Methanol Extract of Bitter Melon Alleviates UVB-Induced MMPs Expression via MAP Kinase and AP-1 Signaling in Human Dermal Fibroblastsin vitro

Ultraviolet (UV) irradiation leads to photo-damage of the skin, which in turn induces expression of matrix metalloproteinases (MMPs) and reduces type I procollagen. Bitter melon (Momordica charantia L.) has been widely used as a traditional medicine. In this study, we tested the photo-protective effects of methanol extracts of bitter melon pulp (BM) and the mechanism of these effects in normal human dermal fibroblasts (NHDFs). The effects of BM were investigated by measuring the levels of MMP-1, -3 and -9, and type I procollagen following UVB irradiation. We found that BM alleviates UVB-induced MMP-1, -3 and -9 expression at 100 µg/mL (down to 52.0%, 73.5%, and 55.6%, respectively). However, cells treated with 100 µg/mL BM had weakly stimulated type I procollagen expression (up to 130.0%). Moreover, treatment with BM significantly reduced UVB-induced extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK), and p38 phosphorylation, which resulted in decreasing UVB-induced phosphorylation of c-Fos and c-Jun. Therefore, our results suggest that BM is a potential agent for regulating skin photoaging. Copyright © 2016 John Wiley & Sons, Ltd.