Abstract

COMPARATIVE PHYTOCHEMICAL AND SPECTROPHOTOMETRIC ANTIOXIDANT EVALUATION OF THE ROOT BARK, STEM BARK, LEAF AND SEED OF COLA NITIDA (STERCULACEAE)

Ukwueze Stanley Ejike* and Ugwu Nneka Njideka

Abstract

Cola nitida has been found to be an abundant source of natural antioxidants and also a great therapeutic agent for the prevention and management of free radical-mediated diseases. This study was aimed at evaluating and comparing the phytochemical and in vitro antioxidant activity of different parts of Cola nitida. Total phenolic and flavonoid contents as well as the antioxidant activities of the methanol extracts were evaluated spectrophotometrically using the Folin-Ciocalteau’s reagent, aluminium chloride reagent and 1,1-diphenyl-2- picrylhydrazine (DPPH) methods respectively. Phytochemical screening was done using standard method. The phytochemical screening revealed the presence of alkaloids, tannin, anthraquinone, flavonoids, cardiac glycoside, carbohydrates and phlobatannin in the methanol extract of the various parts of C. nitida. The phenolic contents of the leaves, seeds, stem and root barks were 1.591, 6.047, 4.032, and 1.542 (% w/w GAE) respectively while the total flavonoids content of the respective parts were: 0.4733, 0.250, 0.0333, and 0.2367 (% w/w QE). Consequently, the IC50 of the leaf, seed, root and stem barks were found to be 0.0219, 0.0019, 0.0193 and 0.0437 mg/ml respectively. There was a positive correlation between the polyphenol contents and the in vitro antioxidant activity. These results showed that the various parts of C. nitida, especially the seeds, possess high levels of polyphenols with significant antioxidant capacities. Thus, the seeds of C. nitida should be preferentially utilized for therapeutic or explorative conditions where the antioxidant activity of the plant might be of primary concern.

Keywords: Cola nitida; Phytochemical; Antioxidant activity, Spectrophotometry.