Chaga Medicinal Mushroom, Inonotus obliquus (Agaricomycetes), Polysaccharides Alleviate Photoaging by Regulating Nrf2 Pathway and Autophagy.

Inonotus obliquus is a medicinal mushroom that contains the valuable I. obliquus polysaccharides (IOP), which is known for its bioactive properties. Studies have shown that IOP could inhibit oxidative stress induced premature aging and DNA damage, and delay body aging. However, the molecular mechanism of IOP in improving skin photoaging remains unclear, which prevents the development and utilization of I. obliquus in the field of skin care. In this study, ultraviolet B (UVB) induced human immortalized keratinocyte (HaCaT) cell photoaging model was used to explore the mechanism of IOP in relieving skin photoaging. Results showed that IOP inhibited cell senescence and apoptosis by reducing the protein expressions of p16, p21, and p53. IOP increased HO-1, SOD, and CAT expressions to achieve Nrf2/HO-1 pathway, thus improving antioxidant effects and preventing ROS generation. Furthermore, IOP enhanced the expression levels of p-AMPK, LC3B, and Beclin-1 to alleviate the autophagy inhibition in UVB-induced HaCaT cells. Based on these findings, our data suggested that IOP may be used to develop effective natural anti-photoaging ingredients to promote skin health.