Novel Ca(2+)-ATPase inhibitors from the dried root tubers of Polygonum Multiflorum

The MeOH extract of the dried root tubers of Polygonum multiflorum yielded three bioactive compounds with an inhibitory activity on calmodulin-depleted erythrocyte calcium-dependent ATPase. These compounds were identified as E-2,3,5,4'-tetrahydroxystilbene 2-O-beta-D-glucopyranoside [2] (IC50 = 240 microM) and cis- and trans-E-3-butylidene-4,5,6,7-tetrahydro-6,7-dihydroxy-1(3H)- isobenzofuranone [3 and 4](IC50 = 160 and 260 microM, respectively). E-2,4,6,4'-Tetrahydroxystilbene 2-O-beta-D-glucopyranoside [1] was also isolated but was found to have no inhibitory effect on the enzyme.