Crude caffeine was isolated from kola nut, by treating the filtrate obtained from powdered kola nut with lead (II) acetate to precipitate acids and albumins, along with HCl to precipitate lead ions, and to make some insoluble tannins to be soluble, then Na2CO3 solution was added to neutralise the acidic HCl solution. Dichloromethane is added to the filtrate to extract the caffeine from the aqueous layer and then distilled to obtain the crude caffeine. The extracted crude caffeine is recrystallized with activated charcoal and tested for its antioxidant capacity, using the DPPH assay, which screens the antioxidant activity of plant extracts. The DPPH (2, 2-diphenyl-1-picrylhydrazyl) in methanol helps to facilitate the extraction of the antioxidant compounds from the sample. Ascorbic acid (Vitamin C) is used as the standard for this assay, due to its appreciable antioxidant activity. The IC50 value was calculated from the graph of % inhibition against concentration, and the extracted caffeine from kola nut was found out to have a high antioxidant activity comparable to that of the standard, ascorbic acid.
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