Protective effects of Oroxylum indicum seed extract against ultraviolet-induced skin photodamage through inhibition of STING and NF-κB signaling pathways.

Ultraviolet (UV) radiation can cause several skin issues including inflammation, oxidative stress and photoaging. The seeds of Oroxylum indicum (L.) Kurz are well-known herbal medicines commonly used to treat pharyngitis, bronchitis, and other ailments. This study sought to investigate the protective effects of Oroxylum indicum seed extract (OISE) against UV-induced skin damage and the underlying mechanism. Our findings revealed that OISE effectively attenuated UVB-induced oxidative stress and inflammation in keratinocytes. Specifically, OISE treatment reduced ROS and MDA levels, promoted the expression of genes involved in regulating oxidative stress such as NFE2L2, HMOX1, SOD1, CAT, GCLC, GCLM, and NQO1, suppressed the production of inflammatory cytokines including TNF-α, IL-6 and IL-8, and downregulated the gene expression of pro-inflammatory enzymes such as iNOS and COX-2. Moreover, we employed HFF-1 cells to evaluate the protective effect of OISE against UVA radiation and found that OISE effectively mitigated UVA-induced inflammation and photoaging in HFF-1 cells. Network pharmacological analysis and molecular experiments indicated that OISE effectively inhibited the activation of STING and NF-κB pathways induced by both UVB and UVA radiation. Further research revealed that oroxin A and oroxin B, the major components in OISE, were sufficient to inhibit UVB-induced inflammation and activation of the STING pathway. Thus, this study demonstrated that OISE could effectively alleviate both UVB and UVA-induced skin photodamage through inhibiting the STING and NF-κB pathways and revealed that oroxin A and oroxin B are the key components that enable OISE to protect skin from damage caused by ultraviolet radiation.