Orientin attenuates UVB-induced skin photodamage by inhibiting ROS generation via the AMPK/Nrf2 axis

The accumulation of reactive oxygen species (ROS) in the skin following UVB exposure is a key contributor to ultraviolet-induced skin photodamage. Orientin, a bioactive flavonoid, has demonstrated antioxidant properties in previous studies. However, its efficacy in treating skin photodamage remains inadequately understood. This study investigates the effects of orientin in preventing UVB-induced immortalized human keratinocytes (HaCaT cells) and BALB/c mouse skin photodamage by activating the AMPK/Nrf2 axis. Results show that orientin protects HaCaT cell viability after UVB exposure, reduces ROS levels, and upregulates antioxidant enzymes, including SOD1, HO-1, and NQO-1, while concurrently suppressing the expression of inflammatory mediators such as COX-2, IL-6, and IL-8. Additionally, orientin promotes AMPK phosphorylation, which facilitates Nrf2 nuclear translocation, thereby enhancing the antioxidant defense of cells. This effect is diminished upon inhibition of AMPK or Nrf2. In the BALB/c mouse model of photodamage, topical application of orientin alleviates symptoms like skin roughness, scaling, and erythema induced by UVB irradiation, while also elevating antioxidant enzyme expression in skin tissues. These findings suggest that orientin mitigates ultraviolet-induced skin photodamage both in vitro and in vivo, boosts cellular antioxidant capacity, and diminishes inflammatory responses, suggesting its potential for further exploration in skin photodamage management.