BIOCHEMICAL AND PHARMACOLOGICAL PROPERTIES OF METHANOLIC LEAF EXTRACT OF SPONDIAS MOMBIN LINN

Abstract

Spondias mombin is used traditionally in Nigeria for the management of malaria, diarrhoea and microbial infections but there is insufficient data from pharmacological investigations on its properties. The effects of the Methanolic Extract of Spondias mombin (MES) leaves on isehemia-induced cardiac and cerebral damages in rats were investigated. The antioxidative and antiproliferative properties of MES and its fractions were also investigated. The MES was prepared by macerating Spondias mombin leaves in methanol and concentrating the filtrate obtained and then phytochemically screened according to standard procedure. Total phenolic content (TPC), total flavonoid content (TFC), radical scavenging activities, lipid peroxidation inhibitory activity (LPIA) and reductive potential (RP) were determined spectrophotometrically. Effect of MES on cardiac contractility was evaluated ex vivo in rat heart subjected to ischemia using a GRASS polygraph and compared with that of a standard, ramipril. In a separate in vivo study, rats were treated with carboxymethyl cellulose (vehicle) or 85mg/kg isoproterenol (ISP) with or without MES (100 and 250 mg/kg). Thirty days after treatment, sera, plasma and tissue homogenates were prepared. Levels of malondialdehyde (MDA), glutathione (GHS), cholesterol, phosphate and nitrite as well the activities of superoxide dismutase (SOD), catalase and lactate dehydrogenase (LDH) were evaluated spectrophotochemically. In a neuropharmacological study, rats were subjected to Middle cerebral Artery Occlusion (MCAO) and treated with vehicle MES. Neurological deficit (ND) was estimated from observation of flexion, circling, hemiparesis and non-spontaneous movement. Infaret size, MDA and GSH levels were also evaluated. Protein expressions of gp91ᵖʰᵒˣ and p22ᵖʰᵒˣ (subunits of nicotinamide adenine dinucleotide phosphate oxidase), eNOS and nNOS (isoforms of nitric oxide synthase) and SOD were evaluated by western blotting. The MES was fractioned into water, n-butanol, ethyl acetate, dichloromethane and hexane. Antioxidant and antiproliferative assays were carried out by spectroscopy on the fractions. Data were analysed using ANOVA and Student’s t-test at P>0.05. Phytochemical screening confirmed the presence of tannins, terpenoids and flavonoids. The TPC and TFC were 32.0 ± 11.4 mg/l gallic acid equivalent and 228.0 ± 3.5 pg/ml quereetin equivalent respectively. Radical scavenging activities ranged from 43.0 ± 0.9% to 88.6 ± 3.0% while LPIA and RP were 54.0 ± 1.3% and 0.6 ± 0.0 respectively. The MES stimulated significant cardiac contractile activities similar to that of ramipril. The MES also reduced ISP-induced elevation of LDH activity and MDA, phosphate, cholesterol and nitrite levels and reversed the decreased GSH level and SOD and catalase activities in the ISP-challenged group. It reduced ND and infarct size by 43.0% and 75.0% respectively and significantly ameliorated MCAO-induced elevation of MDA and decrease in GSH levels. It suppressed the expressions of gp91ᵖʰᵒˣ and nNOS but enhanced those of p22ᵖʰᵒˣ, eNOS and SOD. The ethyl acetate and n-butanol fractions showed the highest antioxidant activity while the dichloromethane fraction had the highest antiproliferative activity. Quercetin-3-0-β-D-glucopyranoside and undec-1-ene were characterized from the ethyl acetate and n-butanol fractions. Methanolic extract of Spondias mombin leaves exhibited remarkable antioxidant property that could protect rats from isoproterenol-induced cardiotoxicity, ischemia-induced cardiac and cerebral damages.