Inhibition of advanced glycation end products and protein oxidation by leaf extracts and phenolics from Chilean bean landraces

Phenolics can decrease the levels of advanced glycation end products (AGEs) from proteins, but their mechanisms in complex mixtures are poorly understood. Leaf extracts and the main phenolics from Chilean bean (Phaseolus vulgaris) landraces were assessed for their capacity to inhibit AGEs and oxidative modifications on bovine serum albumin incubated with glucose. The leaf extracts of six bean landraces decreased AGEs (fluorescent AGEs and carboxymethyl lysine) and oxidative (Kyn, Di-Tyr, protein carbonyls) modifications. Fluorescent AGEs were characterized by time-resolved techniques. The composition of the extracts was determined by HPLC-DAD-Q-TOF-MS/MS, and the main compounds were quantified by HPLC. Correlations between the levels of AGEs or protein carbonyls with the main phenolics suggested synergic effects of caffeoyl malic acid (CMA) and rutin. The synergic effect was evaluated using mixtures of rutin and CMA, showing a strong decrease in fluorescent AGEs and protein carbonylation compared with the pure single compounds, supporting this finding.