In Search of a Potent Antimalarial Agent: Antiplasmodial Assessment of Three Herbs with Folkloric Antimalarial Claims

Abstract

Malaria has remained a major cause of morbidity and mortality in the under developed and developing countries of the tropical and sub-tropical regions of the world. In spite of the substantial progress made in the treatment of parasitic diseases, malaria remains a significant therapeutic challenge especially because of the wide spread resistance of malaria parasites to currently available anti-malarial agents, the resistance of the mosquito vectors to currently available insecticides, the limited success in the development of malarial vaccines and the debilitating adverse reactions of conventional anti-malarial drugs. The wide spread resistance of malaria parasites to conventional anti-malarials have stimulated the search for new drug entities with new modes of action. The efficacy of Agelanthus dodoneifolius (A.D), Parkiabiglobosa (P.B) and Vernonia ambigua (V.A) for the treatment of malaria have been widely acclaimed by the Hausa, Ibo and Yoruba communities of the Northern, Eastern and Western Nigeria respectively. The aim of this study is to authenticate this claim as a step in the search for a new anti-malarial. The oral median lethal dose (LD50), phytochemical components and antioxidant activity of the three aqueous extracts were determined. The extracts were also evaluated for in vivo and in vitro antiplasmodial activities against Plasmodium berghei and clinical isolates of Plasmodium falciparum respectively. A. dodoneifolius showed maximum inhibition (78.7±1.6, 80.1±1.0 and 69.8±1.2%) of parasitaemia and moderate anti-plasmodial activity in vitro (21.54μg/ml > IC50 > 50μg/ml) among three plant extracts. The phytochemical analysis revealed the presence of tannins, saponins, steroids, phenols, terpenes and anthraquinones. It also showed a strong free radical scavenging activity on 2,2diphenyl2picrylhydrazyl. The aqueous extract of A. dodoneifolius contains biologically active principles that are relevant in the treatment of malaria, thus supporting further studies of these components.