Structures and bioactivities of dihydrochalcones from Metrodorea stipularis.

Metrodorea stipularis stem extracts were studied in the search for possible antichagastic, antimalarial, and antitumoral compounds using cruzain from Trypanosoma cruzi, Plasmodium falciparum, and cathepsins B and L, as molecular targets, respectively. Dihydrochalcones 1, 2, 3, and 4 showed significant inhibitory activity against all the targets. Compounds 1-4 displayed IC50 values ranging from 7.7 to 21.6 μM against cruzain; dihydrochalcones 2 and 4 inhibited the growth of three different strains of P. falciparum in low micromolar concentrations; and against cathepsins B and L these compounds presented good inhibitory activity with IC50 values ranging from 1.0 to 14.9 μM. The dihydrochalcones showed good selectivity in their inhibitory activities against the cysteine proteases.