Kangethe, Lucy NOmar, SabahNganga, Joseph KKimani, FrancisKinyua, JohnsonHassanali, Ahmed2021-02-262021-02-262016Research and Reviews of Infectious Diseases. Vol 1 Iss. No 12643-6051 |https://scholars.direct/Articles/infectious-diseases/rrid-1-001.php?jid=infectious-diseaseshttp://ir-library.ku.ac.ke/handle/123456789/21652A research article published in Research and Reviews of Infectious DiseasesBackground:Although tea infusions of Artemisia annua L. and Artemisia apiacea have been used > 2000 years in traditional Chinese medicine, there was no apparent resistance development to malaria parasites. Artemisinin was isolated and characterized in 1972 as the major potent antimalarial component of A. annua. This and a number of its derivatives have been promoted in combination therapy (ACTs) with other antimalarials with different mechanisms of action. However, recent reports on artemisinin resistance have posed a major health security risk globally. The aim of the present study was to compare the effects of cyclic exposures of the malaria parasite Plasmodium falciparum to a phytochemical blend of Artemisia annua (extracted with solvents of different polarity) with those of pure artemisinin to see if the natural blend has a built-in resistance-mitigating effect on artemisinin against the parasite. Materials and methods: Upper foliage of Artemisia annua was extracted with solvents of increasing polarity, including hexane, dichloromethane, methanol, and water. The organic solvents were removed on a rotary evaporator and water by freeze-drying. In vitro cyclic exposure experiments to equivalents of IC50 and IC90 of (i) A. annua phytochemical blend and (ii) pure artemisinin were conducted on CQ-resistant strain cultures of P. falciparum W2 from Indochina. Dose-response effects of the parasites were determined after 10, 20, 30 and 40 cycles of exposures and relative shifts in the sensitivities of parasites (IC50 new/IC50 initial, or IC90 new/IC90 initial) expressed as relative sensitivity indices (RSI) were calculated. Results: There were incremental increases in the IC50 or IC90 values with increasing cycles of exposures of W2 parasites to IC50 or IC90 equivalents of artemisinin. No comparable increases were observed with the parasites exposed to IC50 and IC90 equivalents of A. annua blend. On the other hand, parasites repeatedly exposed to the A. annua blend showed decreasing susceptibility to pure artemisinin. Conclusion: The results show that ethnopharmacological mode of use of the phytochemical blend of A. annua is less likely to lead to resistance development to malaria parasites compared with pure artemisinin. This is partially consistent with a recent finding on a rodent malaria model done by Elfawal, which demonstrated that the whole A. annua plant (WP) overcomes existing resistance of Plasmodium yoelii to pure artemisinin. However, further studies are needed to elucidate the nature of observed resistance to artemisinin in the parasites that were repeatedly exposed to A. annua phytochemical blend.enArtemisia annuaPhytochemical blendArtemisininPlasmodium falciparumMalariaCyclic exposuresResistance mitigationArticle