Abstract:
Enzymatic acylation of verbascoside, a polyhydroxylated natural product, has been
reported in this study using five different commercial lipases and taking p-nitrophenyl
alkanoates as acyl donors. Out of these enzymes, the immobilised Candida antarctica
lipase B was found as the enzyme of choice. Mono- and di-acylated products were
formed, with mono as major product indicating high regioselective nature of such
transformations. A series of acyl esters of verbascoside have been synthesised by this
enzymatic transesterification methodology. The lipophilicity of the synthesised
analogues was also checked. The analogues were further subjected to synergistic
antifungal activity with amphotericin B (AmB) against Candida albicans. Fourfold
reduction in minimum inhibitory concentration of AmB was observed with few
synthesised analogues such as verbascoside 400-octanoate (3b), verbascoside 400-
palmitate (3d) and verbascoside 400,40
-dipalmitate (4d) at a concentration of 0.5mg/mL.