Comparative Study on the Antioxidant Activities of Ethyl acetate and Methanolic Leaf Extracts of Celosia argentea
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Date
2014
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Nigeria Society of Biochemistry and Molecular Biology
Abstract
The present study was carried out to compare the secondary metabolites, in vitro and in vivo antioxidant activities as well as the safety of ethyl acetate and methanolic extracts of Celosia argentea leaves in cadmium-induced oxidative stress in rats. The secondary metabolite screening was done by standard methods while the in vitro antioxidant activity of the extract was evaluated using ammonium thiocyanate, reducing power and diphenyl picryl hydrazyl (DPPH) radical scavenging models. In the in-vivo antioxidant and toxicological studies, thirty rats (Rattus novergicus) weighing 137.05 ± 5.84g were completely randomized into six groups (A-F) of five animals each. Animals in group A received orally 0.5ml of distilled water for 7 days while those in groups B, C, D, E and F received same volume corresponding to 8 mg/kg body weight (bw) of cadmium, in addition to simultaneous administration of distilled water, 100 mg/kg b.w of ascorbic acid, 100, 200 and 400 mg/kg b.w. of the extract respectively. Biochemical indices of in vivo antioxidant activities and toxicity were evaluated in the animals after the treatment period. The ethyl acetate extract of C. argentea contained saponins (1.67%), tannins (0.65%), cardenolide and dienolides (1.20%) and phenolics (0.42%) whereas the methanolic extract contained saponins (3.20%), tannins (0.65%), cardenolide and dienolides (0.006%) and phenolics (5.72%). Reducing sugar, steroids, and glycosides were only detected in the ethylacetate extract. The ethyl acetate extract and ascorbic acid, at 50 mg/ml, inhibited linoleic acid oxidation by 51.00 and 24.2% respectively whereas the methanolic extract produced 51.01% inhibition. Ethylacetate extract at 10, 50 and 100 mg/ml produced reducing power of 0.116, 0.092 and 0.127 nm whereas the methanolic extract produced 0.131, 0.185 and 0.183nm when compared with ascorbic acid that gave 0.092, 0.089 and 0.107 nm. The 100 μg/ml of both the ethyl acetate and methanolic extracts scavenged 82% and 30% respectively of the DPPH radical as against 65% in ascorbic acid. Both the extracts attenuated the cadmium chloride treatment related reduction in the activities of superoxide dismutase, catalase, alkaline phosphatase, gamma glutamyl transferase, alanine and aspartate transaminase as well as the levels of uric acid, albumin, total and conjugated bilirubin, total protein and the Cd elevated levels of malondialdehyde in the serum and tissues of the animals in a manner similar to that of the ascorbic acid treated animals and the non-Cd treated animals administered distilled water; with the ethyl acetate producing a better result. The totality of the results conferred antioxidant activity on the ethyl acetate extract and methanolic extract by the phenolic components of the extracts via induction of the antioxidant enzymes and scavenging of free radical. The extracts also reversed cadmium induced changes in the biomarkers of liver damage.
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Keywords
Celosia argentea, Amaranthaceae, Ethyl acetate extract, methanolic extract, Antioxidant, Lipid peroxidation, Cadmium, Oxidative stress