Anti-plasmodial and antioxidant activities of methanol extract of the fresh leaf of <i>Lophira lanceolata</i> (Ochnaceae)

Abstract

This study was aimed at investigating the anti-plasmodial and antioxidant activities of the extract of the leaf of Lophira lanceolata, a traditional medicine recipe. The methanol extract (ME) obtained by 72 h cold maceration was evaluated for acute toxicity test (LD₅₀) and phytochemical constituents. The suppressive and curative anti-plasmodial activities of the extract were investigated using rodent malaria model. Mice (20 to 34 g) infected with 1 × 10⁷ Plasmodium berghei parasitized red blood cell were used to test for suppressive and curative anti-plasmodial activities after oral administration of ME (100, 200 and 400 mg/kg) for four and seven days, respectively. The preliminary antioxidant activity of the extract (25, 50, 100, 200 and 400 μg/ml) was evaluated using in vitro 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, hydrogen peroxide scavenging and reducing (power) ability assays. The methanol leaf extract of L. lanceolata exhibited a dose-dependent suppression of parasitaemia up to 100% suppression at 400 mg/kg. The suppression produced by the extract was significantly (P< 0.05) higher than the chemo suppression produced by 20 mg/kg chloroquine (50.90%). Similarly, the extract at the same doses (100, 200 and 400 mg/kg) exhibited significant (P<0.05) but non-dose-related decreases in parasitaemia in the curative model (60.90, 54.69 and 79.69%) which was comparable to the 82.80% decrease caused by chloroquine (20 mg/kg). Phytochemical studies revealed the presence of flavonoids, alkaloids, oils, saponins, glycosides, carbohydrates, acidic compounds, terpenoids and reducing sugar. The LD₅₀   test caused no deaths in the treated mice up to 5,000 mg/kg body weight. The DPPH assay, for free radical scavenging effect of the methanol extract was significant (P<0.001) as the concentration increases. Hydrogen peroxide scavenging and reducing power assays showed concentration-dependent and significant (P<0.05) results. These findings suggest that methanolic extract of the leaf of L. lanceolata is safe up to a dose of 5,000 mg/kg body weight and possesses anti-plasmodial and anti-oxidant activities.

Keywords: Lophira lanceolata, anti-plasmodial, anti-oxidant, plasmodium berghei, DPPH, hydrogen peroxide, albino mice

African Journal of Biotechnology, Vol 13(16), 1731-1738