New ether diglycosides from Matayba guianensis with antiplasmodial activity

Four new ether diglycosides (1-4), named matayosides A-D, were isolated from the root bark of Matayba guianensis, a plant exhibiting in vitro antiplasmodial activity. They were identified as hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-6-O-palmitoyl-beta-D-glucopyranoside, hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-4,6-di-O-acetyl-beta-D-glucopyranoside, hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-3,6-di-O-acetyl-beta-D-glucopyranoside and hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-6-O-acetyl-beta-D-glucopyranoside, respectively. Their structures were established using one- and two-dimensional NMR techniques, mass spectrometry (MS) and MS/MS experiments. The compounds were found to inhibit the growth of Plasmodium falciparum in vitro with IC50 values ranging from 2.5 to 8.9 microg/mL.