A chemotaxonomic analysis of terpenoid variation in Cannabis

To determine whether the terpenoid composition of the essential oil of Cannabis is useful for chemotaxonomic discrimination, extracts of pistillate inflorescences of 162 greenhouse-grown plants of diverse origin were analyzed by gas chromatography. Peak area ratios of 48 compounds were subjected to multivariate analysis and the results interpreted with respect to geographic origin and taxonomic affiliation. A canonical analysis in which the plants were pre-assigned to C sativa or C indica based on previous genetic, morphological, and chemotaxonomic studies resulted in 91% correct assignment of the plants to their pre-assigned species. A scatterplot on the first two principal component axes shows that plants of accessions from Afghanistan assigned to the wide-leaflet drug biotype (an infraspecific taxon of unspecified rank) of C indica group apart from the other putative taxa. The essential oil of these plants usually had relatively high ratios of guaiol, isomers of eudesmol, and other unidentified compounds. Plants assigned to the narrow-leaflet drug biotype of C indica tended to have relatively high ratios of trans-beta-farnesene. Cultivars of the two drug biotypes may exhibit distinctive medicinal properties due to significant differences in terpenoid composition. (C) 2004 Elsevier Ltd. All rights reserved.