BIOTRANSFORMATIOM OF TWO ENT-15β-HYDROXY-KAUR-16-ENE DERIVATIVES BY GIBBERELLA FUJIKUROI

Article abstract of DOI:10.1016/S0031-9422(00)97539-3

Incubation of the fungus Gibberella fujikuroi with ent-15β-hydroxy-kaur-16-ene gave ent-11α,15β-dihydroxy-kaur-16-ene, ent-7β,11α,15β-trihydroxy-kaur-16-ene, ent-11α,13,15β-trihydroxy-kaur-16-ene, ent-11α,15β,19-trihydroxy-kaur-16-ene, and ent-11α,14α,15β-trihydroxy-kaur-16-ene, and a mixture of products, which was resolved by acetylation to give ent-11α,14α,15β-triacetoxy-kaur-16-ene and ent-7β,15β,17-triacetoxy-11α,16α-epoxy-kaur-16-ene.The addition of candidiol (ent-15β,18-dihydroxy-kaur-16-ene) gave ent-11α,15β,18-trihydroxy-kaur-16-ene, and a mixture of substances, which was resolved by acetylation to give ent-11β,15β,18-triacetoxy-kaur-16-ene, ent-7β,11α,15β,18-tetraacetoxy-kaur-16-ene and ent-15β,17,18-triacetoxy-11α,16α-epoxykaurane.These results confirm that the presence in ent-kaur-16-ene derivatives of a 15α-hydroxy group inhibits oxidation at C-19 to the acid level.The biotransformation of these compounds may be useful for the synthesis of natural 11β-hydroxy-ent-kaurene analogues. Key Word Index: Gibberella fujikuroi; diterpenes; ent-15β-hydroxy-kaur-16-ene; candidiol; microbiological transformations.