Variation of the phenolic composition and α-glucosidase inhibition potential of seeds, soaked seeds, and sprouts of four wild forms and four varieties of common bean (Phaseolus vulgaris)

The determination of the changes in the composition of bioactive phenolic compounds of germinating seeds which accumulate high levels of these compounds could contribute to the understanding of the germination mechanism and the development of markers for the selection of plant genotypes. In the current study, the changes in the phenolic composition and α-glucosidase inhibition activity, taking place during the germination of four wild forms and four varieties of common bean (Phaseolus vulgaris L.) from Durango Mexico, were determined. A total of 66 phenolic compounds (19 phenolic acids, 18 isoflavones, 18 flavonol glycosides, 3 flavonol aglycones, 3 flavones, 2 dihydroflavonoids, 2 chalcones and one non-identified type) were found by HPLC-DAD, which were differentially accumulated by the seeds, 24 h-soaked seeds, and 4 day-sprouts of each genotype. The accumulation of the flavonol aglycones, myricetin, quercetin and kaempferol was distinctive of the wild seeds. Soaking not only caused leaching and degradation but also triggered the synthesis of new phenolic compounds whereas germination diversified the composition of isoflavones and flavonol glycosides. The seeds of all genotypes analyzed were important inhibitors of α-glucosidase, improving their potential after soaking and germination. The results suggested that the structure rather than the concentration of the flavonoids and phenolic acids determined the inhibitory potential of α-glucosidase of samples. The principal component analysis and cluster analysis revealed HPLC-DAD phenolic profiles as genotype-specific chemomarkers at any of the states (seeds, soaked seeds, and sprouts). The results have wide implications on agronomy and food quality.