Abstract: Caesalpinia sappan L., belonging to the family Leguminosae, is a medicinal plant that is distributed in Southeast Asia. The dried heartwood of this plant is used as a traditional ingredient of food, red dyes, and folk medicines in the treatment of diarrhea, dysentery, tuberculosis, skin infections, and inflammation. Brazilin is the major active compound, which has exhibited various pharmacological effects, including anti-platelet activity, anti-hepatotoxicity, induction of immunological tolerance, and anti-inflammatory and antioxidant activities. The present study aimed to evaluate the antioxidant activity and expression of antioxidant enzymes of C. sappan L. extract and its major compound, brazilin, in human epidermal keratinocytes exposed to UVA irradiation. Our results indicated that C. sappan L. extract reduced UVA-induced H₂O₂ production via GPX7 activation. Moreover, brazilin exhibited antioxidant effects that were similar to those of C. sappan L. via glutathione peroxidase 7 (GPX7), suggesting that C. sappan L. extract and its natural compound represent potential treatments for oxidative stress-induced photoaging of skin.