Gérard Aranda

Microbial transformation of diterpenes: Hydroxylation of sclareol, manool and derivatives by Mucor plumbeus

Abstract Microbial transformation of several labd-14-ene derivatives has been carried out with a Mucor plumbeus strain, Sclareol (1) (labd-14-en-8α,13β-diol) affords quantitatively a mixture of triols from which the labd-14-en-3β,8α,13β-triol (2) is obtained in high yield. Incubation of other labdane derivatives, including manool (6) [labd-8(17),14-dien-13β-ol], the corresponding 7α-hydroxy derivative (10), manoyl oxide (14) or sclareolide (15) with the same microorganism results in a mixture of various new hydroxylated and keto- derivatives.

Microbial hydroxylation of natural drimenic lactones

Incubation of confertifolin and isodrimenin with Mucor plumbeus, Aspergillus niger or Rhizopus arrhizus gave in good yields the corresponding 3 beta-hydroxy derivatives. From isodrimenin, the known natural 7 alpha-hydroxy derivative (futronolide) was also obtained and its structure was definitely established by X-ray crystallographic study of its acetate derivative.

Microbial hydroxylation of sclareol by mucor plumbeus

Incubation of sclareol (labd-14-en-8α,13β-diol) with Muco plumbeus affords quantitatively a mixture of triols from which the labd-14-en-3β,8α,13β-triol is obtained in high yield.

Microbiological hydroxylation in the drimane series

Abstract The Products of the microbiological hydroxylation of drimenol and related compounds by Mucor plumbeus and Rhizopus arrhizus were investigated Complementary results (hydroxylation at 3β- and/or 6α-positions) were obtained with both microorganism.

A new example of 1α-hydroxylation of drimanic terpenes through combined microbial and chemical processes

Abstract Among various filamentous fungi, Aspergillus niger ATCC 9142 was the most efficient strain to convert confertifolin in high yield into its 3β-hydroxy derivative, which was then chemically converted to 1α-hydroxy-, 1α,11α-dihydroxy- and 1α-acetoxy-11α-hydroxyconfertifolin, new compounds structurally related to bioactive natural products isolated from plants or marine sponges.

Practical and Efficient 1α-Hydroxylation of 4,4-Dimethyl-2-Ene Derivatives in Terpenic Series

Abstract The third part of a triptycal synthesis providing 1α-hydroxy compounds, through microbial hydroxylation in position-3 of terpenoid substrates, followed by dehydration to 4,4-dimethyl-2-ene compounds and subsequent allylic hydroxylation by SeO2/pyridine N-oxide, is described.

Easy access to an optically pure precursor of forskolin.

Abstract The PLE catatysed resolution of the (±)-1-hydroxy-β-ionone acetoacetate resulted in the (−)-enantiomer 2 with high optical purity (95% e.e.). Cyclisation of this material gives access to the (−)-lactone 1 in an optically pure form.

Synthese d'antibiotiques triterpeniques a partir d'acides biliaires: IV. Etude de l'hydrogenation catalytique du dimethyl-4,4 cholene-5 one-3 oate-24 de methyle

Abstract Catalytic hydrogenation of methyl 4,4 dimethyl chol-5 en-3-one-24 oate, prepared from lithocholic acid has been carefully studied in a variety of conditions (solvent, temperature, pressure, nature and amount of catalyst). Fairly mild conditions have been found, which lead to the 5α dihydroderivative, and do not affect the Δ8(9) double bond of lanosterol. Therefore, one of the major difficulties of the conversion of bile acids into tetracyclic triterpene antibiotics has been overcome.

Identification of NAA-l-aspartate amide as the major metabolite synthesized by tobacco mesophyll protoplasts incubated in the presence of the auxin analogue NAA

Abstract A major metabolite of naphthalene 1-acetic acid (NAA) is rapidly accumulated by tobacco mesophyll protoplasts induced to divide by this growth regulator. A comparison of the natural product with various chemically synthesized NAA-amino acid conjugates was performed. The metabolite was identified as NAA-aspartate amide by negative CIMS. The biological activity of NAA-aspartate on protoplasts was further studied. The significance of the accumulation of this metabolite in dividing protoplasts is discussed.

Action of methomyl analogues on maize mitochondria

Abstract Methomyl analogues were assayed on mitochondria isolated from male sterile (T cytoplasm) and male fertile maize. None of them was more selective than Methomyl. The analogues which were more efficient than Methomyl displayed no selectivity. The results suggest stringent steric requirements for Methomyl action and stress the importance of the electron conjugated system in the Methomyl molecule for its efficiency.