Anti-viral and cytotoxic norbisabolane sesquiterpenoid glycosides from Phyllanthus emblica and their absolute configurations

In an effort to identify anti-viral and cytotoxic compounds from Phyllanthus spp., 14 highly oxygenated norbisabolane sesquiterpenoids, phyllaemblicins H1-H14, were isolated from the roots of Phyllanthus emblica Linn, along with phyllaemblicins B and C and glochicoccinoside D. Their structures were determined on the basis of detailed spectroscopic analysis and chemical methods. Determination of absolute configurations of these compounds was facilitated by theoretical calculations of electronic circular dichroism (ECD) spectra using time-dependent density functional theory (TDDFT) for the aglycone components, and pre-column derivative/chiral HPLC analysis for the monosaccharides. The known glochicoccinoside D displayed potent activity against influenza A virus strain H3N2 and hand, foot and mouth virus EV71, with IC50 values of 4.5 +/- 0.6 and 2.6 +/- 0.7 mu g/ml, respectively. Phyllaemblicin H1 showed moderate cytotoxicity against human cancer cell lines A-549 and SMMC-7721, with IC50 values of 4.7 +/- 0.7 and 9.9 +/- 1.3 mu M, respectively. (C) 2015 Elsevier Ltd. All rights reserved.