Rutin

Rutin is a polyphenol flavonoid found in many plants, for example, citrus fruits. The main reason it's used in cosmetics is its high antioxidant and free radical-scavenging ability (similar to that of superstar ascorbic acid), but also has some antibacterial nature and wound-healing properties.

There is also an in-vitro (made in Petri dishes on animal cell lines) study showing potential for rutin as a skin-whitening agent and people have even tried using it to increase the UV-blocking ability of SPF agents, but with inconsistent results. Either way, its antioxidant abilities should still help protect the skin against sun damage from the UV light that isn’t blocked by SPF agents!