COMPOSITIONS AND THE IN VITRO ANTIMICROBIAL ACTIVITIES OF THE FLOWER, LEAF AND STEM ESSENTIAL OILS AND EXTRACTS OF ACHILLEA MICRANTHA FROM IRAN

Achillea is a one of the most important genera of the Asteraceae family with regard to the number of species. Somespecies of this genus are important medicinal plants and their essential oils and extracts have been used formedicinal purposes. In this investigation flowers, leaves and stem (separately) of Achillea micrantha Willd., knownto has medicinal activity, collected from Neyshabur, Northeast of Iran, was subjected to hydrodistillation (HD).Chemical compositions of the essential oils isolated from flower, leaf and stem of plant were analyzed by GC/MS method, resulted in the identification of 46, 42 and 39 constituents representing 98.9, 97.5 and 96.5% of the total contents, respectively. In the oil of flower; camphene, borneol, p-cymene, geraniol, piperitone, terpinen-4-ol, bornylacetate, β-caryophyllene, β-damascenone, germacrene D, β-bisabolene, γ-cadinene and caryophyllene oxide werethe major constituents, while in leaf oil; sabinene, 1,8-cineole, camphor, pinocarvone, borneol, terpinen-4-ol,thymol, spathulenol, caryophyllene oxide, viridiflorol, (2E,6E)-farnesyl acetate and acorenone were dominant compounds. Camphene, δ-3-carene, 1,8-cineole, camphor, α–terpineol, β-caryophyllene, germacrene D, bicyclogermacrene and caryophyllene oxide were predominant compounds in the stem oil. While amongst thecomponents of the oil of three parts, oxygenated monoterpenes (40.8 to 46.4%) were predominant, sesquiterpene hydrocarbons were in second place in oil of flower and stem (35.1 and 32.0%, respectively), moreover it was in the third amount in oil of stem and oxygenated sesquiterpenes (33.6%) were in second. Hence, chemotype of the essential oils from flower, leaf and stem of A. micrantha were determined, which belongs to germacrene-D/borneol/ bornyl acetate; spathulenol/ camphor and germacrene-D/ bicyclogermacrene/ 1,8-cineole/ camphor chemotypes, respectively. In vitro antimicrobial activity of essential oils and extracts (hexane-ether and methanolic extract) of aerial parts of A. micrantha were investigated against a panel of seven strains of bacteria (gram-positive and gram-negative) by disc diffusion method and the minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) determination. The studied samples were active against gram (+/-) bacteria, but the oil and extracts of A. micrantha exhibited higher activities against the gram (+) tested bacterial strains. The maximum antimicrobial activities were shown by the methanolic extract, as compare to essential oils and the hexane-ether extract.

Keywords:

Achillea micrantha Willd. , Essential oil , Extract , Antimicrobial activity , Chemotype