Phytochemical, Proximate and Nutrient Composition of Vernonia calvaona Hook (Asterecea): A Green-Leafy Vegetable in Nigeria

Abstract

<p>The leaf of <em>Vernonia calvaona</em> was analysed for its phytochemical, proximate, anti-nutrient, mineral elements and vitamin compositions using standard analytical procedures. Flavonoids (7.07 ± 0.43%) were the most dominant plant secondary compound, followed by steroidal saponins (4.42 ± 0.23%), phenolic compounds (3.19 ± 0.05%), and carotenoids (1.62 ± 0.11%). Alkaloids (1.26 ± 0.13%), and sesquiterpene lactones (1.64 ± 0.13%) were also present in the plant. The proximate analysis of the fresh leaf gave a carbohydrate content of 20.80± 0.67 mg/100 g, with a corresponding reducing sugar content of 8.56 ± 0.06 mg/100 g. The sample also gave a protein content of 19.80 ± 0.61 mg/100 g and fat content of 4.17 ±0.15 mg/100 g respectively. The total fatty acid content of the plant was 3.57 ± 0.52 mg/100 g. Overall the green-leafy vegetable of <em>Vernonia calvaona</em> which is usually eaten raw and fresh contains a very balanced nutrient composition and provides a total metabolising energy value of 844.49 ± 6.19 KJ/100 g. The plant has a crude fibre content of 7.63 ± 0.22 mg/100 g and an ash content of 10.67 ± 0.33 mg/100 g respectively. The anti-nutrient levels, including oxalates (0.34 ± 0.04 mg/100 g), phytates (0.94 ± 0.04 mg/100 g) and cyanates (0.09 ± 0.01 mg/100 g) were low compared to many known vegetables. The leaf is rich in vitamins (Vit C 11.33 ± 0.88, Vit A 0.61 ± 0.01 and Vit E 0.99 ± 0.13 mg/100 g). The leaf is also rich in vitamins B₁, B₂, B_6,niacin and folic acid. The mineral profile of the leaf sample is also impressive, and includes some key elements such as, Fe, Zn, Ca, Na, K, Mg, P and Se. It may be concluded that the leaves of <em>V. calvaona</em> contribute to nutrient intake by the consuming populations in Nigeria and can serve as an antimalarial, antidiabetic, fertility agent, anti-cancer, anti-ulcer and cardioprotective agent.</p>