 (2.61 and 2.57, respectively).This study was intended as an initial guidance for making decisions and determining the potential benefit to be gained and the losses that can be avoided. This study also gave an overview of the budget that should be prepared. In conclusion, we recommended the farmers to carry out the rehabilitation over opening up new cultivation land.
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Diverse fungal endophytes are rich fungal resources for the production of an enormous quantity of natural products. In the present study, 53 fungal endophytes were isolated from the bulbs of Fritillaria unibracteata var. wabuensis (FUW). Of these, 49 strains were identified and grouped into 17 different taxa, and priority was conferred to the Fusarium genus. All fungal fermented filtrates displayed antioxidant activities. The DPPH activity, total antioxidant capacities (ABTS), reduction power (FRAP), total phenolic content (TPC), total flavonoid content (TFC) and total saponin content (TSC) were evaluated using petroleum ether, ethyl acetate, n-butyl alcohol and ethanol fractions extracted from five representative fungal cultures. The last three fractions showed more potent antioxidant activity than the first fraction. Significant positive correlations were found between the compositions (TPC, TFC and TSC) and antioxidant capacities (DPPH, ABTS and FRAP). In addition, multifarious natural antioxidant components were identified from the fungal extracts, including gallic acid, rutin, phlorizin, 2,4-di-tert-butylphenol and 2,6-di-tert-butyl hydroquinone; these were determined preliminarily by TLC-bioautography, HPLC and GC-MS analysis. This study showed abundant fungal resources in FUW. Phenolics, flavonoids and saponins are crucial bioactive constituents in these abundant fungal endophytes and can be viewed as new potential antioxidant resources.
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Bisphenol A (BPA) is an important industrial raw material. Because of its widespread use and increasing release into environment, BPA has become a new environmental pollutant. Previous studies about BPA’s effects in plants focus on a certain growth stage. However, the plant’s response to pollutants varies at different growth stages. Therefore, in this work, BPA’s effects in soybean roots at different growth stages were investigated by determining the reactive oxygen species levels, membrane lipid fatty acid composition, membrane lipid peroxidation, and antioxidant systems. The results showed that low-dose BPA exposure slightly caused membrane lipid peroxidation but didn’t activate antioxidant systems at the seedling stage, and this exposure did not affect above process at other growth stages; high-dose BPA increased reactive oxygen species levels and then caused membrane lipid peroxidation at all growth stages although it activated antioxidant systems, and these effects were weaker with prolonging the growth stages. The recovery degree after withdrawal of BPA exposure was negatively related to BPA dose, but was positively related to growth stage. Taken together, the effects of BPA on antioxidant systems in soybean roots were associated with BPA exposure dose and soybean growth stage.
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The rotation of rice and wheat is widely used and highly endorsed, and simetryne (s-triazine herbicide) is one of the principal herbicides widely used in this rotation for weed and grass control. However, little is known regarding the mechanism of the ecological and physiological effects of simetryne on wheat crops. In this study, we performed a comprehensive investigation of crop response to simetryne to elucidate the accumulation and phytotoxicity of the herbicide in wheat crops. Wheat plants exposed to 0.8 to 8.0 mg kg−1 simetryne for 7 d exhibited suppressed growth and decreased chlorophyll content. With simetryne concentration in the soil varied from 0.8 mg kg−1 to 8.0 mg kg−1, simetryne was progressively accumulated by the wheat plants. The accumulation of simetryne in the wheat plants not only induced the over production of ROS and injured the membrane lipids but also stimulated the production of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST). A test of enzymatic activity and gene expression illustrated that the wheat plants were wise enough to motivate the antioxidant enzymes through both molecular and physiological mechanisms to alleviate the simetryne-induced stress. This study offers an illuminating insight into the effective adaptive response of the wheat plants to the simetryne stress.
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BACKGROUND: As the pharmacological effect of eugenol constantly being discovered, its application in medical and food industry becomes wider. However, its toxicity studies have not established a complete database, especially in the improvement of safety assessment of developmental toxicity and teratogenicity. OBJECTIVE: To establish a model of embryonic stem cell test to evaluate the embryotoxicity of eugenol. METHODS: Mouse fibroblasts (3T3) and mouse embryonic stem cells (E14TG2a) were cultured in vitro, and MTT test was performed to detect the cytotoxicity of 3T3 cells and E14TG2a cells with positive control 5-fluorouracil, negative control penicillin G and tested compound eugenol. The concentration of the tested compounds that inhibiting 50% viability of embronic stem cells (IC50 E14TG2a) and 3T3 fibroblasts (IC50 3T3) was calculated. The hanging-suspension-adherent culture systems were used to induce embryonic stem cells into cardiomyocytes, and the concentratin attested compounds that caused 50% inhibiin af differe ntiatiin af E14TG2a cells into cardiomyocytes (ID50 E14TG2a) was calculated. The embrotoxic potential of eugenol was classified by prediction model of the embronic stem cell test. RESULTS AND CONCLUSION: The proliferations of E14TG2a and 3T3 cells were inhibited by eugenol, of which the IC5o3T3 and IC50 E14TG2a values were (3.613±0.192) and (1,799±0.131) mg/L. The differentiation of E14TG2a was also inhibited by eugenol, of which the ID50 E14TG2a was (3.501 ±0.158) mg/L. Eugenol was evaluated as a chemical compound with strong embryotoxicity by the model of embryonic stem cell test.
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The rate of autoxidation of epinephrine and the sensitivity of this autoxidation to inhibition by superoxide dismutase were both augmented, as the pH was raised from 7.8 → 10.2. O2⁻, generated by the xanthine oxidase reaction, caused the oxidation of epinephrine to adrenochrome and the yield of adrenochrome produced per O2⁻ introduced, increased with increasing pH in the range 7.8 → 10.2 and also increased with increasing concentration of epinephrine. These results, in conjunction with complexities in the kinetics of adrenochrome accumulation, lead to the proposal that the autoxidation of epinephrine proceeds by at least two distinct pathways, only one of which is a free radical chain reaction involving O2⁻ and hence inhibitable by superoxide dismutase. This chain reaction accounted for a progressively greater fraction of the total oxidation as the pH was raised. The ability of superoxide dismutase to inhibit the autoxidation of epinephrine at pH 10.2 has been used as the basis of a convenient and sensitive assay for this enzyme.
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Herbicidal activity of clove oil and its main constituents eugenol, β-caryophyllene, and α-humulene was studied by measuring their effects on cell membrane integrity in broccoli and common lambsquarters plants at the three- and nine-leaf stage, respectively. Roles of essential oil constituents in the overall phytotoxicity of clove oil, dose-response (10 to 160 mM) relationships of their phytotoxicity, and the effect of light intensity on phytotoxicity of clove oil and eugenol were studied. Most of the phytotoxicity of clove oil (2.5% solution) was due to eugenol, its largest constituent. β-caryophyllene and α-humulene played little or no role. Dose-response relationships showed that at equimolar concentration, eugenol was the most phytotoxic essential oil constituent of the clove oil. On a per unit biomass basis, membrane damage in response to clove oil and eugenol sprays decreased with increasing light intensity. This suggests that efficacy of essential oil in causing plant damage could be affected by light intensity experienced by plants prior to the oil spray.
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Eugenol is a major volatile constituent of clove essential oil obtained through hydrodistillation of mainly Eugenia caryophyllata (=Syzygium aromaticum) buds and leaves. It is a remarkably versatile molecule incorporated as a functional ingredient in numerous products and has found application in the pharmaceutical, agricultural, fragrance, flavour, cosmetic and various other industries. Its vast range of pharmacological activities has been well-researched and includes antimicrobial, anti-inflammatory, analgesic, anti-oxidant and anticancer activities, amongst others. In addition, it is widely used in agricultural applications to protect foods from micro-organisms during storage, which might have an effect on human health, and as a pesticide and fumigant. As a functional ingredient, it is included in many dental preparations and it has also been shown to enhance skin permeation of various drugs. Eugenol is considered safe as a food additive but due to the wide range of different applications, extensive use and availability of clove oil, it is pertinent to discuss the general toxicity with special reference to contact dermatitis. This review summarises the pharmacological, agricultural and other applications of eugenol with specific emphasis on mechanism of action as well as toxicity data.
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The potential use of natural phytotoxins (including allelochemicals) to develop novel tools for weed management is enhanced by the elucidation of their modes of action. This approach has not been emphasized by the agrochemical industry, although the possibility of discovering new target sites may be promising, since natural products tend to have modes of action different from synthetic herbicides. The approach of testing a compound on all known herbicide molecular target sites for commercial herbicides and other potent phytotoxins is feasible. However, this would preclude the discovery of new mechanisms of action. Discovering new target sites requires more challenging holistic approaches, initiated with physiological and biochemical studies that use whole plant assays. Studying basic plant responses to a compound may yield important clues to the specific physiological processes affected by the compounds and uncover novel mechanisms of action.
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The essential oils from the aerial parts of catmint (Nepeta meyeri Benth.) were analyzed by hydrodistillation with GC-MS. Fourteen compounds were identified in the yellowish essential oil of the plant, representing more than 99.07% of the oil, of which the major components were found to be 4a alpha,7 alpha,7a beta-nepetalactone (83.4%) and 4a alpha,7 alpha,7a alpha-nepetalactone (8.83%). The oils were characterized by relatively high content of oxygenated monoterpenes, and were tested on the germination and antioxidative systems in early seedlings of seven weed species (Amaranthus retroflexus L., Bromus danthoniae Trin., Bromus intermedius Guss., Chenopodium album L., Cynodon dactylon L., Lactuca serriola L., and Portulaca oleracea L.) and autotoxicity. The essential oil of N. meyeri inhibited seed germination by more than 50% in three weed species (B. danthoniae, B. intermedius, and L. serriola) when applied at a concentration of 0.01%. When the same oils were applied at 0.02% concentration, the inhibition of germination was more than 70% in two weeds (C. album and C. dactylon) and was 100% in four weeds (A. retroflexus, B. danthoniae, B. intermedius, and L. serriola). The essential oils increased CAT activity in all the weed species and decreased SOD activity, except in A. retroflexus. POX activity did not exhibit a revealing situation in the weed species tested. The essential oils increased the level of lipid peroxidation and hydrogen peroxide (H2O2) concentration in all the weeds studied. Our results show that the essential oils of N. meyeri have an important phytotoxic effect on seed germination and, consequently, seedling growth by exhausting antioxidative system of the weeds. The phytotoxic activity of the essential oils may be attributed to their relatively high content of oxygenated monoterpenes, especially 4a alpha,7 alpha,7a beta-nepetalactone. It can be suggest that the essential oils of N. meyeri have the potential to be used as a bioherbicide.
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Volatile monoterpenes such as 1,8-cineole inhibit the growth of Brassica campestris seedlings in a dose-dependent manner, and the growth-inhibitory effects are more severe for roots than hypocotyls. The preferential inhibition of root growth may be explained if the compounds inhibit cell proliferation more severely than cell elongation because root growth requires both elongation and proliferation of the constituent cells, whereas hypocotyl growth depends exclusively on elongation of existing cells. In order to examine this possibility, BY-2 suspension-cultured tobacco (Nicotiana tabacum) cells were treated with 1,8-cineole, and the inhibitory effects on cell proliferation and on cell elongation were assessed quantitatively. Treatment with 1,8-cineole lowered both the mitotic index and elongation of the cells in a dose-dependent manner, and the half-maximal inhibitory concentration (IC₅₀) for cell elongation was lower than that for cell proliferation. Moreover, 1,8-cineole also inhibited starch synthesis, with IC₅₀ lower than that for cell proliferation. Thus, the inhibitory effects of 1,8-cineole were not specific to cell proliferation; rather, 1,8-cineole seemed inhibitory to a variety of physiological activities when it was in direct contact with target cells. Based on these results, possible mechanisms for the mode of action of 1,8-cineole and for its preferential inhibition on root growth are discussed.
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Monoterpenes, the main constituents of essential oils, are known for their many biological activities. The present work studied the potential biological activity of twenty-seven monoterpenes, including monoterpene hydrocarbons and oxygenated ones, against seed germination and subsequent primary radicle growth of Raphanus sativus L. (radish) and Lepidium sativum L. (garden cress), under laboratory conditions. The compounds, belonging to different chemical classes, showed different potency in affecting both parameters evaluated. The assayed compounds demonstrated a good inhibitory activity in a dose-dependent way. In general, radish seed is more sensitive than garden cress and its germination appeares more inhibited by alcohols; at the highest concentration tested, the more active substances were geraniol, borneol, (±)-β-citronellol and α-terpineol. Geraniol and carvone inhibited, in a significant way, the germination of garden cress, at the highest concentration tested. Radicle elongation of two test species was inhibited mainly by alcohols and ketones. Carvone inhibited the radicle elongation of both seeds, at almost all concentrations assayed, while 1,8-cineole inhibited their radicle elongation at the lowest concentrations (10(-5) M, 10(-6) M).
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Plants can interact with other plants through the release of chemical compounds or allelochemicals. These compounds released by donor plants influence germination, growth, development, and establishment of receptor plants; having an important role on the pattern of vegetation, i.e as invasive strategy, and on crop productivity. This phytotoxic or negative effect of the released allelochemicals (allelochemical stress) is caused by modifying or altering diverse metabolic processes, having many molecular targets in the receptor plants. Recently, using an aggressive and allelopathic plant Sicyos deppei as the donor plant, and Lycopersicon esculentum as the receptor plant, we showed that the allelochemicals released by S. deppei caused oxidative damage through an increase in reactive oxygen species (ROS) and activation or modification of antioxidant enzymes. Based on this study, we proposed that oxidative stress is one of the mechanisms, among others, by which an allelopathic plant causes phytotoxicity to other plants.
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Exposure to the allelopathic monoterpenes camphor (100 mg/10 L) and menthol (50 mg/10 L) for 24 h enhanced transpiration of Arabidopsis thaliana fully developed rosette leaves similar to de-waxing. As ascertained by ESEM analyses the leaf surfaces were spotted with platelet like structures which seem to be partly mixed with the lipophilic epicuticular layers. The structures are supposed to contain the condensed monoterpenes, which could be identified by GC. Long term exposure (more than 48 h) to 100 mg/50 mg killed the plants by desiccation, a 24 h exposure caused necrotic spots that became visible one to two days after the treatment. Examinations of the stomatal apertures indicated that monoterpenes induced stomatal opening followed by extreme swelling and a final break down of the protoplasts. Exposure of Arabidopsis thaliana to volatiles of Mentha piperita, Lavandula latifolia and Artemisia camphorata resulted in a dramatic increase of the stomata aperture but swelling of the protoplasts was less exhibited.In contrast to de-waxing, expression of the fatty acid condensing enzyme encoding CER6 gene and de novo synthesis of CER6 protein was not induced after 24 h of exposure to the monoterpenes.The aim of the study was to demonstrate that the lipophilic layers of the leaf surface and the stomata are primary targets of monoterpene allelopathic attack. Enhanced transpiration results from a combination of affected lipophilic wax layers and a disturbed stomata function.
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The monoterpenes 1,8-cineole, thymol, geraniol, menthol and camphor strongly inhibited the root growth of Zea mays L. seedlings. They induced an oxidative stress as measured by the production of malondialdehyde, conjugated dienes and peroxides. This oxidative stress depended on the length of the exposure and on the monoterpene applied. The total fatty acid content was measured and fatty acid composition was analyzed. Unsaturated fatty acids increased in the treated samples. The alcoholic and non-alcoholic monoterpenes appeared to have different modes of action.
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To cope with environmental fluctuations and to prevent invasion by pathogens, plant metabolism must be flexible and dynamic. Active oxygen species, whose formation is accelerated under stress conditions, must be rapidly processed if oxidative damage is to be averted. The lifetime of active oxygen species within the cellular environment is determined by the antioxidative system, which provides crucial protection against oxidative damage. The antioxidative system comprises numerous enzymes and compounds of low molecular weight. While research into the former has benefited greatly from advances in molecular technology, the pathways by which the latter are synthesized have received comparatively little attention. The present review emphasizes the roles of ascorbate and glutathione in plant metabolism and stress tolerance. We provide a detailed account of current knowledge of the biosynthesis, compartmentation, and transport of these two important antioxidants, with emphasis on the unique insights and advances gained by molecular exploration.
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The influence of varied Mg supply (10-1000 micromolar) and light intensity (100-580 microeinsteins per square meter per second) on the concentrations of ascorbate (AsA) and nonprotein SH-compounds and the activities of superoxide dismutase (SOD; EC 1.15.11) and the H(2)O(2) scavenging enzymes, AsA peroxidase (EC 1.11.1.7), dehydroascorbate reductase (EC 1.8.5.1), and glutathione reductase (EC 1.6.4.2) were studied in bean (Phaseolus vulgaris L.) leaves over a 13-day period. The concentrations of AsA and SH-compounds and the activities of SOD and H(2)O(2) scavenging enzymes increased with light intensity, in particular in Mg-deficient leaves. Over the 12-day period of growth for a given light intensity, the concentrations of AsA and SH-compounds and the activities of these enzymes remained more or less constant in Mg-sufficient leaves. In contrast, in Mg-deficient leaves, a progressive increase was recorded, particularly in concentrations of AsA and activities of AsA peroxidase and glutathione reductase, whereas the activities of guaiacol peroxidase and catalase were only slightly enhanced. Partial shading of Mg-deficient leaf blades for 4 days prevented chlorosis, and the activities of the O(2) (.-) and H(2)O(2) scavenging enzymes remained at a low level. The results demonstrate the role of both light intensity and Mg nutritional status on the regulation of O(2) (.-) and H(2)O(2) scavenging enzymes in chloroplasts.
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Nitro blue tetrazolium has been used to intercept O2⁻ generated enzymically or photochemically. The reduction of NBT by O2⁻ has been utilized as the basis of assays for superoxide dismutase, which exposes its presence by inhibiting the reduction of NBT. Superoxide dismutase could thus be assayed either in crude extracts or in purified protein fractions. The assays described are sensitive to ng/ml levels of super-oxide dismutase and were applicable in free solution or on polyacrylamide gels. The staining procedure for localizing superoxide dismutase on polyacrylamide electrophoretograms has been applied to extracts obtained from a variety of sources. E. coli has been found to contain two superoxide dismutases whereas bovine heart, brain, lung, and erthrocytes contain only one.
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A photo-induced cyclic peroxidation in isolated chloroplasts is described. In an osmotic buffered medium, chloroplasts upon illumination produce malondialdehyde (MDA)—a decomposition product of tri-unsaturated fatty acid hydroperoxides—bleach endogenous chlorophyll, and consume oxygen. These processes show (a) no reaction in the absence of illumination; (b) an initial lag phase upon illumination of 10-20 minutes duration; (c) a linear phase in which the rate is proportional to the square root of the light intensity; (d) cessation of reaction occurring within 3 minutes after illumination ceases; and (e) a termination phase after several hours of illumination. The kinetics of the above processes fit a cyclic peroxidation equation with velocity coefficients near those for chemical peroxidation. The stoichiometry of MDA/O2 = 0.02, and O2/Chlbleached = 6.9 correlates well with MDA production efficiency in other biological systems and with the molar ratio of unsaturated fatty acids to chlorophyll. The energies of activation for the lag and linear phases are 17 and 0 kcal/mole, respectively, the same as that for autoxidation. During the linear phase of oxygen uptake the dependence upon temperature and O2 concentration indicates that during the reaction, oxygen tension at the site of peroxidation is 100-fold lower than in the aqueous phase. It is concluded that isolated chloroplasts upon illumination can undergo a cyclic peroxidation initiated by the light absorbed by chlorophyll. Photoperoxidation results in a destruction of the chlorophyll and tri-unsaturated fatty acids of the chloroplast membranes.
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A simple, rapid method requiring few manipulations for the extraction of chlorophylls from fragmented leaf tissue of angiosperms and gymnosperms is compared with the widely used acetone method. Unlike the acetone method where grinding and subsequent centrifugation are essential, this method makes use of incubation at 65 °C of leaf tissue immersed in dimethyl sulphoxide. The new method was found to be as efficient as acetone for chlorophyll extraction and superior in terms of chlorophyll stability.
Article
The bioassay of T. minuta and S. areira oils and their pure principal components revealed strong inhibitory activity of the root growth of Zea mays seedlings. Both T. minuta and S. areira oils treatment presented an increase in malondialdehyde values from 24 to 48 h, while the main components of the essential oils, ocimenone, alpha-pinene and limonene, presented an increase from 24 to 96 h indicating lipid peroxidation. The T. minuta essential oil had a greater inhibitory action and oxidant effect on the root of Zea mays than S. areira oil.
Article
The present study investigated the phytotoxic potential of eugenol, a major component from the essential oil of clove [Syzygium aromaticum (L.) Merrill and Perry], towards four grassy [Echinochloa crus-galli (L.) Beauv., Phalaris minor Retz., Sorghum halepense (L.) Pers. and Leptochloa chinensis (L.) Nees] and four broad-leaved [Ageratum conyziodes L., Commelina benghalensis L., Cassia occidentalis L. and Bidens pilosa L.] weeds. The effect of eugenol (50–1,000 μM) on the growth and development of seedlings after 7 days of treatment was studied in terms of percent germination, root and shoot length, total chlorophyll content and cellular respiration. Eugenol at 1,000 μM caused 55–70 and 42–90 % decrease in percent germination in grassy and broad-leaved weeds, respectively. Likewise, root length declined by 55–90 and 57–71 %, whereas shoot length was decreased by 50–83 and 36–73 % in grassy and broad-leaved weeds, respectively, in response to 1,000 μM eugenol. The observed reduction in the plant growth was accompanied by a decline in the total chlorophyll content (37–53 %) and cellular respiration (36–57 %) in the test plants. However, the inhibitory effect was stronger towards grassy weeds than towards the broad-leaved ones. Thus, future research can be focused on developing eugenol, a natural plant product, as an environmentally safe herbicide in replacement to the harmful chemical herbicides.
Article
The seed coats of S. spinosa (prickly sida, Malvaceae) become impermeable to water during seed development on the mother plant. After the seeds have dehydrated during the final maturation stages, piercing of seed coats is necessary to induce imbibition of water and germination. Onset of impermeability occurs during seed coat browning, well in advance of seed dehydration. I. Marbach and A.M. Mayer (1975, Plant Physiol. 56, 93-96) implicated polyphenol oxidase (PO; EC 1.10.3.1) as catechol oxidase in the formation of insoluble polymers during development of coat impermeability in a wild strain of pea (Pisum elatius) seeds. We found, however, that peroxidase (EC 1.11.1.7), not PO, is instrumental in the development of water-impermeable seed coats in prickly sida. We isolated coats and embryos from seeds harvested at several stages of development. Highest peroxidase activity of coat extracts correlated well with the developmental stages of maximum conversion of soluble phenolics to insoluble lignin polymers. Although seed extracts oxidized dihydroxyphenylalanine, this activity was eliminated by catalase, indicating that the oxidation of phenolics in the coat is catalyzed by peroxidase rather than PO. Histochemical localization of peroxidase was strongest in the palisade layer; both the level and time of appearance of activity was proportional to the spectrophotometric assays of seed-coat extracts. The presence of peroxidase and the absence of PO in the seed coat were also confirmed with immunocytochemistry. Our results support the view that peroxidase is involved in the polymerization of soluble phenolics to insoluble lignin polymers during development of prickly sida seed coats, causing the formation of a water-impermeable barrier prior to seed dehydration. As dehydration proceeds, the chalazal area finally becomes impermeable resulting in the hard mature seeds of prickly sida.
Article
We aimed to analyze the phytotoxic effect of the allelopathic volatile myrcene on rice seedlings, particularly root growth, reactive oxygen species (ROS) generation, and activity of antioxidant enzymes and defense-related genes. Myrcene inhibited the growth of rice seedlings. The activity of ROS and lipoxygenase (LOX) was significantly increased with increasing myrcene concentration in roots and that of antioxidant enzymes was altered dose-dependently. The activity of superoxide dismutase and peroxidase was changed at 24 h after myrcene treatment in rice roots. Furthermore, the mRNA expression of three mitogen-activated protein kinase genes (OsMPK2, 3, and 4), WRKY transcription factor gene (OsWRKY71), LOX gene (OsLOX3), pathogenesis-related protein 1b gene (OsPR1b) and cyclin-dependent protein kinase inhibitor (OsCKI) was upregulated and that of cyclin genes OsCycA1;1, OsCycB1;1 and OsCycD1;1 was downregulated with myrcene treatment in rice roots. These results may provide new insights into the molecular basis of the allelopathic volatile response in plants.
Article
Plant cells possess a number of membrane bound organelles that play important roles in compartmentalizing a large number of biochemical pathways and physiological functions that have potentially harmful intermediates or by-products. The plasma membrane is particularly important as it holds the entire cellular structure whole and is at the interface between the cell and its environment. Consequently, breaches in the integrity of the lipid bilayer, often via reactive oxygen species (ROS)-induced stress membrane peroxidation, result in uncontrolled electrolyte leakage and in cell death. A simple 3-step bioassay was developed to identify compounds that cause electrolyte leakage and to differentiate light-dependent mechanisms of action from those that work in darkness. Herbicides representative of all known modes of action (as well as several natural phytotoxins) were selected to survey their effects on membrane integrity of cucumber cotyledon discs. The most active compounds were those that are known to generate ROS such as the electron diverters and uncouplers (paraquat and dinoterb) and those that either were photodynamic (cercosporin) or caused the accumulation of photodynamic products (acifluorfen-methyl and sulfentrazone). Other active compounds targeted lipids (diclofop-methyl, triclosan and pelargonic acid) or formed pores in the plasma membrane (syringomycin). Herbicides that inhibit amino acid, protein, nucleotide, cell wall or microtubule synthesis did not have any effect. Therefore, it was concluded that the plant plasma membrane is a good biomarker to help identify certain herbicide modes of action and their dependence on light for bioactivity.
Article
The effect of simulated acid rain (AR) (pH 1.8) on H2O2 and malonyldialdehyde (MDA) levels and activities of peroxidase and catalase in bean plants were investigated. The influence of exogenous polyamines spermidine and spermine on these parameters was also studied. AR treatment induced lipid peroxidation and increased level of H2O2 in leaves. Pretreatment with spermidine and spermine prevented these changes. The protective effect of spermine was higher than that of spermidine. The impact of polyamines could be attributed to their acid neutralizing and antioxidant effects, as well as to their ability to stabilize membranes by associating with negatively charged phospholipids. It was also found that AR significantly increased peroxidase and decreased catalase activities at the first hours after treatment. Later, both enzyme activities were enhanced that could contribute to the scavenging and detoxification of active oxygen species.
Article
A simple, rapid method requiring few manipulations for the extraction of chlorophylls from fragmented leaf tissue of angiosperms and gymnosperms is compared with the widely used acetone method. Unlike the acetone method where grinding and subsequent centrifugation are essential, this method makes use of incubation at 65 °C of leaf tissue immersed in dimethyl sulphoxide. The new method was found to be as efficient as acetone for chlorophyll extraction and superior in terms of chlorophyll stability.
Article
Laboratory and greenhouse experiments were conducted to determine the herbicidal effect of plant-derived oils and to identify the active ingredient in an oil with herbicide activity. Twenty-five different oils were applied to detached leaves of dandelion in the laboratory. Essential oils (1%, v/v) from red thyme, summer savory, cinnamon, and clove were the most phytotoxic and caused electrolyte leakage resulting in cell death. Each of these essential oils in aqueous concentrations from 5 to 10% (v/v) plus two adjuvants (nonionic surfactant and paraffinic oil blend at 0.2% [v/v]) were applied to shoots of common lambsquarters, common ragweed, and johnsongrass in the greenhouse; shoot death occurred within 1 h to 1 d after application. Essential oil of cinnamon had high herbicidal activity, and eugenol (2-methoxy-4-[2-propenyl]phenol) was determined to be this oil's major component (84%, v/v). Dandelion leaf disk and whole-plant assays verified that eugenol was the active ingredient in the essential oil of cinnamon. Essential oils are extracted from plants and thus may be useful as “natural product herbicides” for organic farming systems. Nomenclature: Cinnamon, Cinnamomum zeylanicum; clove, Syzgium aromaticum; red thyme, Thymus vulgaris; summer savory, Satureja hortensis; common lambsquarters, Chenopodium album L. CHEAL; common ragweed, Ambrosia artemisiifolia L. AMBEL; dandelion, Taraxacum officinale Weber in Wiggers TAROF; johnsongrass, Sorghum halepense (L.) Pers. SORHA.
Article
Herbicidal activities of clove oil and its primary constituent eugenol on broccoli, common lambsquarters, and redroot pigweed and the role of crystalline leaf epicuticular wax (LEW) in susceptibility and retention of these essential oils were studied. Clove oil (2.5%) and eugenol (1.5%) were applied to leaves of greenhouse-grown broccoli, common lambsquarters, and redroot pigweed seedlings and effects on seedling growth and leaf cell membrane integrity were studied. Compared with eugenol, clove oil caused greater inhibition of seedling growth in all species. Both eugenol and clove oil caused greater loss of membrane integrity and inhibition of seedling growth in redroot pigweed, which has no crystalline LEW, compared with common lambsquarters, which has a thick layer of crystalline LEW. In broccoli seedlings with LEW, clove oil caused greater inhibition of growth than eugenol. Both clove oil and eugenol caused greater electrolyte leakage from broccoli leaves without LEW than in the leaves with LEW. Removal of LEW increased electrolyte leakage, an indicator of cell membrane damage, by 97% in eugenol-treated and 26% in clove oil–treated broccoli leaves. Susceptibility of broccoli seedlings and possibly some weed species may, therefore, be affected by factors (e.g., genetic, environmental) that influence the amount of LEW. Although the presence of LEW greatly reduced the retention of the essential oil solutions, there was no significant difference between the retention of clove oil and eugenol solutions, indicating that differences in their phytotoxicity to broccoli leaves was not due to differential foliar retention. Nomenclature: Common lambsquarters, Chenopodium album L. CHEAL; redroot pigweed, Amaranthus retroflexus L. AMARE; clove, Syzygium aromaticum (L.) Merr. & Perr.; purple sprouting broccoli, Brassica oleracea var. italica.
Article
β-Pinene, an oxygenated monoterpene, is abundantly found in the environment and widely occurring in plants as a constituent of essential oils. We investigated the phytotoxicity of β-pinene against two grassy (Phalaris minor, Echinochloa crus-galli) and one broad-leaved (Cassia occidentalis) weeds in terms of germination and root and shoot growth. β-Pinene (0.02-0.80 mg/ml) inhibited the germination, root length, and shoot length of test weeds in a dose-response manner. The inhibitory effect of β-pinene was greater in grassy weeds and on root growth than on shoot growth. β-Pinene (0.04-0.80 mg/ml) reduced the root length in P. minor, E. crus-galli, and C. occidentalis over that in the control by 58-60, 44-92, and 26-85 %, respectively. In contrast, shoot length was reduced over the control by 45-97 % in P. minor, 48-78 % in E. crus-galli, and 11-75 % in C. occidentalis at similar concentrations. Further, we examined the impact of β-pinene on membrane integrity in P. minor as one of the possible mechanisms of action. Membrane integrity was evaluated in terms of lipid peroxidation, conjugated diene content, electrolyte leakage, and the activity of lipoxygenases (LOX). β-Pinene (≥0.04 mg/ml) enhanced electrolyte leakage by 23-80 %, malondialdehyde content by 15-67 %, hydrogen peroxide content by 9-39 %, and lipoxygenases activity by 38-383 % over that in the control. It indicated membrane peroxidation and loss of membrane integrity that could be the primary target of β-pinene. Even the enhanced (9-62 %) activity of protecting enzymes, peroxidases (POX), was not able to protect the membranes from β-pinene (0.04-0.20 mg/ml)-induced toxicity. In conclusion, our results show that β-pinene inhibits root growth of the tested weed species through disruption of membrane integrity as indicated by enhanced peroxidation, electrolyte leakage, and LOX activity despite the upregulation of POX activity.