Scientific Baseline Information for the Potential Use of Hibiscus surattensis L against Malaria: Phytochemistry and Biological Studies

Abstract

Background and aim: Hibiscus surattensis L. is a medicinal plant widely used traditionally in Benin to treat malaria. This study was designed to investigate antiplasmodial activity, hemolytic power, acute toxicity, antioxidant activity and phytochemical content of H. surattensis. Methodology: Bioassay-guided isolation approach was adopted and extracts and fractions collected were continuously tested in vitro against Chloroquine-sensitive and field isolate strains of Plasmodium falciparum by immune-dosage of Plasmodium lactate dehydrogenase. Hemolytic effect and acute toxicity of extracts were evaluated respectively on human erythrocytes and according to OECD guideline N°423. 2, 2-diphenyl-1- picrylhydrazyl) radical scavenging, Ferric reducing antioxidant power, superoxyde radical scavenging and hydrogen peroxide radical scavenging methods were used to investigate antioxidant activity. Results and conclusion:  The best antiplasmodial activity was obtained with ethanolic extract of H. surattensis L. against field isolate (IC50 = 5.03±0.31 µg/mL) and Chloroquine -sensitive (IC50 = 7.55±0.59 µg/mL) whereas aqueous extract exhibited moderate activity. Bioassay-guided fractionation of ethanolic extract shows progressive decrease of the antiplasmodial activity. Both extracts exhibited strong antioxidant activity, hemolytic power less than 1%. No mortality of rats was recorded with ethanolic extract at 2000 mg/kg body weight. Flavonoids, anthraquinones, coumarins, and triterpenes are present in both extracts with tannins in the ethanolic extract. In summary, the extracts of H. surattensis have interesting antiplasmodial and antioxidant properties probably resulting from a synergetic action of their secondary metabolites, without toxicity effect on rats and human erythrocytes. These findings strengthen the traditional use of H. surattensis as antimalarial plants. Keywords: Hibiscus surattensis; antiplasmodial; antioxidant; toxicity; phytoconstituents.