Antioxidant Potential of Common Leafy Vegetables in Bangladesh

Amount of polyphenols, flavonoids, anthocyanins in ethanol extracts and antioxidant activity of both ethanol and lipophilic extracts of common leafy vegetables in Bangladesh were compared. Among the 12 leafy vegetables, Ipomoea aquatica Forssk. showed the highest content of total polyphenols (38.9 mg gallic acid equivalent (GAE)/g extract) and flavonoids (23.2 mg (+)-catechin equivalent (CE)/g extract). Highest anthocyanins content was found in Amaranthus gangeticus L. (1.15 μmol/g extract) followed by Pisum sativum L. (0.85 μmol/g extract). Ethanol extracts of Brassica campestris L., Enhydra fluctuans Lour., I. aquatica, Lagenaria siceraria (Mol.) Standl. and P. sativum exhibited high DPPH free radical scavenging activity with IC50 of 104.2, 85.5, 26.9, 125 and 68.5 μg/ml, respectively whereas for the same lipophilic pentane extracts of Basella alba L. showed the lowest (68.4 μg/ml) IC50 followed by I. aquatica (70.4 μg/ml), E. fluctuans (75.7 μg/ml), L. siceraria (78.3 μg/ml) and B. campestris (80.6 μg/ml). I. aquatica also showed the highest NO free radical scavenging followed by B. campestris and B. alba. Highest reducing power (O.D. = 1.7) was observed for I. aquatica followed by P. sativum (O.D. = 1.12), B. alba (O.D. = 0.86) and L. siceraria (O.D. = 0.72) at 400 μg/ml extract. They also displayed high total antioxidant capacity. Therefore, the top five potential leafy vegetables consist of both hydrophilic and lipophilic antioxidant(s), the order being I. aquatica > B. campestris > B. alba > P. sativum > and L. siceraria. Introduction Leafy vegetables are widely consumed in many countries because of their nutritional quality and anthocyanin, ascorbic acid, β-carotene, flavonoid, folic acid, polyphenol and alkaloid contents. These components have a wide range of biological functions such as antiallergic, anticancer, antidiabetic, antimicrobial, antioxidant, anticardiovascular diseases (Scalbert et al. 2005). Reportedly, various epidemiological studies have suggested that consumption of fruits and vegetables is associated with reduced risk of aging, inflammation, cancer, cardiovascular diseases, Alzheimer’s and Parkinson’s. Nowadays, antioxidants are considered as important as vitamins for promotion of health and prevention of various diseases linked to reactive oxygen species (ROS). ROS have been linked to over 100 disorders (Halliwell and Gutteridge 2000). Therefore, for maintaining a healthy biological system, it is critical to have the balance between oxidation and antioxidation. Excess generation of ROS causes oxidative stress that damage DNA, lipids and proteins of cells leading to pathogenesis of various diseases such as cardiovascular disorders, diabetes, cancer, inflammation, aging, brain dysfunction, etc. A variety of phytochemicals have been reported as showing antioxidant potential (Tsao and Akhtar 2005). The majority of antioxidants are hydrophilic and they can easily contribute to keep up physiological health of hydrophilic organs whether lipophilic antioxidants are essential for lipophilic organs such as brain, cell membrane and Author for correspondence: .