Major Volatile Constituents Research Articles

Physiological and Biochemical Responses of Lavandula angustifolia to Salinity Under Mineral Foliar Application.

Saline water has been proposed as a solution to partially cover plant water demands due to scarcity of irrigation water in hot arid areas. Lavender (Lavandula angustifolia Mill.) plants were grown hydroponically under salinity (0–25–50–100 mM NaCl). The overcome of salinity stress was examined by K, Zn, and Si foliar application for the plant physiological and biochemical characteristics. The present study indicated that high (100 mM NaCl) salinity decreased plant growth, content of phenolics and antioxidant status and essential oil (EO) yield, while low-moderate salinity levels maintained the volatile oil profile in lavender. The integrated foliar application of K and Zn lighten the presumable detrimental effects of salinity in terms of fresh biomass, antioxidant capacity, and EO yield. Moderate salinity stress along with balanced concentration of K though foliar application changed the primary metabolites pathways in favor of major volatile oil constituents biosynthesis and therefore lavender plant has the potential for cultivation under prevalent semi-saline conditions. Zn and Si application, had lesser effects on the content of EO constituents, even though altered salinity induced changings. Our results have demonstrated that lavender growth/development and EO production may be affected by saline levels, whereas mechanisms for alteration of induced stress are of great significance considering the importance of the oil composition, as well.

Effects of plant growth regulators, different culture media and strength MS on production of volatile fraction composition in shoot cultures of Ocimum basilicum

The influence of different culture media, strength MS media and plant growth regulators (PGR) was assessed through the growth and production of the volatile fraction composition in Ocimum basilicum (basil). The treatments were: the use of different culture media (MS, B5 and WPM), strength MS media (2MS, MS, ½MS and ¼MS) and different PGR combinations or only IAA, NAA, IBA, BAP and TDZ. The leaf number, nodal segment, shoot number, lenght, shoot dry weight, root number, root size, root dry weight, as well as the volatile fraction analysis through Head-Space – GC/MS were assessed at the 40th culture day. The present results suggest that media type, MS concentration and the growth regulator types have qualitative and quantitatively influenced the growth and volatile composition. A higher amount of methyleugenol in the media 2MS and ¼MS, and higher content of linalool and 1,8-cineole in MS and WPM were observed. The PGR improved biomass production and induced quantitative modifications in the production of major volatile constituents in Ocimum basilicum plantlets, although the same major compounds were produced in all treatments. There was a tendency to estragole synthesis in the presence of auxin combined with cytokinin. There was a tendency to linalool synthesis in the presence of auxin isolates.

Verification of Argentine ant defensive compounds and their behavioral effects on heterospecific competitors and conspecific nestmates

The invasive Argentine ant (Linepithema humile) has become established worldwide in regions with Mediterranean or subtropical climates. The species typically disrupts the balance of natural ecosystems by competitively displacing some native ant species via strong exploitation and interference competition. Here we report that Argentine ants utilize glandular secretions for inter and intra-specific communications during aggressive interactions with a heterospecific competitor, California harvester ant (Pogonomyrmex californicus). Chemical analyses indicated that Argentine ants deploy glandular secretions containing two major volatile iridoids, dolichodial and iridomyrmecin, on the competitor’s cuticular surface during aggressive interactions. Bioassays indicated that the glandular secretions function as a defensive allomone, causing high levels of irritation in the heterospecific. Furthermore, the same glandular secretions elicited alarm and attraction of conspecific nestmates, potentially enabling more rapid/coordinated defense by the Argentine ants. Two major volatile constituents of the glandular secretion, dolichodial and iridomyrmecin, were sufficient to elicit these responses in conspecifics (as a mixture or individual compounds). The current study suggests that invasive Argentine ants’ superior exploitation and interference competition may rely on the species’ effective semiochemical parsimony.

Composition and potential of Tanacetum haussknechtii Bornm. Grierson as antioxidant and inhibitor of acetylcholinesterase, tyrosinase, and α-amylase enzymes

ABSTRACTThe phytochemical composition of essential oils and extracts of Tanacetum haussknechtii were investigated with GC–FID–MS and LC–MS/MS techniques and evaluated against oxidation, acetylcholinesterase, tyrosinase, and α-amylase enzymes. The major volatile constituents of T. haussknectii were found to be α- and β-pinene, and borneol. Caffeoylquinic acid derivatives and flavonoids were detected in the aqueous, alcohol, and ethyl acetate extracts. In DPPH assay, the methanol extracts exhibited the highest activity. TEAC assay resulted with superiority of all methanol and the capitula ethyl acetate extract. In β-carotene bleaching assay, linoleic acid was the best protected by the ethyl acetate extract of flower. The flower oil inhibited higher acetylcholinesterase activity than the remaining extracts. The flower ethyl acetate extract was found as the most effective inhibitor of α-amylase. The herb and the leaf+stem water extracts possess highest inhibitory effect on tyrosinase.

Eugenol inhibits oxidative phosphorylation and fatty acid oxidation via downregulation of c-Myc/PGC-1\u03b2/ERR\u03b1 signaling pathway in MCF10A-ras cells

Alteration in cellular energy metabolism plays a critical role in the development and progression of cancer. Targeting metabolic pathways for cancer treatment has been investigated as potential preventive or therapeutic methods. Eugenol (Eu), a major volatile constituent of clove essential oil mainly obtained from Syzygium, has been reported as a potential chemopreventive drug. However, the mechanism by which Eu regulates cellular energy metabolism is still not well defined. This study was designed to determine the effect of Eu on cellular energy metabolism during early cancer progression employing untransformed and H-ras oncogene transfected MCF10A human breast epithelial cells. Eu showed dose-dependent selective cytotoxicity toward MCF10A-ras cells but exhibited no apparent cytotoxicity in MCF10A cells. Treatment with Eu also significantly reduced intracellular ATP levels in MCF10A-ras cells but not in MCF10A cells. This effect was mediated mainly through inhibiting oxidative phosphorylation (OXPHOS) complexs and the expression of fatty acid oxidation (FAO) proteins including PPARα, MCAD and CPT1C by downregulating c-Myc/PGC-1β/ERRα pathway and decreasing oxidative stress in MCF10A-ras cells. These results indicate a novel mechanism involving the regulation of cellular energy metabolism by which Eu may prevent breast cancer progression.

Chemo-divergence in essential oil composition among germplasm collection of five Ocimum species from eastern coastal plains of India

The present work was aimed to study chemical diversity among Ocimum species collected from Eastern Coastal Plains of India. Seventeen accessions representing five Ocimum species namely; O. basilicum L., O. tenuiflorum, O. gratissimum L., O. americanum L. and O. citriodorum Vis. were investigated for essential oil content and oil composition by GC/FID and GC/MS. Essential oil content isolated from aerial parts of Ocimum species varied from 0.27% to 0.47% on fresh weight basis. A total of eighty-three compounds, constituting 95.2–99.9% of total oil were identified in five Ocimum species. Major volatile constituents identified were monoterpenoids (camphor, linalool, neral, nerol, geraniol, 1,8-cineole, ocimenes) and phenylpropanoids (methyl chavicol, eugenol, methyl eugenol, methyl cinnamate). Ocimum species germplasm was classified into different chemotypes. O. americanum accessions belonged to camphor-rich chemotype (38.7–51.4%); while O. gratissimum belonged to eugenol-rich chemotype (59.7–71.8%). A unique high (E)-methyl cinnamate-rich chemotype (61.3–69.0%) was identified in O. basilicum whereas eugenol and methyl eugenol-rich two chemotypes were identified in O. tenuiflorum germplasm. Essential oil profiling of O. citriodorum showed two distinct chemotypes rich in geranial/neral and methyl chavicol.

Chemical and genetic stability of methyl chavicol-rich Indian basil (Ocimum basilicum var. CIM-Saumya) micropropagated in vitro

Indian basil i.e. Ocimum basilicum L., an important essential oil yielding plant, is used in high-grade perfumes, flavoring, dental and oral products. A methyl chavicol-rich, high essential oil yielding variety of Indian basil CIM-Saumya, released by the Central Institute of Medicinal and Aromatic Plants, India, has immense industrial potential due to the occurrence of two important aromatic components, i.e. methyl chavicol (62.5–77.6%) and linalool (14.4–34.1%). The Ocimum being highly cross-pollinated and seed propagated, produce heterogeneous progeny thereby restricting its commercial application. In the present investigation, an attempt has been made to produce a large number of genetically and chemically uniform plants of this improved variety CIM-Saumya for the first time using nodal explants. Multiple shoot cultures developed on Murashige and Skoog's medium (MS) supplemented with BA (N6-benzyladenine, 2.67μM) and these shoots were further transferred to half strength MS medium supplemented with NAA (α-naphthalene acetic acid, 0.27μM) for rhizogenesis. These plantlets were maintained under in vitro conditions for more than three years. The established plantlets were successfully shifted in a glasshouse and finally in the field. Flow cytometry, inter simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) markers, were employed to evaluate genetic similarity amongst micro-clones and the mother plant. In all, 28 primers (18 RAPD and 10 ISSR) generated 178 distinct, monomorphic and reproducible bands. Head space gas chromatography showed the similarity in the qualitative profile of 11 major volatile constituents. These results clearly demonstrated that the developed protocol can be efficiently utilized to generate genetically and chemically uniform population of an industrially important variety CIM-Saumya.

Comparative study on major chemical constituents in volatile oil of true cinnamon (<i>Cinnamomum verum</i> Presl. syn. <i>C. zeylanicum</i> Blum.) and five wild cinnamon species grown in Sri Lanka

The genus Cinnamomum has 250 species distributed from South, East and South East Asia to Australia. There are eight species of cinnamon grown in Sri Lanka, of which, Cinnamomum verum Pres1 (syn. C. zeylanicum Blume) which is widely cultivated in the country. In addition, seven other species of wild cinnamon are also grown which are endemic to Sri Lanka which are considered wild cinnamon. In this study, six Cinnamomum species were selected namely Cinnamomum verum, Cinnamomum dubium Nees (Sinhala: Sewel Kurundu or Wal Kurundu), Cinnamomum citriodorum (Sinhala: Pangiri Kurundu), Cinnamomum rivulorum Kostermans, Cinnamomum sinharajense Kostermans, Cinnamomum capparu-corende (Sinhala: Kapuru Kurundu). Much work has been carried out with Cinnamomum verum, however, work on wild cinnamon varieties is scanty. In this backdrop, this study was carried out to identify and quantify the major chemical constituents of volatile oils obtained from bark and leaves of wild and true cinnamon species cultivated or grown in Sri Lanka. It was revealed that leaf oil of Cinnamomum verum contains significantly (p<0.05) higher percentage of volatile oil (3.23%). The highest bark oil content (3.53%) was observed in Cinnamomum sinharajense, the lowest leaf oil (0.41%) and stem bark oil (0.51%) contents were observed in the Cinnamomum rivulorum. Fifteen major volatile chemical constituents were identified by Liquid Gas Chromatographic analysis in the essential oils obtained from bark and leaf of different cinnamon species. The highest cinnamaldehyde content (67.57%) was observed in Cinnamomum verum. Cinnamomum sinharajense contained comparatively higher amount of cinnamaldehyde (57.46%) than the other wild cinnamon species. The highest euginol content (87.53%) was observed in Cinnamomum sinharajense leaf. When compared with the chemical composition of Cinnamomum dubium leaf oil, geraniol was the most abundant (24.05%) among the volatile chemical constituents. β-Caryophyllene (41.31%) was identified in Cinnamomum dubium stem bark oil. The highest Euginol (22.29%) content was present in essential oil obtained from Cinnamomum rivulorum stem bark which was not observed in other cinnamon species.

Chemical and Biological Diversity of the Leaf and Rhizome Volatiles of Acorus calamus L. from Turkey

Two different isolation techniques, conventional hydrodistillation (HD) and micro-steam distillation-solid-phase microextraction (MSD-SPME), have been used to analyze the volatile constituents from the leaves and rhizomes of Acorus calamus L. by gas chromatography (GC-FID) and gas chromatography coupled to mass spectrometry (GC-MS). In all the samples studied, phenylpropanoids (16.9-35.3 %) predominated by β-asarone (15.3-16.3 % in rhizomes, 23.4-31.7 % in leaves) were the main constituent. In addition to phenylpropanoids, the acorane type sesquiterpene acorenone B (7.4-16.4 %) and elemene-type sesquiterpenes, epi-isoshyobunone (3.3-7.3 %) and shyobunone (1.5-4.6 %) were detected among the major volatile constituents in the rhizomes. The monoterpenes were represented by camphor (7.5-13.9 %) and camphene (6.1-7.7 %). In the leaf, myrcene (0.3-7.1 %), limonene (1.0-5.6 %), (Z)-β-ocimene (2.9-6.1 %) were among the major constituents. Qualitative difference of the volatiles composition in the rhizomes and leaves are discussed as well as of the volatiles obtained by HD and MSD-SPME techniques are discussed. Biological activity tests resulted in moderate anti-acetylcholinesterase effect and significant cupric reducing antioxidant potential of the leaf oil, while the rhizome oil demonstrated relatively lower effects.

Volatile Constituents of Three Stachys L. Species from Turkey

Volatile compounds of three Stachys species; Stachys macrantha (C. Koch) Stearn , Stachys sylvatica L. and Stachys annua ssp. annua var. annua L. were analyzed by a solid phase micro extraction (SPME) method with gas chromatography-mass spectrometry (GC-MS). A total of 38 (99.2%), 38 (99.0%) and 32 (98.8%) volatile compounds were identified with different constituents from S. annua ssp. annua var. annua, S. sylvatica and S. macrantha respectively. The major volatile constituents of the investigated three Stachys species were; α -pinene (11.2%), p -cymene (18.2%), carvacrol (28.8%) in S. macrantha , γ -muurolene (10.2%), α -cedrene (11.2%), limonene (37.0%) in S. sylvatica and α -pinene (11,4%), β -pinene (23.1%), (Z)-β -ocimene (24.8%) in S. annua ssp. annua var. annua. Comparison studies of all three Stachys species showed the high percentage of monoterpene hydrocarbons within 65.8%, 49.8% area in S. annua ssp . annua var. annua and S. sylvatica respectively. And oxygenated monoterpenes were the main group of constituents (42.1% area) of S. macrantha.

Volatile components of horsetail (Hippuris vulgaris L.) growing in central Italy

Hippuris vulgaris, also known as horsetail or marestail, is a freshwater macrophyte occurring in lakes, rivers, ponds and marshes. According to ‘The IUCN Red List of Threatened Species’, H. vulgaris is at a high risk of extinction in Italy in the medium-term future. In the present study, we analysed for the first time the volatile composition of H. vulgaris growing in central Italy. For the purpose, the essential oil was obtained by hydrodistillation and analysed by GC-MS. The chemical composition was dominated by aliphatic compounds such as fatty acids (26.0%), ketones (18.7%) and alkanes (11.4%), whereas terpenoids were poorer and mostly represented by diterpenes (7.4%). n-Hexadecanoic acid (25.5%), hexahydrofarnesyl acetone (17.5%) and trans-phytol (7.4%) were the major volatile constituents. These compounds are here proposed as chemotaxonomic markers of the species.

Effects of different rootstocks on aroma volatile constituents in the fruits of peach (Prunus persica L. Batsch cv. ‘Cresthaven’)

ABSTRACTThe consumption of peaches is dependent on fruit quality. Aromatic compounds directly affect the sensorial quality and consumer acceptance of peaches. This study evaluated the fruit quality and aroma volatile constituents of the peach cultivar ‘Cresthaven’ grafted on to five different rootstocks in 2012 and 2013. The rootstocks used were ‘Uzunoglu Seedling’ (Prunus persica), ‘GF677’ (P. persica × P. dulcis), ‘Nemaguard’ (P. persica × P. davidiana), ‘Cadaman’ (P. persica × P. davidiana) and ‘St. Julien GF 655/2’ (P. insititia). Fruits were sampled at the commercial maturity stage around mid-August. Fruit quality characteristics and aroma volatiles differed significantly in peaches grown on different rootstocks. The largest fruits and highest titratable acidity were obtained from ‘Cadaman’. The major volatile constituents of ‘Cresthaven’ fruits were acetaldehyde, hexanal, benzaldehyde, ethanol, 1-hexanol, (Z)-3-hexenol, (E)-2-hexen-1-ol, linalool, ethyl acetate, hexyl acetate, (Z)-3-hexenyl acetate, (E)-2-hexenyl acetate, 6-methyl-5-hepten-2-one, (E)-β-ionone, γ-decalactone and limonene. The type and concentration of volatile compounds showed great variability in ‘Cresthaven’ peach grafted on to different rootstocks. A total of 91 volatile compounds were detected and the highest volatile content was found in ‘GF677’.

Bioactive Constituents of Zanthoxylum rhetsa Bark and Its Cytotoxic Potential against B16-F10 Melanoma Cancer and Normal Human Dermal Fibroblast (HDF) Cell Lines.

Zanthoxylum rhetsa is an aromatic tree, known vernacularly as “Indian Prickly Ash”. It has been predominantly used by Indian tribes for the treatment of many infirmities like diabetes, inflammation, rheumatism, toothache and diarrhea. In this study, we identified major volatile constituents present in different solvent fractions of Z. rhetsa bark using GC-MS analysis and isolated two tetrahydrofuran lignans (yangambin and kobusin), a berberine alkaloid (columbamine) and a triterpenoid (lupeol) from the bioactive chloroform fraction. The solvent fractions and purified compounds were tested for their cytotoxic potential against human dermal fibroblasts (HDF) and mouse melanoma (B16-F10) cells, using the MTT assay. All the solvent fractions and purified compounds were found to be non-cytotoxic to HDF cells. However, the chloroform fraction and kobusin exhibited cytotoxic effect against B16-F10 melanoma cells. The presence of bioactive lignans and alkaloids were suggested to be responsible for the cytotoxic property of Z. rhetsa bark against B16-F10 cells.

Integrated nutrient regimes ameliorate crop productivity, nutritive value, antioxidant activity and volatiles in basil (Ocimum basilicum L.)

Basil is a fragrant edible herb with abundant minerals, micronutrients, and pharmacological activities. The effect of organic and chemical fertilizers on the crop biomass, essential oil yield and composition, plant mineral nutrition and antioxidant activity in Ocimum basilicum cv. CIM-SAUMYA (basil) was studied under field conditions. The nutritional quality and antioxidant value of the basil enhanced with the use of different organic and chemical regimes. The field study reveals that the integrated nutrient management comprising poultry manure (PM), farmyard manure (FYM), and chemical fertilizer (CF) gives higher crop yield in basil. PM+CF and FYM+CF treatments produce crop yields that are 60% and 34% higher over the control, respectively. PM+CF resulted in the maximum mean values of chlorophyll-a (0.55mgg−1) and chlorophyll-b (0.063mgg−1). The application of chemical fertilizers culminated in significant changes (p<0.05) in N, P and K contents of basil leaves that were respectively 28%, 36%, and 50% higher over the control. The application of organic fertilizers improved Ca, Mg and vitamin C contents, and antioxidant activity in the basil leaf. The highest level of vitamin C was achieved in the organically amended treatments, i.e., vermicompost (VC) and PM that were 3% higher over the control. The major volatile constituents of the basil oil were methyl chavicol (70.35%–72.60%) and linalool (21.49–30.89%). Other volatile components, i.e., chavicol, β-caryophyllene, α-cadinene, (E)-β-farnesense and γ-muurolene were in a minor amount.

Essential oil composition and variability of Artemisia herba-alba Asso. growing in Tunisia: comparison and chemometric investigation of different plant organs

This study was conceived to investigate the composition of four essential oils (EOs) extracted by hydrodistillation from four parts (leaves, stems, leaves/stems, roots) of Artemisia herba-alba growing wild in the center of Tunisia. Artemisia herba-alba aerial and roots parts were shade dried at room temperature with ventilation. The material was cut into small pieces and subjected to hydrodistillation using a Clevenger-type apparatus. The GC analyses were accomplished with a HP-5890 Series II instrument. A total of 152 compounds were characterized by GC and GC-MS, representing 91.3-99.7% of the total oil compositions. All four oils are dominated by monoterpene derivatives (68.2-99.5%) and the major volatile constituent was α-thujone (18.2-45.5%). Qualitative and quantitative differences between the four essential oils have been observed for some compounds. The main compounds of the essential oil from the leaves were α-thujone (45.5%), β-thujone (11.4%), trans-sabinyl acetate (10.1%), 1,8-cineole (7.4%) and camphor (6.8%). α-thujone (27.5%) was also the main compound in the essential oil of leaves/stems, followed by camphor (22.9%), 1,8-cineole (8.3%), β-thujone (8.2%) and camphene (5.6%). The essential oil of stems was dominated by α-thujone (28%) followed by β-thujone (11.4%) and chrysantenone (11%). In the essential oil of roots, α-thujone was less represented (18.2%), followed by camphor (14.6%) and curcumen-15-al (14.3%). Curcumen-15-al has been reported for the first time in Artemisia herba-alba oil and should be considered as a new chemotype. The results showed a variation in chemical compositions and yield of the EOs from Artemisia herba-alba. Curcumen-15-al is a new chemotype that was found in Artemisia herba-alba from Tunisia.

GC-MS ANALYSES OF ESSENTIAL OILS OF THREE VARIETIES OF Mangifera indica

Mangifera indica or commonly known as mango, is one of the 30 species of Mangifera genus from the family of Anacardiaceae. The fruit of M. indica is consumed for its antioxidant and health promoting activities in addition to its exotic flavor and texture. The present study was aimed to comparatively analyze the volatile constituents in the peel and pulp of M. indica cultivar Falan, Water Lily and Chok-anan. The mango peel and pulp were subjected to hydrodistillation using Clavenger type apparatus and the essential oils obtained were analyzed using GC-MS. There were 32 compounds identified in the essential oils of peel and pulp of three M. indica L. cultivars. Falan mango has the highest monoterpenes hydrocarbon composition in the essential oils of peel and pulp with 30.67% and 45.65%, respectively, whereas the essential oils of Water Lily mango are mainly dominated by the presence of sesquiterpenes hydrocarbon in both peel and pulp with 50.75% and 67.11%, respectively. The essential oils of Chok-anan mango are mainly consist of miscellaneous compounds in the peel and pulp with 22.56% and 44.1%, respectively. 4-Carene, b-caryophyllene, a-terpinolene, cyclohexadecane and n-hexadecanoic acid were the major volatile constituents in the essential oils of the three mango varieties.

Chemical analysis of essential oils from different parts of Ferula communis L. growing in central Italy

Ferula communis is a showy herbaceous plant typical of the Mediterranean area where it is used as a traditional medicine. The plant is a source of bioactive compounds such as daucane sesquiterpenes and prenylated coumarins. In Italy, most of phytochemical studies focused on Sardinian populations where poisonous and nonpoisonous chemotypes were found, while investigations on peninsular populations are scarce. In this work, we report the chemical characterisation of the essential oils obtained from different parts of F. communis growing in central Italy. The chemical profiles of the plant parts, as detected by GC-FID and GC-MS, were different from each other and from those reported in insular populations. Notably, α-pinene (10.5%), γ-terpinene (7.6%) and hedycariol (8.4%) were the major volatile constituents in flowers; α-pinene (55.9%), β-pinene (16.8%) and myrcene (5.9%) in fruits; β-eudesmol (12.1%), α-eudesmol (12.1%) and hedycariol (10.3%) in leaves; (E)-β-farnesene (9.5%), β-cubebene (8.2%) and (E)-caryophyllene (7.2%) in roots. The volatile profiles detected did not allow to classify the investigated central Italy population into the poisonous and nonpoisonous chemotypes previously described in Sardinia.

Chemical composition and insecticidal activities of essential oils against diamondback moth, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae)

Five Himalayan plants namely, Acorus calamus, Cedrus deodara, Aegle marmelos, Tagetes minuta and Murraya koenigii were used for the extraction of essential oils through hydrodistillation and the major volatile constituents as identified by GC and GC–MS techniques were β-asarone (91.1%), β-himachalene (45.8%), limonene (59.5%), Z-ocimene (37.9%) and α-pinene (54.2%), respectively. Essential oils were tested for their insecticidal properties against larvae of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae). Results showed that A. calamus was most toxic (LC50 = 0.29 mg mL−1) to P. xylostella followed by C. deodara (LC50 = 1.08 mg mL−1) and M. koenigii (LC50 = 1.93 mg mL−1) via residual toxicity bioassay. Per cent feeding deterrence index and growth inhibition was significantly higher in A. calamus (42.20 and 68.55, respectively) followed by C. deodara (35.41 and 52.47). In repellent activity studies, C. deodara showed high repellence (64.76%) followed by A. calamus (55.05%).

Chemical composition and antibacterial activity of essential oil isolated from Omani basil (Ocimum basilicum Linn.)

ObjectiveTo identify the major volatile constituents and evaluate the antibacterial activity of essential oil isolated from the aerial parts of Ocimum basilicum (O. basilicum) Linn. grown in Oman. MethodsThe fresh plant material was collected in the month of September from Seeb Nursery in Muscat Governorate, Sultanate of Oman. The aerial parts of O. basilicum Linn. were separated from fresh plant and essential oil was isolated by hydrodistillation method by using Clevenger apparatus. A greenish yellow oil was obtained in 0.6% v/w yield which was analyzed by gas chromatography–mass spectrometry for its chemical composition. The antibacterial activity of oil was also evaluated against three Gram–positive and four Gram–negative pathogenic bacterial strains by agar well diffusion method. ResultsA total of thirty six chemical constituents were identified and linalool (69.87%) was found to be the major constituent. Other main identified constituents included geraniol (9.75%), p-allylanisole (6.02%), 1,8–cineole (4.90%), trans–α–bergamotene (2.36%) and neryl acetate (1.24%). The essential oil of O. basilicum showed excellent antibacterial activity against Gram–positive bacteria and moderate activity against Gram–negative bacteria. ConclusionsOmani basil is characterized by a high content of linalool which makes it useful in food, pharmaceutical and perfumery industries.

Coping with matrix effects in headspace solid phase microextraction gas chromatography using multivariate calibration strategies

SPME is extremely sensitive to experimental parameters affecting liquid–gas and gas–solid distribution coefficients. Our aims were to measure the weights of these factors and to design a multivariate strategy based on the addition of a pool of internal standards, to minimize matrix effects. Synthetic but real-like wines containing selected analytes and variable amounts of ethanol, non-volatile constituents and major volatile compounds were prepared following a factorial design. The ANOVA study revealed that even using a strong matrix dilution, matrix effects are important and additive with non-significant interaction effects and that it is the presence of major volatile constituents the most dominant factor.A single internal standard provided a robust calibration for 15 out of 47 analytes. Then, two different multivariate calibration strategies based on Partial Least Square Regression were run in order to build calibration functions based on 13 different internal standards able to cope with matrix effects. The first one is based in the calculation of Multivariate Internal Standards (MIS), linear combinations of the normalized signals of the 13 internal standards, which provide the expected area of a given unit of analyte present in each sample. The second strategy is a direct calibration relating concentration to the 13 relative areas measured in each sample for each analyte. Overall, 47 different compounds can be reliably quantified in a single fully automated method with overall uncertainties better than 15%.