Variability of the Chemical Composition and Bioactivity between the Essential Oils Isolated from Male and Female Specimens of Hedyosmum racemosum (Ruiz & Pav.) G. Don.

Hedyosmum racemosum (Ruiz & Pav.) G. is a native species of Ecuador used in traditional medicine for treatment of rheumatism, bronchitis, cold, cough, asthma, bone pain, and stomach pain. In this study, fresh H. racemosum leaves of male and female specimens were collected and subjected to hydrodistillation for the extraction of the essential oil. The chemical composition of male and female essential oil was determined by gas chromatography-gas chromatography equipped with a flame ionization detector and coupled to a mass spectrometer using a non-polar and a polar chromatographic column. The antibacterial activity was assayed against five Gram-positive and two Gram-negative bacteria, and two dermatophytes fungi. The scavenging radical properties of the essential oil were evaluated by DPPH and ABTS assays. The chemical analysis allowed us to identify forty-three compounds that represent more than 98% of the total composition. In the non-polar and polar column, α-phellandrene was the principal constituent in male (28.24 and 25.90%) and female (26.47 and 23.90%) essential oil. Other main compounds were methyl chavicol, germacrene D, methyl eugenol, and α-pinene. Female essential oil presented a strong activity against Klebsiella pneumoniae (ATCC 9997) with an minimum inhibitory concentration (MIC) of 500 µg/mL and a scavenging capacity SC50 of 800 µg/mL.

Extraction and purification of cis/trans asarone from Acorus tatarinowii Schott: Accelerated solvent extraction and silver ion coordination high-speed counter-current chromatography.

Acorus tatarinowii Schott is a traditional Chinese medicine used to treat memory and cognitive dysfunction. Because of their efficacy and lower toxic effects, research on α- and ß-asarone, the phytoconstituents, has attracted attention owing to their remarkable pharmacological activities. Silver ion coordination complexation high-speed counter-current chromatography was used to separate these isomers from A. tatarinowii extract, coupled with accelerated solvent extraction. Accelerated solvent extraction parameters were investigated with single-factor and orthogonal testing. A two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (2:1:2:1, v/v) with 0.50 mol/L silver ions was selected for separation. From 2.0 g crude extract, 1.4 g of ß-asarone and 0.09 g of α-asarone were obtained with purities over 98% by sequential sample loading in 20 h. The isolated compounds were identified by electrospray ionization mass spectrometry, 1H and 13C NMR. Silver ions significantly increased the separation factor and retention of the stationary phase. The chromatographic behavior indicated that cis-configuration was more strongly complexed with the silver ion. This was further demonstrated with the help of computational analysis. In conclusion, the established method could be employed to separate other cis-trans or E/Z isomers that form coordination complexes.

Partitioning of Selected Anisole and Veratrole Derivatives between Water and Anionic Surfactant Micelles.

The UV absorption spectra of six structurally related derivatives of anisole and veratrole, i.e., anisaldehyde, (E)-anethole, estragole, veratraldehyde, methyleugenol and (E)-methylisoeugenol, were recorded at various concentrations of the anionic surfactants, either sodium lauryl sulfate (SLS) or sodium lauryl ether sulfate (SLES) at T = 298 K. In addition, conductivity and density measurements were made for the SLS and SLES solutions to determine the volumetric properties of the studied surfactants. Next, using the W. Al-Soufi, L. Pineiro and M. Novo model (APN model) including the pseudo-phase model for micellar solubilization, the values of micelle-water partition coefficients for each perfume-surfactant system were determined. In addition, the relations between the molecular structures of the solute and the head group of the surfactant and the value of the micelle-water partition coefficient as well as the octanol-water one were discussed.

Dehydrodieugenol B and hexane extract from Endlicheria paniculata regulate inflammation, angiogenesis, and collagen deposition induced by a murine sponge model.

The present study reports the evaluation of hexane extract from Endlicheria paniculata and its main metabolite dehydrodieugenol B in the inflammatory response induced by a murine implant sponge model. As a result, a reduction in the inflammatory markers (myeloperoxidase and N-acetyl-ß-D-glucosaminidase) and number of mast cells were observed in comparison to the control group. All doses were also able to reduce angiogenic parameters evaluated in fibrovascular tissue. In implants treated with dehydrodieugenol B a reduction in total collagen deposition and types I and III collagen fibers were observed, while an increased in total collagen deposition and types I and III collagen fibers were observed in the treatment with hexane extract. Docking studies into cyclooxygenase-2 active site revealed that the dehydrodieugenol B had binding modes and energies comparable with celecoxib, diclofenac and ibuprofen. Therefore, dehydrodieugenol B was able to alter key components of chronic inflammation, resulting in a reduced inflammatory response and also presenting antifibrogenic and antiangiogenic effects. However, treatment with hexane extract resulted in a reduced inflammatory response with antiangiogenic effects, but caused fibrogenic effects.

Characteristic Odor of the Japanese Liverwort (Leptolejeunea elliptica).

The volatile components produced by Leptolejeunea elliptica (Lejeuneaceae), which is a liverwort grown on the leaves of tea (Camellia sinensis), were collected and analyzed using headspace solid-phase microextraction-gas chromatography/mass spectrometry (HS-SPME-GC/MS). 1-Ethyl-4-methoxybenzene (1), 1-ethyl-4-hydroxybenzene (2), and 1-acetoxy-4-ethylbenzene (3) were identified as the major components together with several other phenolic compounds, including 1,2-dimethoxy-4-ethylbenzene, and 4-ethylguaiacol in addition to sesquiterpene hydrocarbons, such as α-selinene, ß-selinene, ß-elemene, and ß-caryophyllene. GC/Olfactometry showed the presence of linalool, acetic acid, isovaleric acid, trans-methyl cinnamate, and trans-4,5-epoxy-(2E)-decenal, as the volatile components produced by L. elliptica.

The asarone-derived phenylpropanoids from the rhizome of Acorus calamus var. angustatus Besser.

Phenylpropanoids comprise a broad spectrum of biologically active natural products. As part of our ongoing research on antiepileptic active compounds from traditional Chinese herb, Acorus calamus var. angustatus Besser, three undescribed phenylpropanoids and twenty-two known ones were isolated. All the undescribed structures were determined by a combination of 1D and 2D NMR, HRMS. In addition, γ-asaronol was identified as racemates and its absolute configuration were determined by the modified Mosher's method and ECD spectral data. Furthermore, some selected isolated compounds were evaluated for their cell viability and neuroprotective activities in H2O2-induced SH-SY5Y cells. α-Asaronol, ß-asaronol, 3-(2,4,5-trimethoxyphenyl)propan-1-ol and 1,2,4-trimethoxy-5-(3-methoxypropyl)benzene exerted potential protective activity from neuronal oxidative stress in all test concentrations ranging from 0.01 to 100 µM, in which the neuroprotective activity of ß-asaronol was the best.

Anti-Amyloidogenic Effects of Asarone Derivatives From Perilla frutescens Leaves against Beta-Amyloid Aggregation and Nitric Oxide Production.

Alzheimer's disease (AD) is a progressive, neurodegenerative brain disorder associated with loss of memory and cognitive function. Beta-amyloid (Aß) aggregates, in particular, are known to be highly neurotoxic and lead to neurodegeneration. Therefore, blockade or reduction of Aß aggregation is a promising therapeutic approach in AD. We have previously reported an inhibitory effect of the methanol extract of Perilla frutescens (L.) Britton (Lamiaceae) and its hexane fraction on Aß aggregation. Here, the hexane fraction of P. frutescens was subjected to diverse column chromatography based on activity-guided isolation methodology. This approach identified five asarone derivatives including 2,3-dimethoxy-5-(1E)-1-propen-1-yl-phenol (1), ß-asarone (2), 3-(2,4,5-trimethoxyphenyl)-(2E)-2-propen-1-ol (3), asaronealdehyde (4), and α-asarone (5). All five asarone derivatives efficiently reduced the aggregation of Aß and disaggregated preformed Aß aggregates in a dose-dependent manner as determined by a Thioflavin T (ThT) fluorescence assay. Furthermore, asarone derivatives protected PC12 cells from Aß aggregate-induced toxicity by reducing the aggregation of Aß, and significantly reduced NO production from LPS-stimulated BV2 microglial cells. Taken together, these results suggest that asarone derivatives derived from P. frutescens are neuroprotective and have the prophylactic and therapeutic potential in AD.

Antibacterial and Antispore Activities of Isolated Compounds from Piper cubeba L.

Piper cubeba L. is the berry of a shrub that is indigenous to Java, Southern Borneo, Sumatra, and other islands in the Indian Ocean. The plant is usually used in folk traditional medicine and is an important ingredient in cooking. The purpose of this study was to isolate and purify the bioactive compounds from P. cubeba L. fractions. In addition, the isolated compounds were tested for their antibacterial and antispore activities against vegetative cells and spores of Bacillus cereus ATCC33019, B. subtilis ATCC6633, B. pumilus ATCC14884, and B. megaterium ATCC14581. The phytochemical investigation of the DCM fraction yielded two known compounds: ß-asarone (1), and asaronaldehyde (2) were successfully isolated and identified from the methanol extract and its fractions of P. cubeba L. Results showed that exposing the vegetative cells of Bacillus sp. to isolated compounds resulted in an inhibition zone with a large diameter ranging between 7.21 to 9.61 mm. The range of the minimum inhibitory concentration (MIC) was between 63.0 to 125.0 µg/mL and had minimum bactericidal concentration (MBC) at 250.0 to 500.0 µg/mL against Bacillus sp. Isolated compounds at a concentration of 0.05% inactivated more than 3-Log10 (90.99%) of the spores of Bacillus sp. after an incubation period of four hours, and all the spores were killed at a concentration of 0.1%. The structures were recognizably elucidated based on 1D and 2D-NMR analyses (1H, 13C, COSY, HSQC, and HMBC) and mass spectrometry data. Compounds 1, and 2 were isolated for the first time from this plant. In conclusion, the two compounds show a promising potential of antibacterial and sporicidal activities against Bacillus sp. and thus can be developed as an anti-Bacillus agent.

Asarones from Acori Tatarinowii Rhizoma stimulate expression and secretion of neurotrophic factors in cultured astrocytes.

Acori Tatarinowii Rhizoma (ATR, the dried rhizome of Acorus tatarinowii Schott.) is a traditional Chinese medicine widely used to treat brain diseases, e.g. depression, forgetfulness, anxiety and epilepsy. Several lines of evidence support that ATR has neuronal beneficial functions in animal models, but its action mechanism in cellular level is unknown. Here, we identified α-asarone and ß-asarone could be the major active ingredients of ATR, which, when applied onto cultured rat astrocytes, significantly stimulated the expression and secretion of neurotrophic factors, i.e. nerve growth factor (NGF), brain derived neurotrophic factor (BDNF) and glial derived neurotrophic factor (GDNF), in dose-dependent manners. These results suggested that the neuronal action of ATR, triggered by asarone, might be mediated by an increase of expression of neurotrophic factors in astrocytes, which therefore could support the clinical usage of ATR. In addition, application of PKA inhibitor, H89, in cultured astrocytes partially blocked the asarone-induced neurotrophic factor expression, suggesting the involvement of PKA signaling. The results proposed that α-asarone and ß-asarone from ATR could serve as potential candidates for drug development in neurodegenerative diseases.

A semi-synthetic neolignan derivative from dihydrodieugenol B selectively affects the bioenergetic system of Leishmania infantum and inhibits cell division.

Leishmaniasis is a neglected disease that affects more than 12 million people, with a limited therapy. Plant-derived natural products represent a useful source of anti-protozoan prototypes. In this work, four derivatives were prepared from neolignans isolated from the Brazilian plant Nectandra leucantha, and their effects against intracellular amastigotes of Leishmania (L.) infantum evaluated in vitro. IC50 values between 6 and 35 µM were observed and in silico predictions suggested good oral bioavailability, no PAINS similarities, and ADMET risks typical of lipophilic compounds. The most selective (SI > 32) compound was chosen for lethal action and immunomodulatory studies. This compound caused a transient depolarization of the plasma membrane potential and induced an imbalance of intracellular Ca2+, possibly resulting in a mitochondrial impairment and leading to a strong depolarization of the membrane potential and decrease of ATP levels. The derivative also interfered with the cell cycle of Leishmania, inducing a programmed cell death-like mechanism and affecting DNA replication. Further immunomodulatory studies demonstrated that the compound eliminates amastigotes via an independent activation of the host cell, with decrease levels of IL-10, TNF and MCP-1. Additionally, this derivative caused no hemolytic effects in murine erythrocytes and could be considered promising for future lead studies.

In vitro susceptibility of Microsporum spp. and mammalian cells to Eugenia caryophyllus essential oil, eugenol and semisynthetic derivatives.

BACKGROUND: Microsporum spp. are keratinophilic dermatophytes that mainly invade the stratum corneum of the skin and hair causing clinical symptoms associated with tinea. Its treatment has several limitations, and the search for new active molecules is necessary. OBJECTIVE: To evaluate the antifungal and cytotoxic potential of Eugenia caryophyllus essential oil (EO), eugenol, isoeugenol and methylisoeugenol against Microsporum canis, M. gypseum and Vero cells. METHODS: The EO was extracted by conventional heating-assisted hydrodistillation, the eugenol obtained commercially and the derivatives through Williamson synthesis. Minimal inhibitory concentration (MICs), minimum fungicidal concentration, inhibition of radial mycelial growth and germination inhibition were used to evaluate the antifungal activity. In addition, a colorimetric test was conducted to evaluate cytotoxic activity. RESULTS: MIC and MFC values for all compounds were 62.5-500 µg/mL for both of the species of Microsporum evaluated. Also, concentrations of 300 µg/mL of the compounds inhibited 100% of M. canis mycelium. The inhibition of germination was observed after 6 hours of treatment (11.86 ± 3.46-85.31 ± 0%). No cytotoxicity was observed in Vero cells (CC50  > 105 µg/mL), whereas terbinafine showed CC50 31.00 ± 0.61 µg/mL. CONCLUSIONS: Our study indicates an interesting bioactivity of isoeugenol and methylisoeugenol against M. canis, M. gypseum and mammalian cells.

Morphophysiological and Phytochemical Variability in Some Wild Populations of Ducrosia anethifolia from Iran.

In order to determine the morphophysiological and phytochemical properties of various Ducrosia anethifolia populations, the plant samples were collected from 20 locations in native regions. Current study indicated significant differences in the morphophysiological and phytochemical characteristics of D. anethifolia populations collected from 20 locations in Sistan and Baluchestan Province, Iran. The highest value of plant height and the number of lateral stems, node per plant, umbellate per umbel, seeds per umbellate and the roots fresh and dry weight were related to the location with relatively high rainfall (130-161 mm) and low altitude (up to 1165 m) compared with others. Based on the essential oil components, D. anethifolia populations were divided into five different chemotypes. Chemotypes I, II and III were characterized by high amounts of methyl chavicol, chrysanthenyl acetate and decanal, respectively. Moreover, the populations with high amounts of decanal, anethole and dodecanal were placed in chemotype IV. Chemotype V was attributed to the Naserabad population with 1-decanol as the major compound.

Chiral resolution, absolute configuration, and bioactivity of a new racemic asarone derivative from the rhizome of Acorus tatarinowii.

A new asarone-derived racemate (1) was isolated from the rhizome of Acorus tatarinowii. The structure of 1 was established by comprehensive spectroscopic analyses, and it was successfully resolved by chiral HPLC, demonstrating that it is racemic. The absolute configurations of 1a [(-)-acortatarone A] and 1b [(+)-acortatarone A] were determined using quantum chemical calculations. Compounds 1a and 1b were the first cases of asarone derivatives with the 5,7-dialkyl-6-aryl-8-oxabicyclo[3.2.1]oct-3-en-2-one core. The α-glucosidase inhibitory and acetylcholinesterase (AChE) inhibitory activities of 1 were evaluated, and it exhibited α-glucosidase inhibitory activity with potency close to that of the positive control (acarbose).

Rapid High Performance Liquid Chromatography Determination and Optimization of Extraction Parameters of the α-Asarone Isolated from Perilla frutescens L.

Response surface methodology (RSM), based on a central composite design, was used to determine the best liquid-to-raw material ratio (10:3-15 mL/g), extraction time (1-3 h), and ethanol concentration (50%-100%) for maximum content of α-asarone from Perilla frutescens (PF) extract. Experimental values of α-asarone were 9.51-46.36 mg/g; the results fitted a second-order quadratic polynomial model and correlated with the proposed model (R2 > 0.9354). The best conditions were obtained with extraction time of 1.76 h, liquid-to-raw material ratio of 10:13.5 mL/g, and ethanol concentration of 90.37%. Under these conditions, the model predicted extraction content of 40.56 mg/g, while experimental PF content of α-asarone was 43.84 mg/g dried plant. Optimized conditions determined for maximum content of α-asarone were similar to the experimental range. Experimental values agreed with those predicted, thus validating and indicating suitability of both the model and the RSM approach for optimizing extraction conditions. In addition, a reliable, reproducible and accurate method for the quantitative determination of α-asarone by High Performance Liquid Chromatography (HPLC) analysis was developed with limit of detection (LOD), limit of quantitation (LOQ) values of 0.10 and 0.29 µg/mL and excellent linearity (R2 > 0.9999).

Leishmania amazonensis and Leishmania chagasi: In vitro leishmanicide activity of Virola surinamensis (rol.) warb.

Virola species have been used in traditional medicine as healing in skin infections. From V. surinanensis oil were isolated several sesquiterpene as the nerolidol which showed activity against species of Leishmania. The current study aimed to evaluate the leishmanicide activity and toxicity of extracts, fractions and surinamesin obtained from leaves of Virola surinamensis. Hexane, Ethyl Acetate, and Methanol extracts were obtained from powder of dry leaves of V. surinamensis. The hexane and ethyl acetate extracts were fractionated by silica gel column chromatography and increasingly polar gradient. The viability of L. chagasi and L. amazonensis promastigotes was assessed by tetrazolium salt assay (MTT). Peritoneal macrophages were exposed to L. amazonensis promastigotes. The treatment was performed with the extracts for 24 h. Then, the coverslips were stained and the infection index was determined. Cytotoxicity was determined in macrophage cells by peritoneum viability assay (MTT). The selectivity index was calculated as the product of cytotoxic concentration 50% and inhibitory concentration 50%. The hexane extract showed leishmanicide activity in promastigotes. The ethyl acetate, methanol extracts and fractions (C1-C6), were inactive against promastigote form of L. chagasi and L. amzazonensis. None extract showed effect on L. amazonensis amastigotes. All samples tested showed low cytotoxicity (CC50 > 500 µg/mL). The selectivity index of the hexane extract was greater than 5. The hexane extract of V. surinamensis was active against L. chagasi and L. amazonensis promastigotes. The extract fractionation did not increase significantly its antipromastigote activity. The surinamensin is probably not responsible for the activity. The extracts were inactive against amastigotes of L. amazonensis.

Foeniculum vulgare Mill. increases cytosolic Ca2+ concentration and inhibits store-operated Ca2+ entry in vascular endothelial cells.

This study assessed the effects of essential oil of Foeniculum vulgare Mill. (fennel oil) and of trans-anethole, the main component of fennel oil, on extracellular Ca2+-induced store-operated Ca2+ entry (SOCE) into vascular endothelial (EA) cells and their mechanisms of action. Components of fennel oil were analyzed by gas chromatography-mass spectrometry. Cytosolic Ca2+ concentration ([Ca2+]c) in EA cells was determined using Fura-2 fluorescence. In the presence of extracellular Ca2+, fennel oil significantly increased [Ca2+]c in EA cells; this increase was significantly inhibited by the Ca2+ channel blockers La3+ and nifedipine. In contrast, fennel oil induced [Ca2+]c was significantly lower in Ca2+-free solution, suggesting that fennel oil increases [Ca2+]c mainly by enhancing Ca2+ influx into EA cells. [Ca2+]c mobilization by trans-anethole was similar to that of fennel oil. Moreover, SOCE was suppressed by fennel oil and trans-anethole. SOCE was also attenuated by lanthanum (La3+), a non-selective cation channel (NSC) blocker; 2-aminoethoxydiphenyl borane (2-APB), an inositol 1,4,5-triphosphate (IP3) receptor inhibitor and SOCE blocker; and U73122, an inhibitor of phospholipase C (PLC). Further, SOCE was more strongly inhibited by La3+ plus fennel oil or trans-anethole than by La3+ alone. These findings suggest that fennel oil and trans-anethole significantly inhibit SOCE-induced [Ca2+]c increase in vascular endothelial cells and that these reactions may be mediated by NSC, IP3-dependent Ca2+ mobilization, and PLC activation.

Hierridin B Isolated from a Marine Cyanobacterium Alters VDAC1, Mitochondrial Activity, and Cell Cycle Genes on HT-29 Colon Adenocarcinoma Cells.

BACKGROUND: Hierridin B was isolated from a marine cyanobacterium Cyanobium sp. strain and induced cytotoxicity selectively in HT-29 adenocarcinoma cells. The underlying molecular mechanism was not yet elucidated. METHODS: HT-29 cells were exposed to the IC50 concentration of hierridin B (100.2 µM) for 48 h. Non-targeted proteomics was performed using 2D gel electrophoresis and MALDI-TOF/TOF mass spectrometry. The mRNA expression of apoptotic and cell cycle genes were analyzed by real-time PCR. Automated quantification of 160 cytoplasm and mitochondrial parameter was done by fluorescence microscopy using CellProfiler software. RESULTS: Proteomics identified 21 significant different proteins, which belonged to protein folding/synthesis and cell structure amongst others. Increase of VDAC1 protein responsible for formation of mitochondrial channels was confirmed by mRNA expression. A 10-fold decrease of cytoskeleton proteins (STMN1, TBCA) provided a link to alterations of the cell cycle. CCNB1 and CCNE mRNA were decreased two-fold, and P21CIP increased 10-fold, indicative of cell cycle arrest. Morphological analysis of mitochondrial parameter confirmed a reduced mitochondrial activity. CONCLUSION: Hierridin B is a potential anticancer compound that targets mitochondrial activity and function.

A two-stage extraction procedure for insensitive munition (IM) explosive compounds in soils.

The Department of Defense (DoD) is developing a new category of insensitive munitions (IMs) that are more resistant to detonation or promulgation from external stimuli than traditional munition formulations. The new explosive constituent compounds are 2,4-dinitroanisole (DNAN), nitroguanidine (NQ), and nitrotriazolone (NTO). The production and use of IM formulations may result in interaction of IM component compounds with soil. The chemical properties of these IM compounds present unique challenges for extraction from environmental matrices such as soil. A two-stage extraction procedure was developed and tested using several soil types amended with known concentrations of IM compounds. This procedure incorporates both an acidified phase and an organic phase to account for the chemical properties of the IM compounds. The method detection limits (MDLs) for all IM compounds in all soil types were <5 mg/kg and met non-regulatory risk-based Regional Screening Level (RSL) criteria for soil proposed by the U.S. Army Public Health Center. At defined environmentally relevant concentrations, the average recovery of each IM compound in each soil type was consistent and greater than 85%. The two-stage extraction method decreased the influence of soil composition on IM compound recovery. UV analysis of NTO established an isosbestic point based on varied pH at a detection wavelength of 341 nm. The two-stage soil extraction method is equally effective for traditional munition compounds, a potentially important point when examining soils exposed to both traditional and insensitive munitions.

Acorus calamus Linn.: phytoconstituents and bactericidal property.

Acorus calamus Linn. of the family Araceae (Acoraceae), commonly known as Sweet Flag and Vacha. The rhizome of this plant has medicinal properties against bugs, moths, lice and emetic stomach in dyspepsia. Chemical composition of the hydro-distilled essential oil obtained from the rhizomes of A. calamus was analyzed by gas chromatography equipped with flame ionization detector and gas chromatography coupled with mass spectrometry. The essential oil of A. calamus and its major compound ß-asarone were tested against five Gram-positive, eight Gram-negative bacteria, and three fungi by the tube-dilution method at a concentration rang of 5.0-0.009 mg/mL. Forty constituents were identified which comprised 98.3 % of the total oil. The major compound ß-asarone (80.6 %) was identified and confirm by NMR ((1)H- & (13)C-) in rhizome oil of A. calamus. The organism Micrococcus luteus was found to be more susceptible to the oil with minimum bactericidal concentration (MBC) value of 0.032 ± 0.004 mg/mL, followed by Aspergillus fumigatus, Aspergillus niger and Micrococcus flavus with MBC values of 0.104 ± 0.016, 0.117 ± 0.017 and 0.143 ± 0.013 mg/mL, respectively. The compound ß-asarone was susceptible to the microorganism A. niger with MBC value 0.416 ± 0.065 mg/mL. The present study revealed that tetraploid variety of A. calamus is growing in this region with substantial amount of ß-asarone. The oil showed bactericidal property against tested bacteria and fungi. The ß-asarone exhibited poorer bactericidal activity against test microorganisms.

Comparative functional characterization of eugenol synthase from four different Ocimum species: Implications on eugenol accumulation.

Isoprenoids and phenylpropanoids are the major secondary metabolite constituents in Ocimum genus. Though enzymes from phenylpropanoid pathway have been characterized from few plants, limited information exists on how they modulate levels of secondary metabolites. Here, we performed phenylpropanoid profiling in different tissues from five Ocimum species, which revealed significant variations in secondary metabolites including eugenol, eugenol methyl ether, estragole and methyl cinnamate levels. Expression analysis of eugenol synthase (EGS) gene showed higher transcript levels especially in young leaves and inflorescence; and were positively correlated with eugenol contents. Additionally, transcript levels of coniferyl alcohol acyl transferase, a key enzyme diverting pool of substrate to phenylpropanoids, were in accordance with their abundance in respective species. In particular, eugenol methyl transferase expression positively correlated with higher levels of eugenol methyl ether in Ocimum tenuiflorum. Further, EGSs were functionally characterized from four Ocimum species varying in their eugenol contents. Kinetic and expression analyses indicated, higher enzyme turnover and transcripts levels, in species accumulating more eugenol. Moreover, biochemical and bioinformatics studies demonstrated that coniferyl acetate was the preferred substrate over coumaryl acetate when used, individually or together, in the enzyme assay. Overall, this study revealed the preliminary evidence for varied accumulation of eugenol and its abundance over chavicol in these Ocimum species. Current findings could potentially provide novel insights for metabolic modulations in medicinal and aromatic plants.