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Chemical composition and antimicrobial properties of essential oils of three Australian Eucalyptus species
Abstract
The chemical composition and antimicrobial properties of the essential oils of three common Australian Eucalyptus species, namely E. olida, E. staigeriana and E. dives were determined by gas chromatography/mass spectrometry and the agar disc diffusion method, respectively. A total of 24 compounds were identified from the essential oil of E. dives, with the dominant compounds being piperitone (40.5%), α-phellandrene (17.4%), p-cymene (8.5%) and terpin-4-ol (4.7%). For E. staigeriana, 29 compounds were identified with 1,8-cineole (34.8%), neral (10.8%), geranial (10.8%), α-phellandrene (8.8%) and methyl geranate (5.2%) being the dominant ones. In contrast, a single compound, (E)-methyl cinnamate, accounted for 99.4% of the essential oils of E. oilda, although 20 compounds were identified. The essential oils displayed a variable degree of antimicrobial activity with E. staigeriana oil showing the highest activity. In general, Gram-positive bacteria were found to be more sensitive to the essential oils than Gram-negative bacteria. Staphylococcus aureus was the most sensitive strain while Pseudomonas aeruginosa was the most resistant.
... The World Health Organization published a list of priority microorganisms known as the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli) which requires urgent attention with respect to antimicrobial resistance [3]. Essential oils have been identified as alternative antimicrobial options due to their observed antimicrobial properties against a wide range of pathogens, especially against Gram-positive microorganisms [4][5][6][7][8][9][10]. ...
... Essential oils comprise anywhere from 10 to more than 300 compounds belonging to many different chemical classes such as alcohols, oxides or ethers, aldehydes, esters, ketones, amides, amines, heterocycles, phenols, and terpenes [23]. These compounds possess antimicrobial activity, with different compounds such as carvacrol, cinnamaldehyde, eugenol, geraniol, and thymol exhibiting varying degrees of activity against pathogens such as S. aureus and E. coli [4,6,[23][24][25]. Despite the extensive use of these compounds and the plethora of studies reporting their antimicrobial potential, their use in humans is limited by their toxicity which has been shown Several compounds tested displayed noteworthy antimicrobial activity (≤1.00 mg/mL) against all pathogenic reference strains tested (Table 2). ...
... 3 Bold values represent biological non-toxicity. 4 NV-no value could be calculated as the % mortality of the combination was 0.00. ...
Essential oil compounds have been identified as alternative antimicrobials; however, their use is limited due to their toxicity on human lymphocytes, skin, and reproduction. Carrier oils can reduce the toxicity of essential oils, which raises the question as to whether such activity would extend to the essential oil compounds. Thus, this study aimed to investigate the antimicrobial and toxicity activity of essential oil compounds in combination with carrier oils. The antimicrobial properties of the essential oil compounds, alone and in combination with carrier oils, were determined using the broth microdilution assay. The toxicity was determined using the brine shrimp lethality assay. Antimicrobial synergy (ΣFIC ≤ 0.50) occurred in 3% of the samples when tested against the ESKAPE pathogens. The compound thymoquinone in combination with the carrier oil Prunus armeniaca demonstrated broad-spectrum synergistic activity and a selectivity index above four, highlighting this combination as the most favorable. The carrier oils reduced the toxicity of several compounds, with Calendula officinalis and P. armeniaca carrier oils being responsible for the majority of the reduced toxicity observed. This study provides insight into the interactions that may occur when adding a carrier oil to essential oil compounds.
... The yield obtained from an essential oil can differ concerning the environment of study and seasons (Ben Hassine et al., 2010;Robles and Garzino, 2000). Gilles et al. (2010) also reported that the geo-climatic factors can influence the total yield of the recovered essential oil from the plants (Gilles et al., 2010). It was perceived in the above section that Eucalyptus camaldulensis species were grown under different climatic conditions and light intensity. ...
... The yield obtained from an essential oil can differ concerning the environment of study and seasons (Ben Hassine et al., 2010;Robles and Garzino, 2000). Gilles et al. (2010) also reported that the geo-climatic factors can influence the total yield of the recovered essential oil from the plants (Gilles et al., 2010). It was perceived in the above section that Eucalyptus camaldulensis species were grown under different climatic conditions and light intensity. ...
... This essential oil was considered to have cytotoxic activity and anticancer effects, which makes it valuable in the pharmaceutical field (Mubarak et al., 2015). Furthermore, γ-terpinene also has high antimicrobial and antioxidant activities (Gilles et al., 2010;Silifat et al., 2005). ...
The chemical composition of essential oils (EOs) can vary from one plant to another of the same species and can be affected by several factors including the environment of growth. The research was carried out on the EOs of Eucalyptus camaldulensis leaves grown in three separate greenhouses differentiated by their low-density polyethylene (LDPE) covering material. This study aimed to compare the impact of the type of the greenhouse cover film on the internal microclimate, light intensity, and chemical composition of E. camaldulensis EOs. Eucalyptus species was initially cultivated from the seeds and the EOs were extracted from the leaves of 14 weeks aged trees. The extraction was performed by hydrodistillation using a Clevenger-type apparatus. Qualitative and quantitative analyses of the extracted EOs were performed using gas chromatography coupled with mass spectrometry (GC-MS) and gas chromatography coupled with a flame ionization detector (GC-FID). The analyzed samples were rich in terpenes with a total of 66 identified compounds. The oxygenated monoterpenes pinocarvone and D-carvone were only identified in the essential oils from multilayered greenhouses. cis-1-Methyl-4-(1-methylethyl-)-2-cyclohexen-1-ol was absent in eucalyptus EOs from the three-layer greenhouse, unlike the others that had it. Different compound contents were detected in the extracted essential oils, according to their greenhouse cover conditions. 1,8-Cineol was the compound present in a higher amount as expected, with the highest value of c.a 164.78 mg/gdw from the leaves of E. camaldulensis cultivated in the ordinary greenhouse. Contents of 51.55 mg/gdw and 42.11 mg/gdw were obtained from E. camaldulensis cultivated in the three-layers and monolayer greenhouses, respectively. In contrast, the EOs of E. camaldulensis grown under the monolayer greenhouse presented the highest content of some aromadendranes family compounds. This study shows that the greenhouse cover-film should be chosen thoughtfully because it plays a major function regarding its effect on the chemical composition of the EOs of E. camaldulensis cultivated in greenhouse environments.
... As shown in Figure 2, the highest amount of flavonoid compounds (4.55 mg Gallic acid / g dry weight) is present in eucalyptus leaves; The lowest amount of flavonoid compounds (1.97 mg Gallic acid / g dry weight) was found in Musquit bean leaves ( Figure 3). Our results were consistent with previous result [29] which confirm the high polyphenolic content in rosemary, especially flavonoid compounds. Martin and colleagues Identified 20 bioactive compounds in E. oilda essential oil. ...
... it was shown that gram-positive bacteria were more sensitive to the eucalyptus essential oil than gram-negative bacteria. S. aureus was the most sensitive strain to eucalyptus essential oil: P. aeruginosa was the most resistant strain [29]. Data are reported based on the standard deviation of the mean. ...
In general, the resistance of microorganisms to antibiotics has become one of the major concerns of human society and the health care system. The aim of this study was to evaluate total phenol, flavonoids content, alkaloids, antioxidant capacity and antibacterial activity of 7 medicinal plants extracts in Sistan climatic conditions against pathogens. Plant samples were collected from the collection of the Agricultural Research Institute of medicinal plants, University of Zabol and dried in normal shade and room temperature. A Methanolic extract of the leaves of snake grass, eucalyptus, tatura, Musquit bean, Watercress, rosemary and olive was prepared by cold maceration method. Total phenol content by using folin-ciocalteu reagent method, total flavonoid content by aluminum chloride colorimetric method, antioxidant capacity by DPPH free radical scavenging assay and antibacterial activity of extracts by agar diffusion method and measurement of growth inhibition zone or Disk diffusion was measured. The analysis of variance showed that there was a statistically significant difference between different medicinal plants at a probability level of 5%. In the present experiment, the highest phenolic content (110.78 mg/q D.W.) in the Rosemary methanolic extract, the highest total flavonoid content (4.55 mg GA/g D.W.) in Eucalyptus extract and the highest antioxidant activity (93.1%) in the Olive extract were observed. Also, the largest diameter of Disk diffusion (25 mm) was observed in the medium containing Rosemary extract and against Streptococcus pyogenes.
... The geographical origin also highly affects this production; in this, good extraction yields were observed for plants from Tunisia. In fact, several studies reviewed the parameters that can influence the total essential oil content of plant including part of plant (Silva et al., 2011), geographic origin (Gilles et al., 2010;Almas et al., 2018), the seasonal variations (Silva et al., 2011), the phenological stage (Salem et al., 2018), method of extraction (Ben Hassine et al., 2010;Herzi et al., 2013;Chamali et al., 2021), rainfall and harvesting regime (Gilles et al., 2010). Chemical profiling of Chemical profiling of Chemical profiling of Chemical profiling of E. torquata E. torquata E. torquata E. torquata essential oils essential oils essential oils essential oils Essential oils obtained from Eucalyptus are usually rich in monoterpenes and in some cases sesquiterpenes. ...
... The geographical origin also highly affects this production; in this, good extraction yields were observed for plants from Tunisia. In fact, several studies reviewed the parameters that can influence the total essential oil content of plant including part of plant (Silva et al., 2011), geographic origin (Gilles et al., 2010;Almas et al., 2018), the seasonal variations (Silva et al., 2011), the phenological stage (Salem et al., 2018), method of extraction (Ben Hassine et al., 2010;Herzi et al., 2013;Chamali et al., 2021), rainfall and harvesting regime (Gilles et al., 2010). Chemical profiling of Chemical profiling of Chemical profiling of Chemical profiling of E. torquata E. torquata E. torquata E. torquata essential oils essential oils essential oils essential oils Essential oils obtained from Eucalyptus are usually rich in monoterpenes and in some cases sesquiterpenes. ...
Eucalyptus has become one of the most widely planted genera in the world because of its tolerance to a wide range of soil types and climates, as well as for its many industrial, commercial and medicinal uses. Eucalyptus torquata Luehm. is a plantation species frequently planted in semi-arid and arid regions for its ecological, forestry, ornamental and melliferous interests. Based on literature, drought tolerance of this species was mostly directed to adaptation mechanisms. Physiological investigations reveal the importance of stomatal closure and increased solute contents suggesting that osmotic adjustment is one of the main responses to drought in E. torquata. On the other hand, it showed low sensitivity to salt stress. This paper also highlights the immense benefits of E. torquata which contains essential oils with variable chemical composition and rich essentially in 1,8-cineole, torquatone, α-pinene, trans-myrtanol, α-eudesmol, β-eudesmol, globulol, trans-pinocarveol and aromadendrene. These oils, as well as the methanol and aqueous extracts possess a wide variety of bioactivities of great importance which are particularly valuable as antibacterial and antifungal agents also have a strong toxicity against insects and mites in addition to antiproliferative and cytotoxic effects against different types of cancer cells.
... The geographical origin also highly affects this production; in this, good extraction yields were observed for plants from Tunisia. In fact, several studies reviewed the parameters that can influence the total essential oil content of plant including part of plant (Silva et al., 2011), geographic origin (Gilles et al., 2010;Almas et al., 2018), the seasonal variations (Silva et al., 2011), the phenological stage (Salem et al., 2018), method of extraction (Ben Hassine et al., 2010;Herzi et al., 2013;Chamali et al., 2021), rainfall and harvesting regime (Gilles et al., 2010). Chemical profiling of Chemical profiling of Chemical profiling of Chemical profiling of E. torquata E. torquata E. torquata E. torquata essential oils essential oils essential oils essential oils Essential oils obtained from Eucalyptus are usually rich in monoterpenes and in some cases sesquiterpenes. ...
... The geographical origin also highly affects this production; in this, good extraction yields were observed for plants from Tunisia. In fact, several studies reviewed the parameters that can influence the total essential oil content of plant including part of plant (Silva et al., 2011), geographic origin (Gilles et al., 2010;Almas et al., 2018), the seasonal variations (Silva et al., 2011), the phenological stage (Salem et al., 2018), method of extraction (Ben Hassine et al., 2010;Herzi et al., 2013;Chamali et al., 2021), rainfall and harvesting regime (Gilles et al., 2010). Chemical profiling of Chemical profiling of Chemical profiling of Chemical profiling of E. torquata E. torquata E. torquata E. torquata essential oils essential oils essential oils essential oils Essential oils obtained from Eucalyptus are usually rich in monoterpenes and in some cases sesquiterpenes. ...
Eucalyptus has become one of the most widely planted genera in the world because of its tolerance to a wide range of soil types and climates, as well as for its many industrial, commercial and medicinal uses. Eucalyptus torquata Luehm. is a plantation species frequently planted in semi-arid and arid regions for its
ecological, forestry, ornamental and melliferous interests. Based on literature, drought tolerance of this species was mostly directed to adaptation mechanisms. Physiological investigations reveal the importance of stomatal closure and increased solute contents suggesting that osmotic adjustment is one of the main responses to
drought in E. torquata. On the other hand, it showed low sensitivity to salt stress. This paper also highlights the immense benefits of E. torquata which contains essential oils with variable chemical composition and rich essentially in 1,8-cineole, torquatone, α-pinene, trans-myrtanol, α-eudesmol, β-eudesmol, globulol, trans�pinocarveol and aromadendrene. These oils, as well as the methanol and aqueous extracts possess a wide variety of bioactivities of great importance which are particularly valuable as antibacterial and antifungal agents also have a strong toxicity against insects and mites in addition to antiproliferative and cytotoxic effects against different types of cancer cells.
... Studies based on various species of Eucalyptus, generally, indicate that Gram-positive bacterial strains are more sensitive to essential oils than Gram-negative ones [37][38][39]. This trend can be rationalized taking into account that Gram-negative bacilli have a lipopolysaccharide membrane that is restrictive for the diffusion of hydrophobic compounds present mainly in essential oils; thus, preventing components from exerting their effect, such as increasing ion permeability, leakage of vital intracellular components, or compromising bacterial enzymes [38,39]. ...
... Studies based on various species of Eucalyptus, generally, indicate that Gram-positive bacterial strains are more sensitive to essential oils than Gram-negative ones [37][38][39]. This trend can be rationalized taking into account that Gram-negative bacilli have a lipopolysaccharide membrane that is restrictive for the diffusion of hydrophobic compounds present mainly in essential oils; thus, preventing components from exerting their effect, such as increasing ion permeability, leakage of vital intracellular components, or compromising bacterial enzymes [38,39]. However, other species in the Piperaceae family have shown antibacterial activity against Gram-negative bacilli strains [7]. ...
The essential oil of the fresh leaves and stems of Piper eriopodon (Piperaceae), was extracted by hydro-distillation, using the Clevenger trap, with a yield of 0.188%. Thirty-eight compounds were identified by gas-chromatography, coupled with mass spectrometry (GC-MS). The main components were: 1,8-cineole (37.2%), β-pinene (9.38%), myristicin (7.82%), α-pinene (7.27%), trans-caryophyllene (5.80%) and β-selinene (4.04%). The antibacterial activity assessment was carried out using the disk diffusion agar method technique (Kirby-Bauer). Results showed that the essential oil from the Piper eriopodon showed no antibacterial activity against Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae). In contrast, against Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis), it only showed activity against Staphylococcus aureus, determining a Minimum Inhibitory Concentration of 2,500 μg/mL.
... PHE is found in plants, such as Angelica and Eucalyptus, and due to its pleasant scent, it has been used [20] 2 Xylopia aromatica L. 2.2-6.4 [21] 3 Rosmarinus officinalis L. 0.1-0.4 [22] 4 Eucalyptus dives 17.4 [23] 5 ...
... Eucalyptus staigeriana 8.8 [23] 7 Schinus terebinthifolius Raddi 15.7 [24] 34.38 [25] 6 Schinus molle L. 46.52 [25] 8 Solanum erianthum D. Don. 17.5 [26] 9 ...
Aromatic essential oils play a significant role in pharmaceuticals, food additives, cosmetics, and perfumery. Essential oils mostly comprise aliphatic hydrocarbons, monoterpenoids, sesquiter-penoids and diterpenes. Plant extracts comprise a complex mixture of terpenes, terpenoids, aliphatic and phenol-derived aromatic components. Terpenes are a significant class of hydrocarbons with numerous health benefits. These biological functions of essential oil components are examined in vitro and in vivo studies. Some studies evaluated the properties and functions of α-phellandrene (α-PHE). Detailed evaluation to determine the functions of α-PHE over a spectrum of health care domains needs to be initiated. Its possible mechanism of action in a biological system could reveal the future opportunities and challenges in using α-PHE as a pharmaceutical candidate. The biological functions of α-PHE are reported, including anti-microbial, insecticidal, anti-inflammatory, anti-cancer, wound healing, analgesic, and neuronal responses. The present narrative review summarizes the synthesis, biotransformation, atmospheric emission, properties, and biological activities of α-PHE. The literature review suggests that extended pre-clinical studies are necessary to develop α-PHE-based adjuvant therapeutic approaches.
... These trees of the genus Eucalyptus belong to the Myrtaceae family and were named by the French botanist Charles Louis L'Héritier de Brutelle in 1788 [1]. This plant is native to Australia and Tasmania and was reclassified by Hill and Johnson in 1995 based on morphology and molecular characteristics [2][3][4][5][6][7]. The natural distribution of Eucalyptus is mainly limited to the southern hemisphere [8]. ...
... Units of some species can reach 400-500 years of age [8]. This tall evergreen tree ( Figure 1) has been successfully introduced into many countries around the world, where it is currently one of the most widely planted trees [3,[9][10][11][12][13]. Eucalyptus species are grown in the tropics and subtropics, including Asia, America, Europe and Africa. ...
Eucalyptus plants have attracted the attention of researchers and environmentalists worldwide because they are a rapidly growing source of wood and a source of oil used for multiple purposes. The main and the most important oil component is 1,8-cineole (eucalyptol: 60%–85%). This review summarizes the literature reported to date involving the use of 1,8-cineole for the treatment of disorders. Additionally, we describe our efforts in the use of eucalyptol as a solvent for the synthesis of O,S,N-heterocycles. Solvents used in chemistry are a fundamental element of the environmental performance of processes in corporate and academic laboratories. Their influence on costs, safety and health cannot be neglected. Green solvents such as bio-based systems hold considerable additional promise to reduce the environmental impact of organic chemistry. The first section outlines the process leading to our discovery of an unprecedented solvent and its validation in the first coupling reactions. This section continues with the description of its properties and characteristics and its reuse as reported in the various studies conducted. The second section highlights the use of eucalyptol in a series of coupling reactions (i.e., Suzuki–Miyaura, Sonogashira–Hagihara, Buchwald–Hartwig, Migita–Kosugi–Stille, Hiyama and cyanation) that form O,S,N-heterocycles. We describe the optimization process applied to reach the ideal conditions. We also show that eucalyptol can be a good alternative to build heterocycles that contain oxygen, sulfur and nitrogen. These studies allowed us to demonstrate the viability and potential that bio solvents can have in synthesis laboratories.
... Consequently, the discovery of new, innovative, and environmentally friendly strategies has become a vital trend to control fungal pathogens [5,12,13]. Applying different essential oils and medicinal plant extracts might be a sustainable environmental and economical solution for controlling phytopathogens due to their having little or no toxicity to humans and the environment [14]. In this context, the search for innovative, safer, and available alternatives that are derived naturally must be developed in order to decrease the postharvest fruit losses. ...
... Consequently, the discovery of new, innovative, and environmentally friendly strategie has become a vital trend to control fungal pathogens [5,12,13]. Applying different essentia oils and medicinal plant extracts might be a sustainable environmental and economica solution for controlling phytopathogens due to their having little or no toxicity to human and the environment [14]. In this context, the search for innovative, safer, and availabl alternatives that are derived naturally must be developed in order to decrease th postharvest fruit losses. ...
Recently, there have been urgent economic and scientific demands to decrease the use of chemical fungicides during the treatment of phytopathogens, due to their human health and environmental impacts. This study explored the biocontrol efficacy of novel and eco-friendly preen (uropygial) oil and endophytic Bacillus safensis in managing postharvest Botrytis grey mold in strawberry fruit. The preen oil (25 μL/mL) showed high antifungal activity against B. cinerea Str5 in terms of the reduction in the fungal radial growth (41.3%) and the fungal colony-forming units (28.6%) compared to the control. A new strain of Bacillus safensis B3 had a good potential to produce chitinase enzymes (3.69 ± 0.31 U/mL), hydrolytic lipase (10.65 ± 0.51 U/mL), and protease enzymes (13.28 ± 0.65 U/mL), which are responsible for the hydrolysis of the B. cinerea Str5 cell wall and, consequently, restrict fungal growth. The in vivo experiment on strawberry fruit showed that preen (uropygial) oil reduced the disease severity by 87.25%, while the endophytic bacteria B. safensis B3 reduced it by 86.52%. This study reports the efficiency of individually applied bioagents in the control of phytopathogenic fungi for the first time and, consequently, encourages their application as a new and innovative strategy for prospective agricultural technology and food safety.
... The biomass contains 1.1 wt% of N, 53.2 wt% of C, 6.1 wt% of H, and 0.14 wt% of S based on CHNS analysis [26]. The eucalyptus leave is a complex lignin biomass, which is mainly composed of a-pinene, 1,8-cineole, oxygenated monoterpenes, piperitone, phellandrene, terpin-4-ol, p-cymene, cinnamate, etc [44,45]. The ash of eucalyptus leaves contains some metals (such as Ca, Mg, K, Na, Mn, Al) [26]. ...
... Finally, p-cymene undergoes hydroxylation to produce Carvacrol ( Fig. 6.36) [59]. Carvacrol can be produced synthetically by several methods as follows (Fig. 6.37) given below (Fig. 6.38) [60]. Fig. 6.38. ...
Cancer is considered the leading cause of death worldwide. World Health Organization (WHO) reported 14.1 million new cancer cases and 8.2 million deaths globally in the year 2012 and over 70% of new cancer cases have been estimated during the next twenty years [1-3]. Cancer is mainly characterized by the uncontrolled growth of abnormal cells that finally leads to metastasis. The uncontrolled proliferation of a normal cell leads to genetic instabilities and alterations within the cells and tissues that transform normal cells into
malignant cells [4].
... However, many studies that focused on the chemical composition of the genus Eucalyptus (E. dives) EO revealed other chemotypes: piperitone (40.50%), α-phellandrene (17.40%), and p-cymene (8.50%) with a low rate of 1,8-cineole (0.70%) [54]. ...
This study aims to identify the volatile profile of three essential oils obtained from Eucalyptus polybractea cryptonifera (EPEO), Ormenis mixta (OMEO), and Lavandula burnatii briquet (LBEO) and to examine their combined antibacterial activity that affords the optimal inhibitory ability against S. aureus and E. coli using simplex-centroid mixture design and checkerboard assay. Essential oils (EOs) were isolated by hydrodistillation and characterized using gas chromatography-mass spectrometry (GC-MS) and gas chromatography coupled with flame-ionization detector (GC-FID). The antibacterial activity was performed using disc diffusion and microdilution assays. The chemical analysis revealed that 1,8-cineole (23.75%), p-cymene (22.47%), and α-pinene (11.20%) and p-menthane-1,8-diol (18.19%), α-pinene (10.81%), and D-germacrene (9.17%) were the main components detected in E. polybractea and O. mixta EOs, respectively. However, L. burnatii EO was mainly represented by linalool (24.40%) and linalyl acetate (18.68%). The EPEO, LBEO, and OMEO had a strong antibacterial effect on S. aureus with minimal inhibitory concentrations (MICs) values ranging from 0.25 to 0.5% (v/v). Furthermore, the combination of 1/2048 MICEPEO + 1/4 MICLBEO showed a synergistic antibacterial effect on S. aureus with a FIC index of 0.25, while the formulation of 1/4 MICEPEO + 1/4 MICOMEO demonstrated an antibacterial synergistic activity on E. coli with a FIC index of 0.5. Moreover, the simplex-centroid mixture design reported that the most effective combinations on E. coli and S. aureus correspond to 32%/28%/40% and 35%/30%/35% of E. polybractea, O. mixta, and L. burnatii, respectively. Presented information highlights the action of antibacterial formulations of these EOs and suggests their potential applications as alternatives to commercialized drugs to contract the development of bacteria causing serious infections and food deterioration.
... The family of Myrtaceae covers about 140 genera and 3800 to 5650 species worldwide (Govaerts et al. 2008). Eucalyptus L'Hérit, native to Australia, as the focal genus that covers some 900 species and subspecies (Brooker and Kleinig 2004;Gilles et al. 2010;Pereiraa et al. 2014;Sebei et al. 2015). It's the most important and extensive plant genus in the world, including Tunisia. ...
This work was designed to explore the chemical composition, antioxidant, antibacterial and insecticidal activities of Eucalyp-tus cinerea essential oil collected from Ain Draham, NorthWestern of Tunisia. GC/MS analysis revealed the identification of twenty two compounds with 1,8-cineole (63.51%), camphene (15.53%), α-pinene (7.55%) and α-terpineol (3.52%) as major components. The antioxidant potential was assessed using two methods 1.1-diphenyl-2-picrylhydrazyl radical (DPPH) and Ferric Reducing Antioxidant Power (FRAP). IC 50 value was 161.59 µg/mL in the DPPH assay. Moreover, the antibacterial acitivity was evaluated towards Gram positive and Gram negative bacteria (Escherichia coli ATCC25922, Staphylococcus aureus ATCC29213, Enterococcus faecalis ATCC29212). The diameter of inhibition varied between 22 ± 0.57 mm and 7 ± 0.5 mm. The largest one was found in Staphylococcus aureus. However, the smallest one was found in Enterococcus fea-calis. The insecticidal potential was established against Ceratitis capitata adults using contact toxicity by topical application. Results revealed that all E. cinerea oil concentrations exhibited strong contact properties. The originality of this research is to offer farmers an innovative solution to control C. capitata based on the application of natural insecticidal molecules extracted from Eucalyptus cinerea. Moreover, this oil deserves better considerations due to its antioxidant and antibacterial properties. Highlights • Eucalyptus cinerea essential oil extracted with Clevenger apparatus are analyzed by GC and GC/MS. • E. cinerea essential oil has a radical scavenging and antibacterial activities. • E. cinerea essential oil displayed insecticidal potential against Medfly adults.
... The results showed that chitosan nanoencapsulation significantly induced the antifungal activity in in vivo assay [24,25]. Gilles et al. showed increased bioactivity of Eucalyptus staigeriana-loaded nanocapsulation [26]. Nanoencapsulation has developed a new period of abundant possibilities, including create the biopolymer films with good efficiency in pharmaceutical application. ...
Natural sources have shown biological activities against pathogens in vitro, but have not yet been discovered widely in vivo. The volatile nature, poor stability, and solubility of them restrict their usage in pharmaceutical industries. In recent years, nanotechnology has been proposed as a key to answer this problem. Nanoencapsulation has been used in various pharmaceutical and therapeutic applications. Nanocarriers can enhance the biological properties due to the small size that improves the cellular uptake. The present study evaluated how nanoencapsulation of cumin essential oil (CEO) affects the chemical composition and inhibition of nosocomial infections and standard pathogens. Following isolation of the CEO and nanoencapsulation cumin essential oil (NECEO), the chemical components was analyzed by gas chromatography-mass spectrometry (GC/MS) and their antibacterial/antifungal of the nosocomial infections and standard pathogens effects were evaluated. Nanoencapsulation significantly increased NECEO yield and the concentration of main components (cumin aldehyde and cumic alcohol). Results showed that nanoencapsulation significantly decreased the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of NECEO against nosocomial infections and standard pathogens. The results suggested that NECEO can be regarded as a promising pharmaceutical source. Therefore, nanoparticle may be considered as a useful agent for improving EO chemical and biological properties. These observations could be used for future experiments to further evaluate potential nanoparticles and other medicinal plants.
... Otro estudio evaluó la actividad antiviral de Uncaria tomentosa, encontrando que algunos de sus (44) componentes tendrían actividad contra el SARS-CoV-2 . Acerca de las especies de Eucalyptus y Zingiber officinale, tiene potencial actividad contra virus como el Virus sincitial respiratorio (VSR), herpes simple tipo 1 y 2 (VHS-1 y VHS-2), influenza (H1N1), adenovirus, Chikungunya, Mycobacterium tuberculosis; e incluso actividad antibacteriana y (45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55) antiparasitaria . ...
Introducción:
La expansión acelerada del SARS-CoV-2 trajo consigo una crisis mundial, y una serie de estudios y recomendaciones para manejarlo; mientras que estudios previos a la pandemia, evidencia elevada prevalencia de automedicación en estudiantes universitarios.
Objetivo:
Identificar la frecuencia y características de automedicación contra la COVID-19 con fármacos y/o plantas medicinales en los estudiantes de la Universidad Nacional de la Amazonía Peruana (UNAP), Iquitos, Loreto-Perú, durante la primera ola por COVID-19.
Material y Métodos:
Se realizó un estudio descriptivo de corte transversal en 338 estudiantes mediante una encuesta semiestructurada ad-hoc con preguntas distribuidas en 3 dimensiones: características sociodemográficas, características de COVID-19 y características del uso de fármacos/plantas medicinales. Resultados: El promedio de la edad fue 22,39 años (DE ± 5,59), predomino el sexo femenino con 61,2 % (n=207), el 55,3% (n=187) presentaron síntomas sugestivos de COVID-19. Además, el 76,9% (n=260) utilizaron medicación, distribuido de mayor a menor 65,4 % (n=170) fármacos y plantas, 25,8 % (n=67) solo plantas, y 8,8 % (n=23) solo fármacos; incurrieron en automedicación el 79,2% (n=206). Los principales fármacos empleados fueron dexametasona, paracetamol, azitromicina, e ivermectina. Las plantas medicinales principalmente empleadas fueron eucalipto, kion, manzanilla y matico. Se presentó probable asociación a la automedicación con antecedente de síntomas sugestivos de COVID-19 (p=0.001, IC 95%), y contacto de COVID-19 (p=0,011, IC 95%).
Conclusión:
Entre los estudiantes de una universidad de la Amazonía Peruana, se identificó elevada prevalencia y los factores asociados a la automedicación con fármacos y plantas medicinales.
... Esses compostos, avaliados em sua forma pura, mostram ação antimicrobiana em diferentes estudos (SIQUI et al., 2000;DAN et al., 2010;GILLES et al., 2010;HUSSAIN et al., 2010;COMBRINCK;REGNIER;KAMATOU, 2011;OLIVEIRA et al., 2011;PEREIRA et al., 2011;SEIXAS et al., 2011 ...
Cada vez mais infecções fúngicas resistentes à ação farmacológicas têm estado presentes cenário brasileiro e mundial, tornando-se um sério problema de saúde pública. Nesse sentido, tem sido incentivadas pesquisas a respeito da ação antifúngica dos óleos voláteis de plantas medicinais. Diante disto, o presente estudo descritivo, quantitativo e bibliométrico tem por objetivo mapear o perfil de publicações sobre a atividade antifúngica de óleos essenciais no gênero candida. Essa pesquisa ocorreu no ano de 2022 e para a efetivação foi utilizada a Biblioteca Virtual em Saúde (BVS), sendo selecionados 14 artigos dos anos 2012 a 2022, e grande parte deles publicados entre os anos de 2012 e 2015, além de todos em análise, estarem no idioma português. Em relação à publicação desses artigos, destacou-se a Revista Brasileira de Plantas Medicinais, além disso, a maioria desses períódicos são de Qualis B, destacando-se B4 e B5. Destaca-se que o maior número de autores são mulheres, sendo estas majoritariamente formadas em cursos da área da saúde. No estudo foi notória a necessidade de mais pesquisas sobre a temática e assim contribuir para o tratamento de infecções do gênero candida resistentes de forma eficaz.
... In previous studies, results showing the antimicrobial and antiviral effects of Eucalyptus essential oil were reported [6,7]. It is well documented that Eucalyptus essential oils are prominent with their antimicrobial activities, especially against upper respiratory tract pathogens and infections [8][9][10][11][12]. The Eucalyptus oil was previously demonstrated to be effective against influenza and herpes viruses [13,14]. ...
Coldmix ® is a commercially available Eucalyptus aetheroleum and, Abies aetheroleum blend for medicinal applications. In this present study, the in vitro antiviral potential of Coldmix ® , and its major constituents 1,8-cineole and α-pinene were evaluated by using the in vitro ACE2 enzyme inhibition assay as well as the direct contact test against SARS-CoV-2. The observed ACE2 enzyme inhibitory activity of Coldmix ® , 1,8-cineole, and α-pinene were 72%, 88%, and 80%, respectively; whereas in the direct contact test in the vapor phase, the destruction of the virus was 79.9% within 5 min and 93.2% in the 30th min, respectively. In a similar Coldmix ® vapor phase setup using the in vitro cytotoxicity cell assay, E6 VERO healthy cells were experimentally not affected by toxicity. According to the promising initial antiviral results of Coldmix ® and the individually tested constituents, detailed further in vivo evaluation using different virus classes is suggested.
... Various scientists tested essential oils of Eucalypts by Simeon method (Simeon, 1976) and reported antimicrobial activity against bacteria as well as fungi (Beylier andGivaudan, 1979. Gilles et al. 2010) [12,39] . Anti-inflammatory properties: One study has demonstrated that pre-treatment of LPS/ IFN-® stimulated cells with E. ...
Introduction: In recent years, many infectious diseases are emerging as a pandemic. COVID-19 is one of the major challenges for mankind at present. The third wave of SARS-CoV-2 outbreak has already started hitting the world and new variants has also started spreading. At present, patients with severe COVID-19 are treated with antiviral drugs for controlling viral infection and supportive treatment with anti-inflammatory and antibacterial drugs to control hyper inflammatory response and secondary infection respectively. Antioxidant drugs are also gaining importance in COVID-19 patient's supportive care. Many herbal preparations are known and have been proven for their health benefits such as immune-modulatory, anti-viral, anti-inflammatory, anti-microbial and Antioxidant roles. Methods: Four herbal plants of household use were selected for the study namely garlic, cloves, cinnamon and eucalypts. Research data was collected for all the plants for their immune-modulatory, anti-viral, anti-inflammatory, anti-microbial and Antioxidant roles and presented comprehensively in the preparation of this manuscript. Results: Essential oils and extracts of medicinal plants such as garlic, cloves, cinnamon and eucalypts have all those characteristics required to prevent as well as control infection and supportive care which is important in the fight against COVID-19. Discussion: There is relevance in the treatment strategy for COVID-19 and medicinal properties of plant extracts which make these medicinal plants as a potential alternative to pharmacological agents for immunity boost up, treatment and management of viral pandemics including COVID-19 outbreak.
... Eucalyptus belongs to the myrtacea family and includes more than 700 species (Gilles et al. 2010). According to previous reports, Eucalyptus has valuable biological activities against illnesses such as liver diseases, cough, sore throat, and bacterial infections of the respiratory and urinary tracts (Swanston-Flatt et al. 1990;Adeniyi, Lawal, and Olaleye 2006;Youse et al. 2012;Kpodar et al. 2016). ...
The Eucalyptus species is traditionally used to cure many diseases. The goal of the present work was to study the phytochemical components of the Eucalyptus camaldulensis seed extract (EC) and to explore the antioxidant and the enzyme inhibitory effects. High-performance liquid chromatography – photodiode array – mass spectrometry analysis (HPLC-PDA-MS/MS) revealed the presence of fifty-seven molecules in the Eucalyptus camaldulensis extract. The main compounds detected were malic acid, gallic acid, and ellagic acid. The results showed that the extract had significant dose–response antioxidant properties and also inhibitory capacity against α-amylase and α-glucosidase. These results highlight the importance of Eucalyptus seeds as a source of biomolecules with beneficial effects.
... Extracts obtained from the leaves and roots of C. citriodora (syn. E. citriodora) have been found to exhibit anticancer and antioxidant activities (Gilles et al., 2010). ...
... It is conceivable that this difference in composition could be attributed to the source of the plant sample, variation in season of harvest, genetics as well as the extraction approach. 20,26,28 The extraction method adopted herein is not tailored specifically for essential oils. Rather the objective was to obtain a broad spectrum of lipophilic components in the leaves presumably including essential oils and many other bioactive secondary metabolites. ...
Although a number of pharmacological properties have been linked to Eucalyptus camaldulensis leaf essential oil and extracts, the biological attributes of the lipophilic fraction remain unknown. Moreover, only a limited number of active compounds have so far been identified. This work aimed to investigate the anti-oxidative, anti-aggregation, and cytotoxic properties as well as profile the secondary metabolites in the lipophilic fraction of E. camaldulensis leaf extract (Lipo-Eucam) using UHPLC-ESI-QTOF-MS and gas chromatography-mass spectrometry (GC-MS). It was found that Lipo-Eucam possessed potent antioxidant properties against DPPH, ABTS, and FRAP with IC50 values of 31.46, 32.78, and 10.12 μg/mL, respectively. The fraction was able to attenuate metal-catalyzed oxidation of bovine serum albumin (BSA) in a dose-dependent manner (p < 0.05) and abrogated the aggregation of amyloidogenic BSA as revealed by the Congo red assay and transmission electron microscopy. Furthermore, Lipo-Eucam demonstrated potent cytotoxic effects against MCF-7 (IC50 7.34 μg/mL) but was noncytotoxic at used concentrations against HEK-293 cells (IC50 > 80 μg/mL), suggestive of its selective anticancer properties. Spectrophotometric, UHPLC-MS, and GC-MS analysis revealed that Lipo-Eucam is rich in phenolics, flavonoids, terpenoids, volatile constituents, and a plethora of active metabolites, probably responsible for the observed activities. These findings indicate that Lipo-Eucam is endowed with pharmacologically relevant active principles with strong potential for use in the amelioration of disease conditions related to oxidative stress, protein aggregation, and breast cancer and therefore worthy of further investigations.
... The antibacterial activity may be the result of the presence of α-pinene, α-terpineol and linalool, compounds that are known to possess antibacterial activity [47]. Although present in low concentrations, those constituents could have imparted a significant effect on the antibacterial activities of the oils via a synergistic effect [48]. Escherichia coli 0 ± 00 0 ± 00 0 ± 00 0 ± 00 0 ± 00 0 ± 00 0 ± 00 0 ± 00 0 0 ...
The aim of this work was to study the chemical composition of the essential oil extracted from ginger rhizomes (Zingiber officinale Roscoe) and cardamom seeds (Elettaria cardamomum (L.) Maton). Using gas chromatography coupled with mass spectrometry (GC/MS), a total of 43 compounds were identified in ginger essential oil and 17 compounds in cardamom. The most abundant components, respectively, were zingiberene (22.18%) and 1.8-cinéol (43.47%). Essential oils, metha-nol, ethanol and chloroform extracts for both plants were tested against nine bacteria and yeast. The highest sensitivity was noticed against Staphylococcus aureus with a 25 mm inhibition zone. The an-tioxidant potency of both oils and extracts were measured using DPPH (1,1-diphenyl-2-picryl hy-drazyl) free radical scavenging and the ferric reducing power (FRP) method; the ethanolic extract of cardamom fruits exhibited the best results for both tests, with an IC 50 = 0.423 ± 0.015 mg/mL and 95.03 ± 0.076 FRP mg AAE/g.
... Eucalyptus extracts can exhibit toxicity against a wide range of microbes, including bacteria, fungi, and soil-borne pathogens (Dhakad et al., 2018;Sabo and Knezevic, 2019). Such antimicrobial effects can be attributed to the presence of terpenoid and phenolic compounds, which have antimicrobial activities in pure form (Gilles et al., 2010). These antimicrobial reagents can be released into the surrounding environment when Eucalyptus residuals are improperly handled, and a vast ecotoxicological risk is raised in real-world scenarios. ...
Eucalyptus is widely planted in China for wood industries, and there are increasing concerns about its ecotoxicity in the environment. This study explored the in-vitro toxicity of Eucalyptus extracts by assessing the impacts of water-soluble and dimethylsulfoxide (DMSO)-soluble fractions via a whole-cell bioreporter, Acinetobacter baylyi ADPWH_recA. Compounds identified in Eucalyptus extracts included one tannin, two phenolic acids, four terpenoids, four glycosides, and five flavonoids. The leaf extracts contained more biological-active components than barks and roots. Genotoxicity induced by Eucalyptus extracts was mainly associated with water extracts (e.g., flavonoids, phenolic acids) instead of DMSO extracts. The significant cytotoxicity was explained by programmed cell death (PCD), suggested by the results of propidium iodide (PI) and 2′,7′-dichlorofluorescein-diacetate (DCFH-DA) assays. Generally, water-soluble fractions contributed more toxicities than DMSO-soluble fractions, particularly at high concentrations. A robust linear regression was built between the compromised toxicity and PCD index (Compromised toxicity = −2.192 × PCD index + 2.219; R² = 0.8886), suggesting a PCD-dependent compromised toxicity which was greatly underestimated. Our results implied non-neglectable ecotoxicological risks of Eucalyptus extracts, hinting at the possible magnified ecological impacts of its large-scale plantation and the potential adverse outcomes to the surrounding ecosystems.
... Essential oils are organic chemicals extracted from plant parts such as leaves, twigs, wood, roots, and barks (1). One of the essential oil characteristics is the presence of various essences or volatile compounds with beneficial properties such as antioxidants (2), antibacterial (3), and anti-inflammatory (4). The development of the essential oil industry started in the early 20th century due to its wide use, making them one of the most important processed products (5). ...
Essential oils such as eucalyptus oil are widely used as antioxidants, antimicrobial, anti-inflammatory, fragrance, and other medical needs. This oil is extracted from eucalyptus terpenoid compounds, e.g., cineole. This study aims to evaluate the effect of the leaf storage time and distillation time (DT) on Eucalyptus grandis essential oil yield and quality. Three DT treatments (i.e., 2 h, 3 h, and 4 h) and storage time of eucalyptus leaf in warehouse (i.e., 2 h, 3 h, and 4 h) were applied on eucalyptus leaf samples. The quality of the eucalyptus essential oil was determined using cineole content, solubility in alcohol, and optical rotation. The essential oil yield ranges between 0.165-0.220%, with the maximum yield of 0.220% on 3 days of storage and 4-hour distillation time. The cineole content ranged between 10-30% and the highest at 3 h DT with a storage time of 2 days. The optical rotation on the tested specimen showed that the index of refraction produced in oil projections was positive. The samples in all treatments showed high solubility in alcohol. This study showed that storage time of 3 days and 3-hour distillation time resulted in the most optimal eucalyptus essential oil yield, and the excellent quality of oil produced has a high potential for health product applications.
... In addition to antimicrobial and antioxidant effects, some natural compounds have beneficial effects on human health (Sutherland et al., 2009). Essential oils, plant extracts, bacteriophages, peptides, bacteriocins, and probiotic bacteria are examples of natural preservatives used to improve food quality (Aziz & Karboune, 2018;Gao et al., 2015;Gilles et al., 2010;Pandini et al., 2017). ...
The objectives of present study were to evaluate the potential of Lactobacillus reuteri or Lactobacillus casei combined with black pepper extract (BPE) and ethylenediamine tetraacetic acid (EDTA) for controlling the growth of E. coli O157:H7 and improving the chemical, microbiological and sensory quality of ground beef stored at 10 °C for 12 days. The in vitro results indicated that the combination of L. casei with BPE and EDTA had the most potent antibacterial effect against E. coli and resulted in 2.7 log CFU/ml reduction. In ground beef, the combination of L. reuteri or L. casei with BPE and EDTA decreased E. coli and aerobic mesophilic bacteria counts up to 1 and 1.6 log CFU/g, respectively. Meanwhile, this combination significantly reduced the lipid oxidation rate (up to 60%) and improved odor and overall acceptability scores of ground beef. It was concluded that the combination of L. casei with BPE and EDTA could be used in ground beef to control microbial proliferation, retard lipid oxidation, and improve sensory quality.
... Therefore, mixing of lemongrass oil with other essential oils for potential synergistic effects needs further investigations. The phytotoxicity of eucalyptus essential oil mainly refers to the monoterpene 1,8-cineol, causing oxidative stress followed by membrane disruption and electrolyte leakage [131,146,204]. It inhibits mitosis by inhibiting G1 phase and several enzymes as p38, resulting in further metabolic interceptions, for example, in photosynthesis and energy metabolism [148], which lead to cellular damage and death of the target plant [205]. ...
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.
... Different EOs had been reported for their antimicrobial activities as EO of thyme (Tohidpour et al. 2010;Hazzit et al. 2009;Rota et al. 2008;Braga et al. 2008;Khadir et al. 2016), basil (Hussain et al. 2008;Bozin et al. 2006), eucalyptus (Gilles et al. 2010), pistachio (Koutsoudaki et al. 2005) (Taran et al. 2010), savory (Oke et al. 2009;Cavar et al. 2008;Vagionas et al. 2007;Skocibusic et al. 2006), oregano (Carneiro De Barros et al. 2009;Winward et al. 2008;Bendahou et al. 2008), black cumin (Ramadan 2007;Piras et al. 2013), coriander (Lo Cantore et al. 2004), peppermint (Gulluce et al. 2007), sumac (Fazeli et al. 2007), clove, cinnamon (Oussalah et al. 2007;Oussalah et al. 2006), guarana (Majhenic et al. 2007), fennel (Lai and Roy 2004), orange, geranium, juniper, rosemary (Schelz et al. 2006), cumin, laurel, marjoram, sage (Ozcan et al. 2006;Kelen and Tepe 2008;Tepe et al. 2005), pepper, turmeric, ginger, and pine (Sacchetti et al. 2005). 16 Delivery Systems of Plant-Derived Antimicrobials 402 ...
In recent years, there has been a continuous increase in resistance to traditional antibiotics developed by pathogenic bacteria. However, in many parts of the world, several medicinal plants are traditionally used to control infectious microorganisms. Because of this, antimicrobial agents derived from natural products have received a lot of attention, both for their effectiveness and also for being more economically accessible. Therefore, the research discussed in this chapter aims to conduct a systematic review on the use of medicinal plants and isolated compounds as a potential antimicrobial agent. The study focuses on an investigation of several electronic databases: Scopus, Web of Science, Academic Google, SciELO, PubMed, SciFinder, and ScienceDirect. The results may contribute to the increase of strategies for the treatment of infections caused by microorganisms. Since medicinal plants play an essential role in health, they may represent a significant source of new antimicrobial drugs to combat microorganisms resistant to multidrug.
... Different EOs had been reported for their antimicrobial activities as EO of thyme (Tohidpour et al. 2010;Hazzit et al. 2009;Rota et al. 2008;Braga et al. 2008;Khadir et al. 2016), basil (Hussain et al. 2008;Bozin et al. 2006), eucalyptus (Gilles et al. 2010), pistachio (Koutsoudaki et al. 2005) (Taran et al. 2010), savory (Oke et al. 2009;Cavar et al. 2008;Vagionas et al. 2007;Skocibusic et al. 2006), oregano (Carneiro De Barros et al. 2009;Winward et al. 2008;Bendahou et al. 2008), black cumin (Ramadan 2007;Piras et al. 2013), coriander (Lo Cantore et al. 2004), peppermint (Gulluce et al. 2007), sumac (Fazeli et al. 2007), clove, cinnamon (Oussalah et al. 2007;Oussalah et al. 2006), guarana (Majhenic et al. 2007), fennel (Lai and Roy 2004), orange, geranium, juniper, rosemary (Schelz et al. 2006), cumin, laurel, marjoram, sage (Ozcan et al. 2006;Kelen and Tepe 2008;Tepe et al. 2005), pepper, turmeric, ginger, and pine (Sacchetti et al. 2005). 16 Delivery Systems of Plant-Derived Antimicrobials 402 ...
Pteridophytes constitute the primitive vascular plant group, which are found scattered all over the world. There are 580 taxa of Nepalese pteridophytes, which are most diverse and adapted in different climatic zones forming an attractive component of the vegetation showing different ecological habits such as epiphytic, lithophytic, terrestrial, tree ferns, hanging club mosses, climbers, and hydrophytic. Human beings have been using pteridophytes because of their several useful properties, including food and medicine. Some important bioactive compounds have been identified from the Nepalese pteridophytes and the chemical compounds isolated have shown antimicrobial properties, which has revealed that pteridophytes play a potential role in Nepalese pharmacopoeia and drug discovery. Finally, the challenges and opportunities of pteridophyte research are discussed.
... Different EOs had been reported for their antimicrobial activities as EO of thyme (Tohidpour et al. 2010;Hazzit et al. 2009;Rota et al. 2008;Braga et al. 2008;Khadir et al. 2016), basil (Hussain et al. 2008;Bozin et al. 2006), eucalyptus (Gilles et al. 2010), pistachio (Koutsoudaki et al. 2005) (Taran et al. 2010), savory (Oke et al. 2009;Cavar et al. 2008;Vagionas et al. 2007;Skocibusic et al. 2006), oregano (Carneiro De Barros et al. 2009;Winward et al. 2008;Bendahou et al. 2008), black cumin (Ramadan 2007;Piras et al. 2013), coriander (Lo Cantore et al. 2004), peppermint (Gulluce et al. 2007), sumac (Fazeli et al. 2007), clove, cinnamon (Oussalah et al. 2007;Oussalah et al. 2006), guarana (Majhenic et al. 2007), fennel (Lai and Roy 2004), orange, geranium, juniper, rosemary (Schelz et al. 2006), cumin, laurel, marjoram, sage (Ozcan et al. 2006;Kelen and Tepe 2008;Tepe et al. 2005), pepper, turmeric, ginger, and pine (Sacchetti et al. 2005). 16 Delivery Systems of Plant-Derived Antimicrobials 402 ...
The Brazilian Amazon is the largest biome in the country and encompasses about 40% of the forest remnants of the humid tropic. The use of homemade medicines from medicinal plants has been practiced since the dawn of human civilization. In prehistoric age, man sought to alleviate his pain or treat his illnesses through the action of bioactive compounds present in plants, although in an intuitive way based on random discoveries. Such secondary metabolites of medicinal plants have proven to have antimicrobial activity due to the action of their bioactive compounds. The extraction of bioactive compounds is an especially important step, not only for the separation of compounds, but also during the analysis of solid materials. There are several conventional and unconventional techniques for the extraction of bioactive compounds from plant matrices, those that use a solvent. Nanotechnology emerges as a potential technology to enhance the action of bioactive compounds present in plant matrices, as it can maintain its characteristics and stability, making these compounds used in several areas. As many of the biologically active compounds have insolubility and hydrophobicity, nanoencapsulation facilitates the delivery of these poorly bioavailable compounds when applied to functional products and drugs, which increases their absorption into cellular structures through properties of favorable particles of shape, size, and surface. Nanotechnology has proved to be a great tool to potentiate the action of such bioactive compounds.
... Different EOs had been reported for their antimicrobial activities as EO of thyme (Tohidpour et al. 2010;Hazzit et al. 2009;Rota et al. 2008;Braga et al. 2008;Khadir et al. 2016), basil (Hussain et al. 2008;Bozin et al. 2006), eucalyptus (Gilles et al. 2010), pistachio (Koutsoudaki et al. 2005) (Taran et al. 2010), savory (Oke et al. 2009;Cavar et al. 2008;Vagionas et al. 2007;Skocibusic et al. 2006), oregano (Carneiro De Barros et al. 2009;Winward et al. 2008;Bendahou et al. 2008), black cumin (Ramadan 2007;Piras et al. 2013), coriander (Lo Cantore et al. 2004), peppermint (Gulluce et al. 2007), sumac (Fazeli et al. 2007), clove, cinnamon (Oussalah et al. 2007;Oussalah et al. 2006), guarana (Majhenic et al. 2007), fennel (Lai and Roy 2004), orange, geranium, juniper, rosemary (Schelz et al. 2006), cumin, laurel, marjoram, sage (Ozcan et al. 2006;Kelen and Tepe 2008;Tepe et al. 2005), pepper, turmeric, ginger, and pine (Sacchetti et al. 2005). 16 Delivery Systems of Plant-Derived Antimicrobials 402 ...
Honey bee products have been used since ancient times as food and therapeutics. There is increasing knowledge on their content and molecular mechanism of action. Their bioactive compounds are a combination of both honey bee and plant origin. Plant immune response effectors are secondary metabolites (polyphenols, terpenes, antimicrobial peptides), and they are responsible for the antimicrobial effects of honey bee products like honey, propolis, and bee pollen. Honey bee innate immunity effectors are antimicrobial peptides, like defensin 1 and 2, apidaecins, abaecins, and hymenoptaecin, and some of them have been found in royal jelly, honey, and pollen. Plant secondary metabolites and honey bee antimicrobial peptides combine in beehive mixtures with synergistic antimicrobial activity and undoubtedly represent an interesting alternative to standard antibiotics. Further research should elucidate their interactions in honey bee products as well as their potential biotechnology applications.
... Different EOs had been reported for their antimicrobial activities as EO of thyme (Tohidpour et al. 2010;Hazzit et al. 2009;Rota et al. 2008;Braga et al. 2008;Khadir et al. 2016), basil (Hussain et al. 2008;Bozin et al. 2006), eucalyptus (Gilles et al. 2010), pistachio (Koutsoudaki et al. 2005) (Taran et al. 2010), savory (Oke et al. 2009;Cavar et al. 2008;Vagionas et al. 2007;Skocibusic et al. 2006), oregano (Carneiro De Barros et al. 2009Winward et al. 2008;Bendahou et al. 2008), black cumin (Ramadan 2007;Piras et al. 2013), coriander (Lo Cantore et al. 2004), peppermint (Gulluce et al. 2007), sumac (Fazeli et al. 2007), clove, cinnamon (Oussalah et al. 2007;Oussalah et al. 2006), guarana (Majhenic et al. 2007), fennel (Lai and Roy 2004), orange, geranium, juniper, rosemary (Schelz et al. 2006), cumin, laurel, marjoram, sage (Ozcan et al. 2006Kelen and Tepe 2008;Tepe et al. 2005), pepper, turmeric, ginger, and pine (Sacchetti et al. 2005). ...
The use of essential oils as antimicrobial agents is widely applied in medical field, pharmaceutical industry, and food preservation. However, essential oils are hydrophobic, volatile, and unstable; in addition, they undergo degradation by environmental factors, such as light, oxygen, and heat, which represent obstacles for their wide utility. Green industry via incorporating these natural substances in pharmaceutical vehicles is one of the most commonly used technologies to impart exclusive features for the essential oils. Desirably, assortment of lipid and non-lipid-based delivery systems have been employed aiming to improve their stability and antimicrobial activity, provide sustained release pattern, and boost their bioavailability. This chapter offers an overview of various delivery systems that have been utilized to encapsulate some antimicrobial essential oils exploitable in the pharmaceutical field in recent literature. The versatility of nature of the proposed vehicles and harnessed natural and synthetic polymers, as well as advancement in fabrication techniques, are highlighted. Specifically, the stability and fulfillment of antimicrobial effectiveness of encapsulated essential oils are greatly emphasized.
... The RGEO exhibited a moderate MIC for S. mutans and S. pyogenes and showed low activity against the rest of the analyzed bacteria. Overall, RGEO showed low efficiency in inhibiting the Gram-negative strains compared to Gram-positive strains, following previous studies [6,27,49,61,62]. These differences in susceptibility could be associated with different rates of penetration of EO constituents into the cell wall and cell membrane structures. ...
The research aimed to investigate the chemical composition and antioxidant and antibac-terial potential of the essential oil (EO) isolated from the aerial parts (flowers, leaves, and stems) of Ruta graveolens L., growing in western Romania. Ruta graveolens L. essential oil (RGEO) was isolated by steam distillation (0.29% v/w), and the content was assessed by gas chromatography-mass spec-trometry (GC-MS). Findings revealed that 2-Undecanone (76.19%) and 2-Nonanone (7.83%) followed by 2-Undecanol (1.85%) and 2-Tridecanone (1.42%) are the main detected compounds of the oil. The RGEO exerted broad-spectrum antibacterial and antifungal effects, S. pyogenes, S. aureus, and S. mutans being the most susceptible tested strains. The antioxidant activity of RGEO was assessed by peroxide and thiobarbituric acid value, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), and β-carotene/linoleic acid bleaching testing. The results indicated moderate radical scavenging and relative antioxidative activity in DPPH and β-carotene bleaching tests. However, between the 8th and 16th days of the incubation period, the inhibition of primary oxidation compounds induced by the RGEO was significantly stronger (p < 0.001) than butylated hydroxyanisole (BHA). Molecular docking analysis highlighted that a potential antimicrobial mechanism of the RGEO could be exerted through the inhibition of D-Alanine-d-alanine ligase (DDl) by several RGEO components. Docking analysis also revealed that a high number RGEO components could exert a potential in vitro protein-targeted antioxidant effect through xanthine oxidase and lipoxygenase inhibition. Consequently, RGEO could be a new natural source of antiseptics and antioxidants, representing an option for the use of synthetic additives in the food and pharmaceutical industry. Citation: Jianu, C.; Goleț, I.; Stoin, D.; Cocan, I.; Bujancă, G.; Mișcă, C.; Mioc, M.; Mioc, A.; Șoica, C.; Lukinich-Gruia, A.T.; et al.
Background and objectives: Medicinal plants have a much healthier effect than chemical drugs, and due to the presence of various effective substances, they can be used in the prevention and treatment of many diseases. This research aims to compare the performance of hydroalcoholic extracts of eucalyptus and garlic in reducing the fungal and bacterial load of Persian sturgeon (Acipenser persicus) eggs during incubation. Methodology: At first, enough sperm and eggs were obtained from Persian sturgeon male and female breeders after artificial propagation stages. After fertilization, the eggs were weighed by a digital scale. The number of eggs per gram, the total weight of eggs per tray, and the final number of eggs stored in the incubator were calculated. Considering the allocation of three trays for each treatment, the number of stored eggs for each treatment was 15000. The total number of stored eggs for five treatments was 75000. Hydroalcoholic extracts (70% ethanol solvent) of eucalyptus (appearance: clear, color: brown, pH=5.02) and garlic (appearance: clear, color: light brown, pH=6.49) were prepared. Five experimental treatments containing control (no extract), Eucalyptus 50 mg.l-1 , eucalyptus 100 mg.l-1 , Garlic 50 mg.l-1 , and 100 mg.l-1 were designed in three replicates by the short-term bath method in three stages (days). At the end of the three disinfection stages, eggs were randomly sampled from each replicate for the total bacterial and fungal count. Results: No significant difference was observed in the water's physical and chemical factors, such as pH, dissolved oxygen, and temperature, during the disinfection stages of eggs (p<0.05). The results showed that treatments containing eucalyptus and garlic extracts at 50 and 100 mg/l showed lower total bacterial and fungal counts than the control treatment (P<0.05). Still, the eucalyptus extract at 100 mg/l performed much better than the rest of the experimental treatments (P<0.05). In incubation indices such as hatching rate and healthy larvae, statistically significant differences were observed in four treatments containing garlic and eucalyptus extracts (50 and 100 mg.l-1) with the control (P<0.05). Based on Duncan's test, the average rate of hatching and the number of healthy larvae were more in eucalyptus at 100 mg.l-1 than in other studied treatments (P<0.05). Egg hatching rates were equal in garlic and eucalyptus at 100 and 50 mg.l-1 , respectively. Conclusion: During the research, there was no change in the appearance of the larvae, which can be considered the safety of plant extracts. Various factors such as the type and compounds
This study presents systematic data on the major percentage of compounds from aromatic plants, the yield of oil, the method used to extract oil, the scent profile, and their uses. Since then, essential oils have gained popularity due to the high potential of their novel properties, i.e. as fragrant raw materials for many products such as toothpaste, hand soap, shampoos, hair oils, bath soap, cosmetic products, floor cleaner, mosquito repellents, incense sticks, food products, therapeutic products, herbal medicines, etc. Therefore, before using some raw materials that are naturally fragrant in products, it is crucial to understand their features, such as the percentage of molecules from aromatic plants, the percentage of oil yield, the used process for oil extraction, and their fragrance profiles. It will be highly beneficial in the development of new, high-quality products items. Researchers, scientists, business owners, farmers, and industries will all benefit at the same time when new fragrance goods are developed. Abstract Introduction The secondary metabolites, volatile, fragrant oils known as essential oils (EOs) are derived from the different parts of plants and are utilised by them as defence mechanism against attacks by herbivore (Blowman, K., et.al., 2018). The hydrophobic liquids that make up these complex, concentrated combinations of terpenoid hydrocarbons,
O objetivo deste trabalho foi avaliar a atividade antimicrobiana, in vitro, dos óleos essenciais de Cymbopogon citratus e Lippia alba (Mill) N. E. Brown contra microrganismos patogênicos e deterioradores de alimentos. Os óleos foram extraídos por hidrodestilação e caracterizados quanto à composição química por cromatografia gasosa. A atividade antimicrobiana dos óleos foi determinada pelo método de difusão em ágar e, as concentrações inibitórias e bactericidas mínimas foram determinadas pelo método de microdiluição em caldo. As espécies bacterianas utilizadas foram Staphylococcus aureus, Listeria monocytogenes, Listeria innocua, Escherichia coli, Pseudomonas aeruginosa e Salmonella choleraesuis. Os principais componentes identificados no óleo de C. citratus foram geranial e neral, enquanto os componentes majoritários do óleo de L. alba foram e-citral e neral. Os dois óleos apresentaram atividade antimicrobiana contra todas as espécies bacterianas testadas. A zona de inibição do óleo de C. citratus variou de 33 ± 2,8 mm (S. aureus) a 10 ± 0,0 mm (S. choleraesuis) e a zona de inibição do óleo de L. alba variou de 15,5 ± 0,7 mm (S. aureus) a 8,0 ± 0,0 mm (P. aeruginosa). As concentrações inibitórias mínimas (CIM) e as concentrações bactericidas mínimas (CBM) do óleo essencial de L. alba foram menores para S. aureus, L. monocytogenes, L. innocua e E. coli, enquanto que o óleo de C. citratus apresentou CIM e CBM menores para P. aeruginosa e S. choleraesuis. Os resultados mostram que os óleos essenciais avaliados podem ser uma alternativa eficiente para o controle de bactérias patogênicas e deterioradoras de alimentos.
Este trabalho de pesquisa teve como foco o desenvolvimento da formulação de um xarope à base de extratos vegetais de buganvília, canela, calêndula, eucalipto e ítamo para inibir o crescimento de S. aureus e S. pyogenes, bactérias associadas a infecções respiratórias. Determinar os metabólitos secundários nos extratos metanólicos de cada espécie, bem como avaliar a atividade antibacteriana dos extratos em xaropes, e sua capacidade antioxidante. Verificou-se que o extrato de eucalipto é o melhor para inibir as bactérias, assim como na forma de xarope, e o extrato de canela é o melhor antioxidante.
Os fungos causam diversos prejuízos à indústria alimentícia, como a deterioração de alimentos e doenças nas lavouras, sendo um problema constante. A utilização excessiva de compostos químicos, para o controle desses microrganismos, vem causando graves danos ao meio ambiente e à saúde humana. O uso de métodos controles, de origem natural, no combate a essas populações é uma excelente opção de substituição de substâncias sintéticas tóxicas. O pequi (Caryocar brasiliense), um fruto do Cerrado, tem sido retratado na bibliografia com grande potencial antifúngico e antibacteriano. No presente estudo, avaliou-se in vitro, o efeito do óleo essencial extraído da polpa do pequi (Caryocar brasiliense) no controle do crescimento das espécies fúngicas Aspergillus carbonarius, Aspergillus niger e Aspergillus ochraceus. O óleo essencial foi extraído pelo processo de hidrodestilação, utilizando aparelho de Clevenger, e sua atividade antifúngica foi avaliada através da determinação da Concentração Mínima Inibitória e com a utilização do óleo essencial no meio de cultura. Não foram detectadas concentrações mínimas inibitórias do óleo essencial sobre as espécies testadas. Houve inibição do crescimento micelial das espécies, ao utilizar o óleo no meio de cultura, na concentração de 125 µL mL-1, demonstrando a atividade antifúngica do óleo essencial sobre as cepas estudadas.
In this study, the antibacterial effect of eucalyptus extract on different bacteria
showed that the bulk of compounds present in the sap of eucalyptus leaves were
formed by the phenolic compounds. starch was prepared for the production of
starch film was used to improve the quality of film by 10 % of the volume of
glycerol. ground beef production was evaluated by adding 0.5 and 1.5 percent of
eucalyptus oil to the film, then ground mutton meat was packed with film, and
microbial and chemical properties and transparency of meat after preservation in
the fridge were studied in times 1, 3 and 6 days. according to the results,
inhibition of DPPH increased with an increase in the amount of extract and the
highest percentage was reported on day 3. also the results of TBA with a decrease
in the amount of extract decreased and the maximum reduction rate was reported
on day 3. according to the results, the total population count of microorganisms
decreased with an increase in the amount of extract and the maximum reduction
rate was reported on day 3, but did not have significant differences with the
sample count on the day 6 with the spread of corruption. (P> 0.05) is based on the
results that Staphylococcus aureus has decreased by increasing the amount of
extract and the maximum reduction rate is reported on day 3. However, on the
day 3 at 0.5 % extract, its extracts and on the day 6 with the spread of corruption,
the number of samples did not show significant differences. according to the
results, the amount of transparency and color spectrum decreased with the
increase of the extract and had significant differences with the sample (p < 0.05).
In this study, the antibacterial effect of eucalyptus extract on different bacteria
showed that the bulk of compounds present in the sap of eucalyptus leaves were
formed by the phenolic compounds. starch was prepared for the production of
starch film was used to improve the quality of film by 10 % of the volume of
glycerol. ground beef production was evaluated by adding 0.5 and 1.5 percent of
eucalyptus oil to the film, then ground mutton meat was packed with film, and
microbial and chemical properties and transparency of meat after preservation in
the fridge were studied in times 1, 3 and 6 days. according to the results,
inhibition of DPPH increased with an increase in the amount of extract and the
highest percentage was reported on day 3. also the results of TBA with a decrease
in the amount of extract decreased and the maximum reduction rate was reported
on day 3. according to the results, the total population count of microorganisms
decreased with an increase in the amount of extract and the maximum reduction
rate was reported on day 3, but did not have significant differences with the
sample count on the day 6 with the spread of corruption. (P> 0.05) is based on the
results that Staphylococcus aureus has decreased by increasing the amount of
extract and the maximum reduction rate is reported on day 3. However, on the
day 3 at 0.5 % extract, its extracts and on the day 6 with the spread of corruption,
the number of samples did not show significant differences. according to the
results, the amount of transparency and color spectrum decreased with the
increase of the extract and had significant differences with the sample (p < 0.05).
The present study aims to determine and compare the chemical composition of essential oils (EO) and hydrolat extracts (HE), isolated from three wild varieties of Moroccan thyme (T. satureioides Coss., T. willdenowii Boiss. and T. zygis L.) and to assess their antibacterial activity against four bacterial strains: Gram- (E. coli, Pr. Mirabilis) and Gram+ (B. subtilis, S. aureus). The findings showed that carvacrol (44.95%) and its biogenetic precursor p-cymene (23.36%) were the most dominant compounds of T. zygis L EO. The major volatile compounds in T. willdenowii Boiss EO were found to be thymol (42.38%), carvacrol (16.49%), and p-cymene (13.29%). Thus, T. satureioides Coss EO consists mainly of carvacrol (27.57%) and borneol (21.56%). On the other hand, carvacrol (72.33 %) and thymol (10.70%) were the most prominent constituents in T. zygis L HE. T. willdenowii Boiss was dominated by thymol (65.01%) and carvacrol (21.74%). Furthermore, T. satureioides Coss HE was characterized by a high percentage of carvacrol (47.45%), borneol (25.04%), and γ-terpineol (19.34%). All investigated extracts exercised a strong antibacterial power against both tested Gram-positive and Gram-negative strains. However, the weakest activity was observed with T. satureioides Coss. EO and HE. The biological potential of HEs was found much higher than that of the corresponding EOs, which may give hydrolats a great value in aromatherapy to the detriment of essential oils.
The complex taxonomy of Eucalyptus genus, the renewed interest in natural compounds able to combat microbial strains, the overuse of synthetic pesticides, the consequent request for alternative control methods were the reasons for this research. The essential oils (Eos) of Eucalyptus bosistoana, Eucalyptus melliodora, Eucalyptus odorata, Eucalyptus paniculata, Eucalyptus salmonopholia, and Eucalyptus transcontinentalis were analyzed by GC/MS and their potential phytotoxic activity was evaluated against the germination and radicle elongation of Sinapis arvensis, Raphanus sativus and Lolium multiflorum. The antibiofilm activity was assayed against both Gram-positive (Staphylo-coccus aureus and Listeria monocytogenes) and Gram-negative (Pseudomonas aeruginosa, Escherichia coli, and Acinetobacter baumannii) bacteria. Monoterpenoids were the most representative constituents in all EOs and eucalyptol was the dominant component except in E. melliodora EO, in which p-cymene was the most abundant. In phytotoxic assays, the EOs from E. odorata and E. paniculata were the most active against germination and radical elongation of the tested seeds. Finally, the Eucalyptus EOs proved their capacity to effectively inhibit the adhesion process of all five pathogen strains, with percentages often reaching and exceeding 90%. These Eucalytpus EOs could have possible em-ployments in the food, health and agricultural fields.
Eucalyptus plants are found to be located in a variety of places such as low rainfall areas, schools, colleges, and government hospitals. The leaves remain fallen beneath the plants for several months, as they contain a variety of phenolic compounds and terpenes, which are responsible for its multipurpose properties, such as antifungal, antibacterial, analgesic and anti-inflammatory. Out of this 1.8 cineol is found to be major constituent and responsible for inhibiting microbial growth, which is a prime requirement of biological waste degradation and composting. To fasten the degradation process, the phenolic compounds were isolated smoothly by grinding the eucalyptus leaves, followed by extraction with hot boiling water, precomposting of residue with available garden soil and water from bio-reactor of effluent treatment plant (ETP), instead of cow dung and then vermicomposting. This process was found to be cost-effective, giving better quality of vermicompost with good carbon-to-nitrogen (C/N) ratio, macro- and micronutrients for valuable soil amendment and sustainable agriculture growth. The process was found to be user-friendly, eco-friendly, sustainable and could be used for available substrates with possible pre-treatment. The process could be converted from conventional batch process to continuous process by the technique of precomposting with carbon- and nitrogen-rich biodegradable substrates. Physico-chemical analysis techniques such as electrical conductivity, pH, humification index, FT-IR spectroscopic technique and C/N ratio are found to be comparatively easy, fast, and effective techniques for monitoring vermicomposting process as well as determining completion, quality, and stability of vermicompost produced.
Catalytic hydropyrolysis of eucalyptus leaves was investigated in a batch reactor over four catalysts (H-BEA, Ni/BEA, Ni/Fe-BEA and Fe/BEA). HBEA catalyst exhibited a higher monoaromatic hydrocarbons (MAHs) selectivity compared to non-catalytic pyrolysis. However, the selectivity to polyaromatic hydrocarbons (PAHs) was not significantly reduced by the addition of a protonic zeolite. The highest cycloalkanes selectivity (78.5%) was observed over Ni/BEA, owing to its high concentration of Ni sites as well as acid sites, facilitating the hydrogenation and ring-opening of polyaromatic hydrocarbons together with the hydrodeoxygenation of phenols. In contrast, the Ni/Fe-BEA exhibits the highest selectivity of MAHs, suggesting the Ni-Fe species facilitate the partial hydrogenation of PAHs and hydrogenolysis of phenols but restrict the further hydrogenation of aromatic monomers. Moreover, the reduction of CO to CH4 was restricted over Ni-Fe/BEA compared to Ni/BEA. A high selectivity of phenols and PAHs was detected over Fe/BEA due to the high oxophilicity but low hydrogenation activity of Fe species, hindering the hydrogenation of PAHs and HDO of phenols. The spent Ni/BEA and spent Ni/Fe-BEA catalysts exhibited a higher surface area and pore volume as well as lower mass of deposited carbon compared to spent HBEA and spent Fe/BEA catalysts, suggesting the catalyst deactivation was restricted by hydrogenation metal (Ni, Ni-Fe) and dissociated H species. Besides, high H2 pressure promoted the hydrogenation and ring-opening of polyaromatic hydrocarbons, and high reaction temperature hindered the hydrogenation of MAHs to cycloalkanes. The highest selectivity to MAHs (85.1%) with a 62% selectivity of BTEX was observed over Ni/Fe-BEA catalyst at 400 °C and an initial H2 pressure of 3.0 MPa.
We have successfully constructed citrus essential oil (CEO, d-limonene is its main active component) nanoemulsion by the high-pressure homogenization method, whose droplet size, polydispersity index, and zeta potential were 34.23 nm, 0.235, and −25.87 mV, respectively. The effects of thermal treatment (−20–48 °C), pH (5–9), ionic strength (100–500 mM NaCl) and storage time (200 days) were examined on the physicochemical properties of all treatments. The antimicrobial activity of nanoemulsion was tested by determining the minimal inhibitory concentration against the four foodborne microorganisms (Escherichia coli (10 mg/mL), Staphylococcus aureus (0.150 mg/mL), Bacillus subtilis (0.312 mg/mL) and Saccharomyces cerevisiae (0.312 mg/mL)). Especially, compared with pure CEO, the antibacterial activity of its nanoemulsion against S. aureus (0.150 mg/mL) and B. subtilis (0.312 mg/mL) was increased by 43 and 86 times respectively. Industrial relevance: In this work, we constructed robust CEO nanoemulsions based on a combination of emulsifiers via the high-pressure homogenization method, which bring new insights into the preparation of nanoemulsions. There is great potential for nanoencapsulation of natural compounds in the field of food preservation. Furthermore, the results may provide valuable data for industrial scale-up application.
Several species of the genus Eucalyptus are used in many traditional medicine systems for the treatment of respiratory tract infections, colds, flu, sore throats, and bronchitis. The genus Eucalyptus (Myrtaceae) is a well‐known natural source of bioactive phloroglucinols. These polyphenolic compounds bear an aromatic phenyl ring with three hydroxy groups (1,3,5‐trihydroxybenzene) which have been exhibiting a variety of biological activities such as antimicrobial, anticancer, anti‐allergic, anti‐inflammatory, and antioxidant activities. This review summarizes the literature published from 1997 until the end of 2021 and addresses the structure diversity of phloroglucinols isolated from Eucalyptus species and their biological activities. Phloroglucinol‐terpene adducts are the main class of compounds that have been reported in this genus.
Medicinal traditional plants are a source of inspiration for the discovery of new bioactive substances. Plant infusions, extracts, and essential oils are known for their diverse biological activity since they are rich in secondary metabolites. The Mediterranean area in general and Lebanon in particular is known for its plant diversity due to its climate and geographical location. This chapter will provide an overview of Lebanese plants with antimicrobial activity. Many of these plants are known for their culinary and traditional medicinal uses for the treatment of different ailments. The main plant families discussed here include Amaryllidaceae, Anacardiaceae, Apiaceae, Asteraceae, Berberidaceae, Cannabaceae, Cistaceae, Lamiaceae, Myrtaceae, Pinaceae, Portulacaceae, Ranunculaceae, Rutaceae, Rosaceae, and others.
Understanding immunity in wildlife populations is important from both One Health and conservation perspectives. The constitutive innate immune system is the first line of defence against pathogens, and comparisons among taxa can test the impact of evolution and life history on immune function. We investigated serum bacterial killing ability (BKA) of five marsupial species that employ varying life history strategies, demonstrated to influence immunity in other vertebrates. The brushtail possum and eastern grey kangaroo had the greatest BKA, while ringtail possums and koalas had the least. These differences were independent of social structure, captivity status and phylogeny, but were associated with diet and body size. Sex and disease status had no effect on BKA in koalas, however potential for differences between wild and captive koalas warrants further investigation. The current study has provided a foundation for future investigations into how adaptive and innate immunity interact in marsupials from an eco-evolutionary perspective.
The antibacterial activity and mechanism of plant essential oils against the specific spoilage organism of aquatic products in vitro were studied. All four selected essential oils performe antibacterial activities against five targeted bacterial strains (Escherichia coli, Shewanella putrefaciens, Pseudomonas aeruginosa, Vibrio parahaemolyticus, and Staphylococcus aureus), while eucalyptus essential oil (EEO) displayed the highest inhibitory effect in five strains. The minimum inhibitory concentrations (MIC) of EEO against five bacteria was in the range of 0.63–2.00 µl/ml. Scanning electron microscopy and transmission electron microscopy displayed noticeable damages of bacterial morphology and ultrastructure on two model bacteria. The increments of electric conductivity and the optical density at 260 nm and the decrease of intracellular ATP content, suggesting that the permeability of bacterial membrane increased while cell integrity and cell physiological function were damaged when treated with EEO at MIC. Therefore, the great potential of EEO in seafood preservation has been shown, which provides new insight for further researches. Essential oils extracted from natural plants are considered to be served as alternative sources of antibacterial components. In our study, eucalyptus essential oil (EEO) showed excellent antibacterial ability by affecting cell physiological function, which was possibly resulted from a loss of cell homeostasis. Therefore, it has a great potential in the utilization of EEO in seafood preservation.
Adams, R. P. 2007. Identification of essential oil components by gas chromatography/ mass spectrometry, 4th Edition. Allured Publ., Carol Stream, IL
Is out of print, but you can obtain a free pdf of it at
www.juniperus.org
During screening of twenty six essential oils against Botrytis cinerea, the essential oils of the ten plants viz. Chenopodium ambrosioides, Eucalyptus citriodora, Eupatorium cannabinum, Lawsonia inermis, Ocimum canum, O. gratissimum, O. sanctum, Prunus persica, Zingiber cassumunar and Z. officinale were found to exhibit absolute fungitoxic activity (100% growth inhibition). The essential oils of O. sanctum, P. persica and Z. officinale were selected for further investigation because these oils showed lower Minimum Inhibitory Concentration (MIC) as compared
to the other fungitoxic oils. The selected oils were subsequently standardized through physico-chemical and fungitoxic properties.
The MIC values of O. sanctum, P. persica and Z. officinale were found to be 200, 100 and 100ppm (mg/l) respectively. The oils showed fungistatic nature at their respective MIC. The
oils were thermostable, and exhibited a wide range of fungitoxicity against 15 other post-harvest fungal pathogens. The oils
had the potency to withstand high inoculum density. The antifungal potency of oils was found to be greater in comparison to
some prevalent synthetic fungicides. Practical applicability of the essential oils was observed in control of grey mould of
grapes caused by B. cinerea during storage. The O. sanctum- and P. persica-oil-treated grapes showed enhancement of storage life up to 5 and 4days respectively. The storage life of Z. officinale-oil-treated grapes was found to be enhanced up to 6days. The oils did not exhibit any phytotoxic effect on the fruit peel.
Therefore, the oils could be recommended as a potential source of ecofriendly botanical fungicide, after long term and wide
ranging trials.
The present study describes the phytochemical profile and antimicrobial activity of Satureja subspicata Vis. essential oils, collected in Dalmatia (Croatia). Three samples of essential oils were obtained from the aerial parts of the plant by hydrodistillation and analyzed by GC–MS. From the 24 compounds representing 97.47% of the oils, carvacrol (16.76%), α-pinene (13.58), p-cymene (10.76%), γ-terpinene (9.54%) and thymol methyl ether (8.83%) appear as the main components. The oils also contained smaller percentages of myrcene, linalool, β-caryophyllene, limonene, geranyl acetate, 1-Octen-3-ol, nerol, thymol and borneol. Furthermore, antimicrobial activity of the oil was evaluated using agar diffusion and broth microdilution methods. The antimicrobial test results showed that the oils had a great potential antimicrobial activity against all 13 bacteria and 9 fungal strains. Gram-positive bacteria are more sensitive to the investigated oil, with a range of 0.09 to 6.25 μl/ml than Gram-negative bacteria in the range which is significantly higher from 1.56 to 25.00 μl/ml. Results presented here may suggest that the essential oil of S. subspicata possesses antimicrobial properties, and is therefore a potential source of antimicrobial ingredients for the food and pharmaceutical industry.
The composition and variability of the essential oils of several populations of Thymus caespititius from Portugal were investigated by GC, GC-mass spectrometry and 13C NMR. All samples from NW Portugal were characterized by their high α-terpineol content, while the main components in the oil sample from Pico island (Azores archipelago) were carvacrol and thymol. The analytical data of individual samples from NW Portugal showed no chemical polymorphism in this area. The different areas of distribution (NW Portugal and Azores) that show great climatic and soil variation conditions may be the origin of the α-terpineol-type oil from NW Portugal and the carvacrol/thymol-type oil from the Azores. 13C NMR spectra of the essential oil, previously fractionated by column chromatography, led to the identification of trans-dihydroagarofuran, a new oxygenated sesquiterpene for the genus Thymus and a characteristic compound of T.caespitiuius.
Diffusion and dilution methods have been employed to study the antimicrobial activity of medicinal plants. A number of modifications have been made in the technique in order to obtain better results. Since some factors (culture medium composition, microorganisms tested, extractive method, pH, solubility of the sample in the culture medium, etc.) can change results, it is difficult using these methods to standardize a procedure for the study of antimicrobial plants. Bioautography is another method for studying antimicrobial activity. With it, previously chromatographed principles are diffused to the agar. The results can also change according to the method employed. All the various techniques are reviewed here and, in order to unify the different criteria and parameters, standard methods to study the antimicrobial activity of medicinal plants are proposed.
The beneficial health effects of extracts from many types of plants that are used as seasoning agents in foods and beverages have been claimed for centuries. The purpose of this study was to examine the effectiveness of selected herb and spice essential oils for control of growth and survival of microorganisms. Inhibition of growth was tested by the paper disc agar diffusion method. Antibiotic susceptibility discs were used as control. Minimum lethal concentration (MLC) was determined by the tube dilution method. Essential oils from anise, angelica, basil, carrot, celery, cardamom, coriander, dill weed, fennel, oregano, parsley, and rosemary were evaluated. Inhibition ranged from complete with oregano to no inhibition with carrot oil for each of the test strains that included: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O:157:H7, Yersinia enterocolitica, Pseudomonas aeruginosa, Lactobacillus plantarum, Aspergillus niger, Geotrichum, and Rhodotorula. Oregano essential oil showed the greatest inhibition (zone, > or = 70 to 80 mm) (MLC, approximately 8 ppm). Coriander and basil were also highly inhibitory (MLC, approximately 25 to 50 ppm) to E. coli O:157:H7 and to the other bacteria and fungi tested. Anise oil was not particularly inhibitory to bacteria (inhibition zone, approximately 25 mm); however, anise oil was highly inhibitory to molds. Because some of the herbal and spice essential oils are highly inhibitory to selected pathogenic and spoilage microorganisms, they may provide alternatives and supplements to conventional antimicrobial additives in foods.
The antimicrobial activity of three Salvia species, i.e. S. santolinifolia, S. hydrangea and S. mirzayanii, essential oils were investigated. The essential oils were obtained from the aerial parts of plants and analyzed by GC-MS. The main constituents of aforementioned species were alpha-pinene (72.4%), beta-pinene (6.6%) and limonene (5.3%); beta-caryophyllene (25.1%), 1,8-cineol (15.2%) and caryophyllene oxide (11.5%); alpha-terpinenyl acetate (22.6%), 1,8-cineol (21.2%) and linalool (8.9%), respectively. Bioassays exhibited that the property of the oil of S. myrzayanii was superior to others. The antimicrobial activity of essential oil from Salvia species may well be due to the presence of synergy between six tested compounds (linalool, 1,8-cineol, alpha-pinene, beta-pinene, beta-caryophyllene and limonene) and other constituents of the oils with various degrees of antimicrobial activity. Among these, linalool and 1,8-cineol had the highest antimicrobial activity.
Unlabelled:
The objective of the present study was that of verifying a possible synergistic antibacterial effect between Pelargonium graveolens [Lis-Balchin, M., Deans, S.G., Hart, S., 1996. Bioactive Geranium oils from different commercial sources. J. Essential Oil Res. 8, 281-290.] essential oil (and its main components) and Norfloxacin antibiotic. As a first step growth inhibition by some types of essential oils was assessed in five microbial species. The antimicrobial effects of P. graveolens oil, as well as those of its components, were evaluated by means of the agar dilution method (ADM) against Bacillus cereus ATCC 11778, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 35218, Staphylococcus aureus ATCC 6538 and S. aureus ATCC 29213. The results obtained highlighted the occurrence of a pronounced synergism between P. graveolens essential oil and Norfloxacin against three of the five bacterial species under study with a FIC index in the 0.37-0.50 range. Such antibacterial effects were also shown to increase, although to a lesser extent, when Norfloxacin was given with the main components of P. graveolens essential oil.
Significance and impact of the study:
The combination of Norfloxacin with either P. graveolens essential oil, or with some of the main components of this latter, in the treatment of infections caused by some bacterial species is likely to reduce the minimum effective dose of Norfloxacin thus minimizing the side effects of the antibiotic.
A total of 39 essential oils were tested for antifungal activities as volatile compounds against five phytopathogenic fungi at a dose of 1 per plate. Five essential oils showed inhibitory activities against mycelial growth of at least one phytopathogenic fungus. Origanum vulgare essential oil inhibited mycelial growth of all of the five fungi tested. Both Cuminum cyminum and Eucalyptus citriodora oils displayed in vitro antifungal activities against four phytopathogenic fungi except for Colletotrichum gloeosporioides. The essential oil of Thymus vulgaris suppressed the mycelial growth of C. gloeosporioides, Fusarium oxysporum and Rhizoctonia solani and that of Cymbopogon citratus was active to only F. oxysporum. The chemical compositions of the five active essential oils were determined by gas chromatography-mass spectrometry. This study suggests that both E. citriodora and C. cyminum oils have a potential as antifungal preservatives for the control of storage diseases of various crops.
Nine plant essential oils (EOs) were studied for their anti-bacterial effect on spores and vegetative cells ofClostridium botulinum62A andBacillus cereusT. Cedar oil at the concentration of 300 ppm was the most active againstB. cereusT andC. botulinumspores and vegetative cells. Spores were generally less resistant than vegetative cells, except for the essential oils of eucalyptus and camomile (300 ppm), which demonstrated a significant activity againstB. cereusT andC. botulinumvegetative cells. In general, spores ofBacillus were more sensitive to these essential oils thanClostridiumspores. ForB. cereusT, EO of rosemary (≥170 ppm), eucalyptus (≥450 ppm), orange (≥300 ppm), savage carrots (≥400 ppm) and artemisia (≥500 ppm) were partially sporicidal; whereas, EO of camomile and grapefruit (≥300 ppm) were sporostatic. In the case ofC. botulinum62A, eucalyptus, camomile, savage carrots, vervain, grapefruit and orange oils were sporostatic at the tested concentrations. However, EO of cedar (≥300 ppm) was partially sporicidal. These EOs inhibited specifically one or more stage(s) of the spore cycle depending on the EO and its concentration. Eucalyptus, orange, artemisia and cedar oils (300 ppm) and grapefruit, savage carrots and vervain (400 ppm) inhibited the growth ofC. botulinum62A spores by blocking their germination inL-alanine. The inhibition of spore germination ofC. botulinum62A by EOs (at ≥300 ppm) was by inhibition of commitment-to-germinate of spores. However, the outgrowth was not sensitive to cedar, eucalyptus, vervain and savage carrots oils at the concentration of 400 ppm.
Pet. Ether (65°-69°C) extracts of Eucalyptus olida L. Johnson et K. Hill leaves and stems from 3-5 year old trees in a trial planting generally contained very high levels (>91% of oil yield) of methyl cinnamate (MC). Some trees had low (0%) or variable levels (0-21%) of MC, highlighting the need to explore selection of proven clones for plantation-scale production of MC. Leaf age and time of harvesting affected MC levels and yields, and also oil yields, which peaked in younger leaves in mid summer. In general, higher MC yields were more closely related to high yields of oil in the foliage rather than high levels of MC in the oil.
The seasonal variation in essential oil yield and composition from naturalized Thymus vulgaris L. in Central Otago, New Zealand, is reported. Essential oil yield (l/ha), from replicated, pilot-scale distillations, was influenced by both the field production of herb and the essential oil content of the herb. The oil yield peaked at 22.8 l/ha in December, after flowering had finished. Essential oil composition also varied significantly during the 13-month sampling period. Levels of the phenolic components, thymol and carvacrol, peaked at a total of 37% after flowering in summer (December and January). p-Cymene was an important component of Central Otago thyme oils and ranged from 40% to 50% in winter and early spring (May to October), declining to 21% in January. To maximize yields and phenol content of the oil, naturalized thyme in Central Otago should be harvested after flowering has finished in December.
The fungitoxicity of crude extracts and essential oils of Achillea millefolium, Cymbopogon citratus, Eucalyptus citriodora and Ageratum conyzoides on the fungus Didymella bryoniae was verified in vitro by means of germination of spores and mycelial growth. In addition, some observations were made using scanning electron microscopy (SEM) to detect possible alterations on the hyphae of Didymella bryoniae. The results revealed that crude extracts of E. citriodora and A. conyzoides were more effective in inhibiting the mycelial growth of D. bryoniae whereas in the germination of spores A. conyzoides and A. millefolium were responsible for most of the inhibition, namely, 52 and 46%, respectively. The essential oils of C. citratus, A. conyzoides and E. citriodora provided 100% inhibition of the mycelial growth and germination of spores of D. bryoniae. SEM observations revealed alterations in the growth pattern of hyphae of D. bryoniae when the essential oil of A. millefolium was present.
The bacteriostatic and bactericidal activities of six components of conifer essential oils (α and β pinene, R- and S-limonene, 1,8 cineole, borneol) were tested on Listeria monocytogenes serovars 4b and 1/2c. α Pinene was the most active component with an average minimal inhibitory concentration (MIC) of 0.019% against L. monocytogenes 4b. Conversely, the concentration of 1,8 cineole required to achieve the same effect on this serovar was 0.375%, although this concentration was directly bactericidal. The bacteriostatic and bactericidal activities differed more between different components than between different serovars. Given that these products are highly active against L. monocytogenes, they might be used to kill this species or to prevent its growth.
Technological application of essential oils, as natural sanitizing agents, to reduce food pathogens in the post-harvest processing of foods requires the establishment of the optimal conditions. The present work evaluated the parameters of antimicrobial activity of the essential oils of eucalyptus (Eucalyptus globules), tea tree (Melaleuca alternifolia), rosemary (Rosmarinus officinalis), mint (Mentha piperita), rosa moschata (Rosa moschata), clove (Syzygium aromaticum), lemon (Citrus limonum), oregano (Origanum vulgare), pine (Pinus silvestrys) and sweet basil (Ocimum basilicum) on survival and growth of different strains of E. coli O157:H7. The strains of E. coli exhibited similar susceptibilities to the action of the essential oils assayed. The essential oil with the lowest MIC and MBC (Minimum Inhibitory and Bactericidal Concentration, respectively) was clove (0.25 ml/100 ml and 0.3 ml/100 ml, respectively) and the results demonstrated that clove exerted a significant bactericidal and bacteriostatic action.
The inhibitory effect of 60 different essential oils was evaluated on a Pseudomonas putida strain of meat origin, associated with meat spoilage. Essential oils were tested at concentrations from 0.003 to 0.8% (wt/vol) to determine minimum inhibitory and maximal tolerated concentrations (MIC and MTC, respectively) using an agar medium culture. Of the 60 samples tested, Corydothymus capitatus essential oil was the most active showing a MIC of 0.025% and a MTC of 0.06%. Seven essential oils (Cinnamomum cassia, Origanum compactum, Origanum heracleoticum, Satureja hortensis, Satureja montana, Thymus vulgaris carvacroliferum, Thymus vulgaris thymoliferum) have shown a strong antimicrobial activity against P. putida with a MIC of 0.05% and a MTC ranging from 0.013% to 0.025%. Ten other oils (Cinnamomum verum (leaf and bark), Eugenia caryophyllus, Cymbopogon martinii var. motia, Cymbopogon nardus, Melaleuca linariifolia, Origanum majorana, Pimenta dioica, Thymus satureoides, Thymus serpyllum) showed a high antimicrobial activity showing a MIC ranging from 0.1% to 0.4%, while the remaining were less active showing a MIC⩾0.8%.
The aim of the study was to evaluate the potential of essential of from local plant in controlling some major seed-borne fungi of sorghum grow in Burkina Faso. Essential oils from Cymbopogon citratus (Lemongrass) Eucalyptus camaldulensis , (Eucalyptus) and crude oil from Azadirachta indica (Neem) were tested in vitro for inhibitory activity against Colletotrichum graminicola , Phoma sorghina and Fusarium moniliforme . Plant extracts were also tested on naturally infected sorghum seeds for controlling the fungi above mentioned. Essential oil from C. citratus significantly inhibited the in vitro radial growth of C. graminicola (76.2% inhibition), compared to the fungicide Dithane M-45. The mycelial growth of P. sorghina and F. moniliforme was slightly affected by this oil at the concentrations used. The extent of inhibition of the fungal growth was dependent on the concentration of essential oil used. Neem crude oil and Eucalyptus essential oil presented low inhibitory activity against test fungi. Concentrations of Eucalyptus essential oil were not harmful to sorghum seedling growth, while neem crude oil was highly phytotoxic. Essential oil of lemongrass at the concentration of 6% was effective in controlling seed-borne infection and seed-to-seedling transmission of C. graminicola and P. sorghina without affecting seedling development. Lemongrass has the potential to be used as sorghum seed treatment for controlling C. graminicola , P. sorghina and F. moniliforme .
The flowering aerial parts of Mentha pulegium L. (Labiatae) has been traditionally used for its antiseptic properties for treatment of infectious diseases.
In order to validate its antiseptic properties with respect to traditional uses, we have screened the antimicrobial activity of flowering aerial parts of Mentha pulegium L. essential oil against different microorganisms.
This oil was obtained using hydrodistillation method and analyzed by GC and GC/MS. The antimicrobial activity was achieved using disc diffusion method and microbroth dilution assay.
Analysis of the essential oil revealed the presence of piperitone (38.0%), piperitenone (33.0%), alpha-terpineol (4.7%), and pulegone (2.3%) as the major components. The results showed a significant activity against microorganisms especially Gram-positive bacteria with inhibition zones and minimal inhibitory concentration values in the range of 8-21 mm and 0.25-4 microl/ml, respectively, whereas the least susceptible were Gram-negative bacteria especially Escherichia coli.
This investigation showed that the oil of Mentha pulegium L. has a potent antimicrobial activity and the Iranian Mentha pulegium L. oil belongs to piperitone/piperitenone type. Further research is required to evaluate the practical values of therapeutic applications.
Essential oils from dill (Anethum graveolens L.), coriander (seeds of Coriandrum sativum L.), cilantro (leaves of immature C. sativum L.) and eucalyptus (Eucalyptus dives) were separated into heterogeneous mixtures of components by fractional distillation and were analyzed by gas chromatography-mass spectroscopy. Minimum inhibitory concentrations against gram-positive bacteria, gram-negative bacteria and Saccharomyces cerevisiae were determined for the crude oils and their fractions. Essential oil of cilantro was particularly effective against Listeria monocytogenes, likely due to the presence of long chain (C6-C10) alcohols and aldehydes. The strength and spectrum of inhibition for the fractions often exceeded those determined in the crude oils. Mixing of fractions resulted in additive, synergistic or antagonistic effects against individual test microorganisms.
The volatile oil extracted from the leaves of Eucalyptus citriodora showed a wide spectrum of antifungal activity.
The volatile metabolites of Salvia fruticosa plants, growing wild in 15 localities scattered across Greece, were analyzed by means of GC and GC-MS. The essential oil content ranged from 0.69 to 4.68%, and the results of the analyses showed a noticeable variation in the amounts of the five main components [1,8-cineole, alpha-thujone, beta-thujone, camphor, and (E)-caryophyllene]. The antifungal activities of the essential oils from two localities, belonging in two different groups of cluster and principal component analysis, and their main components (1,8-cineole and camphor) were evaluated in vitro against five phytopathogenic fungi. Both oils were slightly effective against Fusarium oxysporum f. sp. dianthi and Fusarium proliferatum, whereas against Rhizoctonia solani, Sclerotinia sclerotiorum, and Fusarium solani f. sp. cucurbitae the oils exhibited high antifungal activities.
We investigated the antimicrobial activities of eucalyptus leaf extracts to find effective antibacterial agents.
The antimicrobial activities of leaf extracts from 26 species of eucalyptus were measured. Extracts of Eucalyptus globulus, E. maculata and E. viminalis significantly inhibited the growth of six Gram-positive bacteria (Staphylococcus aureus, MRSA, Bacillus cereus, Enterococcus faecalis, Alicyclobacillus acidoterrestris, Propionibacterium acnes), and of a fungus (Trichophyton mentagrophytes), but they did not show strong antibacterial activity against Gram-negative bacteria (Escherichia coli, Pseudomonas putida). 2',6'-dihydroxy-3'-methyl-4'-methoxy-dihydrochalcone, eucalyptin and 8-desmethyl-eucalyptin, isolated from E. maculata extracts, exhibited potent antimicrobial activities against seven micro-organisms with minimum inhibitory concentrations (MIC) ranging from 1.0 to 31 mg l(-1).
The eucalyptus extracts and three compounds from E. maculata were found to be effective against micro-organisms that cause food poisoning, acne and athlete's foot.
This study shows potential uses of extracts from E. globulus, E. maculata and E. viminalis, and antimicrobial compounds isolated from E. maculata.
In vitro studies have demonstrated antibacterial activity of essential oils (EOs) against Listeria monocytogenes, Salmonella typhimurium, Escherichia coli O157:H7, Shigella dysenteria, Bacillus cereus and Staphylococcus aureus at levels between 0.2 and 10 microl ml(-1). Gram-negative organisms are slightly less susceptible than gram-positive bacteria. A number of EO components has been identified as effective antibacterials, e.g. carvacrol, thymol, eugenol, perillaldehyde, cinnamaldehyde and cinnamic acid, having minimum inhibitory concentrations (MICs) of 0.05-5 microl ml(-1) in vitro. A higher concentration is needed to achieve the same effect in foods. Studies with fresh meat, meat products, fish, milk, dairy products, vegetables, fruit and cooked rice have shown that the concentration needed to achieve a significant antibacterial effect is around 0.5-20 microl g(-1) in foods and about 0.1-10 microl ml(-1) in solutions for washing fruit and vegetables. EOs comprise a large number of components and it is likely that their mode of action involves several targets in the bacterial cell. The hydrophobicity of EOs enables them to partition in the lipids of the cell membrane and mitochondria, rendering them permeable and leading to leakage of cell contents. Physical conditions that improve the action of EOs are low pH, low temperature and low oxygen levels. Synergism has been observed between carvacrol and its precursor p-cymene and between cinnamaldehyde and eugenol. Synergy between EO components and mild preservation methods has also been observed. Some EO components are legally registered flavourings in the EU and the USA. Undesirable organoleptic effects can be limited by careful selection of EOs according to the type of food.
The leaf-essential oil from Eucalyptus robusta and E. saligna, the latter in two phenologic stages, were analysed by gas chromatography coupled to mass spectrometry (GC-MS). The major constituent in E. robusta oil was the monoterpene alpha-pinene (73.0% of the total amount). The oil composition of the E. saligna was dependent of the phenologic stage. In the vegetative phase, the major constituents were p-cymene (54.2%) and gamma-terpinene (43.8%), while during the blossoming alpha-pinene became the major constituent followed by p-cymene (22.5%). Additionally, the antimicrobial activity for all three oils was evaluated against Staphylococcus aureus, Escherichia coli and Candida albicans. The E. robusta oil presented the highest growth inhibition for all the microorganisms tested.
Relative activity of essential oils from plants against Penicillium digitatum causing post-harvest fruit rot of Kinnow mandarin
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