Ruth Anyango Omole1,2*, Mainen Julius Moshi1, Muhammad Ilias3, Walker Larry3, Hamisi M. Malebo4, Leonida Kerubo Omosa5, Jacob O. Midiwo5
1Institute of Traditional Medicine, Muhimbili University of Health and Allied Sciences, P.O. Box 65001, Dar es Salaam, TANZANIA.
2Department of Chemical Science and Technology, Technical University of Kenya, P.O. Box 52428- 00200, Nairobi, KENYA.
3Research Institute of Pharmaceutical Sciences, University of Mississippi, P.O Box 1848-38677 USA.
4Department of Traditional Medicine Research, National Institute for Medical Research, P.O. Box 9653, Dar es Salaam, TANZANIA.
5Department of Chemistry, University of Nairobi, P.O. Box 30197, Chiromo Road, Nairobi, KENYA.
Published: January 2020
Type: Original Article
Introduction: Reports of emergence of Artemisinin Combination Therapies (ACTs) resistant malaria parasites in Greater Mekong region and Equatorial Guinea, is a strong reason necessitating increased efforts to discover new antimalarial compounds with novel mechanisms of action. Plants have potential to yield new antiplasmodial compounds. This study investigated the safety and efficacy of three plants; Bersama abyssinica Fresen, Rubus keniensis Standl and Hypoestes verticillaris (L.f.) Sol. ex Roem. and Schult that are used by the Ogiek community of Kenya for treatment of malaria. Methodology: The crude extracts were tested for in vitro antimalarial activity using Plasmodium falciparum strains W2 (chloroquine resistant) and D6 (chloroquine sensitive). Safety evaluation was done using monkey kidney Vero cells and the brine shrimp lethality test. Results: Dichloromethane: methanol (1:1) and 5% aqueous methanol extracts of the three plants exhibited in vitro antiplasmodial activity against the W2 and D6 Plasmodium falciparum strains with IC50= 12.11–19.18 μg/mL, 5.46-7.04 μg/mL and 9.82 – 34.52 μg/mL, respectively. H. verticillaris extracts were the most active against the two Plasmodium falciparum strains. The dichloromethane: methanol extracts of the three plants exhibited lower toxicity on monkey kidney Vero cells relative to antiplasmodial activity as compared to the 5% aqueous methanol extracts. The mean Vero cells: parasite selectivity index of the dichloromethane: methanol extracts was (4.8), B. abyssinica (3.75) and R. keniensis (1.9), while for the 5% aqueous methanol extracts they were H. verticillaris (1.0), B. abyssinica (1.95) and R. keniensis (1.75). A similar toxicity profile was exhibited by brine shrimp lethality results. Conclusion: The results support the use of the three plants for the treatment of malaria. Therefore, they have potential to yield safe and effective compounds targeting P. falciparum malaria.
Key words: Antiplasmodial activity, Cytotoxic activity, Bersama abyssinica, Rubus keniensis, Hypoestes verticillaris.