Traditional herbal antimalarial therapy in Kilifi district, Kenya

Area of Science:

• Ethnobotany and Phytochemistry
• Pharmacology and Toxicology
• Infectious Diseases Research

Background:

• Malaria remains a significant global health challenge, necessitating the discovery of novel antimalarial agents.
• Traditional health practitioners (THPs) utilize diverse plant species for malaria treatment, offering a rich source for drug discovery.
• Understanding the efficacy and safety of these traditional remedies is crucial for potential pharmaceutical development.

Purpose of the Study:

• To identify and evaluate the antiplasmodial activity of plant species used by THPs in malaria treatment.
• To assess the cytotoxicity and in vivo efficacy of selected plant extracts.
• To investigate the synergistic or antagonistic effects of combining different plant extracts.

Main Methods:

• Plant species were identified through interviews with traditional healers.
• In vitro antiplasmodial activity was assessed using radio-labelled hypoxanthine incorporation assays.
• In vivo efficacy was determined using Peter's 4-day suppressive test in mice, and cytotoxicity was evaluated using Vero E6 cells.

Main Results:

• Several plant extracts exhibited significant in vitro antiplasmodial activity, with Azadirachta indica, Premna chrysoclada, and Uvaria acuminata showing high potency (IC50 < 10 μg/ml).
• In vivo studies demonstrated high parasite clearance and chemo-suppression for Azadirachta indica (89%), Rhus natalensis (82%), and Grewia plagiophylla (78%).
• Synergistic antiplasmodial effects were observed in some combinations, notably between Uvaria acuminata and Premna chrysoclada, while others showed antagonism. Most plants displayed favorable selectivity indices, indicating low cytotoxicity, with Uvaria acuminata, Hoslundia opposita, and Lannea schweinfurthii showing some toxicity.

Conclusions:

• The study identified several plant species with significant antiplasmodial activity, low cytotoxicity, and potential for developing novel antimalarial drugs.
• The demonstrated synergy in certain plant combinations provides scientific validation for the traditional practice of using combined medicinal plants for malaria treatment.