The effects of alginate lyase treatment on structural characteristics and anti-photoaging activity of alginate from Sargassum fusiforme

An alginate (named P1) prepared from Sargassum fusiforme has been proven to have significant anti-photoaging activity in our previous study. In this study, alginate lyase was used to obtain P1 hydrolysates with different molecular weights, and their structural characteristics and anti-photoaging activity were compared. Results showed that alginate lyases could rapidly degrade the molecular weight of P1 and slightly changed its chemical composition. Fourier transform infrared spectra indicated that alginate lyase treatment did not change the main functional groups of P1. Moreover, the inhibitory effects of P1 on MMPs (MMP-1, MMP-3 and MMP-9) and reactive oxygen species were also improved after hydrolyzed with alginate lyase, especially sample A-30 (hydrolysis for 30 min). Methylation and nuclear magnetic resonance results indicated that the main chain of A-30 was -> 4)-beta-ManA-(1 -> 4)-alpha-GulA-(1 -> 4)-beta-ManA-(1 -> 4)-beta-ManA-(1 -> 4)-alpha-GulA-(1 -> 4)-beta-ManA-(1 -> 3, 4)-beta-ManA-(1 ->, with the end group of alpha-Fucp-(1 -> attached to the O-3 position of -> 3, 4)-beta-ManA-(1 -> on the side chain. It indicated that alginate lyase did not change the backbone of P1 but decreased the molecular or degree of polymerization at 30 min of hydrolysis. This is the first report on the anti-photoaging activity of alginate hydrolysates. The results will provide effective theoretical support for improving the utilization and promoting the application of S. fusiforme.