Total phenolics and antioxidant capacity of indigenous vegetables in the southeast United States: Alabama Collaboration for Cardiovascular Equality Project

Abstract

Collard greens, mustard greens, kale, okra, green onion, butter beans, butter peas, purple hull peas, rutabagas, and eggplant are frequently consumed by African Americans in the southeast United States. Sweet potato greens and purslane are two novel vegetables in this region. The objective of this study was to analyze total phenolics and antioxidant capacity in these indigenous vegetables. The total phenolic content was analyzed using the Folin–Ciocalteu method and ranged from 7.4 to 53.5 mg gallic acid equivalents per gram of dried sample. The antioxidant capacity was analyzed using the radical DPPH^• scavenging capacity assay and oxygen radical absorbance capacity assay (ORAC). At a concentration of 10.0 mg dried vegetable equivalent/ml, the extract of these vegetables was able to quench 13.2–88.5% DPPH^• radical in 30 min. The ORAC value ranged from 2.5 to 100.7 µmoles of trolox equivalents per gram of dried sample. The antioxidant capacity of the vegetable samples was highly related to their total phenolic content. The results suggest that these indigenous vegetables consumed by African Americans in the southeastern United States are good sources of the phenolic compounds, which might provide anti-oxidative protection against free radicals in the human body. Consumption of these vegetables might reduce the risk of chronic diseases.

• Total phenolic content
• antioxidant capacity
• vegetables