Hypoglycaemic and Antioxidant Effects of Dichloromethane: Methanolic Leaf and Stem Bark Extracts of Pappea Capensis from Embu County, Kenya
Ngai, David Nyaga
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Diabetes mellitus is a group of metabolic disorders that result in hyperglycaemia due to reduced insulin production or poor utilisation of insulin in the body. On the other hand, oxidative stress is defined as excessive formation and/or insufficient removal of highly unstable molecules such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the body tissues. In persistent hyperglycaemia oxidative stress has always been found and this is mainly due to a rise in the production of free radicals and a reduction in antioxidant defences and tissue antioxidant status. It is this oxidative stress that leads to development of diabetic complications. Earlier research works have shown that, patients with insulin resistance, with or without type 2 diabetes, are more likely to develop many metabolic syndromes, unless they alleviate their oxidative stress levels by taking more antioxidants in food. The treatment of diabetes mellitus has been confined to use of conventional anti-diabetic drugs and insulin which are not readily available, unaffordable and are known to cause many side effects. This has led to increased demand for antioxidant and hypoglycaemic herbal products that have less side effects, are affordable and more readily available. The leaf extract of Pappea capensis, at doses of 50, 100 and 150mg/kg body weight, reduced the blood glucose levels of alloxan induced diabetic male albino rats to 7.62, 7.06 and 6.70mMol/L respectively while the stem bark extract at doses of 50, 100 and 150mg/kg body weight, reduced the blood glucose levels to 8.26, 7.22 and 6.54mMol/L within seven days. The hypoglycaemic activity of the stem bark extract was insignificantly different from that of the leaf extract. From the histopathological studies of the liver, kidney and pancreas of alloxan induced diabetic rats, there was evidence of cure as far as recovery from alloxan induced damage is concerned and this followed a dose related pattern. The DCM: MeOH leaf and stem bark extracts of P. capensis also demonstrated a dose-dependent reducing power and DPPH and hydrogen peroxide scavenging activities. These properties of P. capensis extracts may be attributed to the presence of phytochemicals such as glycosides, saponins, steroids, alkaloids, terpenoids, phenolics and flavonoids that are associated with either antioxidant or hypoglycaemic activity or both. Thus, the present study has scientifically confirmed the hypoglycaemic, curative and antioxidant properties of DCM: MeOH leaf and stem bark extracts of P. capensis and recommended them for development of herbal remedies for diabetes mellitus and oxidative stress in general.