Chemical composition and bioactivity of essential oils and extracts from Oregano from Madeira Island, Portugal

Abstract

In the course of ongoing investigations on polymorphic Lamiaceae species, we studied Origanum vulgare spp. virens growing wild in several locations of Madeira Island, Portugal. Variation in essential oil composition with climate conditions was studied. The antimicrobial activity of the various essential oils was determined against 10 strains of bacteria and yeasts, usually found as human pathogenic or food contaminants. The essential oils inhibited all the bacteria tested excepting for P. aeruginosa. The most sensitive microorganism was M. smegmatis with MIC = 25 µg ml-1 for two of the oils. The results of this study suggest a potential application of these oils in preventing the human pathogenic and food contaminant microorganisms growth. Radical scavenging capacity of essential oils and solvent extract (hexane, chloroform, ethyl acetate and methanol) were also determined, since interest of oregano resides in both non polar and polar fractions, all known by their very high antioxidant activity. From the hexane fraction, we obtained a large amount of 1-hexacosanol, C26H54O, a long chain alcohol, which was previously extracted in the non-esterified form only from Hygrophila erecta.info:eu-repo/semantics/publishedVersio