In vitro anti-photoaging activity of fermented polysaccharides from Sargassum fusiforme by Lactobacillus plantarum

High molecular weights of seaweed polysaccharides usually limit their bioavailability. Fermentation of polysaccharides can reduce their molecular weight and improve their bioactivity, which effectively increase their application in food industry. In this study, Lactobacillus plantarum was used to ferment Sargassum fusiforme polysaccharides (SFP). The structure of fermented polysaccharide was characterized. Results showed that fermentation drastically reduced the average molecular weight of SFP by 75.2%. The percentage of reducing sugars and uronic acid gradually increased with time during fermentation. The functional groups of the fermented polysaccharides did not change, but the apparent morphology changed from rough and porous to smooth and fragmented. Fermented SFP exhibited better anti-photoaging activity in UVB-irradiated HaCaT cells. Specifically, it increased cell viability and hydroxyproline level. Additionally, it promoted the gene expression of Pro-collagen I α1 synthesis while inhibiting matrix metalloproteinases (MMP-1, MMP-3, MMP-9) and pro-inflammatory cytokines (IL-1β, TNF-α). These findings suggested that fermentation could enhance the anti-photoaging activity of seaweed polysaccharide, and could be developed as an alternative method for degrading polysaccharides.