Phyllanemblinins A-F, new ellagitannins from Phyllanthus emblica

Six new ellagitannins, phyllanemblinins A-F (1-6), were isolated from Phyllanthus emblica, along with 30 known tannins and related compounds. Their structures were determined by spectral and chemical methods. Phyllanemblinins A (1) and B (2) were confirmed to be ellagitannins having a tetrahydroxybenzofuran dicarboxyl group and a hexahydroxydiphenoyl group, respectively, by chemical synthesis from furosin (8). Phyllanemblinin C (3) has a new acyl group at the glucose 2,4-positions and is structurally related to chebulagic acid. Phyllanemblinins D (4), E (5), and F (6) were found to be positional isomers of neochebuloyl 1(beta)-O-galloylglucose.