Anti-plasmodial activity and phytochemical analysis of leaf extract of Chenopodium Opulifolium Schrad. EX W.D.J. Koch and Ziz used in Uganda

Abstract

Malaria is a life-threatening disease caused by Plasmodium species. It had one of the highest motality and morbidity rates globally. with 229 million cases and 409,000 malaria death in 2019. In Uganda. Malaria has an incidence rate of 26% and it kills 34 people per day. Malaria control has been more effective with antimalarial drugs commonly developed from natural products but are toxic and plasmodium species has evolved, developed resistance where control will greatly require new alternative effective, tolerable, and affordable antimalarial medicines. In this study, Chenopodium opulifolium was investigated for its antiplasmodial activity, phytochemical and antiplasmodial compounds present in its leaves. The plant was selected based on its widespread use in traditional herbal medicine. The plant leaves were collected from Mbirizi, Masaka District, Uganda in June 2019. Extraction was done seqentially with n-hexane, DCM, EtOAc, MeOH and water by means of maceration. The antiplasmodial activity of each extract and compound was tested against P. falciparum 3D7 strain and clinical field isolates KOM_234 and KDH_204 using a fluorescence based SYBR Green 1 assay technique. Separation and purification of the compounds in the most active methanol and DCM extracts was done using column and thin layer chromatography. The compounds were identified by one dimensional and two dimensional (1D and 2D) 1H and 13C NMR, FTIR, Mpt and GC-MS techniques. The antiplasmodial activity test against P. falciparum 3D7 strain, it showed that DCM extract obtained the highest activity with IC50 value of 0.1177 µg/mL followed by methanol extract (1.189 µg/mL), hexane extract (4.850 µg/mL), EtOAc extract (4.856 µg/mL) and aqueous extract (10.24 µg/mL). Methanol extract also demonstrated a promising antiplasmodial activity against P. falciparum clinical field isolate KOM_234 and KDH_204 with IC50 of 5.30 µg/mL ±1.10 and 5.06 µg/mL ±2.23 respectively. Isolation and purification resulted in the identification of two known compounds which are allantoin and decan-2-one. In addition, 19 compounds were identified in the volatile components of the plant using GC-MS analysis which were reported to have numerous bioactivities. Allantoin demonstrated a high antiplasmodial activity against the clinical field isolate KOM_234 with IC50 of 2.29 µg/mL ± 0.98 and a promising activity against clinical field isolate (KDH_204) with IC50 of 10.94 µg/mL ± 1.51. The findings show that the crude extracts, isolated pure and characterised compounds of C. opulifolium leaves have got antiplasmodial activity. This justifies the use of this plant in traditional medicine and indicates a promising potential for the development of medicinal agents.