title: Microbiological transformation of two 15α-hydroxy-ent-kaur-9(11),16-diene derivatives by the fungus Fusarium fujikuroi.
abstract: The incubation of 15α-hydroxy-ent-kaur-9(11),16-dien-19-oic acid (15α-hydroxy-grandiflorenic acid) with the fungus Fusarium fujikuroi gave as main metabolite its 3β,6β-dihydroxy derivative, which by an oxidative decarboxylation afforded a 19-nor compound with a 4,18-double bond. Other substances obtained were a 3α-hydroxy-19,6α-lactone, 3β-hydroxy-6β,7β-epoxy-ent-kaur-9(11),16-dien-19-oic acid and 3β-hydroxy-6-oxo-ent-kaur-9(11),16-dien-19-oic acid. Moreover, the biotransformation of 15α,18-dihydroxy-ent-kaur-9(11),16-diene led to the isolation of the corresponding 3β-, 6β-, 7α- and 12β-hydroxy derivatives. Two metabolites formed by 16β,17-epoxidation of the last compound and of the substrate were also obtained. These results indicated that the presence of the 9,11-double bond in the substrate impedes its 7β-hydroxylation, which is necessary for the formation of gibberellins and seco-ring B ent-kaurenoids. However, this 9,11-unsaturation does not hinder a 6,7-dehydrogenation and further 6β,7β-epoxidation, characteristic steps of the kaurenolide biosynthetic pathway.
authors: Instituto de Productos Naturales y Agrobiología, C.S.I.C., Avda. Astrofísico F. Sánchez 3, 38206-La Laguna, Tenerife, Canary Islands, Spain. bmfraga@ipna.csic.es
authors: Braulio M
authors: BM
authors: Fraga
authors: Victoria
authors: V
authors: González-Vallejo
authors: Ricardo
authors: R
authors: Guillermo
authors: Juan M
authors: JM
authors: Amaro-Luis
mesh_terms: D001711:Biotransformation; D004224:Diterpenes / Q000737:chemistry* / Q000378:metabolism*; D005670:Fusarium / Q000378:metabolism*
chemical_list: D004224:Diterpenes; C014576:grandiflorenic acid