Nephroprotective Effect of a Low-Molecular-Weight Peptide Fraction from Common Bean ( <i>Phaseolus vulgaris</i> ) against Renal Ischemia and Reperfusion

Ischemia–reperfusion (I/R) injury contributes to acute kidney injury. Reactive oxygen species produced during tissue reoxygenation may be targeted by antioxidant molecules obtained from dietary sources. We previously showed that peptides smaller than 3 kDa (PV3) from common hardened bean (Phaseolus vulgaris) exert antioxidant and renal vasodilator effects. We next evaluated whether PV3 may mitigate the ischemic damage related to oxidative stress in the kidney. The diphenyl picrylhydrazyl method was used to evaluate the PV3 antioxidant activity in vitro. Human endothelial cells were incubated with diaminofluorescein diacetate and dihydroethidium to probe nitric oxide (NO) and reactive oxygen species, respectively; fluorescence was analyzed by confocal microscopy. In our in vivo tests (CEUA 057/22), we used Wistar rats that underwent a sham surgery or an I/R procedure and were treated with PV3 (50 μg/kg). Phosphate-buffered saline 1× was used to control for hypercapnia-related metabolic acidosis, and the control group received NaCl 0.9%. Ingestive parameters, metabolism, and renal function were evaluated in metabolic cages. PV3 exerted antioxidant effects and increased NO production in endothelial cells. In rats, PV3 reverted the deleterious effects of I/R on renal function and attenuated the I/R-evoked reductions in the activity of renal superoxide dismutase and catalase enzymes in a copper- and iron-dependent manner. In conclusion, PV3 attenuates the detrimental effects of I/R on renal function, most likely through its antioxidant and oxidonitrergic properties, thereby exerting nutraceutical benefits on pathophysiological processes driven by oxidative stress.