Chemical diversity in the genus Alpinia (Zingiberaceae): comparative composition of four Alpinia species grown in Northern India.

The essential-oil compositions of leaves, flowers, and rhizomes of Alpinia galanga (L.) Willd., Alpinia calcarata Rosc., Alpinia speciosa K. Schum., and Alpinia allughas Rosc. were examined and compared by capillary GC and GC/MS. Monoterpenoids were the major oil constituents identified. 1,8-Cineole, alpha-terpineol, (E)-methyl cinnamate, camphor, terpinen-4-ol, and alpha- and beta-pinenes were the major constituents commonly distributed in leaf and flower essential oils. The presence of endo-fenchyl acetate, exo-fenchyl acetate, and endo-fenchol was the unique feature of rhizome essential oils of A. galanga, A. calcarata, and A. speciosa. On contrary, the rhizome oil of A. allughas was dominated by beta-pinene. Significant qualitative and quantitative variations were observed in essential-oil compositions of different parts of Alpinia species growing in subtemperate and subtropical regions of Northern India. Cluster analysis was performed to find similarities and differences in essential-oil compositions based on representative molecular skeletons. Monoterpenoids, viz., 1,8-cineole, terpinen-4-ol, camphor, pinenes, (E)-methyl cinnamate, and fenchyl derivatives, were used as chemotaxonomic markers.