Hz and free heme levels from cultured P. falciparum treated with varying concentrations of benzamides a) 15j, a negative control showing no statistically significant difference in Hz or free heme as a function of dose, b) 12d, a monobenzamide and c) 15i, a dibenzamide exhibit strong dose dependent changes. Asterisks indicate statistical significance relative to no drug (2-tailed t-test): *P < 0.05; **P < 0.01; ***P < 0.001, n = 3.