Isolation and identification of carotenoid producing yeast and evaluation of antimalarial activity of the extracted carotenoid(s) against P. falciparum

Abstract Background: Malaria is a big threat and one of the major diseases and important cause of human illness and death in developing countries, in which majority of deaths were found to be due to Plasmodium falciparum malaria. It is becoming a serious challenge to fight against malaria because of the emergence of Plasmodium falciparum strains resistant to all anti-malarial drugs. As microbial carotenoids are well-known anti-oxidants, performing critical functions in plants and animals, in this study, the extracted microbial carotenoids were tested for their anti-malarial activity. Methods: To determine the anti-malarial activity of microbial carotenoids, five isolated yeast strains were identified, and characterized for their carotenoid production. The evaluation of anti-malarial activity of extracted carotenoids was tested on Plasmodium falciparum strain 3D7 using in vitro growth inhibition assay. Data was analyzed by FACS (Fluorescence activated cell sorter) and counted via gold standard Geimsa-stained smears. Extracted yeast carotenoids showed a profound inhibitory effect at a certain concentration when compared to β- carotenoid as control. Results: Yeast carotenoids showed a profound inhibitory effect at a concentration of 10-3 µg/µl and 10-4µg/µl when compared to β- carotenoid as control. SYBR Green1 fluorescent dye was used to confirm the decrease in parasitemia at given range of concentration. Egress assay results suggested that treated parasite remained stalled at schizont stage with constricted morphology and were darkly stained. Non-toxicity of carotenoids on erythrocytes and on human liver hepatocellular carcinoma cells (HepG2 cells) was shown at a given concentration. Conclusions: Anti-oxidant and anti-carcinogenic activity of carotenoids is well established, so we embarked upon predicting anti-parasitic effects of yeast carotenoids to fight the dreaded disease, malaria. Results suggest that the extracted yeast carotenoids was able to kill the parasite by 98.3% and it was non-toxic to RBCs and HepG2 cells. This is the first report which provides strong evidence for anti-malarial effects of extracted yeast-carotenoids, which can be produced via a sustainable and cost-effective strategy and may be scaled up for industrial application. Keywords: Carotenoids, yeast, Rhodotorula, β carotene, Plasmodium falciparum, malaria