Biotransformation of (-)-α-Bisabolol by Absidia coerulea .

(-)-α-Bisabolol, a bioactive monocyclic sesquiterpene alcohol, has been used in pharmaceutical and cosmetic products with anti-inflammatory, antibacterial and skin-caring properties. However, the poor water solubility of (-)-α-bisabolol limits its pharmaceutical applications. It has been recognized that microbial transformation is a very useful approach to generate more polar metabolites. Fifteen microorganisms were screened for their ability to metabolize (-)-α-bisabolol in order to obtain its more polar derivatives, and the filamentous fungus Absidia coerulea was selected for scale-up fermentation. Seven new and four known metabolites were obtained from biotransformation of (-)-α-bisabolol ( 1 ), and all the metabolites exhibited higher aqueous solubility than that of the parent compound 1 . The structures of newly formed metabolites were established as (1 R ,5 R ,7 S )- and (1 R ,5 S ,7 S )-5-hydroxy-α-bisabolol ( 2 and 3 ), (1 R ,5 R ,7 S ,10 S )-5-hydroxybisabolol oxide B ( 4 ), (1 R ,7 S ,10 S )-1-hydroxybisabolol oxide B ( 5 ), 12-hydroxy-α-bisabolol ( 7 ), (1 S ,3 R ,4 S ,7 S )- and (1 S ,3 S ,4 S ,7 S )-3,4-dihydroxy-α-bisabolol ( 8 and 10 ) on the basis of spectroscopic analyses. These compounds could also be used as reference standards for the detection and identification of the metabolic products of 1 in the mammalian system.