Biotransformation of Lactones with Methylcyclohexane Ring and Their Biological Activity

The aim of the study was to obtain biological active compounds during biotransformation. Three bicyclic halolactones with methylcyclohexane ring (2-chloro-4-methyl-9-oxabicyclo-[4.3.0]nonan-8-one, 2-bromo-4-methyl-9-oxabicyclo[4.3.0]nona- -8-one and 2-iodo-4-methyl-9-oxabicyclo[4.3.0]nonan-8-one) obtained from the corresponding γ,δ-unsaturated acid were subjected to a screening biotransformation using 22 fungal strains. Two of these strains (Cunninghamella japonica AM472 and Fusarium culmorum AM10) were able to transform halolactones into 2-hydroxy-4-methyl-9-oxabicyclo[4.3.0]nonan-8-one by hydrolytic dehalogenation with good yield. The biotransformation product was structurally different from its synthetically prepared analog. All halolactones and hydroxylactones were tested for their biological activity. The chlorolactone inhibited growth of Staphylococcus aureus (max ΔOD = 0), Escherichia coli (max ΔOD = 0.3) and Candida albicans (max ΔOD = 0) strains. Bromolactone caused inhibition of growth of Staphylococcus aureus (max ΔOD = 0) and Fusarium linii (max ΔOD = 0) strains. Iodolactone limited growth of Staphylococcus aureus (max ΔOD = 0), Escherichia coli (max ΔOD = 0.25), Candida albicans (max ΔOD = 0.45) and Pseudomonas fluorescens (max ΔOD = 0.42) strains. Hydroxylactone caused inhibition of growth of Staphylococcus aureus (max ΔOD = 0.36) and Pseudomonas fluorescens (max ΔOD = 0.39) strains only. The test performed on aphids Myzus persicae (Sulz.) showed that chloro- and bromolactone exhibited deterrent activity after 24 h (ID = 0.5 and 0.4, respectively), while hydroxylactone was a weak attractant (ID = −0.3).