A review of efficacy and safety of Ugandan anti-malarial plants with application of RITAM score

Jimmy R. Angupale, Jonans Tusiimire, Ndidi C. Ngwuluka

Malaria, a treatable disease mainly caused by Plasmodium falciparum has remained a health challenge in Africa, a continent that accounted for 96% of total global cases and deaths in 2021. Uganda, a malaria endemic country is experiencing malaria parasite resistance to some of the drugs used in the artemisinin-based combination therapy (ACT). In an effort to prioritize herbal medicines for new product development, this review synthesized the available safety and efficacy literature on the Ugandan anti-malarial plants to suggest most effective herbal plants. Literature was exhaustively searched using engines and databases, such as Google scholar, Pubmed, and Scopus-indexed journals during the period of June 2020-December 2021. In the first phase, information on ethnobotanical uses of anti-malarial plants in Uganda was gathered and synthetized to generate a list of plants, followed by data on anti-malarial efficacy (both in vitro and in vivo) on each listed plant. Minimum inhibitory concentrations (µg/ml), and % parasite suppression for every plant were scored using The Research Initiative on Traditional and Antimalarial Methods (RITAM) scoring system. The best twenty (20) plants were evaluated for acute safety (LD50) data in rat model, plant parts used, ease of cultivation, presence of clinical studies and other relevant factors for suggesting the best three (3) plants for future anti-malarial product development. Over one hundred twenty-six (126) plant species are used in Uganda for treatment of malaria in local communities. Out of these, about 33% (41) have been studied for efficacy and safety, with Artemisia annua and Vernonia amygdalina being the most extensively studied and among the best twenty (20) anti-malarial plants in Uganda. Both are limited by parasite recrudescence in clinical studies. Microglossa pyrifolia, a very potent plant (IC50 = 0.03 - 0.05 µg/ml has potential to penetrate the liver and could ameliorate the challenge of recrudescence if combined with A. annua and V. amygdalina in a polyherbal formulation. There are many plants with promising potential for malaria treatment in Uganda and a herbal combination of A. annua, V. amydalina and M. pyrifolia could offer the next herbal ACT if carefully studied and developed.