Distribution of the anti-inflammatory and anti-depressant compounds: Incensole and incensole acetate in genus Boswellia.

Incensole and its acetate have shown anti-inflammatory and anti-depression activities due to their ability to activate ion channels in the brain to alleviate anxiety or depression. The natural occurrence of these two structurally and medicinally fascinating 14-membered diterpenoids was reported mainly from the genus Boswellia. Incensole and incensole acetate were detected in and isolated from both essential oils and resins of frankincense. One total synthesis was reported for incensole. Both incensole and its acetate served as precursors for several synthetic transformations. Given the fact that no specific enzymes were isolated from Boswellia trees, the major sources for incensole and incensole acetate, the biosynthetic pathway of these two compounds was only speculated. Recent studies on incensole and incensole acetate including ours have revealed another secret of the ancient drug. Understanding their mode of action will open a door in modern neurobiology and provides new insights on the mysterious diseases of the nervous system. This review interpretatively discusses the natural existence of incensole and incensole acetate, the variation of their percentages in different Boswellia species and other sources, their synthetic modifications, their biosynthesis and their therapeutic potential.