Taken together, our results demonstrate that the polyphenol-rich extract of a native Brazilian plant has decreased ROS levels, increased proliferation, and enhanced the expression of the Nrf2/HO-1 pathway, while also stimulating the endogenous antioxidant enzymes SOD1, SOD2, CAT, and GPx in coronary artery endothelial cells obtained from patients with diabetes. The gene discussed is SOD2; the disease is diabetes mellitus.