Phytochemical composition, antioxidant and anti-nutritional properties of root-bark and leaf methanol extracts of Senna alata L. grown in Nigeria

Abstract

Senna alata L. has been ethnobotanically used extensively in traditional medicines for the treatment of a variety of diseases such as skin problems, arthritis, HBP (high blood pressure), and laxative or purgative. The phytochemical, anti-nutritive and antioxidant activities of the leaf and root bark of Senna alata L. grown in Bida Niger State, Nigeria were determined using standard analytical methods. Phytochemical screening of the flower and seed of the plant revealed the presence of flavonoids, phenols, saponins, tannins, alkaloid and anthraquinone. Steroid and cardiac glycosides, were slightly present, while resins were absent. The metabolites present were quantitatively determined with alkaloid contents of 14.09±0.50 and 15.89±0.72, saponin 40.57±0.57 and 33.02±0.07, flavonoid 42.28±0.90 and 36.52±0.38, tannin 59.48±0.50 and 44.38±0.72, and phenol 7.84±0.49 and 9.91±0.68 mg/100 g for leaf and root bark respectively. These results confirm that the metabolites obtained from the two parts of this plant were within the range of toxicity levels according to World Health Organization safe limits. The results of anti-nutritional factors revealed oxalate contents of 7.84±0.74 and 9.91±0.62, cyanide content 13.04±0.09 and 21.69±0.11 and phytate content 15.07±0.58 and 12.44±0.31 mg/100 g for leaf and root bark respectively. The values of anti-nutritional factors obtained from this work show that they may not pose any effects based on their toxicity levels and as recommended by World Health Organization. The major components of the chemical compounds deduced from GC/MS for the two parts of this plant investigated revealed the presence of α-d-mannofuranoside (53.35%), oleic acid (12.30%), β-d-glucopyranoside (12.59%), β-d-mannofuranoside (22.41%), n-hexadecenoic acid (5.73%), 1,2,3- propanetriol (21.54%), α-d-glucopyranoside (16.41%) and oleic acid (14.65%). Thus, if properly domesticated and produced in commercial quantities, this plant will serve as a source of bioactive agents for pharmaceuticals.   Key words: Antioxidant, phytochemical, anti-nutritional, leaf, root bark and Senna alata.