Antioxidants and Antioxidant Capacity in Leafy, Stem, and Fruit Vegetables Including 50 Species

Abstract

Epidemiological studies have confirmed that high intake of fruits and vegetables is associated with low incidence of many kinds of diseases, which are hypothesized to be owing to antioxidants in fruits and vegetables. In this study, three types (leafy, stem, fruit) vegetables including 50 species were systematically evaluated for their antioxidant capacity (AC) and antioxidants including total phenolic compound (TPC), total flavonoids (TF), and L-ascorbic acid (LAA). Results showed that vegetables types had no significant effects on antioxidants. Vegetables with vivid color like purple cabbage, purple dolichos lablab, purple cowpea, red pepper, yellow pepper, lotus root, and ginger ranked high in their antioxidants (TPC 32.76-117.63 mg gallic acid/g FW, TF 25.78-152.96 mg rutin/100g FW, LAA 69.11-165.44 mg/100g FW) and AC (FRAP 69.38-109.13 μmol Fe2+/100gFW, ABTS 2.19-3.75 μmol Trolox/gFW). Relatively, crown daisy, endive, celery stem, and cucumber had low antioxidants (TPC 2.66-6.29 mg gallic acid/g FW, TF 10.37-37.56 mg rutin/100g FW, LAA 14.64-39.44 mg/100g FW) and AC (FRAP 1.99-10.81 μmol Fe2+/100gFW, ABTS 0.39-0.68 μmol Trolox/gFW). TPC and LAA had strong positive correlations with AC regardless of vegetable types, while TF was positively related to AC only in leafy vegetables. The result would be valuable for both epidemiological research and dietary guidelines as these vegetables are affordable and widely available.