Standard curve of the quantitative test with the 95% confidence interval for artesunate controls samples. The equation of the curve (■) was y = −1831x + 292150 (r² = 0.9373). The antimalarial activities of the controls (), plotted against their respective expected concentrations (Q1 = 15 nM and Q2 = 30 nM), fell outside the 95% confidence interval of the curve. Data are presented as mean ± SD (n ≥ 6). FU = fluorescence unit; AS = artesunate; nM = nanomolar.