Microbial transformation of 5α-hydroxycaryophylla-4(12), 8(13)-diene with Macrophomina phaseolina

Biotransformation of 5α-hydroxycaryophylla-4(12), 8(13)-diene (1) by the fungus Macrophomina phaseolina resulted into regioselective oxidation at C-4(12) exocyclic double bond and C-11 gem-methyl groups, leading to the formation of three new metabolites, 4β-methoxycaryophyllene-5α, (11S)-14-diol (2), 4β-methoxycaryophyllene-5α, (11R)-15-diol (3), and caryophyllene-5α, (11R)-15-diol (4). The structures of metabolites were deduced by spectroscopic and single-crystal X-ray diffraction analysis. Compounds 1–4 were evaluated for in vitro antimalarial activity, where compound 2 exhibited an IC50 value of 0.72 ± 0.17 μg/ml (standard chloroquine diphosphate, IC50 = 0.025 ± 0.01 μg/ml).