Isolation of a pentacyclic triterpenoid from the antiplasmodial bioactive fraction of Nauclea latifolia (Sm) roots

Abstract

Purpose: To research the antiplasmodial property of aqueous extract, fractions, and residue of Nauclea latifolia roots and to isolate the components responsible for the antiplasmodial activity.Methods: Roots of N. latifolia were macerated with distilled water; the extract was obtained, successively partitioned with ethyl acetate and butanol. The extract, fractions, and the residue obtained were evaluated for their in vivo antiplasmodial activity and compared with amodiaquine and artesunate. The residue (which exhibited the best therapeutic index) was subjected to column and thin layer chromatography to isolate its components. Purification led to the isolation of betulinic acid, which was characterized with the aid of spectroscopic techniques (1H, 13C NMR, and EI-MS).Results: The residue significantly inhibited parasite growth from 42.8 % (D2) to 77.6 % (D5). Therefore, residue exhibited the highest therapeutic index against Plasmodium berghei in the three in vivo antiplasmodial (prophylactic, suppressive, and curative) models and it compared favourably with amodiaquine (80.5 %) and artesunate (85.9 %). The major component of the residue was betulinic acid.Conclusion: The results validate the antiplasmodial claims of the roots of N. latifolia in folkloric medicine, and demonstrated that the isolate has a high therapeutic index in this regard. Further investigations, however, are required to determine the clinical efficacy and safety of the compound/isolate.