Plant Derived Antimalarial Agents: New Leads and Challenges

Abstract

New treatments for malaria are urgently needed due to the increasing problem of drug-resistance in malaria parasites. The long-established use of quinine and the more recent introduction of artemisinin and its derivatives as highly effective antimalarials demonstrates that plant species are an important resource for the discovery of new antimalarial agents. Furthermore, many plant species continue to be used in traditional medicines for the treatment of malaria and many people depend on such remedies as they cannot afford and/or do not have access to effective antimalarial drugs. In this paper the potential of plant species to yield new leads to antimalarial drugs will be illustrated with reference to cryptolepine, the main alkaloid present in the species, Cryptolepis sanguinolenta. In addition to this approach, there is currently increasing interest in the use and development of traditional herbal remedies for the treatment of malaria as these may have the potential to provide affordable antimalarial treatment for many who cannot afford the drugs needed to treat chloroquine-resistant Plasmodium falciparum infections. However, little is known with respect to the efficacy and safety of traditional antimalarials and clinical studies are urgently needed to establish their value. Some of the issues pertinent to this area will be briefly reviewed and it is hoped that this will stimulate further discussion and research on this important topic.

Antimalarial Flavonol Glycosides fromEuphorbia hirta.

“…Mortality exceeds 1-3 million people per year, most of them being children in Africa under the age of 4 years, a number that is continuously increasing due to the rapid spread of drug-resistant Plasmodium parasites (Greenwood & Mutabingwa, 2002;Schwikkard & van Heeden, 2002;Wright, 2005). After an antimalarial screening of Congolese medicinal plants, we have observed that the MeOH extract of Euphorbia hirta Linn (Euphorbiaceae) (OliverBever, 1986;Iwu, 1993) demonstrated not only potent in vitro antimalarial activity against P. falciparum but also little cytotoxic property against human epidermoid carcinoma KB 3-1 cells.…”

Antiplasmodial Activity of Aryltetralone Lignans from Holostylis reniformis

“…Many natural products of various structural types have shown antiparasitic potency in the laboratory, and they represent interesting lead structures for the development of new drugs (12). The molecular diversity and efficacy of antiparasitic plants, extracts, and herbal preparations have been intensively discussed in recent reviews (22,26,27).…”

Schistosomicidal and molluscicidal activities of aminoalkylamino substituted neo- and norneocryptolepine derivatives

“…This is isolated from the roots of the climbing shrub Cryptolepis sanguinolenta (Lindi) Schitr (Alajarin et al, 1997) that is used in Central and West Africa in traditional medicine for the treatment of malaria (Wright, 2005).…”