Influence of UV-B treatment on the accumulation of free phenols and tannins in the legumes of Abrus precatorius L. and Vigna mungo (L.) Hepper

•UV-B radiation stress triggers the increase of secondary metabolites in legume seeds/grains.•The secondary metabolites of legume seeds/grains include phenolic compounds.•The phenolic anti-nutritional factors in the legume seeds/grains are antioxidant antinutrients.•UV-B exposure to legume seeds/grains fortifies anti-nutritional factors.•In this study, UV-B exposure increased the levels of anti-nutritional factors in legume seeds. Ultraviolet B radiation with a wavelength from 280 to 320 nm (UV-B) is a prime abiotic factor and environmental stress that can trigger the accumulation/increase of secondary metabolites like phenolic compounds that are unique sources of pharmaceuticals. The Fabaceae family legume seeds or grains contain different kinds of bioactive compounds chiefly classified under phenolic compounds whose potential benefits to human health need to be evaluated for their orderly utilization. This paper aims to study the influence of UV-B radiation on the increase of total free phenols and tannins in the seeds of a wild legume and a crop legume (Abrus precatorius L. and Vigna mungo (L.) Hepper) as a process of fortifying the levels of these bioactive secondary metabolites. The flour of raw seeds, UV-B exposed raw seeds, soaked seeds, and UV-B exposed soaked seeds of Abrus precatorius and Vigna mungo was used to study the influence of UV-B on the accumulation/increase of total free phenols and tannins in the seeds selected for this study. Both raw (dry) and overnight soaked seeds showed increased levels of total free phenols and tannins in response to UV-B exposure. It is concluded that UV-B radiation-related stress (an external stimulus) will have a major influence on the accumulation/increase of secondary metabolites in higher plants. [Display omitted]