Salinity stress enhances color parameters, bioactive leaf pigments, vitamins, polyphenols, flavonoids and antioxidant activity in selected Amaranthus leafy vegetables

BACKGROUND Amaranthus tricolor is a unique source of betalain (beta-cyanin and beta-xanthin) and a source of natural antioxidants, such as leaf pigments, vitamins, polyphenols and flavonoids in leafy vegetables. It has substantial importance for the food industry, since these compounds detoxify reactive oxygen species in humans and are involved in defense against several diseases. In addition, previous research has shown that salt stress elevates these compounds in many leafy vegetables. Therefore, we evaluated the effect of salinity stress on these compounds. RESULTS Three selected A. tricolor genotypes were studied under three salinity levels to evaluate the response of these compounds. Genotype, salinity stress and their interactions significantly affected all the traits studied. A significant and remarkable increase in L, a*, b*, chroma, beta-cyanin, beta-xanthin, betalain, total carotenoids, beta-carotene, ascorbic acid, total polyphenolic content, total flavonoid content and total antioxidant capacity were observed under 50 and 100 mmol L-1 NaCl concentrations. Bioactive leaf pigments, beta-carotene, vitamin C, phenolics and flavonoids showed good antioxidant activity due to positive and significant interrelationships with total antioxidant capacity. CONCLUSIONS Amaranthus tricolor can tolerate salinity stress without compromising the high quality of the final product. Therefore, it could be a promising alternative crop in saline-prone areas around the globe. (c) 2018 Society of Chemical Industry