The extract of buddleja officinalis maxim. alleviates UVB-induced oxidative damage via the NRF2 pathway in HaCaT cells

Buddleja officinalis Maxim., a prominent medicinal plant from the Scrophulariaceae family, is extensively distributed throught China, Korea, Vietnam, and Myanmar. This phytotherapeutic agent has demonstrated significant clinical efficacy in treating various ophthalmic disorders, such as xerophthalmia, infectious conjunctivitis, keratopathies, corneal ulcerations, and neuropathic ocular pain. To explore the potential photoprotective effects of Buddleja officinalis Maxim. extract (BOE) against UVB-induced oxidative damage in human immortalized keratinocytes. In this study, we analyzed BOE components using HPLC and evaluated scavenging activities against 2, 2'-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azinobis 3-ethylbenzothiazoline 6-sulfonate (ABTS), and Superoxide anion (O2·-) through biochemical assays. Cell viability was assessed with cell counting kit-8 assay (CCK-8) and lactate dehydrogenase (LDH) kits, intracellular reactive oxygen species (ROS) levels were quantified by flow cytometry, and cellular antioxidant enzyme activities were determined using commercial assay kits. To investigate specific antioxidant pathways, qPCR and Western blot analyses were performed. The biochemical assays demonstrated that BOE possesses significant antioxidant activity. Additionally, BOE significantly alleviated the adverse effects of UVB exposure (30 mJ/cm2), which were characterized by decreased cell viability, elevated LDH activity, increased intracellular ROS levels, reduced activities of superoxide dismutase (SOD), decreased the levels of reduced glutathione (GSH), and increased Malondialdehyde (MDA) content. And the BOE modulates the antioxidant defense pathway by upregulating the mRNA and protein expression levels of nuclear factor erythroid 2-related factor 2(NRF2), heme oxygenase-1 (HO-1), and NAD(P)H: quinone oxidoreductase 1 (NQO1). Our findings indicate that the photoprotective efficacy of BOE makes it a promising candidate for incorporation as a natural component in pharmaceutical and cosmetic formulations.