Phytochemical screening and antioxidant activity of <i>Pseudocedrela kotschyi</i> Schweinf Harms (Meliaceae) and <i>Strophanthus sarmentosus</i> DC (Apocynaceae)

Abstract

Medicinal plants often have secondary metabolites that possess some antioxidant properties, which could provide protection for living organisms from damage caused by reactive oxygen species (ROS), with concomitant lipid peroxidation, and DNA strand breaking because of their redox properties. The aim of this work was the phytochemical screening and evaluation of antioxidant activity of Pseudocedrela kotschyi (PK) Schweinf Harms and Strophanthus sarmentosus (SS) DC. Plants were collected, identified and authenticated using standard procedures. The phytochemical screening of the medicinal plants was carried out using the standard official methods. The antioxidant activities were determined by DPPH free radical scavenging method as described by Brand-Williams and co-workers with a slight modification. The probit analysis graph pad prism 7 software was used for statistical analysis. The results showed that flavonoids, tannins and saponins are more abundant in PK-L (leaf) than PK-B (bark) whereas alkaloids and cardiac glycosides are more in SS-R (root) and SS-L. The IC₅₀ of the extracts were 7.94, 14.96, 50.11 and 251.20 μg/ml for (PK-B > PK-L>SS-L>SS-R) respectively, thus indicating activity resides more in the bark and leaf of Pseudocedrela kotschyi than the Strophanthus sarmentosus. Furthermore, the IC₅₀ of PK-B (7.94 μg/ml) has a higher activity compared to the standard, rutin (10.00 μg/ml). Thus, Pseudocedrela kotschyi is a potential source of active constituents that could be used in further drug development.

Keywords: Medicinal plants; Phytochemicals screening; Antioxidant; Free radical scavenging; Tarok people