A reference document on Permissible Limits for solvents and buffers during in vitro antimalarial screening

Antimalarial drug discovery expands on targeted and phenotype-based screening of potential inhibitory molecules to ascertain overall efficacy, phenotypic characteristics and toxicity, prior to exploring pharmacological optimizations. Candidate inhibitors may have varying chemical properties, thereby requiring specific reconstitution conditions to ensure solubility, stability or bioavailability. Hence, a variety of solvents, buffers, detergents and stabilizers become part of antimalarial efficacy assays, all of which, above certain threshold could interfere with parasite viability, invasion or red blood cell properties leading to misinterpretation of the results. Despite their routine use across malaria research laboratories, there is no documentation on non-toxic range for common constituents including DMSO, glycerol, ethanol and methanol. We herein constructed a compatibility reference guide for 14 such chemicals and estimated their Permissible Limit against P. falciparum asexual stages at which viability and replication of parasites are not compromised. We also demonstrate that at the estimated Permissible Limit, red blood cells remain healthy and viable for infection by merozoites. Taken together, this dataset provides a valuable reference tool for the acceptable concentration range for common chemicals during in vitro antimalarial tests.