Microbial transformations of halolactones with p-menthane system.

Area of Science:

• Biotechnology
• Organic Chemistry
• Microbial Biotransformation

Background:

• Piperitone derivatives are biologically active compounds.
• Halolactones are versatile synthetic intermediates.
• Microbial transformations offer selective functionalization pathways.

Purpose of the Study:

• To investigate the microbial biotransformation of piperitone-derived halolactones.
• To identify novel hydroxylated metabolites produced by filamentous fungi.
• To explore the regioselectivity of enzymatic hydroxylation in halolactones.

Main Methods:

• Biotransformation of racemic iodo-, bromo-, and chlorolactones using four fungal strains (Absidia glauca, Absidia cylindrospora, Mortierella vinaceae, Nigrospora oryzae).
• Isolation and structural elucidation of new halohydroxylactone products using spectral data analysis.

Main Results:

• Four new halohydroxylactones (compounds 4-7) were successfully synthesized via microbial biotransformation.
• Hydroxylation consistently occurred at the methine carbon atom of the isopropyl substituent.
• Nigrospora oryzae AM8 produced an additional bromolactone with an alpha-hydroxy group on the lactone ring.

Conclusions:

• Filamentous fungi effectively biotransform piperitone-derived halolactones, yielding novel hydroxylated compounds.
• The enzymatic systems exhibit specific regioselectivity for hydroxylation on the isopropyl group.
• This study expands the scope of microbial biotransformation for generating functionalized lactone derivatives.