Abstract

IN VITRO ANTIOXIDANT ACTIVITY OF DICHLOROMETHANE: METHANOLIC LEAF AND STEM EXTRACTS OF PAPPEA CAPENSIS

David N. Ngai*, Michael N. Musila, Gervason A. Moriasi, Shadrack M. Njagi, James K. Kamau, Mathew Piero Ngugi and Joan M. Njagi

Abstract

Oxidative stress is a metabolic disorder characterised by overproduction of the highly reactive free radicals that damage body tissues. Such radicals include the unstable and destructive reactive oxygen and nitrogen species among other free radicals. A reduction in the immunological antioxidant defences of the body coupled to a declining tissue antioxidant status is the main causes of oxidative stress. Too much free radical in the tissues ultimately triggers the onset of lifestyle diseases such as diabetes. The current tremendous rise in cases of diabetes mellitus and lack of its effective management strategies has made it necessary to search for antioxidant plant products that are more effective and have fewer side effects. Plant extracts are also known to be more affordable especially in the regions harbouring high populations of the plant in question and because of the fact that they are mostly used in their crude aqueous form. Many studies have been carried out on plants said to possess bioactive components and a good number of herbal products have been reported as possessing antioxidant properties. The current project was designed to evaluate the reducing potential of DCM: Methanolic stem bark and leaf extracts of P. capensis. The parameters used to assess the reducing potential of the two extracts are; 1,1- diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, hydrogen peroxide scavenging activity, the total reducing power and phenolics and flavonoids content. The reducing power tests carried out showed that the stem bark extract of P. capensis had statistically significant more reducing power activity compared to the leaf extract. The DPPH and H2O2 radical neutralising properties exhibited by the stem bark extract of P. capensis was significantly more in comparison to the leaf extract. The study established that the stem bark and leaf extracts of P. capensis had similar contents of phenolics, but the leaf extract proved to contain a higher level of flavonoids. This study demonstrated in vitro reducing potential of DCM: Methanolic leaf and stem bark extracts of P. capensis. The qualitative phytochemicals screening demonstrated the fact that terpenoids, phenolics, glycosides, alkaloids and flavonoids which are associated with antioxidant activity were present in the extracts.

Keywords: Antioxidant, oxidative stress, phytochemicals.