Inhibitory Effect of Oroxylin A in a Mouse Model of Atopic Dermatitis

Oroxylin A suppress LL-37 generated rosacea-like skin inflammation through the modulation of SIRT3-SOD2-NF-κB signaling pathway

Rosacea is a long-term inflammatory skin disease associated with the dysfunction of vascular and immunological systems. Treatment options for rosacea are difficult to implement. Oroxylin A(OA), a traditional Chinese medicine, has anti-inflammation effects in a variety of inflammatory diseases. However, it is not known that whether OA exerts protective effects against LL-37-induced rosacea. In this study, bioinformatics analyses showed that the mechanisms of rosacea and the pharmacological targets of OA were highly overlapped. Subsequently, it was shown that the administration of OA resulted in a notable amelioration of rosacea-like skin lesions, as evidenced by a reduction in immune cell infiltration, modulation of cytokine production, and inhibition of angiogenesis. Plus, it was shown that OA effectively suppressed the generation of ROS generated by LL-37, as well as the subsequent activation of NF-κB signaling pathway. To explore further, we found that OA inhibited LL-37-induced ROS production via SIRT3-SOD2 signaling pathway in keratinocytes. Based on the aforementioned evidence, it can be inferred that OA exhibits a mitigating effect on the inflammatory response in rosacea by modulating the SIRT3-SOD2-NF-κB signaling pathway.

Oroxylin A ameliorates ultraviolet radiation-induced premature skin aging by regulating oxidative stress via the Sirt1 pathway

Skin is susceptible to premature aging in response to ultraviolet (UV) radiation-induced oxidative stress, which can ultimately result in aberrant aging or age-related disorders. Accordingly, strategies that can be adopted to mitigate oxidative stress may contribute to protecting skin from induced aging-related damage, thereby offering promising approaches for the treatment of skin diseases and disorders. In this regard, oroxylin A (OA), a natural flavonoid isolated from certain plants used in traditional Chinese medicine, is considered to have notable antioxidant, anti-inflammatory, and anti-apoptotic properties, and is often used to treat certain inflammatory diseases. To date, however, there has been comparatively little research on the effects of OA with respect skin aging. In this study, we utilized UV radiation-induced mouse and cellular models of aging to assess the efficacy of OA in protecting against skin aging. Subsequently, to elucidate the potential mechanisms underlying the protective effect of OA on skin aging, we performed molecular docking analysis to investigate the involvement of the anti-aging gene Sirt1, which was further confirmed on the basis of Sirt1 gene silencing. We accordingly demonstrated that by promoting an increase in the expression of Sirt1, OA can contribute to suppressing UV-induced skin photo-aging in cells/mice by reducing oxidative stress. Furthermore, we established that by activating Sirt1, OA can also promote the dissociation of Nrf2 from Keap1 and its subsequent nuclear translocation. Collectively, our findings in this study reveal OA to be an effective natural compound that can be administered to delay the aging of skin triggered by UV, both in vivo and in vitro, by binding to Sirt1 to promote the deacetylation and nuclear translocation of Nrf2, thereby contributing to a reduction in oxidative stress. These findings may this provide a therapeutic target for the prevention of skin aging or aging-induced skin diseases.