Antileishmanial Activity of Kenyan Medicinal Plants

Abstract

The EtOH extracts of two hundred thirteen medicinal plants, collected in various parts of Kenya, were tested for in vitro antileishmanial activity using Leishmania donovanii promastigotes. Thirty five plant extracts (i.e., ˜16% of total plants) showed antileishmanial activity with IC50 value of=60 µg/mL, suggesting as potential active extracts for further investigations. In addition, eight of these plants (i.e., 3% of total plants) further displayed strong leishmanicidal activity with IC50 value of=10µg/mL, especially the extracts of Albizia gummifera, Albizia schimperiana, Abrus schimperi, Warbugia stuhlmanii, Sphaeranthus bullatus, Suregada procera, Triclisia sacleuxii and Pittosporum viridiflorum. A bioassay guided fractionation yielded four macrocyclic spermine alkaloids from A schimperiana (i.e., 5,14-dimethylbudmunchiamine L1 (1), 6-hydroxybudmunchiamine K (2), 5-normethylbudmunchiamine K (3) and 6-hydroxy-5-normethylbudmunchiamine K (4) with IC50's 1.2, 3.4, 0.8 and 2.1 µg/mL, respectively), four abietane diterpenoids from Clerodendrum eriophyllum (i.e., taxodione (5), ferruginol (6), 6-hydroxysalvinolone (7) and uncinatone (8) with IC50's 0.08, 4, 3.2 and 0.2µg/mL, respectively) and two flavanquinones from A. schimperi (i.e., amorphaquinone (9) and pendulone (10) with IC50's 0.63 and 0.43µg/mL, respectively) as active antileishmanial constituents.