Investigation of essential oils of Plectranthus glandulosus Hook f. (Lamiaceae) from Cameroon

The essential oil of fresh and dried leaves of Plectranthus glandulosus Hoo k f. [syn. Coleus laxiflorus (Benth.) Roberty] from Cameroon were analysed by GC and GC/MS. The oils were characterized by a high percentage of oxygen ated monoterpenes (58.6% and 84.6% respectively) represented by cis-piperit one oxide (3.0% and 35.1%), trans-piperitone oxide (0.5% and 12.6%), fencho ne (30.8% and 21.6%) and piperitenone oxide (10.9% and 6.0%). The main mono terpene hydrocarbons were terpinolene (25.2% and 7.7%), limonene (3.2% and 1.7%) and myrcene (2.2% and 1.6%). The sesquiterpene derivatives were found in a very low percentage (< 2.5%), represented mainly by germacrene D (1.4 % and 1.0%).