Phospholipase D inhibitors from a Myrsine species

The phospholipase D-inhibitory activity of a methanol extract from the leaves of a New Zealand plant, Myrsine australis, has been attributed to two new saponins 1 and 2. Compound 1 was assigned as 3-0-[-beta-D-xylopyranosyl-(1-->2)-0-beta-D-glucopyranosyl-(1-->4)- -[0-beta-D -glucopyranosyl-(1-->2)]-alpha-L-arabinosyl]-16alpha-hydroxy-+ ++13beta,28-epoxyoleanane and 2 as 3beta-0-[-beta-rhamnopyranosyl-(1-->2)-0-beta-D-glucopyranosyl-(1-->4)-[ 0-beta-D-glucopranosyl]-alpha-L-arabinopyranosyl]-16alpha -hydroxy-13beta, 28-epoxyleanane. Compounds 1 and 2 showed IC50 values of 3 and 2 microM, respectively, versus phorbol 12-myrisate-13-acetate-stimulated phosphlipase D in human promyelocytic leukemic (HL-60) cells. Compounds 1 and 2 also inhibited fMLP (formyl-Met-Leu-Phe) stimulated phospholipase D with IC50 values of 8 and 24 microM, respectively.