Comparison of the antioxidant activity, phytochemical and nutritional contents of two antihypertensive ethnomedicinal plants

Abstract

The fruits of Xylopia aethiopica (Dunal) A. Rich and leaves of Persea americana (Mill.) are ethnomedicinally used in combination (1:10) as a remedy for the treatment of hypertension in southwest Nigeria. This study compared the antiradical activity, phytochemical and proximate components of the two plants, with a view to providing scientific information on the therapeutic properties and potential of the plants. The antioxidant activity of the samples was against 1, 1–diphenyl–2–picrylhydrazyl (DPPH) radicals. The phytochemical and proximate analyses were carried out using standard laboratory techniques. The plants showed varied antioxidant activity. X. aethiopica had 39.10 mg GAE/g polyphenol content and gave 67.43% inhibition against DPPH⁺ whereas P. americana with 24.3 mg GAE/g polyphenol content had 48.3% inhibition against DPPH⁺. It was observed that there was direct relationship between polyphenol content and antioxidant activity of the plants. There were also significant variations in the chemical components of the plants. Quantitative phytochemical screening showed that alkaloids (1483.33 mg/100g), proanthocyanidins (16.17mg GAE/g), tannins (968.33 mg/100g) and anthraquinones (58.3 mg/100g) were higher in X. aethiopica than in P. americana. On the other hand, P. americana contained more flavonoids (777.67 mg/100g), cardiac glycosides (41.67 mg/100g) and saponins (610 mg/100g) than X. aethiopica. X. aethiopica was richer in ash (4.47%), fats (22.43%), crude fibre (12.47%), moisture content (10.23%) and energy (2716.30Kcal) than P. americana. However, P. americana had higher contents of crude protein (21.57%) and carbohydrates (50.73%). The observed antioxidant activity and chemical components of the two plants might be responsible for their therapeutic use as antihypertensive remedy.

Keywords: Xylopia aethiopica, Persea americana, Antioxidant activity, Phytochemical components, nutritional