Structural characterization and chondroprotective activity evaluation of four novel polysaccharides purified from Anoectochilus zhejiangensis on transgenic fluorescent zebrafish

Abstract

Anoectochilus zhejiangensis (AZJ) exhibits notable anti-inflammatory and anti-swelling properties, making it a potential therapeutic agent for osteoarthritis. However, the specific component responsible for its anti-osteoarthritis effects remains unidentified. In this study, four novel polysaccharides were purified from Anoectochilus zhejiangensis (i.e., AZJP-1a, AZJP-2a, AZJP-2b, and AZJP-2c) through DEAE-cellulose 52 and Sephadex G-200 column chromatographic separation. Their structural and conformational characteristics were comprehensively analyzed. AZJP-1a and AZJP-2a owned high molecular weights of 387 kDa and 947 kDa, while AZJP-2b and AZJP-2c were comparatively lower at 3.989 kDa and 3.045 kDa. The polysaccharides contained predominantly β-glycosidic linkages over α-glycosidic linkages. AZJP-1a primarily consists of mannose, while AZJP-2a and AZJP-2b are rich in glucose, galactose, and arabinose, and AZJP-2c is mainly composed of glucose. Chondroprotective effects of these polysaccharides were evaluated using fluorescence imaging in transgenic fluorescent zebrafish (Tg Col2a1a: eGFP), with all four polysaccharides demonstrating significant cartilage repair activity, surpassing that of the positive control drug alendronate. Among them, AZJP-2c exhibited the most potent effect. The observed variations in their biological activities are likely attributed to differences in their structural compositions.