High Content Of Thymol Research Articles

Nano Silicon Modulates Chemical Composition and Antioxidant Capacities of Ajowan (Trachyspermum ammi) Under Water Deficit Condition.

Ajowan (Trachyspermum ammi) is an important spice in the food industry, as a well as a medicinal plant with remarkable antioxidant properties. In this study, its essential oil content, chemical composition, flavonoid content, phenolic content, and antioxidant capacity were evaluated under three irrigation regimes (50, 70, and 90% field capacity) and different amounts of nano silicon (0, 1.5, and 3 mM) in ten populations of ajowan. Based on the GC-MS analysis, thymol, carvacrol, p-cymene, and γ-terpinene were determined as the main components of the oil. The thymol content ranged from 34.16% in the Ardabil population (irrigation at 50% and nano silicon at 1.5 mM) to 65.71% in the Khorbir population (without nano silicon and irrigation at 50%). The highest phenolic content was in Khormo with irrigation at 90% and without nano silicon (172.3 mg TAE/g DW), while the lowest was found in Hamedan (irrigation at 50% and without nano silicon (7.2 mg TAE/g DW)). Irrigation at 50% and no nano silicon treatment led to an increase in total flavonoids in Ardabil (46.786 mg QUE/g DW). The antioxidant activity of ajowan was evaluated using the DPPH assay. Accordingly, the highest antioxidant capacity was observed in Khormo (irrigation at 90% without nano silicon; 4126 µg/mL). Moreover, the highest thymol content was observed in the Khorbir population with irrigation at 50% and without nano silicon treatment. Furthermore, correlation and principal component analysis (PCA) provide new insights into the production of ajowan from their substrates under nano silicon treatment and water deficit conditions. Finally, the results revealed information on how to improve the desired essential oil profile and antioxidant capacity of extracts for industrial producers.

Phenolic Monoterpenes Conversion of Conobea scoparioides Essential Oil by Hydrotalcite Synthesized from Blast-Furnace Slag.

Conobea scoparioides (Plantaginaceae) is an herbaceous plant known as "pataqueira" that grows wild in seasonally wet areas of the Amazon region. It is used for aromatic baths and anti-protozoan remedies by the Brazilian Amazon native people. The main volatile compounds identified in the essential oil of "Pataqueira" were the phenolic monoterpenes thymol and thymol methyl ether and their precursors, the monoterpene hydrocarbons α-phellandrene and p-cymene. A hydrotalcite synthesized from blast-furnace slag exhibited a 3:2 (Mg/Al) molar ratio, and this layered double hydroxide (LDH) was evaluated as a catalyst in converting the main monoterpenes of the "Pataqueira" oil. This action significantly increased the thymol content, from 41% to 95%, associated with the percentual reduction in other main components, such as thymol methyl ether, α-phellandrene, and p-cymene. The LDH reaction showed a strong tendency towards producing hydroxylated derivatives, and its behavior was similar to the hypothetical plant biosynthetic pathway, which leads to the production of the monoterpenes of "Pataqueira" oil. Thymol and its derivatives are potent antiseptics applied in pharmaceutical and hygienic products as antibacterial, antifungal, and antioxidant properties, among others. The present work reports a natural source with a high thymol content in aromatic plants from the Amazon, with evident economic value.

Changes in Essential Oil Composition, Polyphenolic Compounds and Antioxidant Capacity of Ajowan (Trachyspermum ammi L.) Populations in Response to Water Deficit.

Ajowan (Trachyspermum ammi L.) is considered a valuable spice plant with a high thymol content. Seed yield, essential oil constituents, polyphenolic composition, and antioxidant capacity of ajowan (Trachyspermum ammi L.) populations were evaluated in three (normal, moderate, and severe) water irrigation regimes. The highest essential oil content (5.55%) was obtained under normal condition in the Yazd population. However, both essential oil and seed yield showed significant reductions as a result of water stress. According to gas chromatography–mass spectrometry (GC–MS) analysis, thymol (61.44%), γ-terpinene (26.96%), and p-cymene (20.32%) were identified as the major components of the oil. The highest (89.01%) and the lowest (37.54%) thymol contents were in Farsmar and Hamadan populations in severe stress condition, respectively. Based on HPLC analysis, chlorogenic (3.75–47.35 mg/100 g), caffeic (13.2–40.10 mg/100 g), and ferulic acid (11.25–40.10 mg/100 g) were identified as the major phenolic acids, while rutin was determined as the major flavonoid (11.741–20.123 mg/100 g). Moreover, total phenolic and flavonoid contents were elevated under drought stress treatment, while antioxidants responded inconsistently to stress based on two model systems. Overall, the Yazd population exhibited a superior response to water stress, as evidenced by its less reduced thymol and oil yield content, while Arak and Khormo had the highest accumulation of polyphenolic compounds.

Chemical variability of lemon beebalm (Monarda citriodora Cerv. ex Lag.) during plant phenology

Lemon beebalm (Monarda citriodora Cerv. ex Lag.) is a well-known source of thymol and other active ingredients with recognised antimicrobial properties. However, no previous research investigated the chemical variability of M. citriodora organs during plant phenology. In this paper, above-ground organs of lemon beebalm harvested during three phenological stages were studied for the content and composition of essential oil (EO) and phenolic compounds as well as antimicrobial and antioxidant activity. The EO content in leaves and inflorescences during the full flowering stage was 3.34% and 3.83%, respectively. The phenological stage of plants mainly influenced the content and chemical composition of EO in leaves. The main component of the EOs both from leaves and inflorescences was thymol (52.63–61.83%). The EOs from these organs collected at the full flowering stage inhibited the growth of all the tested microbial strains at the concentration range 0.156–0.625 µL × mL-1. Plant organs differed in the content of total phenolics, flavonoids, and individual phenolic compounds. The effect of phenological stage on these contents was more pronounced in leaves and stems than in inflorescences. Total flavonoid content in stems and inflorescences was higher than in leaves. Leaves harvested during vegetative stage were characterised by the highest level of linarin, a flavone glycoside (80.66 mg × 100 g-1 of dry raw material). All the tested parts of plants were found to be rich in rosmarinic acid, in particular inflorescences (507.41 mg × 100 g-1). The identified high antimicrobial and antioxidant activity of the studied EOs and extracts can be explained by the high content of thymol in EO and rosmarinic acid in the aerial parts of plants.

Antimicrobial Potential and Phytochemical Profile of Wild and Cultivated Populations of Thyme (Thymus sp.) Growing in Western Romania

The purpose of this study was to analyze the chemical composition and antimicrobial activity of some thymus populations collected from five different locations in Western Romania. The chemical compositions of the essential oils (EOs) were studied through GC–MS, and the biological activities were evaluated using the microdilution method. The EO yield ranged between 0.44% and 0.81%. Overall, 60 chemical compounds were identified belonging to three chemotypes: thymol (three populations), geraniol (one population) and carvacrol (one population). Thymus vulgaris L. is distinguished by a high content of thymol, while species of spontaneous flora (Th. odoratissimus and Th. pulegioides) contain, in addition to thymol, appreciable amounts of carvacrol and geraniol. The antimicrobial activity of each the five oils was tested on Staphylococcus aureus (ATCC 25923), Streptococcus pyogenes (ATCC 19615), Esherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Shigella flexneri (ATCC 12022), Salmonella typhimurium (ATCC 14028), Haemophilus influenzae type B (ATCC 10211), Candida albicans (ATCC 10231) and Candida parapsilopsis (ATCC 22019). The EOs showed biological activity on Gram-positive/Gram-negative/fungal pathogens, the most sensitive strains proving to be S. pyogenes, S. flexneri, S. typhimurium and C. parapsilopsis with an MIC starting at 2 µL EO/100 µL. The species sensitive to the action of Thymus sp. from culture or spontaneous flora are generally the same, but it should be noted that T. odoratissimus has a positive inhibition rate higher than other investigated EOs, regardless of the administered oil concentration. To date, there is no research work presenting the chemical and antimicrobial profiling of T. odoratissimus and the correlations between the antimicrobial potential and chemical composition of wild and cultivated populations of thyme (Thymus sp.) growing in Western Romania.

PRODUCTIVITY AND OIL QUALITY OF THYMUS VULGARIS L. UNDER GROWTH PROMOTERS AND SOILLESS CULTURE CONDITIONS

Thyme (Thymus vulgaris L.) belongs to the lamiaceae family. It is characterized by its medicinal and economic values. Thymus is grown worldwide for cosmetic and medical use. Plant bio-stimulants are classified as substances which have positive effects on growth and productivity of plants. Bio-stimulants are obtained naturally from various economically and environmentally viable sources. The current experiment aimed to investigate the response of thymus physical and chemical properties to the different types and concentrations of bio-stimulators under soil less culture conditions for two successive seasons 2019 and 2020. Thymus seedlings were planted in pots filled with mixed media of perlite: sand (1:1v/v). Plants were sprayed with aqueous solution of ascorbic acid (1 and 2g/l), aspartic acids (500 and 1000 ppm) and dry yest (2 and 4g/l) and combination of them compared with control. The herp was harvested in mid- July (First cutting) and first week of October (second cut). Growth and yield characters were measured. The essential oil percentage was determined and analyzed by GC in both cuts from the fresh herb. Results showed that, spraying of mixtures of ascorbic acid (2g/l), aspartic acids (1000 ppm) and yeast (4g/l)) significantly increased yield, total carbohydrates, total phenols, total pigments, essential oil percentage and yield as well as its NPK content characters and components of essential oil high contents of thymol, ? and ? –Pinene during both cuts and for both seasons. Economic evaluation was carried out by calculating with the highest return in the mixture treatment. It is clear that all treatments are economically feasible however, one can find that the maximum return or profit comes from mixture treatments where the benefit to cost ratio were 3.99 and 3.9 for Mix2 and Mix1 respectively.

Thymol Chemotype Origanum vulgare L. Essential Oil as a Potential Selective Bio-Based Herbicide on Monocot Plant Species.

Searching for new bio-based herbicides is crucial for decreasing chemical pollution, protecting the environment, and sustaining biodiversity. Origanum vulgare is considered a promising source of essential oil with herbicidal effect. The mode of action is not known. The present study focused on (1) comparison of phytotoxic activity of Origanum vulgare EO on monocot (Triticum aestivum and Hordeum vulgare) and dicot species (Lepidium sativum and Sinapis alba); (2) and evaluating other antimicrobial biological activities against phytopatogen bacteria (Clavibacter michiganensis, Pseudomonas syringae pv. phaseolicola, Pseudomonas savastanoi, and Xanthomonas campestris); antifungal activity against Monilinia fructicola, Aspergillus niger, Penicillium expansum, and Botrytis cinerea; cytotoxic activity and antioxidant activity. According to the GC/MS analyses, the EO belongs to the thymol chemotype O. vulgare with its high content of thymol (76%). Germination of all four species was not influenced by EO. The phytotoxic effect was statistically significant in the monocot species, while in the dicot species the opposite was observed—a stimulation effect, which was also statistically significant. Strong biological activity of O. vulgare EO was noted on all phytopatogen bacteria and fungi in the highest dose. Cytotoxic activity showed an IC50 = 50.5 μg/mL. Antioxidant activity showed an IC50 = 106.6 μg/mL after 45 min experimental time. Based on the presented results, it is possible to conclude that thymol chemotype O. vulgare essential oil could be potentially used as a herbicide with selective effects on monocot plant species.

Effects of Colombian oregano essential oil (Lippia origanoides Kunth) and Eimeria species on broiler production and cecal microbiota

The gut microbiota has an important effect on poultry health and production. The aim of this study was to evaluate the effect of Colombianoregano (COO), Lippia origanoidesKunth, essential oil supplementation on broiler chicken performance and their cecal bacterial microbiome by 16S-based sequencing. Essential oil was extracted by steam distillation and analyzed by Gas chromatography/mass spectrometry. Two COO levels in feed, 0 ppm control (C) and 100 ppm (O), were evaluated in 2 groups of broilers either unchallenged (U) or challenged (E) with a viable attenuated Eimeria (coccidia) oocytevaccine. Four treatments, UC, UO, EC, and EO, were distributed among 720 one-day-old male Ross broilers randomly placed in 24 pens. Cecal contents DNA was extracted and pyrosequencing was performed following a standard procedure. Pyrosequencing data were processed, and sequence reads were phylogenetically classified. Similarity of membership and structure in the communities were calculated.At the end of the study, the greatest COO effect was found in coccidia-challenged broilers, with an OE body weight of 1,889 ± 52.4 g with respect to 1,799 ± 36.2 g for CE (P < 0.01). Broiler cecal samples were consistent in that phylum Firmicutes and class Clostridia were highly prevalent; COO had no effect on these taxa levels between the 4 treatments (P > 0.05). A positive correlation (P < 0.01) was observed between the Firmicutes:Bacteriodetes phyla ratio against body weight at 35 D of age. This study provided both positive and negative correlations between broiler body weight against some bacterial groups identified, offering perspectives regarding bacterial groups and their impact on host health and metabolism. Lippia origanoides Kunth high thymol content showed a beneficial effect on body weight and the feed conversion ratio in broilers under coccidia challenge.

Antioxidant and Lipoxygenase Inhibitory Activities of Essential Oils from Endemic Plants of Côte d’Ivoire: Zanthoxylum mezoneurispinosum Ake Assi and Zanthoxylum psammophilum Ake Assi

Zanthoxylum mezoneurispinosum Ake Assi and Zanthoxylum psammophilum Ake Assi are species endemic to Côte d’Ivoire. In this study, we determined, for the first time, the composition and biological activities of essential oils obtained from each of these plants. Essential oils were obtained by hydrodistillation from different organs of each plant with a Clevenger-type apparatus and analyzed by gas chromatography–mass spectrometry (GC-MS). Thirty-four components, accounting for more than 99.9% of the overall composition, were identified in the oils. The Z. psammophilum leaf and trunk bark oils exhibited two unusual methylketones, undecan-2-one and tridecan-2-one, whereas the root oil was rich in thymol and sesquiterpenoids. The Z. mezoneurispinosum leaf and trunk bark oils were rich in monoterpenoids, whereas sesquiterpenoids were predominant in the root oil. These samples produced, for the first time, some new chemical profiles of essential oils. The oils’ antioxidant activities were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and ferric reducing antioxidant power (FRAP) assays. The results showed that the essential oil isolated from roots of Z. mezoneurispinosum had the highest antioxidant activity, which is in accordance with the high thymol content of that oil. We also determined the lipoxygenase inhibitory activities of the essential oils. The results showed that all of the tested oils displayed high and close lipoxygenase inhibitory activities.

Antioxidant properties and anti-quorum sensing potential of Carum copticum essential oil and phenolics against Chromobacterium violaceum

The chemical composition, antimicrobial and antioxidant properties of Carum copticum essential oil and its methanolic extract were investigated. Thirteen compounds were identified representing 99.3% of the total oil composition. Oxygenated monoterpenes (53.0%) dominated the C. copticum essential oil with high contents of thymol (51.7 ± 1.51%), p-cymene (26.9 ± 1.11%), γ-terpinene (16.7 ± 0.76%), and β-pinene (1.6 ± 0.15%). In the methanolic extract, the caffeic, gallic, chlorogenic, coumaric and ferulic acids, flavan-3-ols (catechin), flavone (hyperoside), and the flavonol quercetin were identified. Antimicrobial activity of essential oil and the organic extract was tested by disk diffusion and broth microdilution method. The essential oil was effective against the tested bacteria and yeast strains with the highest activity and the MICs and MBCs values were lower as compared to the methanolic extract. The essential oil showed anti-quorum sensing activity against Chromobacterium violaceum, and the IC50 value for violacein inhibition was 0.23mg/ml. Both the essential oil and the methanolic extract also showed antioxidant activities. The results obtained highlight the potential use of C. copticum as a possible source of antimicrobial and antioxidant compounds to be used both as food flavor and as a broad spectrum antibiotic.

Effect of cytokinins on in vitro multiplication, volatiles composition and rosmarinic acid content of Thymus leucotrichus Hal. shoots.

An efficient in vitro multiplication protocol was designed to Thymus leucotrichus, a subshrub and perennial herb growing naturally in the Northwest of Turkey. Of all basal media studied, Murashige and Skoog medium was found to be superior to the others, providing higher shoot formation and the maximum shoot length. Varying concentrations of cytokinins, i.e., 6-benzyladenine, thidiazuron, 2-isopentenyladenine and kinetin were supplemented in the nutrient media to observe their effects on shoot development and biomass. Rosmarinic acid content and volatile compositions of both naturally growing plants and in vitro multiplied plantlets were also evaluated. 6-benzyladenine (1.0mg/L) and kinetin (0.5mg/L) were found to be optimum for shoot number and shoot elongation, respectively. Thidiazuron (1.0mg/L) was superior for biomass production. Rosmarinic acid content of in vitro multiplied plants was found to be higher than that of wild plants, reaching a maximum with 0.5mg/L 2-isopentenyladenine, which yielded 10.15mg/g dry weight. The highest thymol content was obtained with 1.0mg/L kinetin (55.82%), while thidiazuron (0.1mg/L) increased carvacrol production (12.53%). Overall, Murashige and Skoog medium supplemented with 1.0mg/L kinetin was determined to be the most favorable medium studied.

Chemical Composition, Antibacterial and Antioxidant Activities of Thyme Essential Oil (&amp;lt;i&amp;gt;Thymus vulgaris&amp;lt;/i&amp;gt;)

Herbal medicine from natural resources plays an important role as antibacterial and antioxidant agents. The present investigation was designed to evaluate the antibacterial and antioxidant properties of thyme (Thymus vulgaris L.) essential oil (TEO) and/or chitosan (CH) in vitro. Results indicated that TEO exhibited high radical scavenging activity (RSA) toward DPPH, ABTS, linoleic acid deterioration and iron chelation activity. TEO exhibited high amount of total phenolic compounds (TPC) related to its terpenes. The TPC of TEO was 177.3 mg GAE g-1 demonstrated 149.8 μmol of TE g-1 DPPH-RSA and 192.4 μmol of TE g-1 ABTS-RSA. The antioxidant capacity of TEO exhibited 68.9% reduction when evaluated by β-carotene bleaching assay. The reducing power activity related to iron chelation was 142.8 μmol of AAE g-1. The TEO exhibited a high content of Thymol (41.04%) as major compound over 14 identified components by GC-MS analysis followed by 1,8-Cineole (14.26%), γ-Terpinene (12.06%), p-Cymene (10.50%) and α-Terpinene (9.22%). TEO exhibited antimicrobial activity in vitro and MIC noticed that TEO was efficiently affected pathogens in vitro. Indeed, CH exhibited negligible or very low antimicrobial activity. In conclusion, both investigated TEO and TEO-CHmix have strong antibacterial activity against many pathogenic bacteria and need exploitation as an alternative source of natural antibacterial and antioxidant agents for potential applications.

Essential Oil Chemotypes of Three Ocimum Species Found in Sierra Leone and Nigeria

Chemical composition of the essential oil of Ocimum basilicum L., O. gratissimum L. and O. americanum L. varieties found in Sierra Leone and Nigeria were determined by GC-FID and GC-MS. The antimicrobial test was evaluated by agar diffusion. The Sierra Leone and Nigeria O. americanum L. varieties were identified as the linalool chemotype and similarly, varieties of O. gratissimum L. from both countries are thymol chemotype. The high thymol content is consistent with the relative high antimicrobial activity of the O. gratissimum L oils. The Sierra Leone O. basilicum L. sample was established as the methyl eugenol chemotype while the Nigerian collection is predominantly methyl chavicol in composition. The high methyl eugenol content of the Sierra Leone collection is consistent with the observation of attraction of fruit flies to the distillate. To the best of our knowledge, there has been no report on essential oils of Ocimum species in Sierra Leone, hitherto.

Identification of potential therapeutic role of thymus capitatus essential oil using cellular imaging

Plant derived natural products can provide promising anti-cancer activity and can support the development of novel anti-cancer treatment strategies as cytotoxic activity towards cancer cells was observed in the recent studies in which different human cancer cell lines were exposed to plant essential oils. In our study, thyme (Thymus capitatus) essential oil analyzed by GC and GC/MS showed high content of thymol, p-cymene, carcacrol and γ-terpinene representing 62.3%, 10.9%, 6.7% and 5.1% of total oil respectively. It was tested for its potential therapeutic role by using neoplastic transformed human telomerase reverse transcriptase (hTERT) immortalized mesenchymal stem cells (hMSC- telo1) and a tumorigenic cell line; human telomerase reverse transcriptase immortalized mesenchymal stem cells which are irradiated with 2.5 Gy of gamma-rays. The hMSC- telo1 and irradiated hMSC- telo1cells were exposed to increasing concentrations of thyme essential oil in order to investigate the effects of different concentrations of thyme essential oil on the hMSC- telo1 and irradiated hMSC- telo1cells and to identify any cellular response of thyme essential oil towards these cell lines. The hMSC- telo1and irradiated hMSC- telo1cells were treated with 0.5% (v/v), 1% (v/v) and 2% (v/v) thyme essential oil. Cellular response of hMSC- telo1 and irradiated hMSC- telo1cells to thyme essential oil was evaluated for all three concentrations at different time points (0 h, 2 h, 4 h, 24 h, 72 h and 120 h) by investigating proliferation rate, viability and morphology. Our results demonstrated that there was significant effect of all three concentrations used on hMSC- telo1and irradiated hMSC- telo1cells; particularly the effect was higher on the cells treated with 0.5% (v/v) thyme essential oil. Furthermore, when cellular response at different time points were compared, it was shown that exposure time to thyme essential oil is highly important for cellular viability.

Effect of Vermicompost and Planting Pattern on Oil Production in Satureja sahendica L. under Competition with Pigweed (Amaranthus retroflexus L.)

The sahendi savory (Satureja sahendica Bornm.) is a native medicinal species of Iran which is subjected to extinction. Regarding to the importance of weed management and soil organic fertilization our study focused on plant growth responses to different nutrition systems and competition of redroot pigweed (Amaranthus retroflexux L.) in two planting pattern (rectangles, zigzag). Experiment was carried out in a randomized complete block design with three replications and factorial arrangement of treatments at the Ismael Abad Research Station, Qazvin Agriculture and Natural Resources Research Center on 2010 to 2012. Nutritional treatments include: NPK plus foliar application of micronutrients, four tone/ ha of vermicompost, two tone/ha vermicompost plus 40 liters/ha vermi-tea (liquid formulation of vermicompost). Pigweed density has also been studied at four levels of 0, 6, 12 and 18 plants per square meter. Effect of fertilizer treatments on essential oil percentage of sahendi savory was not significant and relative superiority of essence belonged to vermicompost fertilizer as 2 tone/ha plus 40 liters of vermi-tea .Also among the harvests second harvest was superior than first harvest. Weed treatment had no significant effect on essential oil percentage of sahendi savory. Thymol content in plots fertilized by 4 tons per hectare vermicompost was the highest value (42.95%) and had inverse relation with the p-cymen content (35.3%). Weed free condition produced the highest thymol content (45.18 %), meanwhile and the lowest amount (38.6%) were found in high weed density (18 plants per square meter).

Chemical Composition and Biological Activity of Pulicaria vulgaris Essential Oil from Iran

The present study investigated the chemical composition of the essential oil (EO) from aerial parts (flowering stage) of Pulicaria vulgaris Gaertn. by GC-MS. Also, the antimicrobial activity of the EO against Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Aspergillus niger and Candida albicans) was tested. In total, 23 compounds were recognized, accounting for 98.08% of the EO. The main compounds in the EO were thymol (50.22%), p-menth-6-en-2-one (carvotanacetone, 20.2%), thymol isobutyrate (16.88%), menthan-2-one (4.31%), 1-methyl-1,2-propanedione (4.13%), 2,5-dimethoxy-p-cymene (4.01%), myrtenol (1.22%), linalool (1.1%), and β-myrcene (1.9%). Results of antibacterial test of P. vulgaris essential oil showed that all assayed concentrations significantly inhibited the growth of B. cereus, S. aureus, E. coli, and P. aeruginosa at P < 0.05. MIC for B. cereus, S. aureus, E. coli, P. aeruginosa was 17.5, 25.2, 19.4 and 33.2 μg/mL respectively; antifungal screening of the essential oil of P. vulgaris showed that the oil significantly inhibited the growth of A. niger and C. albicans (MIC = 15.5 and 9.9 μg/mL, respectively). Results of cytotoxicity assay showed that the essential oil exhibited a significant cytotoxic activity against both cell lines. In case of MCF-7 and Hep-G2 cell lines, IC50 of the essential oil were 5.36 and 7.16 μg/ml, respectively. The potent antimicrobial and cytotoxic activities of the EO may be attributed to its high contents of thymol, carvotanacetone and thymol isobutyrate. Antimicrobial and antitumor chemotherapies are showing diminishing effectiveness because of emergence of drug-resistance. Hence, using efficient natural chemotherapeutic agents such as Pulicaria vulgaris essential oil with fewer side effects is an encouraging approach to fight cancer and infectious diseases in medicine, agriculture, food science and related fields.

Histochemical Application for the Identification of Thymol and Carvacrol Chemotypes of Various Essential Oil Producing Plants

Histochemical methods, in combination with various microscopic imaging techniques, have been significantly utilized to study the essential oil secretion in various plants. We are interested in implementing a technique originally developed for the localization of monoterpene phenols using the reagent 4-nitrosophenol in conc. H2SO4. The plant material selected for this study consisted of the leaves obtained from three Lamiaceae species; Thymus vulgaris L., Origanum syriacum L., and Plectranthus amboinicus (Lour.) Spreng., and two Asteraceae species; Eriocephalus africanus L. and Artemisia absinthium L. Mentha piperita L. and Ocimum basilicum L. (Lamiaceae) were used as negative controls devoid of monoterpene phenols. These former species were chosen for their high content of Thymol and/ or Carvacrol which produce colored indophenols of bright red and dark green respectively. In this study, we successfully establish the method for identifying these compounds using the color reaction which was verified by the analysis of the corresponding plant leaf oils using GC and GC-MS techniques. This method could serve for a rapid screening of specific oil components that could help distinguish several plant chemotypes in the field, hence saving time spent in laboratory analyses.

Chemical diversity among different accessions of Origanum vulgare L. ssp. vulgare collected from Central Himalayan region of Uttarakhand, India

The essential oil composition of ten accessions of Origanum vulgare L. ssp. vulgare collected from wild populations of the sub-temperate region of the Central Himalayas and subsequently grown under identical climatic conditions in Uttrakhand state of India were analyzed by gas chromatography (GC) and GC/mass spectrometry (GC/MS). A total of forty-six components representing 92.6–99.8% of the total oil were identified in essential oils isolated from seven different locations. The major constituents of the essential oils were phenolic compounds (13.7–90.5%), represented mainly by thymol (13.7–85.9%) and carvacrol (1.5–63.0%). Two chemotypes were identified: the first, with a prevalence of thymol (IC589087, 85.9%; IC589085, 85.0%) and the second, characterized by the prevalence of carvacrol (IC589079, 63.0%). Results indicated that accessions collected from higher altitude (>3200 m) possessed high thymol content (>85%). This chemical study attempts to provide an insight on the relationship between chemical composition of essential oil and chemotypes in O. vulgare L.

Volatile constituents of Dianthus rupicola Biv. from Sicily: activity against microorganisms affecting cellulosic objects

Dianthus rupicola Biv. (cliffs carnation) is a camephytic, suffruticous, perennial plant growing up to 40 cm high. The plant is widespread in Sicily and neighbouring islands (Egadi, Lampedusa, Lipari) and in some areas of southern Italy. GC and GC-MS analyses of the essential oil distilled from the flowers showed the presence of 66 components. Its composition is characterised by the high content of thymol and carvacrol derivatives. A good antibacterial activity against Bacillus cereus and Bacillussubtilis, both infesting cellulosic historical material, was shown, whereas the antioxidant capacity was determined to be quite poor.

Antimicrobial Activity of Essential Oil Components Against Potential Food Spoilage Microorganisms

The antimicrobial activity of six essential oil components against the potential food spoilage bacteria Aeromonas (A.) hydrophila, Escherichia (E.) coli, Brochothrix (B.) thermosphacta, and Pseudomonas (P.) fragi at single use and in combination with each other was investigated. At single use, the most effective oil components were thymol (bacteriostatic effect starting from 40ppm, bactericidal effect with 100ppm) and carvacrol (50ppm/100ppm), followed by linalool (180ppm/720ppm), α-pinene (400ppm/no bactericidal effect), 1,8-cineol (1,400ppm/2,800ppm), and α-terpineol (600ppm/no bactericidal effect). Antimicrobial effects occurred only at high, sensorial not acceptable concentrations. The most susceptible bacterium was A. hydrophila, followed by B. thermosphacta and E. coli. Most of the essential oil component combinations tested showed a higher antimicrobial effect than tested at single use. Antagonistic antimicrobial effects were observed particularly against B. thermosphacta, rarely against A. hydrophila. The results show that the concentration of at least one of the components necessary for an antibacterial effect is higher than sensorial acceptable. So the use of herbs with a high content of thymol, carvacrol, linalool, 1,8-cineol, α-pinene or α-terpineol alone or in combination must be weighted against sensorial quality.