title: The microbiological transformation of two 15beta-hydroxy-ent-kaurene diterpenes by Gibberella fujikuroi.
abstract: The incubation of 15beta-hydroxy-3-oxo-ent-kaur-16-ene (1) with the fungus Gibberella fujikuroi afforded 11beta-hydroxy-3,15-dioxo-ent-kaurane (6), 11beta,15beta-dihydroxy-3-oxo-ent-kaur-16-ene (8), 7beta,11beta,15beta-trihydroxy-3-oxo-ent-kaur-16-ene (9), 7alpha,11beta-dihydroxy-3,15-dioxo-ent-kaurane (7), and 7alpha,11beta,15beta-trihydroxy-3-oxo-ent-kaur-16-ene (10). The incubation of 15beta-hydroxy-ent-kaur-2,16-diene (3) with the same fungus yielded 7alpha,11beta-dihydroxy-15-oxo-ent-kaur-2-ene (12), 7alpha,11beta,15beta-trihydroxy-ent-kaur-2,16-diene (13), 7beta,15beta-dihydroxy-ent-kaur-2,16-dien-19,6-olide (14), 1beta,7beta,15beta-trihydroxy-ent-kaur-2,16-dien-19-oic acid (15), 7alpha,11beta,16alpha-trihydroxy-15-oxo-ent-kaur-2-ene (17), and 7alpha,15beta,17-trihydroxy-11beta,16beta-epoxy-ent-kaur-2-ene (19). These results indicated that a 3-oxo group in ent-kaur-16-ene derivatives inhibits the oxidation at C-19, typical of the biosynthetic pathway of gibberellins and kaurenolides, while a 2,3-double bond or a 15beta-OH does not. In both substrates a 15beta-alcohol directs hydroxylations at C-11(beta) and C-7(alpha), while in those with a 2,3-double bond the functionalization of C-1(beta) is favored.
authors.affiliation: Instituto de Productos Naturales y Agrobiología, CSIC, Avenida Astrofísico F. Sánchez 3, 38206-La Laguna, Tenerife, Canary Islands, Spain. bmfraga@ipna.csic.es
authors.forename: Braulio M
authors.initials: BM
authors.lastname: Fraga
authors.forename: Ricardo
authors.initials: R
authors.lastname: Guillermo
authors.forename: Melchor G
authors.initials: MG
authors.lastname: Hernández
mesh_terms: D001711:Biotransformation; D045786:Diterpenes, Kaurane / Q000737:chemistry / Q000378:metabolism*; D005874:Gibberella / Q000378:metabolism*; D006900:Hydroxylation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D013237:Stereoisomerism
chemical_list: D045786:Diterpenes, Kaurane