Leaf oil prepared by hydrodistillation of Alpinia zerumbet Pers.) B.L. Burtt & R.M. Sm. was analyzed by GC/FID and GC/MS to determine the major compounds and it was also evaluated for antimicrobial activity. The oil presented a high content of oxygenated monoterpenes (52.5%), terpinen-4-ol, 1,8 cineole and γ-terpinene as the major constituents. The antimicrobial activity of leaf oil was tested by drop diffusion and bioauthography methods. Through drop test, all bacteria and fungi tested were inhibited by leaf oil. Preparative TLC (thin-layer chromatography) plates were developed using the mobile phase hexane: ethyl acetate (70:20, v/v) and fractions of the leaf oil were separated in three zones, scraped, extracted from silica and identified by GC/MS. The bioauthography method permitted to verify pronounced inhibition of Cryptococcus neoformans by fractions F2 and F3, both rich in oxygenated monoterpenes. The fraction F2 comprised 1,8 cineole (9.6%), linalool (3.7%) and caryophyllene oxide (5.4%), while fraction F3 showed mainly terpinen-4-ol (43.6%) and an amount of 32.7% oxygenated sesquiterpenes. The obtained data may be used to suggest the constituents of A. zerumbet leaf oil involved in antimicrobial activity.
Alpinia zerumbet; Zingiberaceae; essential oil; bioauthography; medicinal plant
