The global malaria control and elimination strategies are constrained by the emergence and spread of multi-drug resistant Plasmodium falciparum, Plasmodium vivax and Plasmodium malariae strains to most antimalarials. Currently, studies reveal rising incidences of reduced parasite susceptibility to the artemisinin-based combination therapies (ACTs), the recommended first-line treatment regimen for uncomplicated P. falciparum infections by WHO. This study evaluated the antimalarial activity, acute oral toxicity and absorption, distribution, metabolism, excretion and toxicity (ADMET) profiles of 3-Chloro-4(4-chlorophenoxy) aniline (ANN), designed in silico and artesunate-3-Chloro-4(4-chlorophenoxy) aniline hybrid (ATSA), synthesized by covalent biotherapy approach alongside artesunate (ATS) as a reference drug. Antimalarial activities against P.berghei ANKA, lumefantrine resistant (LuR) and piperaquine resistant parasite (PQR) lines were determined using the standard 4-Day suppressive tests (4DTs) and effective dosage fifties (ED50s) established using Statistica 2000 version 5.5. The acute oral toxicity was determined using the Organization for Economic Co-operation and Development (OECD) guideline 423. ADMET profiles were predicted in silico using PreADMET online prediction tool. One-way analysis of variance (ANOVA) was used to determine statistical significance between percentage activities in treated and control animals, sensitive and resistant parasites and ED50s for test drugs. ATSA and ANN have antimalarial chemosuppression activities of above 40% to both P.berghei ANKA, P.berghei LuR and P.berghei PQR parasites in vivo with wide safety margins; TI of 30 times greater than their individual ED50s. The ED50s for ATSA were 4.211 mg/kg, 2.601 mg/kg, 3.875 mg/kg and ANN 3.068 mg/kg, 3.185 mg/kg, 2.805 mg/kg in P. berghei ANKA, LuR and PQR parasites respectively. There was a significant difference between treated and control mice P< 0.05. However, no significant difference was observed between the percentage activities and ED50s for ATSA and ANN in both sensitive and resistant parasites, P > 0.05. No mortalities were recorded in acute oral toxicity and the mean weight difference for the test and control groups was statistically insignificant P > 0.05. The calculated ADMET parameters demonstrated that both ATSA and ANN have high human intestinal absorptions (HIA) > 95%, are well distributed, and have medium human ether a-go-go-related gene (hERG) K+ channel inhibition risks. ATSA is non-mutagen but ANN reveal mutagenicity to TA 100 strain alone. Both ATSA and ANN manifest carcinogenicity to the rat model but not the mouse model. To confirm the predicted ADMET parameters for ATSA and ANN, in vivo studies are necessary. Pre-clinical and clinical studies should then follow to evaluate their value in the development of novel antimalarial drugs for future use in the management of multi-drug resistant plasmodia.
Keywords: 3-Chloro-4-(4-Chlorophenoxy) aniline, hybrid drug, malaria chemotherapy, acute oral toxicity, ADMET.