| Summary: | (−)-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 <i>Absidia coerulea</i> was selected for scale-up fermentation. Seven new and four known metabolites were obtained from biotransformation of (−)-α-bisabolol (<b>1</b>), and all the metabolites exhibited higher aqueous solubility than that of the parent compound <b>1</b>. The structures of newly formed metabolites were established as (1<i>R</i>,5<i>R</i>,7<i>S</i>)- and (1<i>R</i>,5<i>S</i>,7<i>S</i>)-5-hydroxy-α-bisabolol (<b>2</b> and <b>3</b>), (1<i>R</i>,5<i>R</i>,7<i>S</i>,10<i>S</i>)-5-hydroxybisabolol oxide B (<b>4</b>), (1<i>R</i>,7<i>S</i>,10<i>S</i>)-1-hydroxybisabolol oxide B (<b>5</b>), 12-hydroxy-α-bisabolol (<b>7</b>), (1<i>S</i>,3<i>R</i>,4<i>S</i>,7<i>S</i>)- and (1<i>S</i>,3<i>S</i>,4<i>S</i>,7<i>S</i>)-3,4-dihydroxy-α-bisabolol (<b>8</b> and <b>10</b>) 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 <b>1</b> in the mammalian system.
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