Hypolipidaemic and hepatoprotective effects of six Nigerian antidiabetic plants

The methanol extracts of the leaves of Hoslundia opposita (HOL), Cleistopholis patens (CPL), Dioscoreophyllum cumminsii (DCL), Olax subscorpioidea (OSL) and Plumbago zeylanica (PZL), as well as whole plant of Senecio biafrae (SBW) that have been earlier reported for their antidiabetic activities were evaluated in this study for their hypolipidaemic and hepatoprotective potentials with a view to establishing their possible ability to reduce the complications of diabetes mellitus. Effects of the methanol extracts of these plants on biochemical parameters, such as, total cholesterol, triglycerides, high-density lipoprotein-cholesterol, were estimated in alloxan-induced diabetic rats. Histopathological examinations of pancreases and livers of rats were carried out at 400 mg/kg for leaves of H. opposita, O. subscorpioidea, C. patens and S. biafrae whole plant, while D. cumminsii and P. zeylanica leaves at 200 mg/kg. Results obtained were expressed as mean ± SEM using GraphPad Prism 7 (GraphPad Software Inc., La Jolla, CA, USA). Analysis of Variance (ANOVA), followed by the Dunnett multiple comparison tests were used while p < 0.05 was taken as significant. All the six plants' extracts significantly reduced total cholesterol and triglycerides levels and increased the highdensity lipoprotein-cholesterol levels of the diabetic rats. Leaves of P. zeylanica and C. patens being the most active extracts, reduced cholesterol level from 2.3 to 1.0 and 0.8 mMol/L, respectively and reduced triglyceride from 0.6 to 0.9 mMol/L. The extracts also caused a pronounced reduction in vacuolation within the islet cells with the evidence of regeneration of the cells coupled with reduction in fibrosis, indicating possible reversal of pancreatic lesions in the pancreases of the alloxan-induced diabetic rats. The methanol extracts of these six Nigerian antidiabetic plants demonstrated hypolipidaemic and hepatoprotective effects in alloxan-induced diabetic rats and showed evidence of regeneration of the pancreatic cells.