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Biomedical subjects

H L Holland

Publications and source records attributed to H L Holland.

9 recordsLinked to original sources
PubMed1995

Biotransformation of corticosteroids by Penicillium decumbens ATCC 10436.

The biotransformation of a series of corticosteroids by the fungus Penicillium decumbens ATCC 10436 has been investigated. Conversion to the corresponding 5 alpha-dihydrosteroid was observed for all the delta 4-3-ketosteroids studied with the exception of deoxycorticosterone, which was converted to a delta 1.4-diene. Deoxycorticosterone acetate was, however, converted to a 5 alpha-dihydro product concomitant with ester hydrolysis. Other substrates carrying a C-21 acetoxy group were also hydrolyzed to the alcohol. In two cases (resulting from deoxycorticosterone acetate and 11-deoxycortisone) the 5 alpha-3-keto product was further reduced to the 3 beta-alcohol. No reduction of delta 1.4-dienes was observed.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1994

Formation of 5 alpha steroids by biotransformation involving the 5 alpha-reductase activity of Penicillium decumbens.

The biotransformation of a series of delta 4-3-ketosteroids by the fungus Penicillium decumbens ATCC 10436 has been investigated. Conversion to the 5 alpha-dihydrosteroid was observed for several substrates of the androstene and pregnene series: the reaction is tolerant of non-polar substituents (Cl and CH3) at C-4 of the substrate, but does not occur in the presence of a 4-hydroxyl group, or with additional unsaturation at the delta 1 or delta 6 positions. A-nor-, B-nor-, 3-deoxy-, and 3,5-cycloandrostanes are not reduced, but 6-methylenetestosterone is converted to a 6-methylene-5 alpha-dihydro derivative. Several biotransformations are reported which involve oxidoreductase activity at C-3 and/or C-17, either concomitant or independent of delta 4 reduction: the substrate specificity of the oxidoreductase processes has been examined and defined by the use of 3 alpha-hydroxy, 3 beta-hydroxy, 3-keto, 17 beta-hydroxy and 17-keto substituted steroids. In this way, the existence in P. decumbens of 3 beta-hydroxy-3-keto and 17 beta-hydroxy-17-keto oxidoreductases has been demonstrated.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1994

Biotransformation of organic sulfides--IV. Formation of chiral benzyl alkyl and phenyl alkyl sulfoxides by Helminthosporium species NRRL 4671.

The fungus Helminthosporium species NRRL 4671 has been used for the biotransformation of a series of phenyl alkyl sulfides with alkyl groups ranging from methyl to n-hexyl, and benzyl alkyl sulfides with alkyl groups from methyl to n-nonyl. Several 2-phenylethyl and 3-phenylpropyl sulfides have also been examined as substrates, together with cyclohexyl methyl sulfide and 1- and 2-naphthyl methyl sulfides. For the majority of substrates, sulfoxide formation occurred in moderate yield and with predominant (S) chirality at sulfur; lesser amounts of sulfone product were also obtained in some cases. The data so obtained have been used to define the preparatively useful limits of S-oxidation of phenyl alkyl sulfides and benzyl alkyl sulfides by biotransformation using Helminthosporium.

Biotransformation↗
PubMed1993

Fungal biotransformation of organophosphines.

1. The biotransformations of triphenyl phosphite and of triphenyl-, tri-n.-butyl-, diethylphenyl-, and ethylmethylphenyl-phosphines by the fungi Mortierella isabellina ATCC 42613, Helminthosporium species NRRL 4671, and Aspergillus foetidus ATCC 10254, have been examined. 2. The triaryl and tri-n.-butyl substrates underwent oxidation at phosphorus in low yield, a process attributed largely to auto-oxidation under the experimental conditions used. 3. The alkyl aryl phosphines were enzymically oxidized at phosphorus, but concurrent auto-oxidation also occurred. 4. Incubation of ethylmethylphenyl phosphine with M. isabellina gave the corresponding S(-) phosphine oxide in a 92% yield with an enantiomeric purity of 13%.

Aspergillus↗
PubMed1992

Effect of cell immobilization and organic solvents on sulfoxidation and steroid hydroxylation by Mortierella isabellina.

The effects of calcium alginate bead immobilization and the presence of organic solvents on two bioconversion reactions carried out by Mortierella isabellina ATCC 42613 have been investigated. These reactions, the 14 alpha-hydroxylation of progesterone and the sulfoxidation of thioanisole, both proceed in high yield using resting-cell bioconversions, but are not carried out by alginate bead preparations in the absence of an organic co-solvent, the best results being obtained with 5 or 10% aqueous methanol. The stereoselectivity of sulfoxidation of thioanisole was found to be dependent upon the nature and concentration of organic co-solvent.

Alginates↗
PubMed1992

Bioconversions.

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Biological Products↗
PubMed1986

Biotransformation of polycyclic aromatic compounds by fungi.

Incubations of several polycyclic aromatic hydrocarbons (PAHs) and heteroaromatic compounds with a series of common micro-organisms have been performed. The PAHs were not metabolized by any of the fungi studied. The sulphur-containing heterocyclic aromatic compounds dibenzothiophene, thioxanthone and thiochromanone were oxidized at sulphur by C. elegans. Other fungi are capable of oxidation at the sulphur atom of dibenzothiophene and thioxanthone. C-1 and C-3 methyl substituted thioxanthones are hydroxylated at the methyl group by C. elegans.

Biotransformation↗