Quercetin is a plant-derived flavonol found in a variety of fruits and vegetables, with particularly high concentrations found in the outer skin of onions and shallots. Quercetin and its derivatives have been shown to inhibit inflammation and scarring in models of foreign-body reaction, hypertrophic scar formation and keloid. Quercetin has been reported to reduce tumor necrosis factor-α and TGF-β expression, increase matrix metalloproteinase-1 activity and reduce oxidative stress. - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4281888/