# New Hydroxylactones and Chloro-Hydroxylactones Obtained by Biotransformation of Bicyclic Halolactones and Their Antibacterial Activity

## TL;DR

This study explores new halolactone compounds and their biotransformation by fungi, revealing some with strong antibacterial and antifungal properties.

## Contribution

The paper introduces new halolactone derivatives and identifies their biotransformation pathways and antimicrobial efficacy.

## Key findings

- Only compounds with a gem-dimethyl group at C-5 were biotransformed by fungi.
- Fusarium strains performed dehalogenation, while Absidia strains performed hydroxylation.
- Compound 5b showed strong antifungal activity, and compound 4a showed antimicrobial activity against MRSA.

## Abstract

The aim of this study was to obtain new halolactones with a gem-dimethyl group in the cyclohexane ring (at the C-3 or C-5 carbon) and a methyl group in the lactone ring and then subject them to biotransformations using filamentous fungi. Halolactones in the form of mixtures of two diasteroisomers were subjected to screening biotransformations, which showed that only compounds with a gem-dimethyl group located at the C-5 carbon were transformed. Strains from the genus Fusarium carried out hydrolytic dehalogenation, while strains from the genus Absidia carried out hydroxylation of the C-7 carbon. Both substrates and biotransformation products were then tested for antimicrobial activity against multidrug-resistant strains of both bacteria and yeast-like fungi. The highest antifungal activity against C. dubliniensis and C. albicans strains was obtained for compound 5b, while antimicrobial activity against S. aureus MRSA was obtained for compound 4a.