ABSTRACT
Euphorbia hirta has been variously used to manage different illness in Nigeria ethnomedicine. The study was carried out to determine phytochemical compositions, antioxidant, and in vivo antimalarial properties of Euphorbia hirta whole plant.
The pulverised plant (2.5 kg) was extracted with methanol and concentrated in-vacuo at 40ºC. The total extract was fractionated using different solvents of varying polarity: Hexane, Hexane/EtOAc (in ratio 1:1), EtOAc, MeOH, and MeOH/H2O (in ratio 1:1). Fractions obtained were concentrated to dryness in vacuo at 40ºC. Phytochemical, proximate and elemental analyses of the pulverised plant were done with standard procedures. Toxicity profile of the plant’s total extract was carried out using Lorke’s method. Antioxidant studies (DPPH and FRAP assays) of the extract and fractions of Euphorbia hirta were done using established methods. Total extract and fractions of Euphorbia hirta were also determined for in-vivo antimalarial effect against P. berghei (NK-65) in mice through suppressive and curative assay methods. N-hexane fraction of the plant was subjected to Silica-gel column chromatography. Column fractions were submitted to GC-MS and FTIR analyses for the identification of the compounds present.
The phytochemical tests revealed that alkaloid, carbohydrate, tannins, flavonoids, terpenoids, saponins, reducing sugars, phenolic compounds and protein are present in the plant. Proximate analysis tests revealed that the plant has a moisture content value of 7.83 ± 0.23%, total ash of 11.18 ± 0.41%, acid-insoluble ash value of 3.67± 0.37%, water-soluble ash value of 4.95± 0.27%. Essential minerals and elements present in the sample include Sodium (7.40 ± 0.60 ppm), Magnesium (55.45 ± 2.41 ppm) and Calcium (191.02 ± 0.58 ppm). Total phenolic content and flavonoid content of total extract and fractions ranged from 78.14 ± 2.26 to 150.12 ± 3.47 mgGAE/g extract and 66.69 ± 2.46 to 119.48 ± 3.61 mg QE/g extract, respectively. The Antioxidant capability of total extract and fractions of the plant determined by FRAP assay ranged from 11.22 ± 0.51 to 81.12 ± 0.10 µM FSE/g extract. And the ethyl acetate fraction exhibited very strong scavenging effects in DPPH free radical assay with IC50 value of 5.63 µg/mL. Acute toxicity test of the whole plant of E. hirta showed no mortality at oral dose as high as 5000 mg/kg per b.w. in Swiss-albino mice. In in-vivo antimalarial study, total extract and fractions exhibited antimalarial activity against the infected mice with the ethyl acetate fraction (800 mg/kg b.w.) showing the highest percentage chemo-suppression and curative effects. The GC/MS results of N-hexane and ethylacetate fractions indicated presence of a number of compounds including alkanes, fatty acids, esters, etc. This study has shown that Euphorbia hirta whole plant has significant antioxidant properties and anti-malarial activity which may be attributed to the phytochemicals present.
