The incubation of 13α,17-dihydroxystemodane with Cephalosporium aphidicola.

The biotransformation of 13α,17-dihydroxystemodane (3) with the fungus Cephalosporium aphidicola afforded 13α,17,18-trihydroxystemodane (4), 3β,13α,17-tri-hydroxystemodane (5), 13α,17-dihydroxy-stemodan-18-oic acid (6), 3β,11β,13α,17-tetra-hydroxystemodane (7), 11β,13α,17,18-tetrahydroxystemodane (8) and 3β,13α,17,18-tetra-hydroxystemodane (9). The hydroxylation at C-18 of the substrate points to a biosynthetically-directed transformation, because aphidicolin (2) is hydroxylated at this carbon. However, the C-3(β) and C-11(β) hydroxylations seem to indicate a xenobiotic biotransformation.

A chemotaxonomic study of nine Canarian Sideritis species.

Nine taxa of the Sideritis genus, Sideritis argosphacelus var. spicata, Sideritis candicans var. eriocephala,Sideritis discolor, Sideritis kuegleriana, Sideritis lotsyi, Sideritis lotsyi var.

Biotransformation of two ent-Pimara-9(11),15-diene derivatives by Gibberella fujikuroi.

The incubation of 19-hydroxy-13-epi-ent-pimara-9(11),15-diene (4) with Gibberella fujikuroi gave 8 alpha,19-dihydroxy-9 alpha,11alpha-epoxy-13-epi-ent-pimara-15-ene (6), 7-oxo-11 alpha,19-dihydroxy-13-epi-ent-pimara-8(9),15-diene (7), 7-oxo-11beta,19-dihydroxy-13-epi-ent-pimara-8(9),15-diene (9), and 8 alpha,19-dihydroxy-9 alpha,11 alpha:15,16-diepoxy-13-epi-ent-pimarane (11), while the feeding of 13-epi-ent-pimara-9(11),15-diene-19-oic acid (5) with this fungus afforded 1-oxo-2 alpha,9 alpha-dihydroxy-13-epi-ent-pimara-11,15-dien-19-oic acid (13), 1-oxo-2 beta,9 alpha-dihydroxy-13-epi-ent-pimara-11,15-dien-19-oic acid (14), 13-epi-ent-pimara-9(11),15-dien-1,19-dioic acid 1,2-lactone (15), and 1-oxo-12 beta-hydroxy-13-epi-ent-pimara-9(11),15-dien-19-oic acid (16). In both biotransformations, the main reaction was the epoxidation of the 9(11)-double bond, followed by rearrangement to afford allylic alcohols. The formation of lactone 15 represents the first time that a Baeyer-Villiger oxidation has been observed in a microbiological transformation with this fungus.

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

The biotransformation of 7alpha-hydroxy-ent-kaur-16-ene (epi-candol A) by the fungus Gibberella fujikuroi gave 7alpha,16alpha,17-trihydroxy-ent-kaur-16-ene and a seco-ring B derivative, fujenoic acid, whilst the incubation of candicandiol (7alpha,18-dihydroxy-ent-kaur-16-ene) and canditriol (7alpha,15alpha,18-trihydroxy-ent-kaur-16-ene) afforded 7alpha,18,19-trihydroxy-ent-kaur-16-ene and 7alpha,11beta,15alpha,18-tetrahydroxy-ent-kaur-16-ene, respectively. The presence of a 7alpha-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 15alpha-hydroxyl group in canditriol inhibits oxidation at C-19 and direct hydroxylation at C-11(beta).

The microbiological transformation of two 15beta-hydroxy-ent-kaurene diterpenes by Gibberella fujikuroi.

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.

The microbiological transformation of the diterpenes dehydroabietanol and teideadiol by Mucor plumbeus.

The microbiological transformation of dehydroabietanol (18-hydroxy-dehydroabietane) by Mucor plumbeus led to 2alpha,18-dihydroxy-abieta-8,11,13,15-tetraene, 2alpha,15-dihydroxy-dehydroabietanol, 2alpha-hydroxy-15-methoxy-dehydroabietanol, 7beta-hydroxy-2-oxo-dehydroabietanol, 15-hydroxy-2-oxo-dehydroabietanol and 15,16-dihydroxy-2-oxo-dehydroabietanol, whilst that of teideadiol (1alpha,18-dihydroxy-dehydroabietane) gave 2alpha-hydroxy-teideadiol, 7alpha-hydroxy-teideadiol and 7beta-hydroxy-teideadiol. Thus, 2alpha- and 7beta-hydroxylation occur in both biotransformations and the 15-hydroxylation is inhibited in the biotransformation of teideadiol by the presence of a 1alpha-alcohol.

On the ent-kaurene diterpenes from Sideritis athoa.

The structure of a diterpene, which has been isolated form Sideritis athoa, has been corrected from 3beta,18-dihydroxy-ent-kaur-16-ene to 1alpha,18-dihydroxy-ent-kaur-16-ene (canadiol).

Microbial transformation of 18-hydroxy-9,13-epi-ent-pimara-7,15-diene by Gibberella fujikuroi.

The incubation of the diterpene 18-dihydroxy-9,13-epi-ent-pimara-7,15-diene (3) with the fungus Gibberella fujikuroi gave 14 metabolites, 4 and 6-18. The carbons functionalized were the C-20 methyl and all the secondaries, except C-12. The main reaction observed was the epoxidation of the 7,8-double bond, which rearranged to form 7-keto derivatives, such as 10-17, or the allylic alcohol 18.

The biotransformation of the diterpene 2beta-hydroxy-ent-13-epi-manoyl oxide by Gibberella fujikuroi.

Incubation of the diterpene 2beta-hydroxy-ent-13-epi-manoyl oxide with Gibberella fujikuroi afforded in good yield 2beta,6beta-dihydroxy-ent-13-epi-manoyl oxide, 2beta,12beta-dihydroxy-ent-13-epi-manoyl oxide and 2beta,20-dihydroxy-ent-13-epi-manoyl oxide, confirming that although ent-13-epi-manoyl oxide is a final metabolite of a biosynthetic branch in this fungus, more polar derivatives of this compound can be transformed by this micro-organism.