The microbiological transformation of 7α-hydroxy-ent-kaur-16-ene derivatives by Gibberella fujikuroi

7 pages, 1 table, 1 scheme.-- PMID: 17467750 [PubMed].-- Printed version published Jun 2007.The biotransformation of 7α-hydroxy-ent-kaur-16-ene (epi-candol A) by the fungus Gibberella fujikuroi gave 7α,16α,17-trihydroxy-ent-kaur-16-ene and a seco-ring B derivative, fujenoic acid, whilst the incubation of candicandiol (7α,18-dihydroxy-ent-kaur-16-ene) and canditriol (7α,15α,18-trihydroxy-ent-kaur-16-ene) afforded 7α,18,19-trihydroxy-ent-kaur-16-ene and 7α,11β,15α,18-tetrahydroxy-ent-kaur-16-ene, respectively. The presence of a 7α-hydroxyl group in epi-candol A avoids its biotransformation along the biosynthetic pathway of gibberellins, and directs it to the seco-ring B acids route. The 15α-hydroxyl group in canditriol inhibits oxidation at C-19 and direct hydroxylation at C-11(β). The formation of fujenoic acid, from 7α-hydroxy-ent-kaur-16-ene, probably occurs via 7α-hydroxykaurenoic acid and 7-oxokaurenoic acid, with subsequent hydroxylation at the C-6(β) position