Chemotaxonomic significance of volatile constituents in Hypenia (Mart. ex Benth.) R. Harley (Lamiaceae)

Multivariate analysis of essential oil compositions of thirteen Hypenia species revealed the presence of two taxonomic clusters. Cluster I included three species belonging to section Densiflorae in addition to H. subrosea and H. aristulata, and showed the highest percentages of α-muurolol (5.85 ± 3.08%). In Cluster II, which contained eight species belonging to section Laxiflorae, the major discriminant constituents were (E)-caryophyllene (7.09 ± 4.88%), germacrene D (18.1 ± 11.4%), and bicyclogermacrene (6.65 ± 1.19%). All essential oils showed a predominance of sesquiterpenes, such as spathulenol (4.5-31.6%), caryophyllene oxide (2.2-14.4%) and selin-11-en-4α-ol (0-34.8%). Furthermore, identical clusters were revealed by multivariate analysis of chemical constituents based on carbon skeletons, as well as on 18 morphological leaf characters of the species studied