Chemical composition and antioxidant and antimicrobial activities of essential oil of Allium sphaerocephalon L. subsp. sphaerocephalon (Liliaceae) inflorescences.

BACKGROUND: Allium sphaerocephalon is a wild-growing plant commonly used as an onion substitute. In this study the essential oil obtained from A. sphaerocephalon subsp. sphaerocephalon inflorescences was analysed by gas chromatography and gas chromatography/mass spectrometry and also evaluated for in vitro antioxidant and antimicrobial activities. The obtained results are reported for the first time and discussed with respect to the sulfur compounds detected in the essential oil. RESULTS: Ninty-one compounds were identified, representing 91.6% (w/w) of the total oil. Major constituents of the analysed sample were shyobunol (15.3%), ß-caryophyllene (8.1%), α-cadinol (7.8%), 3,5-diethyl-1,2,4-trithiolane (isomer II, 5.9%) and δ-cadinene (5.2%). The diluted oil had an antioxidant capacity of 160 000 ± 111 micromol α-tocopherol acetate equivalents g(-1). Its antimicrobial activity was evaluated against five bacterial and two fungal strains using the broth microdilution assay. Among the micro-organisms tested, the most susceptible strains were Pseudomonas aeruginosa (minimal inhibitory/bactericidal concentration = 0.08/2.5 mg mL(-1)) and Aspergillus niger (minimal inhibitory/fungicidal concentration = 0.31/0.63 mg mL(-1)). CONCLUSION: The results showed that the examined species had strong antioxidant and antimicrobial properties and are in accordance with the popular use of plants belonging to the genus Allium in traditional medicine, emphasising the necessity of further detailed study of the active principles in Allium species.

The intrasectional chemotaxonomic placement of Hypericum elegans Stephan ex Willd. Inferred from the essential-oil chemical composition.

Here we report, for the first time, the results of detailed GC and GC/MS analyses of the essential oil of a rare taxon in Serbia, Hypericum elegans Stephan ex Willd. One hundred and sixty two constituents identified accounted for 98.6% of the oil. The major components of the oil were undecane (31.9%), alpha-pinene (16.7%), nonane (6.1%), bicyclogermacrene (5.8%), 2-methyloctane (3.7%), and germacrene D (3.6%). Non-terpenoids as chemotaxonomic markers constituted the main fraction of H. elegans oil, whereby n-alkanes were the most abundant contributors of this fraction. Based on these results and previously published ones, we performed an intrasectional multivariate statistical comparison of corresponding essential-oil chemical compositions. Principal component analysis (PCA) and agglomerative hierarchical clustering (AHC) of the data on the volatile profiles of section Hypericum taxa revealed that H. elegans either represents an oil chemotype of its own (AHC) or could be considered related to H. perforatum (PCA).

Synthesis and antimicrobial activity of new 4-heteroarylamino coumarin derivatives containing nitrogen and sulfur as heteroatoms.

Synthesis, spectral analysis and bioactivity of new coumarin derivatives are described in this paper. Eight new coumarin derivatives were synthesized in moderate to good yields by condensation of 4-chloro-3-nitrocoumarin and the corresponding heteroarylamine. The synthesized compounds were tested for their in vitro antimicrobial activity, in a standard disk diffusion assay, against thirteen strains of bacteria and three fungal strains. They have shown a wide range of activity - from one completely inactive compound to medium active ones.

Misidentification of tansy, Tanacetum macrophyllum, as yarrow, Achillea grandifolia: a health risk or benefit?

Tansy, Tanacetum macrophyllum (Waldst. & Kit.) Sch. Bip., is often misidentified by herb collectors as yarrow, Achillea grandifolia Friv. With the former, cases of poisoning induced by its ingestion are well documented, but the latter is widely used for ethnopharmacological purposes. The aim of this study was to estimate, based on the volatile metabolite profiles of the two species, the potential health risk connected with their misidentification. GC and GC-MS analysis of the essential oils hydrodistilled using a Clevenger-type apparatus from A. grandifolia, T. macrophyllum, and two plant samples (reputedly of A. grandifolia, but in fact mixtures of A. grandifolia and T. macrophyllum) obtained from a local market, resulted in the identification of 215 different compounds. The main constituents of A. grandifolia oil were ascaridole (15.5%), alpha-thujone (7.5%), camphor (15.6%), borneol (5.2%) and (Z)-jasmone (6.4%), and of T. macrophyllum oil, 1,8-cineole (8.6%), camphor (6.4%), borneol (9.1%), isobornyl acetate (9.5%), copaborneol (4.2%) and gamma-eudesmol (6.2%). The compositions of the oils extracted from the samples obtained from the market were intermediate to those of A. grandifolia and T. macrophyllum. Significant differences in the corresponding volatile profiles and the literature data concerning the known activities of the pure constituents of the oils, suggested that the pharmacological action of the investigated species (or their unintentional mixtures) would be notably different. It seems, however, that misidentification of T. macrophyllum as A. grandifolia does not represent a health risk and that the absence of the toxic alpha-thujone from T. macrophyllum oil may in fact be regarded as a benefit.