Asres, Kaleab (PhD)Bisrat, Daniel(PhD)Endale, Abyot2018-06-202023-11-292018-06-202023-11-292012-08http://etd.aau.edu.et/handle/123456789/1949Medicinal plants play an important role in the treatment of malaria especially in developing countries where resources are limited. A continued search for other effective, safe and cheap plant-based antimalarial agents thus becomes imperative in the face of these difficulties. The leaves of Otostegia integrifolia Benth. are used traditionally as malarial remedy in Northern Ethiopia. This study was aimed to investigate the antimalarial potentials of the crude leaf extract, solvent fractions as well as isolated compound(s) in vivo in Plasmodium berghei infected mice to give scientific proof to the ethnobotanical claims. Leaves of O. integrifolia were collected and dried under the shade. The dried plant material was pulverized and extracted with 80% methanol. The dried crude extract was then further fractionated with different solvents. Both the crude extract and fractions were evaluated for their antimalarial activity in vivo, in 4-day suppressive assays against P. berghei in mice. Column chromatography was used to isolate compound/s from the most active fraction. The isolated compound was evaluated for its antimalarial activity in vivo, in 4-day suppressive assay against P. berghei and its structure elucidated using spectroscopic methods (MS and NMR). Preliminary phytochemical screening was performed using standard procedure. Acute and sub-acute toxicity studies of the crude extract were carried out in Swiss albino mice prior to antimalarial activity tests. No sign of toxicity was observed up on administration of the 80% methanol extract of the plant up to the highest dose (5000 mg/kg) given. Preliminary phytochemical screening showed the presence of saponins, flavonoids and other phenolic compounds in the hydroalcoholic leaf extract. The hydroalcoholic leaf extract (200, 400 and 600 mg/kg/day) and solvent fractions (200, 400 and 600 mg/kg/day) exhibited significant (P<0.01) antimalarial activity compared to the negative control group in four day suppression test with a considerable mean survival time. The highest parasite suppression (80.52%) was observed at 600 mg/kg /day for the crude extract, while the ethyl acetate fraction was found to be the most active among the solvent fractions and showed highest suppression (60.15%) at 600 mg/kg/day. The isolated compound also showed significant antimalarial (P<0.001) activity at the tested doses (25, 50 and 100 mg/kg/day) with chemosuppression of 50.13, 65.58, and 73.16%, respectively. Structural elucidation revealed that the isolated compound is a labdane type diterpenoid, 15,16-epoxy-3α,9α-dihydroxy-labda-13(16),14-diene. The crude extract, solvent fractions and the isolated compound possess considerable antiplasmodial activities which justify the use in ethnomedicine and can be exploited in the control of malaria.enAntimalarial; Otostegia Integrifolia BenthThesis