Antioxidant activity of Phaseolus L. species seeds with different coat colour

Abstract

The aim of the research was to screen the antioxidant activity of mature seeds of related bean species using the collection samples of the National Center for Plant Genetic Resources of Ukraine: Phaseolus vulgaris L., P. multiflorus Lam., P. lunatus L. and P. acutifolius A. Grey which have different colouration of their seed shell. The determination of antioxidant activity was carried out using the improved method of the stable radical DPPH•: methyl alcohol in the eluting solution was replaced by non-toxic ethyl alcohol. The results of the analysis are presented as the equivalent of a standard antioxidant (chlorogenic acid), expressed in mg of the standard per 1 g of a sample, taking into account dilutions according to the calibration schedule. As a result of the Phaseolus L. collection screening, it was found that the antioxidant activity of bean seeds depended on the colour of the seed coat. Regardless of the bean type, white seeds had the lowest indicator (equivalent to chlorogenic acid is 0.82–0.96 mg g^–1 of seed). Painted seeds have different antioxidant activity. In P. vulgaris L., olive seeds have the highest index (4.21–5.07 mg g^–1 of seeds), it is 2.36–3.60 mg g^–1 in wine red seeds and 2.72–3.21 mg g^–1 in pink ones. And the tendency of the influence of drawing colour and the area of a seed coat is noticed. In P. lunatus L., the antioxidant activity of white seeds with a motley wine-red pattern (2.27 mg g^–1 of seeds) is more than twice as high as of white seeds without a pattern (0.94 mg g^–1 of seeds). In P. multiflorus Lam., all the coloured seeds had a very high antioxidant activity regardless of the seed coat colour and its pattern (6.09–6.16 mg g^–1 of seeds). In P. acutifolius A. Gray, the change in this parameter, depending on the seed coat colour, was small (1.27–1.62 mg g^–1 of seeds). It was found that the antioxidant activity of beans depended on the environmental conditions: the stress of plants because drought leads to its increase.