Abstract
The empirical survey comparatively explores the antioxidant activity and the free radical-scavenging capacity of various fractions of Anthocleista vogelii leaves. The dried and pulverized leaves of A. vogelii were subjected to cold maceration for 4, 8 and 12 days using 70 % methanol and filtered. The filtrate was concentrated to a slurry crude extract by means of a rotary evaporator at 40ºC with a salvaged yield of 34.10 %. Exactly 0.23 kg of crude extract was defatted and fractionated using two chromatographic techniques in chloroform-methanol-hexane solvent system (3:21 v/v). The fractions were screened qualitatively for polyphenolic compounds. The fractions containing these bioactive compounds were quantified and further subjected to free radical-scavenging activity: DPPH assay, ferric reducing power (FRP) assay, hydrogen peroxide scavenging activity (HPA) and total antioxidant capacity (TAC) respectively. There was marked significant difference (p<0.05) in the total phenolic and flavonoid contents (TPC and TFC) among the fractions with ample amount found in n-hexane fraction. There were marked significant differences (p<0.05) in the IC 50 values among fractions for DPPH, FRP, HPA and TAC assays. Thus, the ample antioxidant activity of n-hexane fraction among other fractions was further validated by the extrapolated IC 50 values. The study inferred that A. vogelii leaves are possible sources of antioxidants with health benefits, especially for disease conditions characterized by oxidative stress. Keywords: Anthocleista vogelii , Antioxidant activity, Free radical-scavenging capacity, IC 50 value, Oxidative stress DOI : 10.7176/JNSR/9-12-09 Publication date :June 30 th 2019
Highlights
The undue generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) triggers the compromise of antioxidant defence system as a result of over-exposure to environmental stressors, and its degree of reactivity necessitates the development of deleterious effects, comprising the onset of pathologies and loss of cellular functions
The increasing potency of free radical scavenging ability of natural antioxidants inherent in Anthocleista vogelii was taken into cognisance in this scientific investigation, the need for dietary ingestion of these compounds of plant origin may not be exaggerated in the enhancement of in vivo antioxidant defence system of complex multicellular organisms predisposed to environmental stressors
The nhexane fraction showed the highest amount of these polyphenolic compounds, where total phenolic content (TPC) and total flavonoid content (TFC) were numerically expressed as (263.30 ± 0.60) mgGAE and (1159.67 ± 8.82) mgRE per gram of dried plant sample among other fractions
Summary
The undue generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) triggers the compromise of antioxidant defence system as a result of over-exposure to environmental stressors, and its degree of reactivity necessitates the development of deleterious effects, comprising the onset of pathologies and loss of cellular functions. The capability of antioxidants to switch-off hazardous effects of ROS associated with the development of various diseases at a non-overwhelming rate was indicated in epidemiological reports (Valko et al 2007; Godic et al 2014). To this end, Duarte and Lunec (2005) emphasized that the reducing function of antioxidants, involving their. The increasing potency of free radical scavenging ability of natural antioxidants inherent in Anthocleista vogelii was taken into cognisance in this scientific investigation, the need for dietary ingestion of these compounds of plant origin may not be exaggerated in the enhancement of in vivo antioxidant defence system of complex multicellular organisms predisposed to environmental stressors. The comparative investigation of in vitro antioxidant activity as well as free radical scavenging potential of leaf extracts of A. vogelii was novel and fundamental in the present study to identifying its potential antioxidant efficacy for the improvement of intrinsic antioxidant defence system during exposure of biological systems to environmental stressors
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