(a) Impact of KRB on Pf growth and (b) antimalarial activity of artesunate at 4 nM prepared in culture medium or 12.5% KRB in culture medium for the semi-quantitative test. KRB concentrations above 12.5% (v/v) significantly reduced parasites growth. All samples containing KRB were therefore diluted into culture medium before use to limit its impact. Each concentration was tested in triplicate in two independent assays. Data are presented as the mean ± SD (n = 6). There was no statistical difference between the antimalarial activities of 4 nM artesunate solutions prepared in culture medium and 12.5% (v/v) KRB. Each sample was tested in triplicate in three independent assays. Data are presented as mean ± SD (n = 9). KRB = Krebs ringer buffer; AS = artesunate; FU = fluorescence unit; ns: non-significant. Statistical analyses were performed with GraphPad Prism software, Mann–Whitney test, α = 5%, p-value (**) = 0.0022.