Andrographolide sodium bisulfate attenuates UV-induced photo-damage by activating the keap1/Nrf2 pathway and downregulating the NF-κB pathway in HaCaT keratinocytes

Oxidative and inflammatory damage has been suggested to play important roles in the pathogenesis of skin photoaging. Andrographolide sodium bisulfate (ASB) is a soluble derivative of andrographolide and has known antioxidant and anti-inflammatory properties. In the present study, cellular experiments were designed to investigate the molecular mechanisms underlying the effect of ASB in relieving ultraviolet (UV)-induced photo-damage. Following ASB pretreatment and UV irradiation, the apoptosis and necrosis of HaCaT cells were investigated by Hoechst 33342/propidium iodide staining. Reactive oxygen species (ROS) production was investigated using a DCFH-DA fluorescence probe. Furthermore, the protein expression levels of p65, NF-κB inhibitor-α, nuclear factor E2-related factor 2 (Nrf2) and kelch-like ECH-associated protein 1 (keap1) were measured via western blotting and immunofluorescence analyses. Furthermore, NF-κB-mediated cytokines were assessed by ELISA, and Nrf2-mediated genes were detected by reverse transcription-quantitative PCR. Pretreatment with ASB markedly increased cell viability, decreased cell apoptosis and decreased UV-induced excess ROS levels. In addition, ASB activated the production of Nrf2 and increased the mRNA expression levels of glutamate-cysteine ligase catalytic subunit and NAD(P)H quinone oxidoreductase 1, while ASB downregulated the protein expression of p65 and decreased the production of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α. These results suggested that ASB attenuates UV-induced photo-damage by activating the keap1/Nrf2 pathway and downregulating the NF-κB pathway in HaCaT keratinocytes.