UNCORRECTED PROOF Journal of Ethnopharmacology xxx (xxxx) xxx-xxx Contents lists available at ScienceDirect Journal of Ethnopharmacology journal homepage: http://ees.elsevier.com In vitro and in vivo antitrypanosomal efcacy of combination therapy of Anogeissus leiocarpus, Khaya senegalensis and potash Abdullah M. Tauheed a,∗ , Mohammed Mamman a , Emmanuel O. Balogun b,c , Abubakar Ahmed d , Mohammed M. Suleiman a,e a Department of Veterinary Pharmacology and Toxicology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria, Kaduna State, Nigeria b Department of Biochemistry, Faculty of Life Sciences, Ahmadu Bello University, Zaria, Kaduna State, Nigeria c School of Pharmaceutical Sciences, University of California, San Diego, United States d Department of Pharmacognosy and Drug Development, Faculty of Pharmaceutical Sciences, Ahmadu Bello University, Zaria, Kaduna State, Nigeria e College of Agriculture and Animal Science, Mando, Ahmadu Bello University, Kaduna State, Nigeria ARTICLE INFO Keywords Adjunct therapy Antitrypanosomal combination therapy Drug incubation infectivity test High PCV Synergism ABSTRACT Ethnopharmacological relevance: Pastoralists in Nigeria mix barks of Anogeissus leiocarpus (AL) Khaya senegalensis (KS) and potash (Pt) to treat animal African trypanosomosis. Aim: To evaluate antitrypanosomal potential of A. leiocarpus, K. senegalensis and potash for insights into the tradi- tional claim of antitrypanosomal combination therapy (ATCT). Materials and methods: Fifty microliter each of six different concentrations of AL, KS, Pt, AL + KS, AL + KS + Pt and diminazene aceturate (DA, positive control) was incubated with 50 μL of parasite-laden blood containing 10 8 Trypanosoma congolense cells in a 96-well microtitre plate. Negative control wells were devoid of the extracts and drug but supplemented with phosphate bufered saline. Effcacy of treatment was observed at 1 h interval for complete immobilisation or reduced motility of the parasites. Each incubated mixture was inoculated into mouse at the point of complete immobilisation of parasite motility or at the end of 6-h observation period for concentra- tions that did not immobilise the parasites completely. For in vivo assessment, thirty-fve parasitaemic rats were randomly allocated into seven groups of 5 rats each. Each rat in groups I–V was treated with 500 mg/kg of AL, KS, Pt, AL + KS and AL + KS + Pt, respectively, for 7 days. Rats in groups VI and VII were treated with dimi- nazene aceturate 3.5 mg/kg once and phosphate bufered saline 2 mL/kg (7 days), which served as positive and negative controls, respectively. Daily monitoring of parasitaemia through the tail vein, packed cell volume and malondialdehyde were used to assess effcacy of the treatments. Results: The AL + KS + Pt group significantly (p < 0.05) and dose-dependently reduced parasite motility and completely immobilized the parasites at 10, 5 and 2.5 μg/μL with an IC 50 of 0.91 mg/mL. All the mice with con- ditions that produced complete cessation of parasite motility did not develop parasitaemia within one month of observation. The AL + KS group significantly (p < 0.05) lowered the level of parasitaemia and MDA, and signif- icantly (p < 0.05) maintained higher PCV than PBS group. Conclusion: The combination of A. leiocarpus and K. senegalensis showed better antitrypanosomal effects than sin- gle drug treatment and offers prospects for ATCT. Our fndings support ethnopharmacological use of combined barks of A. leiocarpus and K. senegalensis by pastoralist in the treatment of animal African trypanosomosis in Nige- ria. 1. Introduction African trypanosomosis is a chronic debilitating disease of animals and man ravaging sub-Saharan Africa. Animal African trypanosomo- sis (AAT) is caused primarily by Trypanosoma congolense and T. vi- vax (Giordani et al., 2016); while human African trypanosomosis is caused by T. brucei gambianse and T. brucei rhodensiase. The dis- ease is a great threat to sustainable agricultural and economic pros- perity of sub-Saharan Africa (Okello et al., 2015). It renders vast ar- eas of arable land inhabitable and unsuitable for agriculture (Alsan, 2015). Over 12.3 million of human (Kato et al., 2016) and 50 mil lion heads of cattle are constantly exposed to the infection (Tchmdja et al., 2017). Trypanosomosis has been reclassifed by the World Organi- sation for Animal Health (OIE) as notifable disease because of its huge economic significance (Diall et al., 2017). Prevalence of AAT in an en- demic area is a good indicator of potential threat to human health liv- ing in that community and may necessitate urgent medical intervention (Grant et al., 2016). Treatment and control of trypanosomosis has been faced with high reported cases of treatment failure caused by resistance to the avail- able antitrypanosomal drugs and high toxicity associated with the drugs (Giordani et al., 2016). Even the recently repurposed oral antit- rypanosomal drug, fexinidazole for ∗ Corresponding author. E-mail address: mtauheed@abu.edu.ng (A.M. Tauheed) https://doi.org/10.1016/j.jep.2020.112805