Evaluation of minerals, phytochemical compounds and antioxidant activity of Mexican, Central American, and African green leafy vegetables

Authors: JIMENEZ-AGUILAR, DULCE - Baylor College Of Medicine; Grusak, Michael

Submitted to: Plant Foods for Human Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2015
Publication Date: 12/1/2015
Citation: Jimenez-Aguilar, D.M., Grusak, M.A. 2015. Evaluation of minerals, phytochemical compounds and antioxidant activity of Mexican, Central American, and African green leafy vegetables. Plant Foods for Human Nutrition. 70:357-364.

Interpretive Summary: Leafy vegetables are important dietary sources of vitamins, minerals, and various potential health-beneficial compounds. While lettuce, spinach, kale, and collard greens are common in the U.S. diet, other less-known leafy vegetables exist that are used in diets throughout the world. Because we are interested in understanding the contribution that these vegetables could make to people's health and nutrition, and because we would like to identify new vegetables for promotion in the U.S., we have been studying the compositional attributes of several leafy vegetables from Mexico, Central America, and Africa. We grew plants under controlled conditions in our growth chamber, harvested leaf tissue at an appropriate harvest age, and analyzed the leaves for minerals and various antioxidant chemicals. Several vegetable lines were identified that contained high levels of vitamin C and good levels of various antioxidant compounds. We believe it would be beneficial to introduce these vegetables to farmers and consumers in the U.S., as well as in other developed countries throughout the world.

Technical Abstract: The green leafy vegetables Cnidoscolus aconitifolius and Crotalaria longirostrata are native to Mexico and Central America, while Solanum scabrum and Gynandropsis gynandra are native to Africa. They are consumed in both rural and urban areas in those places as a main food, food ingredient or traditional medicine. Currently, there is limited information about their nutritional and phytochemical composition. Therefore, mineral, vitamin C, phenolic and flavonoid concentration, and antioxidant activity were evaluated in multiple accessions of these leafy vegetables, and their mineral and vitamin C contribution per serving was calculated. The concentrations of Ca, K, Mg and P in these leafy vegetables were 0.82-2.32, 1.61-7.29, 0.61-1.48 and 0.27-1.44 mg/g fresh weight (FW), respectively. The flavonoid concentration in S. scabrum accessions was up to 1413 ug catechin equivalents/g FW, while the highest antioxidant activities were obtained in C. longirostrata accessions (52-60 umol Trolox equivalents/g FW). According to guidelines established by the U.S. Food and Drug Administration a serving size (30 g FW) of C. longirostrata would be considered an excellent source of Mo (20% or more of the daily value), and a serving of any of these green leafy vegetables would be an excellent source of vitamin C. Considering the importance of the minerals, phytochemicals and antioxidants in human health and their presence in these indigenous green leafy vegetables, efforts to promote their consumption should be implemented.