In vitro antimalarial activity evaluation of two ethnomedicinal plants against chloroquine sensitive and resistant strains of Plasmodium falciparum

In this study, we selected two medicinal plants Citrus maxima (Burm.) Merr. and Artemisia nilagirica (C.B. Clarke) Pamp. on the basis of their traditional use in the treatment of fever associated with malaria in Assam (India) and evaluated their antimalarial potential against Plasmodium falciparum strains. The properly processed plant parts of C. maxima (Burm.) Merr. and A. nilagirica (C.B. Clarke) Pamp. were extracted with different solvents from nonpolar to polar by cold maceration technique. After that antimalarial activities of the extracts were evaluated against both chloroquine sensitive (3D7) and resistant (RKL-9) strains of P. falciparum using Giemsa staining light microscopy technique. The most active extract(s) was further screened for cytotoxicity potential against murine macrophage RAW264.7 cell line using MTT assay. Then preliminary phytochemical screening and qualitative fingerprint analysis of the active extract(s) were done to check the presence of different secondary metabolites. From the in vitro study, the hydro-alcoholic extract of C. maxima (Burm.) Merr. and methanol extract of A. nilagirica (C.B. Clarke) Pamp. were found to be the most active against both 3D7 and RKL-9 strains. In the cytotoxicity study, the CC50 values of the active extracts were found to be > 100 μg/ml, which suggested the safety of the extracts. Then phytochemical and fingerprint analysis revealed the presence of various important plant secondary metabolites in both the extracts. The findings of this study confirmed the presence of antimalarial potential of hydro-alcoholic extract of C. maxima (Burm.) Merr. and methanol extract of A. nilagirica (C.B. Clarke) Pamp without having any toxic effect. Both the extracts showed IC50 values below 5 μg/ml against 3D7 and RKL-9 strains.