Biotransformation of (-)-α-Bisabolol by Absidia coerulea

(−)-α-Bisabolol, a bioactive monocyclic sesquiterpene alcohol, has been used in pharmaceutical and cosmetic products with anti-inflammatory, antibacterial and skin-caring properties. However, the poor water solubility of (−)-α-bisabolol limits its pharmaceutical applications. It has been recognized that microbial transformation is a very useful approach to generate more polar metabolites. Fifteen microorganisms were screened for their ability to metabolize (−)-α-bisabolol in order to obtain its more polar derivatives, and the filamentous fungus Absidia coerulea was selected for scale-up fermentation. Seven new and four known metabolites were obtained from biotransformation of (−)-α-bisabolol (1), and all the metabolites exhibited higher aqueous solubility than that of the parent compound 1. The structures of newly formed metabolites were established as (1R,5R,7S)- and (1R,5S,7S)-5-hydroxy-α-bisabolol (2 and 3), (1R,5R,7S,10S)-5-hydroxybisabolol oxide B (4), (1R,7S,10S)-1-hydroxybisabolol oxide B (5), 12-hydroxy-α-bisabolol (7), (1S,3R,4S,7S)- and (1S,3S,4S,7S)-3,4-dihydroxy-α-bisabolol (8 and 10) on the basis of spectroscopic analyses. These compounds could also be used as reference standards for the detection and identification of the metabolic products of 1 in the mammalian system.

Microbial Transformations of Isophorone by Alternaria alternata and Neurospora crassa

Isophorone (3,5,5-trimethyl-2-cyclohexen-1-one), a monoterpene, and the structurally related 1,8-cineole and camphor, have demonstrated a protective effect against cancer, biological activity against a variety of microorganisms, and anti-oxidant properties. The derivatization of isophorone is, therefore, an important field of xenobiochemistry, pharmacology and toxicology. The aim of this study was to obtain derivatives of isophorone through microbial biotransformation and evaluate the biotransformation metabolites as potential antimicrobial agents. Incubation of isophorone with the fungi Alternaria alternata and Neurospora crassa afforded 4α-hydroxy- and 7-hydroxy-isophorone as transformation metabolites. The antimicrobial activities of isophorone and the metabolites were evaluated in vitro both by using agar dilution and microdilution methods. However, no significant antibacterial activity was observed when compared with those of standard substances.

Microbial Hydroxylation of S-(-)-Perillyl Alcohol by Fusarium heterosporium

S-(-)-Perillyl alcohol ( p-mentha-1, 8-diene-7-ol) (1) (500 mg) was converted by Fusarium heterosporium ATCC 15625 over 10 days at 25°C to a new metabolite, 1,2-dihydroxyperillyl alcohol ( p-mentha-8-en-1,2,7-triol) (3) in a yield of 13% (70 mg). The structure of 3 was established by IR and NMR spectroscopic, specific rotation, and mass spectral studies.

Microbial Transformation of Marine Halogenated Sesquiterpenes

The sesquiterpene pacifenol is one of the main constituents of the red alga Laurencia claviformis. Earlier work on the semisynthetic derivatives of pacifenol afforded a series of halogenated sesquiterpenes. The aim of the present work was to obtain new hydroxylated derivatives of halogenated sesquiterpenes by means of microbial transformation using Aspergillus níger, Gibberella fujikuroi and Mucor plumbeus. The best results were obtained with M. plumbeus. The microbiological transformation by M. plumbeus of pacifenol, and two semisynthetic derivatives, is described. The structures of the new compounds obtained were determined by spectroscopic means.

Biotransformation of α-Cedrol and Caryophyllene Oxide by the Fungus Neurospora crassa

Incubation of α-cedrol and caryophyllene oxide with Neurospora crassa afforded 12β-hydroxy cedrol, 10α-hydroxy cedrol, and 3β-hydroxy cedrol, and 12β-hydroxy caryophyllene oxide as major metabolites, respectively. The antibacterial and radical scavenging activities of the metabolites were evaluated in vitro using broth microdilution and bioauthographic techniques. However, no significant antibacterial and antioxidant activities were observed when compared with those of standard substances.