Epidermal structures and composition of epicuticular waxes of Sedum album sensu lato (Crassulaceae) in Balkan Peninsula

Sedum album is a succulent plant, with phenotypic variability resulting in delimitation of a number of taxa with diverse taxonomic recognition. We analyzed the taxa from Sedum album in broad sense (S. album, S. micranthum, S. athoum and S. serpentini) from Balkan Peninsula, to check whether the variability of their epidermal structures and epicuticular wax composition corresponds to their taxonomic reliability. Epidermal structures and epicuticular waxes were analyzed using light and scanning electron microscopy, gas chromatography-mass spectrometry and gas chromatography-flame ionization detector chromatography and multivariate statistical techniques. Analyses of studied taxa have shown that significant systematic characters include adaxial epidermal and guard cell length, stomatal frequency and subsidiary cells area on abaxial epidermis. The content of n-alkanes C-29, C-30, C-27, C-32 and C-33 was shown to be valuable criterion for their phytochemical delimitation. The comparison of epicuticular wax microstructures has shown no significant differences. Results indicate presence of two (micromorphology) or three (phytochemistry) well-defined groups of populations, with S. serpentini manifesting a considerable level of separation toward the others. Sedum athoum have shown weak to moderate degree of differentiation, while S. micranthum has shown general resemblance to S. album

Essential oil composition of different parts of endemic species Seseli gracile Waldst. & Kit. (Apiaceae) from natural and cultivated conditions

The chemical composition of the essential oils of Seseli gracile Waldst. & Kit. from natural habitat (Đerdap Gorge, Serbia) and from cultivated plants (Belgrade, Serbia) were characterized. The essential oils of the root, aerial parts, inflorescence and fruit were analyzed by GC/MS and GC/FID. Monoterpene hydrocarbons were the main compounds in the essential oil of aerial parts (45.2–93.0 %), inflorescences (84.1 and 90.0 %) and fruit (85.0 %). Polyacetylenes (38.8 and 87.6 %) were dominant in the essential oil of root. The cluster analysis revealed that there were significant differences in the chemical composition of the S. gracile oils at different phenological stages. On the other hand, essential oils from the aerial parts from natural and cultivated plants showed quite uniform qualitative composition. The aerial parts essential oil from natural habitat contained higher content of para-cymene (mean values 17.3 vs. 6.5 %) and lower amounts of terpinolene (mean values 23.1 vs. 49.9 %). Also polyacetylene falcarinol was present only in the aerial parts samples from natural habitat. The essential oil of inflorescences from natural habitat contained higher concentration of terpinolene, quite similar amount of para- -cymene and lower content of α-pinene. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 173021 Grant no. 173030

Synergistic effects of Salvia officinalis L. essential oils and antibiotics against methicillin-resistant Staphylococcus aureus

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) due to the acquisition of resistance to current antimicrobials pose a serious challenge for therapy, and new measures to treat and prevent this infectious pathogen are of crucial importance. Plant essential oils (EOs) and their constituents are promising agents with antimicrobial properties. The aim of this study was to evaluate the antistaphylococcal effect of essential oils from Salvia officinalis using the broth-microdilution method. Essential oils of S. officinalis were isolated from the same individual, but at different life stages - young and old leaves. The effects of combinations of sub-inhibitory concentrations of oil and different antibiotics were evaluated by the checkerboard method. The results, expressed as the fractional inhibitory concentration (FIC) and index (FICI), indicate that the essential oil isolated from young leaves potentiated the inhibitory effect of antibiotics against tested MRSA strains. [Projekat Ministarstva nauke Republike Srbije, br. 173021

Chemical composition of the essential oil of Thymus bracteosus Vis. ex Bentham (Lamiaceae)

The oil composition of Thymus bracteosus Vis. ex Bentham, collected from Montenegro, was analyzed by GC and GC/MS. The oil yield was 0.15%. Twenty-seven components were identified. Terpene hydrocarbons were dominant in the oil (68.5%). The main constituents of the oil were germacrene D (15.5%), beta-caryophyllene (14.6%), p-cymene (10.2%) and alpha-pinene (7.2%)