Chemical characterization of basil (Ocimum spp.) based on volatile oils

Essential oils extracted from basil (Ocimum spp.) by steam distillation are used to flavor foods, oral products, in fragrances and in traditional medicines. The genus Ocimum contains around 30 species native to the tropics and subtropics, with some species naturalized and/or cultivated in temperate areas. Inter- and intraspecific hybridization have created significant confusion in the botanical systematics of the Ocimum genus. The taxonomy of O. basilicum is further complicated by the existence of numerous varieties, cultivars and chemotypes within the species that do not differ significantly in morphology. The composition of volatile oil constituents was used to characterize the diversity among the most economically important Ocimum species. Using principal component analysis on the aromatic volatile oils, the Ocimum accessions could be separated into five groups, which do not correspond to the different species: (1) citral-spathulenol accessions; (2) linalool-rich accessions; (3) methylchavicol-rich accessions; (4) linalool-methylchavicol accessions; and (5) methyl(E)-cinnamate-rich accessions. The fact that the groups of Ocimum species are based on morphological characteristics does not correspond to the groups based on volatile oil constituents.