Isolation and characterization of incensole from Boswellia dalzielii stem bark

Boswellia dalzielii is the West African species of the frankincense genus. It is used in ethnomedicine to treat gastrointestinal disorders, rheumatism and various diseases of microbial origin. The dried pulverized bark material was extracted with 50% ethanol by percolation. Column chromatography, gel filtration and preparative thin-layer chromatography (TLC) of the ethyl acetate fraction yielded incensole, a cembrane diterpenoid. Its structure was established by nuclear magnetic resonance (NMR) spectroscopy, including 2-D NMR experiments (reported here for the first time), and fast atom bombardment mass spectrometry (FAB-MS). Tests for antimicrobial and antioxidant (free-radical scavenging) activities revealed that while the extracts and fractions demonstrated strong antioxidant and antimicrobial activities, incensole was only moderately active. Key Words: Boswellia dalzielii; Incensole; Diterpenoid; Antimicrobial activity; Antioxidant activity; Journal of Pharmacy and Bioresources Vol.1(1) 2004: 7-1