Pogostemon hirsutus Oil, Rich in Abietane Diterpenes

Volatile oil extracted from the leaves of Pogostemon hirsutus Benth., a rare species from Anamalai hills of the Western Ghats of Tamil Nadu, India was analyzed by GC-FID and GC-MS. Fifty-four compounds amounting to 90.8% of the oil were identified. The oil was rich in monoterpenes and diterpenes. The major components of the oil were alpha-pinene (11.5%), sabinene (8.5%), beta-pinene (5.2%), abietatriene (16.3%), dehydroabietal (3.5%) and dehydroabietol (21.0%). Abietane diterpenes are reported for the first time in the genus Pogostemon of Lamiaceae with six abietanes representing 42.6% of the oil.