Biotransformation of the diterpenes epicandicandiol and candicandiol by Mucor plumbeus

The microbiological transformation of the diterpene epicandicandiol (1) with Mucor plumbeus gave foliol (3), sideritriol (5), and 7beta,16alpha,17,18-tetrahydroxy-ent-kaurane (7), while the incubation of candicandiol (2) gave 7alpha,9beta,18-trihydroxy-ent-kaur-16-ene (10), canditriol (11), and 7alpha,16alpha,17,18-tetrahydroxy-entkaurane (12). Thus, the main difference observed in both feedings, resulting from the spatial change in the orientation of the 7-hydroxyl, from axial in the substrate 1 to equatorial in 2, was the formation of a 3alpha- and a 9beta-hydroxylated derivative, respectively.