Preparation, characterization and alcoholic liver injury protective effects of algal oligosaccharides from Gracilaria lemaneiformis

•Biodegradation is a promising approach to produce bioactive algal oligosaccharides (AOS) from seaweeds.•The effects of AOS on alcohol-induced liver injuries were explored for the first time.•AOS attenuated alcohol-induced hepatopathy through their antioxidant activities•AOS also enhanced the activities of hepatic alcohol dehydrogenase.•AOS were best taken 2 h before alcohol consumption.

Oligosaccharides derived from seaweeds possess diverse biological functions. However, little is known about their effects on liver damage. In this study, algal oligosaccharides (AOS) were prepared from Gracilaria lemaneiformis by biodegradation approaches. HPLC analysis showed AOS were composed of agarooligosaccharides and neoagarooligosaccharides. In vivo animal studies showed AOS significantly attenuated alcohol-induced hepatopathy in mice to some extent, as revealed by the normalization of several serum liver-damage markers. Besides, AOS increased antioxidant levels of hepatic glutathione (GSH) and superoxide dismutase (SOD), and ameliorated the elevated formation of malonaldehyde (MDA), suggesting AOS attenuated hepatopathy mainly through their antioxidant activities. Interestingly, AOS could also enhance the activities of hepatic alcohol dehydrogenase (ADH). Histological examination of liver tissues showed AOS reduced the alcohol-induced liver injury in a dose-dependent manner. Moreover, the comparison of different administration strategies suggested AOS were best taken 2 h before alcohol consumption. Therefore, our study provided a novel nutritional strategy for reducing alcohol-induced hepatotoxicity.

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