Revisiting the structure of arabinogalactan from Lycium barbarum and the impact of its side chain on anti-ageing activity

In this study, we obtained all the homogeneous LBGP70 (arabinogalactan-protein complex), LBGP70-OL (sugar chain of LBGP70), and LBGP70-OL-I (backbone part of LBGP70-OL) fraction from crude Lycium barbarum polysaccharides (LBP) by stepwise precipitation. The structural features of LBGP70-OL were investigated by a series of analytical techniques and chemical methods, which was identified as a highly branched polysaccharide with an average of 9 branches per 10 sugar backbone units. The backbone was only -> 6)-beta-Galp-(1 -> residues, substituted at the C3 position. The side chains contained beta-Galp-(1 ->, alpha-Araf-(1 ->, alpha-Araf-(1 & RARR; 3)-beta-Araf-(1 -> 3)beta-Araf-(1 ->, alpha-Araf-(1 & RARR; 3)-beta-Gap-(1 -> 3)-beta-Galp-(1 ->, alpha-Araf-(1 & RARR; [5)-beta-Araf-(1]4 -> 3)-beta-Galp-(1 ->. LBGP70-OL had the highest anti-ageing activity, with its side chain and backbone exhibiting a synergistic effect. LBGP70-OL exerted the anti-ageing activity by attenuating SA-beta-Gal activity, preventing cell cycle arrest, increasing antioxidant enzyme activity, protecting the cell membranes from oxidative damage, and regulating the senescence related genes Sirt1 , NAMPT , and Prx1. These results lay the fundamental for further studies on the structure function relationships of LBP.

Automated summary

In this study, LBGP70, LBGP70-OL, and LBGP70-OL-I were obtained from crude Lycium barbarum polysaccharides (LBP) by stepwise precipitation, and the structural features of LBGP70-OL were investigated. The results showed that LBGP70-OL exhibited high anti-ageing activity, with its side chain and backbone synergistically contributing to the activity.