Production of exopolysaccharide from mycelial culture ofGrifola frondosaand its inhibitory effect on matrix metalloproteinase-1 expression in UV-irradiated human dermal fibroblasts

Exopolysaccharide (EPS) was prepared by submerged mycelial culture of a newly isolated mushroom Grifola frondosa HB0071 in a 5-l stirred-tank fermenter. This fungus produced a high concentration of biomass (24.8 gl(-1) at day 4), thereby achieving high EPS concentration (7.2 gl(-1) at day 4). EPS was proven to be a proteoglycan consisting of 85.6% carbohydrates (mostly glucose) and 7.3% proteins with a molecular weight of 1.0 x 10(6) Da. The photoprotective potential of EPS was tested in human dermal fibroblasts (HDF) exposed to ultraviolet-A (UVA) light. It was revealed that EPS had an inhibitory effect on human interstitial collagenase (matrix metalloproteinase, MMP-1) expression in UVA-irradiated HDF without any significant cytotoxicity. The treatment of UVA-irradiated HDF with EPS resulted in a dose-dependent decrease in the expression level of MMP-1 mRNA (by maximum 61.1% at an EPS concentration 250 microgml(-1)). These results suggest that EPS obtained from mycelial culture of G. frondosa HB0071 may contribute to inhibitory action in photoaging skin by reducing the MMP 1-related matrix degradation system.