Antimalarial activity of medicinal plants from the Democratic Republic of Congo: A review

Abstract

Ethnopharmacological relevance: Malaria is the most prevalent parasitic disease and the foremost cause of morbidity and mortality in the Democratic Republic of Congo. For the management of this disease, a large Congolese population recourses to traditional medicinal plants. To date the efficacy and safety of many of these plants have been validated scientifically in rodent malaria models. In order to generate scientific evidence of traditional remedies used in the Democratic Republic of Congo for the management of malaria, and show the potential of Congolese plants as a major source of antimalarial drugs, this review highlights the antiplasmodial and toxicological properties of the Congolese antimalarial plants investigated during the period of 1999-2014. In doing so, a useful resource for further complementary investigations is presented. Furthermore, this review may pave the way for the research and development of several available and affordable antimalarial phytomedicines.

Materials and methods: In order to get information on the different studies, a Google Scholar and PubMed literature search was performed using keywords (malaria, Congolese, medicinal plants, antiplasmodial/antimalarial activity, and toxicity). Data from non-indexed journals, Master and Doctoral dissertations were also collected.

Results: Approximately 120 extracts and fractions obtained from Congolese medicinal plants showed pronounced or good antiplasmodial activity. A number of compounds with interesting antiplasmodial properties were also isolated and identified. Some of these compounds constituted new scaffolds for the synthesis of promising antimalarial drugs. Interestingly, most of these extracts and compounds possessed high selective activity against Plasmodium parasites compared to mammalian cells. The efficacy and safety of several plant-derived products was confirmed in mice, and a good correlation was observed between in vitro and in vivo antimalarial activity. The formulation of several plant-derived products also led to some clinical trials and license of three plant-derived drugs (Manalaria(®), Nsansiphos(®), and Quinine Pharmakina(®)).

Conclusion: The obtained results partly justify and support the use of various medicinal plants to treat malaria in folk medicine in the Democratic Republic of Congo. Antimalarial plants used in Congolese traditional medicine represent an important source for the discovery and development of new antimalarial agents. However, in order to ensure the integration of a larger number of plant-derived products in the Congolese healthcare system, some parameters and trends should be considered in further researches, in agreement with the objectives of the "Traditional Medicine Strategy" proposed by the World Health Organization in 2013. These include evaluation of geographical and seasonal variation, investigation of reproductive biology, assessment of prophylactic antimalarial activity, evaluation of natural products as adjuvant antioxidant therapy for malaria, development of plant-based combination therapies and monitoring of herbal medicines in pharmacovigilance systems.

Keywords: Antimalarial activity; Antimalarial plants; DR Congo; Malaria; Toxicity; Traditional medicine.