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Quantification of the plant terpenome: predicted versus actual emission potentials
Abstract
Plant essential oils are complex mixtures of volatile organic compounds, which play indispensable roles in communication, defense, and adaptive evolution. The complete chemical library produced by a plant is referred to as its terpenome. The potential biological information stored in essential oil composition data can provide an insight into the silent language of plants, as well as roles of terpene emissions in direct and indirect defense, and for playing a crucial role in adaptive evolution. In this work, we have attempted to measure the plant terpenome from a global perspective. One way of measuring the terpenome is to observe and record actual emissions in natural conditions, and this has been in practice for over a century through variously evolving methods of comprehensive GC–MS and HPLC. An alternative method is a knowledge-based prediction of the terpenome, and this method has gained popularity in recent years, with the advent of large-scale genome sequencing technologies. Over the past decade, our laboratory has been involved in compilation and investigation of the plant terpenome using both these methods and this has offered us the opportunity to compare and contrast data from actual and potential emissions, in order to better understand the terpenome and its roles in primary, secondary and adaptive metabolism. We have used emission data in conjunction with genomic data in order to understand how a plant creates the so-called final terpenome, specific to itself, and whether or not plants tap the complete potential for terpene biosynthesis at their disposal according to their genomes. For measuring actual emissions, we have used EssOilDB (the ESSential OIL DataBase), the largest contextual web resource for phytochemicals and for measuring the total plant potential for emissions, we have used TERZYME, an automated algorithm for identification and analysis of genes and proteins involved in isoprenoid biosynthesis.
... Only plants are capable of simultaneously synthesizing terpenoids via MEP and MVA pathways in parallel, suggesting that genes involved in terpenoid biosynthesis in plants have adapted evolutionarily in basal to terrestrial plant lineages [12,13]. In this sense, it is important to understand the evolutionary relationships and duplication events that have occurred within these gene families [3]. ...
Terpenoids are a diverse class of metabolites that impact plant metabolism in response to environmental cues. They are synthesized either via a predominantly cytosolic (MVA) pathway or a plastidic pathway (MEP). In Arabidopsis, several enzymes from the MVA and MEP pathways are encoded by gene families, excluding MVK and DXR, which are single-copy genes. In this study, we assess the diversity, evolution and expression of DXR and MVK genes in selected angiosperms and Coffea arabica in particular. Evolutionary analysis revealed that DXR and MVK underwent purifying selection, but the selection effect for DXR was stronger than it was for MVK. Digital gene expression (DGE) profile analysis of six species revealed that expression levels of MVK in flowers and roots were high, whereas for DXR peak values were observed in leaves. In C. arabica, both genes were highly expressed in flowers, and CaDXR was upregulated in response to methyl jasmonate. C. arabica DGE data were validated by assessing gene expression in selected organs, and by plants treated with hexanoic acid (Hx) using RT-qPCR. MVK expression was upregulated in roots treated with Hx. CaDXR was downregulated in leaves by Hx treatment in a genotype-specific manner, indicating a differential response to priming.
... As an interesting offshoot of this study, we are now integrating Terzyme data with existing species-specific transcriptome datasets and cis-regulome records, in order to construct gene regulatory networks that can shed further light on how the terpenome has expanded and evolved in various taxonomic groups (GY unpublished data). In addition, we recently compared the 'potential' terpenome (as predicted by Terzyme) with the 'actual' terpenome, integrating volatile compound emission data in conjunction with genomic data to understand how a plant creates the so-called final terpenome, specific to itself, and whether or not plants tap the complete potential for terpene biosynthesis at their disposal according to their genomes [28]. Comparison of actual terpenome with the potential terpenome, as performed in this study, revealed how plants modulate their TPSs expression based on condition or environment-specific needs. ...
Background
Terpenoid hydrocarbons represent the largest and most ancient group of phytochemicals, such that the entire chemical library of a plant is often referred to as its ‘terpenome’. Besides having numerous pharmacological properties, terpenes contribute to the scent of the rose, the flavors of cinnamon and the yellow of sunflowers. Rapidly increasing -omics datasets provide an unprecedented opportunity for terpenome detection, paving the way for automated web resources dedicated to phytochemical predictions in genomic data. ResultsWe have developed Terzyme, a predictive algorithm for identification, classification and assignment of broad substrate unit to terpene synthase (TPS) and prenyl transferase (PT) enzymes, known to generate the enormous structural and functional diversity of terpenoid compounds across the plant kingdom. Terzyme uses sequence information, plant taxonomy and machine learning methods for predicting TPSs and PTs in genome and proteome datasets. We demonstrate a significant enrichment of the currently identified terpenome by running Terzyme on more than 40 plants. Conclusions
Terzyme is the result of a rigorous analysis of evolutionary relationships between hundreds of characterized sequences of TPSs and PTs with known specificities, followed by analysis of genome-wide gene distribution patterns, ontology based clustering and optimization of various parameters for building accurate profile Hidden Markov Models. The predictive webserver and database is freely available at http://nipgr.res.in/terzyme.html and would serve as a useful tool for deciphering the species-specific phytochemical potential of plant genomes.
Plant essential oils are complex mixtures of volatile organic compounds, which play indispensable roles in the environment, for the plant itself, as well as for humans. The potential biological information stored in essential oil composition data can provide an insight into the silent language of plants, and the roles of these chemical emissions in defense, communication and pollinator attraction. In order to decipher volatile profile patterns from a global perspective, we have developed the ESSential OIL DataBase (EssOilDB), a continually updated, freely available electronic database designed to provide knowledge resource for plant essential oils, that enables one to address a multitude of queries on volatile profiles of native, invasive, normal or stressed plants, across taxonomic clades, geographical locations and several other biotic and abiotic influences. To our knowledge, EssOilDB is the only database in the public domain providing an opportunity for context based scientific research on volatile patterns in plants. EssOilDB presently contains 123 041 essential oil records spanning a century of published reports on volatile profiles, with data from 92 plant taxonomic families, spread across diverse geographical locations all over the globe. We hope that this huge repository of VOCs will facilitate unraveling of the true significance of volatiles in plants, along with creating potential avenues for industrial applications of essential oils. We also illustrate the use of this database in terpene biology and show how EssOilDB can be used to complement data from computational genomics to gain insights into the diversity and variability of terpenoids in the plant kingdom. EssOilDB would serve as a valuable information resource, for students and researchers in plant biology, in the design and discovery of new odor profiles, as well as for entrepreneurs-the potential for generating consumer specific scents being one of the most attractive and interesting topics in the cosmetic industry. Database URL: http://nipgr.res.in/Essoildb/
© The Author(s) 2014. Published by Oxford University Press.
An overview of the studies carried out in our laboratories on supercritical fluid extraction (SFE) of volatile oils from seven aromatic plants: pennyroyal ( Mentha pulegium L.), fennel seeds ( Foeniculum vulgare Mill.), coriander ( Coriandrum sativum L.), savory ( Satureja fruticosa Béguinot ), winter savory ( Satureja montana L.), cotton lavender ( Santolina chamaecyparisus ) and thyme ( Thymus vulgaris ), is presented. A flow apparatus with a 1 L extractor and two 0.27 L separators was built to perform studies at temperatures ranging from 298 to 353 K and pressures up to 30.0 MPa. The best compromise between yield and composition compared with hydrodistillation (HD) was achieved selecting the optimum experimental conditions of extraction and fractionation. The major differences between HD and SFE oils is the presence of a small percentage of cuticular waxes and the relative amount of thymoquinone, an oxygenated monoterpene with important biological properties, which is present in the oils from thyme and winter savory. On the other hand, the modeling of our data on supercritical extraction of volatile oil from pennyroyal is discussed using Sovová's models. These models have been applied successfully to the other volatile oil extractions. Furthermore, other experimental studies involving supercritical CO2 carried out in our laboratories are also mentioned.
Plants may “eavesdrop” on volatile organic compounds (VOCs) released by herbivore-attacked neighbors to activate defenses
before being attacked themselves. Transcriptome and signal cascade analyses of VOC-exposed plants suggest that plants eavesdrop
to prime direct and indirect defenses and to hone competitive abilities. Advances in research on VOC biosynthesis and perception
have facilitated the production of plants that are genetically “deaf” to particular VOCs or “mute” in elements of their volatile
vocabulary. Such plants, together with advances in VOC analytical instrumentation, will allow researchers to determine whether
fluency enhances the fitness of plants in natural communities.
Terpenoids represent the oldest known biomolecules, having been recovered from sediments as old as 2.5 billion years. Among plant secondary metabolites, they are the most abundant and diverse class of natural compounds. The diversity of terpenoids is probably a reflection of their many biological activities in nature, which has made them a widely used resource for traditional and modern human exploitation. They are usually the main constituents of essential oils of most plants offering a wide variety of pleasant scents from flowery to fruity, to woody or balsamic notes. For this reason terpenoids constitute a very important class of compounds for flavour and fragrance industries, in fact, in the US alone, the demand is forecast to grow 3.7 percent per year to $5.3 billion in 2012. The recent patents on production and extraction of terpenoids commonly used as natural flavouring compounds in food industries are reviewed in the present manuscript.
The sessile nature of plants has resulted in the evolution of an extraordinarily diverse suite of protective mechanisms against biotic and abiotic stresses. Though volatile isoprenoids are known to be involved in many types of biotic interactions, they also play important but relatively unappreciated roles in abiotic stress responses. We review those roles, discuss the proposed mechanistic explanations and examine the evolutionary significance of volatile isoprenoid emission. We note that abiotic stress responses generically involve production of reactive oxygen species in plant cells, and volatile isoprenoids mitigate the effects of oxidative stress by mediating the oxidative status of the plant. On the basis of these observations, we propose a 'single biochemical mechanism for multiple physiological stressors' model, whereby the protective effect against abiotic stress is exerted through direct or indirect improvement in resistance to damage by reactive oxygen species.
Leaves normally release small quantities of volatile chemicals, but when a plant is damaged by herbivorous insects, many more volatiles are released. The chemical identity of the volatile compounds varies with the plant species and with the herbivorous insect species. These volatiles attract both parasitic and predatory insects that are natural enemies of the herbivores. They may also in- duce defense responses in neighboring plants. Such chem- icals, which function in communication between and among species, as well as those that serve as messengers between members of the same species, are called semio- chemicals (from the Greek "semeion," a mark or signal) (Law and Regnier, 1971). Semiochemicals emitted from a diverse group of plants and insects mediate key processes in the behavior of spe- cific insects. Volatile phytochemicals can serve as airborne semiochemicals, promoting or deterring interactions be- tween plants and insect herbivores. For example, wheat seedlings without herbivore damage attract aphids, whereas odors released from wheat seedlings with a high density of aphids repel other aphids (Quiroz et al., 1997). For swallowtail butterflies, volatiles from host plants enhance the effect of contact stimulants, increasing landing rates and oviposition relative to non-host plants (Feeny et al., 1989). In addition to the bouquet of compounds that render leaves attractive or disagreeable to herbivores, volatile ter- penoids and other compounds emitted from leaves in re-
Herbivore attack is known to increase the emission of volatiles, which attract predators to herbivore-damaged plants in the
laboratory and agricultural systems. We quantified volatile emissions fromNicotiana attenuata plants growing in natural populations during attack by three species of leaf-feeding herbivores and mimicked the release
of five commonly emitted volatiles individually. Three compounds (cis-3-hexen-1-ol, linalool, and cis-α-bergamotene) increased egg predation rates by a generalist predator; linalool and the complete blend decreased lepidopteran
oviposition rates. As a consequence, a plant could reduce the number of herbivores by more than 90% by releasing volatiles.
These results confirm that indirect defenses can operate in nature.
Hepatoprotective activity of Foeniculum vulgare (fennel) essential oil (FEO) was studied using carbon tetrachloride (CCl(4)) induced liver injury model in rats. The hepatotoxicity produced by acute CCl(4) administration was found to be inhibited by FEO with evidence of decreased levels of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and bilirubin. The results of this study indicate that FEO has a potent hepatoprotective action against CCl(4)-induced hepatic damage in rats.
Essential oils and their volatile constituents are used widely to prevent and treat human disease. The possible role and mode of action of these natural products is discussed with regard to the prevention and treatment of cancer, cardiovascular diseases including atherosclerosis and thrombosis, as well as their bioactivity as antibacterial, antiviral, antioxidants and antidiabetic agents. Their application as natural skin penetration enhancers for transdermal drug delivery and the therapeutic properties of essential oils in aroma and massage therapy will also be outlined.
Living things use isoprenoids as pigments, hormones, molecular signals, and pheromones. The many variations of isoprenoid are generated by versatile enzymes that synthesize multiple products. In their Perspective, Sacchettini and Poulter discuss what the new structures of three of these cyclases, reported on pages [1811][1], [1815][2], and [1820][3] of this issue, reveal about the mechanisms of isoprenoid formation.
[1]: http://www.sciencemag.org/cgi/content/short/277/5333/1811
[2]: http://www.sciencemag.org/cgi/content/short/277/5333/1815
[3]: http://www.sciencemag.org/cgi/content/short/277/5333/1820
The isoprenoid family represents one of the most ancient and widespread classes of structurally and functionally rich biomolecules known to man. Although these natural products are synthesized in all organisms, the plant kingdom exhibits tremendous variation in their chemistry and roles, ranging from primary metabolism to secondary metabolism and specialized ecological interactions with the environment. Despite enormous diversity in structure and function, all isoprenoids are derived from the universal C5 precursor isoprene. The isoprenoid biosynthetic pathway has three major stages, viz., (1) synthesis of the isoprene building blocks, followed by their (2) assembly into flexible linear and branched hydrocarbon substrates, which then undergo (3) multistep reaction cascades to generate the vast assortment of isoprenoid end products. One of the most interesting aspects of isoprenoid biosynthesis is its being finely tuned by a multilayered and complex regulatory network, which excellently controls the machinery producing one of the most heterogeneous groups of molecules in plants. Terpene synthases, enzymes of the final stage, are key players in the generation of isoprenoid diversity, catalyzing one of the most complex reactions known to chemistry and biology. Unraveling the mechanism by which a minimal pool of substrates is thus converted into tens of thousands of regiospecific and stereospecific products, is a promising research avenue: This knowledge may be practically used for rational design of novel compounds by metabolic engineering, in order to yield plants with improved nutritional efficacy, stress resistance, bio-pharmaceutical properties etc. This review is an attempt to summarize the biochemical, molecular, physiological, structural, genomic and evolutionary aspects of isoprenoid biosynthesis, providing new insights into how these enzymes utilize various innovative strategies for creation of the so-called final terpenome.
The essential oils from two clonal types of Thymus vulgaris (Laval-1 and Laval-2) were characterized and tested for antifungal activity. Contents were high in p-cymene, linalool, terpinen-4-ol and thymol which constituted 53.5% and 66.2% of Laval-1 and Laval-2 essential oils respectively. The essential oil volatiles from two clonal types exhibited antifungal activity against Botrytis cinerea and Rhizopus stolonifer, two common storage pathogens of strawberries (Fragaria ananassa). The inhibition of B. cinerea and R. stolonifer ranged from 26.5 to 63.5% and 5.5 to 50.5% respectively by oil from Laval-1, when exposed to concentrations of 50 to 200 ppm, while values of 36.9 to 90.5% and 11.5 to 65.8% were observed from oil from Laval-2. The decay of strawberry fruits caused by B. cinerea and R. stolonifer was controlled up to 73.6 and 73.0% respectively by volatiles from maximin concentration of Laval-1, and up to 75.8 and 74.8% from Laval-2. No visual phytotoxic symptoms were noticed for the observed period. Essential oil from Laval-2 exhibited higher antifungal activity which was related to its relatively higher content of antimicrobial compounds.
About 100 pure components of essential oils have been tested for their antioxidant effectiveness. The main classes of compounds, namely monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes, benzene derivatives, and non isoprenoid components comprising alcohols, aldehydes, ketones, which are the most common constituents of essential oils, have been analysed. Two model systems for the antioxidant efficacy have been used; the first exploiting the thiobarbituric acid reactive species (TBARS) method using egg yolk as oxydable substrate, the second measuring the formation of hydroperoxydienes from linoleic acid in a micellar system, using in both cases 2,2′-azobis (2-amidinopropane) dihydrochloride (ABAP) as a radical initiator, and α-tocopherol as a reference compound. From a general point of view phenols were confirmed to possess the highest antioxidant activity. In particular some monoterpene hydrocarbons, namely, terpinolene, α- and γ-terpinene showed a significant protective action, whereas among the oxygenated components, beside the aforesaid phenols, allylic alcohols manifested an appreciable activity. Sesquiterpene hydrocarbons and non isoprenoid components subjected to this study showed a low, if any, antioxidant effect. The role of the different model systems and the relationship between structure and antioxidant effectiveness are discussed.
Tens of thousands of terpenoids are present in both terrestrial and marine plants, as well as fungi. In the last 5–10 years, however, it has become evident that terpenes are also produced by numerous bacteria, especially soil-dwelling Gram-positive organisms such as Streptomyces and other Actinomycetes. Although some microbial terpenes, such as geosmin, the degraded sesquiterpene responsible for the smell of moist soil, the characteristic odor of the earth itself, have been known for over 100 years, few terpenoids have been identified by classical structure- or activity-guided screening of bacterial culture extracts. In fact, the majority of cyclic terpenes from bacterial species have only recently been uncovered by the newly developed techniques of “genome mining”. In this new paradigm for biochemical discovery, bacterial genome sequences are first analyzed with powerful bioinformatic tools, such as the BLASTP program or Profile Hidden Markov models, to screen for and identify conserved protein sequences harboring a characteristic set of universally conserved functional domains typical of all terpene synthases. Of particular importance is the presence of variants of two universally conserved domains, the aspartate-rich DDXX(D/E) motif and the NSE/DTE triad, (N/D)DXX(S/T)XX(K/R)(D/E). Both domains have been implicated in the binding of the essential divalent cation, typically Mg2+, that is required for cyclization of the universal acyclic terpene precursors, such as farnesyl and geranyl diphosphate.
This review focuses on the monoterpene, sesquiterpene, and diterpene synthases of plant origin that use the corresponding C10, C15, and C20 prenyl diphosphates as substrates to generate the enormous diversity of carbon skeletons characteristic of the terpenoid family of natural products. A description of the enzymology and mechanism of terpenoid cyclization is followed by a discussion of molecular cloning and heterologous expression of terpenoid synthases. Sequence relatedness and phylogenetic reconstruction, based on 33 members of the Tps gene family, are delineated, and comparison of important structural features of these enzymes is provided. The review concludes with an overview of the organization and regulation of terpenoid metabolism, and of the biotechnological applications of terpenoid synthase genes.
Some plant terpenes such as sterols and carotenes are part of primary metabolism and found essentially in all plants. However, the majority of the terpenes found in plants are classified as 'secondary' compounds, those chemicals whose synthesis has evolved in plants as a result of selection for increased fitness via better adaptation to the local ecological niche of each species. Thousands of such terpenes have been found in the plant kingdom, but each species is capable of synthesizing only a small fraction of this total. In plants, a family of terpene synthases (TPSs) is responsible for the synthesis of the various terpene molecules from two isomeric 5-carbon precursor 'building blocks', leading to 5-carbon isoprene, 10-carbon monoterpenes, 15-carbon sesquiterpenes and 20-carbon diterpenes. The bryophyte Physcomitrella patens has a single TPS gene, copalyl synthase/kaurene synthase (CPS/KS), encoding a bifunctional enzyme producing ent-kaurene, which is a precursor of gibberellins. The genome of the lycophyte Selaginella moellendorffii contains 18 TPS genes, and the genomes of some model angiosperms and gymnosperms contain 40-152 TPS genes, not all of them functional and most of the functional ones having lost activity in either the CPS- or KS-type domains. TPS genes are generally divided into seven clades, with some plant lineages having a majority of their TPS genes in one or two clades, indicating lineage-specific expansion of specific types of genes. Evolutionary plasticity is evident in the TPS family, with closely related enzymes differing in their product profiles, subcellular localization, or the in planta substrates they use.
Essential oils are complex mixtures of substances from vegetable matter, the definition of which is based on their method of extraction. They are characterized by their ambivalence, their ambiguity and their disparity: plant families from which essential oils are extracted are numerous; the composition of each essential oil depends not only on the family but also on the part of the plant from which it is extracted, and sometimes on the soil where the plant grows, or even on the time of the harvest. Gas chromatography is therefore necessary to characterize an essential oil. Essential oils can be found in cosmetics, in drugs, and in food. They are natural substances, but natural is not synonymous with harmless. Evaluation of the toxicity of essential oils and European regulation are underway.
The multitude of terpene carbon skeletons in plants is formed by enzymes known as terpene synthases. This review covers the monoterpene and sesquiterpene synthases presenting an up-to-date list of enzymes reported and evidence for their ability to form multiple products. The reaction mechanisms of these enzyme classes are described, and information on how terpene synthase proteins mediate catalysis is summarized. Correlations between specific amino acid motifs and terpene synthase function are described, including an analysis of the relationships between active site sequence and cyclization type and a discussion of whether specific protein features might facilitate multiple product formation.
Monoterpenes are found in the essential oils of many commonly consumed fruits and vegetables. These compounds have been shown to exert chemopreventive and chemotherapeutic activities in mammary tumor models and represent a new class of breast cancer therapeutic agents. In this study, we investigated the effects of limonene and limonene-related monoterpenes, perillyl alcohol and perillic acid, on cell growth, cell cycle progression, and expression of cyclin D1 cell cycle-regulatory gene in T-47D, MCF-7, and MDA-MB-231 breast cancer cell lines. Our results revealed that limonene-related monoterpenes caused a dose-dependent inhibition of cell proliferation. Of the three monoterpenes tested, perillyl alcohol was the most potent and limonene was the least potent inhibitor of cell growth. The enantiomeric composition of limonene and perillyl alcohol did not interfere with their effect on cell growth. Sensitivity of breast cancer cell lines to monoterpenes was in the following order: T-47D > MCF-7 > MDA-MB-231. Growth inhibition induced by perillyl alcohol and perillic acid was associated with a fall in the proportion of cells in the S phase and an accumulation of cells in the G1 phase of the cell cycle. Finally, we showed that the effects of limonene-related monoterpenes on cell proliferation and cell cycle progression were preceded by a decrease in cyclin D1 mRNA levels.
The monoterpene perillyl alcohol (POH) is a naturally occurring anti-cancer compound which is effective against a variety of rodent organ-specific tumor models. To establish the molecular mechanisms of POH and its major metabolite perillic acid (PA) as anti-proliferative agents, their effects on cell proliferation, cell cycle and cell cycle regulatory proteins were studied in HCT 116 human colon cancer cells. POH, and to a lesser extent, PA, exerted a dose-dependent inhibitory effect on cell growth correlated with a G1 arrest. Analysis of G1 cell cycle regulators expression revealed that monoterpenes increased expression of cdk inhibitor p21(Waf1/Cip1) and cyclin E, and decreased expression of cyclin D1, cyclin-dependent kinase (cdk) 4 and cdk2. Our results suggest that monoterpenes induce growth arrest of colon cancer cells through the up-regulation of p21(Waf1/Cip1) and the down-expression of cyclin D1 and its partner cdk4.
The effects of dietary oregano essential oil and alpha-tocopheryl acetate supplementation on the oxidative stability of long-term frozen stored turkey meat were investigated. Thirty 12-week-old turkeys, randomly divided into five groups, were given a basal diet or a basal diet supplemented with 200 mg of alpha-tocopheryl acetate kg(-1), or 100 or 200 mg of oregano oil kg(-1), or 100 mg of oregano oil plus 100 mg of alpha-tocopheryl acetate kg(-1) for 4 weeks prior to slaughter. Lipid oxidation in breast and thigh meat was assessed after 1, 3, 6, and 9 months of frozen storage at -20 degrees C prior to or following 7 days of refrigerated storage at 4 degrees C. Results showed that oregano oil increased the oxidative stability of breast and thigh meat during the frozen storage. Dietary oregano oil at the inclusion level of 200 mg kg(-1) feed was significantly (p < 0.05) more effective in delaying lipid oxidation compared to the level of 100 mg kg(-1), but equivalent to dietary alpha-tocopheryl acetate supplementation at 200 mg kg(-1), which in turn was inferior to dietary supplementation of 100 mg kg(-1) oregano essential oil plus 100 mg kg(-1) alpha-tocopheryl acetate that was significantly (p < 0.05) superior to all other treatments. Thigh meat was more susceptible to oxidation than breast meat, although the former contained alpha-tocopherol at markedly higher levels. Mean alpha-tocopherol levels in breast and thigh meat from all treatments decreased during the frozen storage, the decrease being sharper between 1 and 3 months of frozen storage for breast and between 3 and 6 months for thigh meat. Oregano oil supplementation increased (p < 0.05) the retention of alpha-tocopherol in meat, the increase being positively correlated with the supplementation level. However, the retention of alpha-tocopherol in meat could only partly elucidate the antioxidant activity exhibited by dietary oregano oil supplementation.
The present study describes the antimicrobial activity and free radical scavenging capacity (RSC) of essential oils from Mentha aquatica L., Mentha longifolia L., and Mentha piperita L. The chemical profile of each essential oil was determined by GC-MS and TLC. All essential oils exhibited very strong antibacterial activity, in particularly against Esherichia coli strains. The most powerful was M. piperita essential oil, especially towards multiresistant strain of Shigella sonei and Micrococcus flavus ATTC 10,240. All tested oils showed significant fungistatic and fungicidal activity [expressed as minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) values, respectively], that were considerably higher than those of the commercial fungicide bifonazole. The essential oils of M. piperita and M. longifolia were found to be more active than the essential oil of M. aquatica. Especially low MIC (4 microL/mL) and MFC (4 microL/mL) were found with M. piperita oil against Trichophyton tonsurans and Candida albicans (both 8 microL/mL). The RSC was evaluated by measuring the scavenging activity of the essential oils on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and OH radicals. All examined essential oils were able to reduce DPPH radicals into the neutral DPPH-H form, and this activity was dose-dependent. However, only the M. piperita oil reduced DPPH to 50 % (IC50 = 2.53 microg/mL). The M. piperita essential oil also exhibited the highest OH radical scavenging activity, reducing OH radical generation in the Fenton reaction by 24 % (pure oil). According to GC-MS and TLC (dot-blot techniques), the most powerful scavenging compounds were monoterpene ketones (menthone and isomenthone) in the essential oils of M. longifolia and M. piperita and 1,8-cineole in the oil of M. aquatica.
The present study investigated the hypotensive responses to intravenous (i.v.) treatment with the essential oil of Alpinia zerumbet (EOAZ) and its main constituent, terpinen-4-ol (Trp-4-ol), in the experimental model of deoxycorticosterone-acetate (DOCA)-salt hypertensive rat.
In both DOCA-salt hypertensive and uninephrectomized, normotensive rats, i.v. bolus injections of EOAZ (1–20 mg/kg) or Trp-4-ol (1–10 mg/kg) decreased mean aortic pressure (MAP) in a dose-related manner. However, hypotensive responses to Trp-4-ol were significantly greater than those evoked by the same doses of EOAZ (1–10 mg/kg). Treatment with DOCA-salt significantly enhanced the maximal percentage decreases in MAP evoked by EOAZ or Trp-4-ol. Likewise, both maximal percentage and absolute decreases in MAP elicited by i.v. injection of the ganglion blocker, hexamethonium (30 mg/kg), were significantly greater in DOCA-salt hypertensive than in control rats. In DOCA-salt hypertensive rats, neither hexamethonium (30 mg/kg, i.v.) nor methylatropine (1 mg/kg, i.v.) pretreatment affected the enhancement of EOAZ-induced hypotension.
These results show that i.v. treatment with either EOAZ or Trp-4-ol dose-dependently decreases blood pressure in conscious DOCA-salt hypertensive rats, and this action is enhanced when compared with uninephrectomized controls. This enhancement could be related mainly to an increase in EOAZ-induced vascular smooth muscle relaxation rather than to enhanced sympathetic nervous system activity in this hypertensive model. The data further support our previous hypothesis that hypotensive effects of EOAZ are partially attributed to the actions of Trp-4-ol.
Satureja Khuzestanica is an endemic plant of Iran that is widely distributed in the southern part of the country. It is famous for its medical uses as an analgesic and antiseptic in folk medicine. The present study was designed to explore the toxicological and pharmacological effects of essential oil of Satureja Khuzestanica (SKEO) in vivo.
The intraperitoneal LD50 of SKEO was determined. Teratogenicity was determined by administration of SKEO at doses of 500, 1000 and 1500 ppm to pregnant rats during days 6 to 015 of gestation. FRAP and TBARS assays were used to determine total antioxidant power and lipid peroxidation respectively. Diabetes and hyperlipidemia were induced by administration of streptozocin and lipid regimen in rats. SKEO (1000 ppm) was administered in drinking water for 10 days.
SKEO is not lethal up to a dose of 2 g kg-1 in rats. In the teratogenicity test, dams of the treated group were active and did not show any signs of toxicity. A significant increase in the number of implantation and live fetuses were observed with SKEO (500 and 1000 ppm) in comparison to the control group. SKEO treatment decreased the normal blood lipid peroxidation level and increased total antioxidant power. Significant decreases in fasting blood glucose and triglyceride levels were observed with SKEO in diabetic and antihyperlipidemic rats respectively.
This preliminary study indicates the safety and interesting stimulatory effect of SKEO on reproduction. The antioxidant properties of SKEO may explain its antidiabetic and triglyceride-lowering effects.
The richness and versatility of biological systems make them ideally suited to solve some of the world's most significant challenges, such as converting cheap, renewable resources into energy-rich molecules; producing high-quality, inexpensive drugs to fight disease; and remediating polluted sites. Over the years, significant strides have been made in engineering microorganisms to produce fuels, bulk chemicals, and valuable drugs from inexpensive starting materials; to detect and degrade nerve agents as well as less toxic organic pollutants; and to accumulate metals and reduce radionuclides. The components needed to engineer the chemistry inside a microbial cell are significantly different from those commonly used to overproduce pharmaceutical proteins. Synthetic biology has had and will continue to have a significant impact on the development of these components to engineer cellular metabolism and microbial chassis to host the chemistry. The ready availability of more well-characterized gene expression components and hosts for chemical synthesis, standards for the connection of these components to make larger functioning devices, computer-aided design software, and debugging tools for biological designs will decrease both the time and the support needed to construct these designs. Some of the most important tools for engineering bacterial metabolism and their use for production of the antimalarial drug artemisinin are reviewed.
Although terpenoid synthases catalyze the most complex reactions in biology, these enzymes appear to play little role in the chemistry of catalysis other than to trigger the ionization and chaperone the conformation of flexible isoprenoid substrates and carbocation intermediates through multistep reaction cascades. Fidelity and promiscuity in this chemistry (whether a terpenoid synthase generates one or several products), depends on the permissiveness of the active site template in chaperoning each step of an isoprenoid coupling or cyclization reaction. Structure-guided mutagenesis studies of terpenoid synthases such as farnesyl diphosphate synthase, 5-epi-aristolochene synthase, and gamma-humulene synthase suggest that the vast diversity of terpenoid natural products is rooted in the facile evolution of alpha-helical folds shared by terpenoid synthases in all forms of life.
Plants perceive biotic stimuli by recognising a multitude of different signalling compounds originating from the interacting organisms. Some of these substances represent pathogen-associated molecular patterns, which act as general elicitors of defence reactions. But also beneficial microorganisms like rhizobia take advantage of compounds structurally related to certain elicitors, i.e. Nod-factors, to communicate their presence to the host plant. In a bioassay-based study we aimed to determine to what extent distinct oligosaccharidic signals are able to elicit overlapping responses, including the emission of volatile organic compounds which is mainly considered a typical mode of inducible indirect defence against herbivores. The model legume Medicago truncatula Gaertn. was challenged with pathogen elicitors (beta-(1,3)-beta-(1,6)-glucans and N,N',N'',N'''-tetraacetylchitotetraose) and two Nod-factors, with one of them being able to induce a nodulation response in M. truncatula. Single oligosaccharidic elicitors caused the emission of volatile organic compounds, mainly sesquiterpenoids. The volatile blends detected were quite characteristic for the applied compounds, which could be pinpointed by multivariate statistical methods. As potential mediators of this response, the levels of jasmonic acid and salicylic acid were determined. Strikingly, neither of these phytohormones exhibited changing levels correlating with enhanced volatile emission. All stimuli tested caused an overproduction of reactive oxygen species, whereas nitric oxide accumulation was only effected by elicitors that were equally able to induce volatile emission. Thus, all signalling compounds tested elicited distinct reaction patterns. However, similarities between defence reactions induced by herbivory and pathogen-derived elicitors could be ascertained; but also Nod-factors were able to trigger defence-related reactions.
Plant terpenoid synthases: Molecular biology and phylogenetic analysis
- J Bohlmann
- G Meyer-Gauen
- R Croteau
Bohlmann, J., Meyer-Gauen, G., & Croteau, R. (1998). Plant
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- J C Sacchettini
- C D Poulter
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