Chemical Variability and Biological Activities of Essential Oils of Micromeria inodora (Desf.) Benth. from Algeria.

The chemical composition of the essential oils isolated from the aerial parts of Micromeria inodora (Desf.) Benth. collected in 24 Algerian localities was investigated from the first time using GC-FID, GC/MS and 13 C-NMR. Altogether, 83 components which accounted for 94.7% of the total oil composition were identified. The main compounds were trans-sesquisabinene hydrate (1; 20.9%), α-terpinyl acetate (2; 19.8%), globulol (3; 4.9%), caryophyllene oxide (4; 4.3%), ß-bisabolol (5; 2.9%) and trans-7-epi-sesquisabinene hydrate (6; 2.6%). Comparison with the literature highlighted the originality of the Algerian M. inodora oil and indicated that 1 might be used as taxonomical marker. The study of the chemical variability allowed the discrimination of two main clusters confirming that there is a relation between the essential-oil compositions and the soil nature of the harvest locations. Biological activity of M. inodora essential oil was assessed against fourteen species of microorganisms involved in nosocomial infections using paper disc diffusion and dilution agar assays. The in vitro study demonstrated a good activity against Gram-positive strains such as Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, and Enterococcus faecalis, and moderate activity against Candida albicans. These results might be useful for the future commercial valorization of M. inodora essential oil as a promising source of natural products with potential against various nosocomial community and toxinic infections.

Chemical composition, antibacterial, antifungal and antioxidant activities of Algerian Eryngium tricuspidatum L. essential oil.

This study describes the chemical composition and the antibacterial, antifungal and antioxidant activities of the essential oil extracted from aerial parts of the Algerian Eryngium tricuspidatum L., obtained by hydrodistillation and analysed by using the combination of gas chromatography (GC) and GC/mass spectrometry. A total of 63 compounds were identified accounting for 93.1% of the total oil. Chemical composition of oil was characterised by a high proportion of oxygenated sesquiterpenes (49.6%) among which α-bisabolol (32.6%) was the predominant compound. The sesquiterpene hydrocarbons represent the second major fraction (31.9%) with α-curcumene (6.5%) being the predominant one. Antibacterial and antifungal activities of the oil were tested using the micro-well determination of minimum inhibitory concentration (MIC) assay against eleven bacteria and two Candida species. It was found that the aerial parts of E. tricuspidatum exhibited interesting antibacterial and anticandidal activities (MIC = 9 µg/mL against several strains of bacteria and MIC = 4.6 µg/mL against Candida albicans). The antioxidant effect of this oil was evaluated using the 2,2-diphenyl-l-1-picrylhydrazil (DPPH) and ferric reducing antioxidant power (FRAP) assays. Results revealed significant activities (DPPH method: IC50 = 510 µg/mL; FRAP assay: reducing power of oil increases from 0.0188 at 5 µg/mL to 0.5016 at 1000 µg/mL).

Antimicrobial activity and evolution of the composition of essential oil from Algerian Anacyclus pyrethrum L. through the vegetative cycle.

Essential oils from the aerial parts of Anacyclus pyrethrum L. were analysed at three developmental stages (vegetative, floral budding and flowering). Oil yield was found to vary depending on the stage of development, and the highest content of oil (0.019% w/w) was obtained at flowering stage. The chemical composition of essential oils studied by GC and GC-MS showed a total of 91 compounds. Whatever the analysed stage is, oxygenated sesquiterpenes were the most abundant group. Their level significantly increased during ripening and varied from 37.1% to 58.6%. The oil showed activity against Candida albicans and Staphylococcus aureus bacteria strains. Thus, they represent an inexpensive source of natural antibacterial substances that may potentially be used in pathogenic systems.