Effect of different photoperiodic regimes on growth, flowering and essential oil in Mentha species

Three major cultivated Mentha spp. (M. arvensis, M. citrata and M. cardiaca) were grown under short-days, normal-days or long-days for 60 cycles. Subsequent to photoperiodic treatment, the plants were assessed for growth behaviour, essential oil content, oil composition and essential oil biosynthesis. The species grew better under long-day conditions. The long-day treatment resulted in flowering in M. citrata, which normally does not flower under our conditions. The oil concentration and biogenesis was maximal in short-day plants. The photoperiodic treatment also affected the oil composition. The observations are discussed in relation to physiology of the oil biogenesis.     

Phytotoxic and antimicrobial activities and chemical analysis of leaf essential oil fromAgastache rugosa

Seasonal variations in the chemical composition of leaves fromAgastache rugosa were analyzed by gas chromatography-mass spectrometry (GC-MS). Phytotoxic and antimicrobial activities of its essential oil were investigated by characterizing 31 components, primarily methylchavicol (80.24%),dl-limonene (3.50%), linalool (4.23%), 5-methyl-2-(1-methylethylidene)-cyclohexanone (3.84%), and β-caryophyllene (2.39%). The contents of most of these chemical constituents varied significantly (P<0.05) over time, with the highest oil yield being early in the growing season (May). Their phytotoxic effects on the seed germination ofMajorana hortensis, Trifolium repens, Rudbeckia hirta, Chrysanthemum zawadskii var.latilobum, Melissa officinalis,Taraxacum platycarpum, andTagetes patula also were determined. These oils partially or completely inhibited germination, and prevented the growth of radicles and hypocotyls. Results of antimicrobial testing showed that the oils also entirely blocked the growth of four microorganisms (Staphylococcus aureus sub.aures, Escherichia coli, Salmonella enteritidis, andPseudomonas aeruginosa). These inhibitory effects might depend on the activity of methylchavicol, a main compound inA. rugosa.     

Antioxidant and antimicrobial activities of essential oil and extracts of Saurauia lantsangensis hu root

Antioxidant and antimicrobial activities of the essential oil and n-hexane (HEE), chloroform (CHE), ethyl acetate (EAE), and methanol (MEE) extracts, respectively, from the root of Saurauia lantsangensis Hu were investigated. The GC-MS analysis revealed 39 compounds representing 96.41% of the oil containing T-muurolol (13.85%), acetophenone (7.46%), alpha-cadinol (6.26%), methyl palmitate (5.36%), n-hexadecanoic acid (4.31%), torreyol (3.69%), and isospathulenol (3.48%) as major components. Antioxidant activities determined by three various testing systems, i.e., DPPH radical scavenging, superoxide anion radical scavenging, and reducing power assay, increased in the order: HEE < CHE < oil < MEE < EAE. CHE, EAE, MEE and oil exhibited a promising antimicrobial effect determined as the diameter of zones of inhibition (13.3-16.2, 16.5-20.4, 13.5-16.6, and 16.5-22.7 mm), respectively, along with their respective MIC values (500-1000, 125-500, 250-500, and 250-500 microg/ml) against Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli), Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus), and a yeast (Hansenula anomala).     

Composition and the in vitro antimicrobial activities of the essential oils of some Thymus species

The genus Thymus (Lamiaceae) is represented by 38 species (64 taxa) in Turkey, and 24 of which are endemic to Turkey. Aerial parts of Thymus longicaulis subsp. chaubardii var. chaubardii, T. zygioides var. lycaonicus, T. longicaulis subsp. longicaulis var. subisophyllus and T. pulvinatus collected from three different localities in Balikesir province were subjected to hydrodistillation to yield essential oils which were subsequently analysed by GC and GC/MS. The main constituents of the oils were identified, and antimicrobial bioassay was applied. Thymol (56.6%, 42.8%, 36.9%) was the main component in the oils of T. longicaulis subsp. chaubardii var. chaubardii (chemotype I), T. longicaulis subsp. chaubardii var. chaubardii (chemotype II) and T. zygioides var. lycaonicus respectively. The oil of T. longicaulis subsp. longicaulis var. subisophyllus contained carvacrol (60.0%) and the oil of T. pulvinatus borneol (27.9%) as main constituents.     

Chemical profile and biological activities of Cedrelopsis grevei H. Baillon bark essential oil

Cedrelopsis grevei H. Baillon bark, endemic plant from Madagascar, is used in folk medicine for the treatment of rheumatism, muscular pain, and for its antifungal and antibiotic activities. In this paper, the phytochemical composition, antioxidant, antimicrobial, and cytotoxic activities of C. grevei bark essential oil (EO), its non-polar (I and II) and polar (III) fractions and its main compounds (ishwarane, β-elemene and α-copaene) were investigated.

The GC–MS analysis pointed out the presence of 36 components, representing about 80% as semi-quantitative characterization of the total. The presence of ishwarane, β-elemene and α-copaene as the main constituents highlighted its peculiar composition as a sesquiterpene-rich phytocomplex. Moreover, the quantification was performed for the first time by means of the experimental and predicted response factors (ERFs and PRFs, respectively).

As regards the biological activity, C. grevei EO and its fractions showed weak antioxidant activity against Trolox. The whole EO demonstrated instead considerable antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis, while its polar-fraction evidenced an interesting bioactivity against Pseudomonas aeruginosa and Candida albicans. Finally, C. grevei EO and its fractions exhibited an interesting cytotoxic activity on human lung cancer cells (A549) and human colorectal cancer cells (CaCo-2).     

Chemical composition, antioxidant and antimicrobial activities of essential oil of Thymus algeriensis wild-growing in Libya

The composition of essential oil isolated from Thymus algeriensis growing wild in Libya was analyzed by GC and GC-MS. The essential oil was characterized with thymol (38.50%) as the major component. The oil was screened for antioxidant activity using DPPH assay, and compared to thymol and carvacrol. Antioxidant activity was high, with the IC₅₀ of 0.299 mg/ml, compared to 0.403 and 0.105 mg/ml for thymol and carvacrol, and 0.0717 mg/ml for BHA. In addition, antimicrobial activity was tested against eight bacteria and eight fungi. T. algeriensis oil showed inhibitory activity against tested bacteria at 0.001–0.05 mg/ml, while bactericidal activity (MBC) was achieved at 0.0025–0.05 mg/ml. For antifungal activity MICs ranged 0.0005–0.025 mg/ml and MFC 0.001–0.05 mg/ml. High antimicrobial activity against the fungi in particular suggests that the essential oil of Thymus algeriensis could have a useful practical application.     

Determination of usnic acid in some Rhizoplaca species from Middle Anatolia and their antimicrobial activities

Three species of lichens, Rhizoplaca chrysoleuca (Sm.) Zopf, Rhizoplaca melanopthalma (DC.) Leuckert & Poelt and Rhizoplaca peltata Ramonds Leuckert, were collected from middle Anatolia, Erciyes Mountain (Kayseri) in Turkey. Their usnic acid amounts were determined by HPLC in acetone extracts. In addition, antimicrobial activities of these extracts were determined against Escherichia coli (ATCC 35218), Enterococcus faecalis (RSKK 508), Proteus mirabilis (Pasteur Ens. 235), Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium and Pseudomonas aeruginosa. It was shown that, as the usnic acid amount increased, the antimicrobial activities increased too. The usnic acid contents of Rhizoplaca species varied between 0.19-4.0% dry weight.     

Composition and antimicrobial activity of the essential oil of six Hypericum species from Serbia

The volatile composition of six Hypericum species has been studied. The essential oils were obtained by steam distillation in 500 mL H₂O for 2 h in a modified Clevenger apparatus with a water-cooled oil receiver to reduce hydrodistillation over-heating artifacts, and their analyses were performed by GC and GC–MS. Identification of the substances was made by comparison of mass spectra and retention indices with literature records. A total of 100 different compounds were identified. The main constituents of the investigated populations of each taxon have been revealed as follows: Hypericum alpinum: (−)-β-pinene, γ-terpinene, (−)-(E)-caryophyllene; Hypericum barbatum: (−)-α-pinene, (−)-β-pinene, (−)-limonene, (−)-(E)-caryophyllene, (−)-caryophyllene oxide; Hypericum rumeliacum: (−)-α-pinene, (−)-β-pinene, (−)-limonene, Hypericum hirsutum: nonane, undecane, (−)-(E)-caryophyllene, (−)-caryophyllene oxide; Hypericum maculatum: spathulenol, globulol; Hypericum perforatum: (−)-α-pinene, (Z)-β-farnesene, germacrene D; Monoterpene hydrocarbons were shown to be the main group of the taxa belonging to the section Drosocarpium, while the taxa of section Hypericum were more rich in sesquiterpene hydrocarbons.     

Biotransformation of monoterpenoids and their antimicrobial activities

Biotransformation is an economically and ecologically viable technology which has been used extensively to modify the structures of many classes of biologically active products. The discovery of novel antimicrobial metabolites from biotransformation is an important alternative to overcome the increasing levels of drug resistance by plant and human pathogens. Monoterpenes, the main constituents of essential oils, are known for their antimicrobial activities. In 2004, Farooq, Atta-Ur-Rahman and Choudhary published a review on fungal transformation of monoterpenes which covers papers published up to 2002. The present review not only updates the previous one but also discusses the antimicrobial activities (antibacterial, antifungal and antiviral) of biotransformed compounds.     

Nutritionally essential amino acids and metabolic signaling in aging

Aging is associated with a gradual decline in skeletal muscle mass and strength leading to increased risk for functional impairments. Although basal rates of protein synthesis and degradation are largely unaffected with age, the sensitivity of older muscle cells to the anabolic actions of essential amino acids appears to decline. The major pathway through which essential amino acids induce anabolic responses involves the mammalian target of rapamycin (mTOR) Complex 1, a signaling pathway that is especially sensitive to regulation by the branched chain amino acid leucine. Recent evidence suggests that muscle of older individuals require increasing concentrations of leucine to maintain robust anabolic responses through the mTOR pathway. While the exact mechanisms for the age-related alterations in nutritional signaling through the mTOR pathway remain elusive, there is increasing evidence that decreased sensitivity to insulin action, reductions in endothelial function, and increased oxidative stress may be underlying factors in this decrease in anabolic sensitivity. Ensuring adequate nutrition, including sources of high quality protein, and promoting regular physical activity will remain among the frontline defenses against the onset of sarcopenia in older individuals.     

Cardiovascular effects of the essential oil of Mentha x villosa in DOCA-salt-hypertensive rats.

The present study investigated the effects of chronic treatment with deoxycorticosterone-acetate (DOCA)-salt on cardiovascular responses to intravenous (i.v.) injection of the essential oil of Mentha x villosa (EOMV) in conscious rats. In both DOCA-salt-hypertensive and uninephrectomized control, conscious rats, i.v. bolus injections of EOMV (1 to 20 mg/kg body wt.) decreased mean aortic pressure (MAP) and heart rate (HR) in a dose-dependent manner. Treatment with DOCA-salt significantly enhanced EOMV-induced decreases in MAP, without affecting bradycardia. Likewise, both maximal percent and absolute decreases in MAP elicited by i.v. injection of the ganglion blocker, hexamethonium (30 mg/kg body wt.), were significantly greater in DOCA-salt-hypertensive than in control rats. In DOCA-salt-hypertensive rats, i.v. pretreatment with hexamethonium (30 mg/kg body wt.) reduced the bradycardia elicited by EOMV (1 to 20 mg/kg body wt.) without affecting the enhancement of EOMV-induced hypotension. These results show that i.v. treatment with EOMV decreases blood pressure in conscious DOCA-salt-hypertensive rats dose-dependently, and that this action is enhanced when compared with uninephrectomized controls. This enhancement could be related mainly to an increase in EOMV-induced vascular smooth muscle relaxation, rather than to enhanced sympathetic nervous system activity in this hypertensive model.     

江西迷迭香精油的成分分析及抗氧化、抑菌活性研究

为了研究江西迷迭香精油的化学成分及抗氧化、抑菌活性,采用水蒸气蒸馏法提取迷迭香精油,利用气相色谱-质谱联用法(GC-MS)对迷迭香精油成分进行分析,通过对DPPH自由基、羟基自由基的清除活性和还原力来研究迷迭香精油的体外抗氧化活性;通过以枯草芽孢杆菌、金黄色葡萄球菌和大肠杆菌为供试菌,测定抑菌圈大小和最低抑菌浓度(MIC)来研究迷迭香精油的抑菌活性。实验结果表明,从迷迭香精油中鉴定出40种化学成分,占精油总量的99.46%,其主要化学成分有α-蒎烯(39.05%)和1,8-桉叶素(16.86%),其次是莰烯(4.22%)、D-柠檬烯(3.87%)、龙脑(3.74%)、β-石竹烯(3.11%)等,α-蒎烯的含量高于国内其他产地;迷迭香精油对DPPH、羟基自由基和还原力的半数清除率IC₅₀值分别为76.42、51.40和49.15μL/mL;精油对枯草芽孢杆菌、金黄色葡萄球菌和大肠杆菌的抑菌圈大小分别为14.40±0.66、11.41±0.19、11.70±0.27 mm,最低抑菌浓度(MIC)分别为2.50、10.00、10.00μL/mL,对枯草芽孢杆菌的抑制作用明显强于金黄色葡萄球菌和大肠杆菌。结果表明迷迭香精油具有较好的抗氧化、抑菌活性。     

Anti-biofilm activities of essential oils rich in carvacrol and thymol against Salmonella Enteritidis

The aim of the present study was to determine the bioactive compounds in four essential oils (EO’s) from Origanum heracleoticum, Origanum vulgare, Thymus vulgaris and Thymus serpyllum and to assess their antimicrobial and anti-biofilm activity against Salmonella Enteritidis. Strains were previously characterized depending on the expression of the extracellular matrix components cellulose and curli fimbriae as rdar (red, dry and rough) and bdar morphotype (brown, dry and rough). This study revealed that the EO’s and EOC’s (carvacrol and thymol) investigated showed inhibition of biofilm formation at sub-minimum inhibitory concentration. Comparing the efficacy of EO’s and EOC’s in the inhibition of biofilm formation between the strains with different morphotype (rdar and bdar) did not show a statistically significant difference. Results related to the effectiveness of EO’s and EOC’s (the essential oil components, carvacrol and thymol) on eradication of preformed 48?h old biofilms indicated that biofilm reduction occurred in a dose-dependent manner over time.     

兴安薄荷挥发油的成分

兴安薄荷（Mentha dahurica Fisch.ex Benth.）为唇形科薄荷属（Mentha L.）多年生草本植物,产于我国黑龙江、吉林、内蒙古东北部。俄罗斯远东地区以及日本北方也有分布。在我国东北有作中药薄荷入药的。其化学成分研究甚少,仅俄国Pulatova报道其含有香豆素类成分。为开发利用我国薄荷植物资源,作者对全国薄荷属植物进行了野外调查,并对其资源、生物学性状、孢粉学和化学等进行了较系统的研究,现仅就兴安薄荷挥发油中化学成分分析结果作一报道。     

Volatile systematics: A novel biochemical interpretation of essential oil compounds enhances their chemophenetic significance

The Essential Oils (EOs) present numerous chemophenetic applications, mostly at infrageneric rank. EOs utilization for this purpose has been questioned because of the external stimulations that control their chemodiversity and quantitative composition. Therefore, they are considered as a class of natural products with questionable systematic significance. Present study exploiting the recent advances on plant volatile biogenesis aims to reestablish and expand the EOs chemophenetic significance. The presented methodology translates EO composition in a biochemical profile, through the chemical structure classification of EOs compounds that links their presence with the activation of endogenous biochemical procedures. The Apiaceae supra-generic classification was utilized to test the proposed methodology. In specific, 44 Greek indigenous Apiaceae taxa, representing all 10 tribes of Apioideae subfamily were collected, distilled and analyzed. The herein applied approach was focused in tribal rank and revealed 10 biochemical entities established on the diversification of their fundamental metabolic routes and biosynthetic pathways activation. The generated biochemical profiles were proven compatible with phenotypic and phylogenetic approaches, but also separated all tribes of Apioideae. Therefore, the proposed methodology can be considered as a promising new systematic tool, which is able to exploit the vast availability of EOs composition data.     

Genetic diversity in Mentha cervina based on morphological traits,essential oils profile and ISSRs markers

Morphological, phytochemical and genetic differences were studied to evaluate the level and distribution of diversity in twelve populations of the Portuguese endangered medicinal plant Mentha cervina L. Morphological variation was correlated with ecological conditions at the site of origin. Pulegone was the major essential oils compound in all of the populations collected at full flowering (68–83%), in different growing conditions (51–82%), and for all the developmental stages studied (47–82%). Although clusters were defined, the analysis revealed a high chemical correlation among all populations (S_corr ≥ 0.95%). Inter-simple sequence repeats markers were used to assess the population structure and genetic variation. Populations exhibited a relatively low genetic diversity (PPB = 14.3–64.6%, H_e = 0.051–0.222, I = 0.076–0.332), with high structuring between them (G_ST = 0.51). However, the genetic diversity at species level was relatively high (PPB = 97.7%; H_e = 0.320). The levels and patterns of genetic diversity were assumed to result largely from a combination of evolutionary history and its unique biological traits, such as breeding system, clonal growth, low capacity of dispersion and habitat fragmentation. The relatively low genetic diversity in the populations analyzed indicates that the maintenance of their evolutionary potential is at risk if population sizes are maintained and if there is no protection of the habitats.     

Synthesis of egonol derivatives and their antimicrobial activities

Eighteen derivatives of egonol (A-R) were synthesized and evaluated for their antimicrobial activities against Staphylococcus aureus ATCC 29213, Bacillus subtilis ATCC 6633, Candida albicans ATCC 10231 and Escherichia coli ATCC 8739 microorganisms comparing with egonol. The obtained data reported that compound B exhibited improved activities against all tested bacteria than egonol, others have shown different range of activities.     

Effect of Mentha piperita and Cuminum cyminum essential oil on Tribolium castaneum and Sitophilus oryzae

Essential oils are one of the known plant materials for insect pest control. The studies about essential oils application for control of insect pest population has been started in recent years. This study aims to investigate repellency effect and fumigant toxicity of Mentha piperita and Cuminum cyminum essential oil on Tribolium castaneum and Sitophilus oryzae. The results showed that the mortality rate of adult insects was increased with increase in essential oil concentration. The highest pest mortality rate in the case of M. piperita and C. cyminum on T. castaneum and S. oryzae was 64, 68, 82 and 78%, respectively. The average insect mortality was significantly different in various concentrations in most of the treatments. Amounts of LC₅₀ were 0.421, 0.271, 0.135 and 0.136 (ml/ml) for M. piperita and C. cyminum essential oil on T. castaneum and S. oryzae, respectively. Different concentrations of M. piperita and C. cyminum essential oil had different repellency effect on T. castaneum and S. oryzae. Repellency effect was increased with increase in essential oil concentration, and the highest repellency effect was belonged to the highest concentration. Essential oils of M. piperita and C. cyminum caused 61.2 and 66.4% repellency on T. castaneum. Meanwhile, their effect was found to be 55.2 and 60.4% repellency on S. oryzae at the highest concentration.     

Thyme essential oil for antimicrobial protection of natural textiles

The study was aimed at increasing the resistance of lignocellulosic textiles to bacteria and mould action using a biocide of plant origin. The biocide used in the study was thyme essential oil. This kind of oil is characterized by low toxicity for humans and the environment. The antimicrobial efficiency of thyme essential oil applied to linen–cotton blended fabric and linen fabric was evaluated by determining bacterial growth, degree of mould growth, and their impact on fabric strength. Thyme essential oil applied as 8% concentration in methanol to linen–cotton blended fabric showed very high antibacterial and antifungal activity – no mould growth and no significant loss of breaking force were observed. Microscopic evaluation of the tested fabrics was also performed by Scanning Electron Microscopy. Applying the eco-friendly biocide to fabrics containing natural fibres in the finishing process produces antimicrobial barrier properties.     

Growth, morphogenesis, and essential oil production in Mentha spicata L. plantlets in vitro

To date, plantlet culture has not been explored as a means to obtain secondary metabolites in vitro. However, plantlets readily produce desirable secondary metabolites, which may not be produced in cell suspension or callus cultures. To optimize plantlet growth in vitro, the influences of various physical environments on the growth (fresh weight), morphogenesis (leaf, root, and shoot number), and volatile carbon metabolites (i.e. monoterpene, (−)-carvone) of Mentha spicata L. (spearmint) plants were studied. The carvone content in different portions of sterile plantlets was analyzed. Carvone was only produced from the foliar regions of cultured plantlets and was absent in the callus and roots. The influence of physical support (e.g., agar, glass gravel, liquid, platform or sponge), frequency of media replacement, and culture vessel capacity on spearmint plantlets growth and carvone production was tested. A comparative study was conducted testing the growth, morphogenesis, and secondary metabolism occurring with three different spearmint cultivars grown in either culture tubes containing 25 ml agar medium or in an automated plant culture system (APCS; a sterile hydroponics system) employing a 1-l medium reservoir. Increasing the number of media immersions (4, 8, 12 or 16 immersions d⁻¹) of plantlets growing in the APCS increased growth and morphogenesis responses. Generally, higher culture growth rates resulted in lower carvone treatment⁻¹ (mg carvone g-FW⁻¹); however, overall total carvone ((mg carvone g-FW⁻¹) × g culture FW) increased because of the production of greater biomass obtained per vessel.