Antimycobacterial activity and low cytotoxicity of leaf extracts of some African Anacardiaceae tree species. Short Title: Antimycobacterial and cytotoxicity of Anacardiaceae tree species Prudence N. Kabongo-Kayoka 1,2 , Jacobus N. Eloff 2 , Chikwelu L. Obi 3 , Lyndy J. McGaw 2 1 Department of Agriculture and Animal Health, College of Agriculture and Environmental Sciences, University of South Africa, Private Bag X 6, Florida 1710, South Africa; kabonpnk@unisa.ac.za 2 Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa 3 Division of Academic Affairs, University of Fort Hare, Alice 5700, South Africa *Corresponding author. E-mail address: kabonpnk@unisa.ac.za (P.N. Kabongo-Kayoka) Treatment of tuberculosis is a challenge due to multi and extremely drug resistant strains of Mycobacterium tuberculosis. Plant species contain antimicrobial compounds that may lead to new anti-TB drugs. Previous screening of some tree species from the Anacardiaceae family revealed the presence of antimicrobial activity, justifying further investigations. Leaf extracts of 15 Anacardiaceae tree species were screened for antimycobacterial activity using a twofold serial microdilution assay against the pathogenic Mycobacterium bovis and multidrug resistant M. tuberculosis and rapidly growing mycobacteria, Mycobacterium smegmatis, Mycobacterium fortuitum and Mycobacterium aurum. The vaccine strain, M. bovis and an avirulent strain, H37Ra M. tuberculosis, were also used. Cytotoxicity was assessed using a colorimetric assay against Vero kidney, human hepatoma and murine macrophage cells. Four out of 15 crude