Protective effects of two alkaloids from Aspergillus terreus C23-3 on skin photoaging induced by UVB and H 2 O 2

Ultraviolet B (UVB) radiation contributes to skin photoaging and inflammation. This study investigated the protective effects of two alkaloids from Aspergillus terreus C23-3 against UVB-irradiated human keratinocytes (HaCaT) and H₂O₂-stimulated fibroblasts (BJ cells). Alkaloids 1 and 2 effectively protected these cells without toxicity at concentrations ranging from 1 to 10 μM, significantly reducing ROS levels and oxidative stress. Molecular docking indicated that alkaloids 1 and 2 can form stable complexes with MMP-1, and inhibit its activity. This finding was verified by Western blot tests, which demonstrated that alkaloids 1 and 2 could effectively inhibit MMP-1 expression in H₂O₂-stimulated BJ cells. In addition, alkaloids 1 and 2 can inhibit UVB-induced activation of the MAPK pathway, reducing c-Jun and c-Fos phosphorylation and thereby reducing MMP-1 transcription. By blocking these signalling pathways and possibly inhibiting the nuclear translocation of p65, alkaloids 1 and 2 attenuate UVB-induced inflammatory responses, in particular by reducing the pro-inflammatory markers IL-6, IL-1β, COX-2 and iNOS. Consequently, these alkaloids may have therapeutic potential for alleviating skin photoaging and inflammation.