Vitamin E

Vitamin E is an antioxidant that reduces the damaging effects of sun exposure on the skin, and can help reduce irritation, inflammation & discolorations. Vitamin E has also been shown to stabilize vitamin c.

Research highlighted a synergistic effect between vitamins C and E, meaning they are more effective together than either one alone in protecting against UV damage. 

Sources:

Vitamin E in Human Skin: Functionality and Topical Products. Vitamin E in Health and Disease - Interactions, Diseases and Health Aspects 2021

Interaction of ascorbate and alpha-tocopherol. Ann N Y Acad Sci 1987

UV photoprotection by combination topical antioxidants vitamin C and vitamin E. J Am Acad Dermatol 2003