Figure 1.

Initial screening of usnic acid derivatives for transmission-blocking activity demonstrating reduced midgut-infection intensity. (a) Structure of usnic acid (UA) and the UA derivatives initially screened by standard membrane feeding assay (SMFA). For each derivative the UA scaffold remains the same, and R represents the point of attachment for each functional group. (b, c) Initial screening of UA derivatives by SMFA carried out at a concentration of 250 μg/mL. The readout for midgut infection is oocyst intensity, plotted as the number of oocysts per female mosquito. DMSO-only treatments were included as negative controls. Experimental details are tabulated below the graphs, where N is the number of mosquito midguts dissected and scored for oocysts, “prev” is the infection prevalence among mosquitoes in a given treatment group with the 95% confidence interval provided in parentheses beneath the observed value, mean is the geometric mean of oocyst number (includes nonzero midguts only), median is the median oocyst number, and % inhibition is calculated as (median_control − median_treatment)/median_control. The level of statistical significance is denoted by asterisks following Bonferroni correction of z-scores, *p < 0.05, ***p < 0.0001.