Assessment of antioxidant potential of selected roadside trees leaves in Kumasi Metropolis, Ghana

Abstract

The roadsides of the Kumasi Metropolis, Ghana are lined with the several species of trees, such as, Terminalia catappa, Mangifera indica, Ficus platyphylla and Polyalthia longifolia. The people use them for their health care needs. The vehicle emissions results in oxidative injury in these plants, due to the production of reactive oxygen species. The present study assessed the antioxidant potential of leaves of these tree species subjected to vehicular pollutants. The free radical scavenging activity of leaf extracts of the four tree species were measured using 1, 1- diphenyl-2-picryl hydrazyl (DPPH). The total phenolic content (TPC) of the extract was determined by a spectrophotometric assay using the Folin-Ciocalteau’s reagent. Total antioxidant capacity (TAC) was measured using Phosphomolybdate assay. In this study, the medicinal properties of leaves of Terminalia catappa, Mangifera indica, Ficus platyphylla and Polyalthia longifolia sampled from the control sites showed better medicinal properties. DPPH scavenging activity at concentration 2.7 ug ml-1 was lower at the arterial road sites in all the four tree species. A higher DPPH percentage inhibition was recorded at the control sites. The IC50 values were higher for the leaf sample extracts from the arterial road sites and lower for the Control site. The total phenolic content of leaf samples of all the four tree species at the arterial road sites were lower than and significantly different from those at the Control site (p=0.000). The TAC values were lower at the arterial road sites in comparison to the control sites. There was a significant difference among the arterial road sites and also when compared with the control (P<0.05). It could be suggested from this study that variability exists in the antioxidant activities of plants due to a decrease in the medicinal properties of plants subjected to constant auto vehicular pollution.