Polyphenol bioaccessibility and anti-inflammatory activity of Mexican common beans (Phaseolus vulgaris L.) with diverse seed colour

Common bean consumption is associated with the prevention of chronic diseases and these effects are partially attributed to their polyphenol content. In this study, the bioaccessibility and anti-inflammatory activity of polyphenols from six Mexican cultivars of beans (Phaseolus vulgaris) varying in their seed colour, was evaluated. In all cultivars, digestion of starch and protein released significantly more polyphenols compared to soaking, cooking and methanol extraction. Pink cultivar 'Marcela' showed the highest total and bioaccessible polyphenol content (>50 mg GAE per gram dry bean). Black cultivar 'Negro Jamapa' showed a moderate anti-inflammatory effect, reducing mRNA levels of IL6, IL1 beta and iNOS by up to 20%. In contrast, cultivars 'Marcela' and yellow 'Azufrado' induced mRNA expression of IL1 beta, IL6, and HO-1, thus inducing both pro- and anti-oxidation pathways. Results indicate that enzymatic digestion promotes the bioaccessibility of common bean polyphenols and bean cultivars can elicit both anti- and pro-inflammatory responses in macrophages.