Microbial carbonylation and hydroxylation of 20(<i>R</i>)-panaxadiol by <i>Aspergillus niger</i>

<p>20(<i>R</i>)-panaxadiol (PD) was metabolised by the fungus <i>Aspergillus niger</i> AS 3.3926 to its C-3 carbonylated metabolite and five other hydroxylated metabolites (<b>1</b>–6). Their structures were elucidated as 3-oxo-20(<i>R</i>)-panaxadiol (<b>1</b>), 3-oxo-7β-hydroxyl- 20(<i>R</i>)-panaxadiol (<b>2</b>), 3-oxo-7β,23α-dihydroxyl-20(<i>R</i>)-panaxadiol (<b>3</b>), 3,12-dioxo- 7β,23β-dihydroxyl-20(<i>R</i>)-panaxadiol (<b>4</b>), 3-oxo-1α,7β-dihydroxyl-20(<i>R</i>)-panaxadiol (<b>5</b>) and 3-oxo-7β,15β-dihydroxyl-20(<i>R</i>)-panaxadiol (<b>6</b>) by spectroscopic analysis. Among them, compounds <b>2</b>–<b>6</b> were new compounds. Pharmacological studies revealed that compound <b>6</b> exhibited significant anti-hepatic fibrosis activity.</p>