Study on the Structural Features of Eight Dendrobium Polysaccharides and Their Protective Effects on Gastric Mucosa

This study aimed to analyze the structure of polysaccharides from eight different <i>Dendrobium</i> species and their protective effects on gastric mucosa. Ultraviolet (UV) analysis showed that the contents of eight polysaccharides ranged from 51.89 ± 6.91% to 80.57 ± 11.63%; the degree of acetylation ranged from 0.17 ± 0.03 to 0.48 ± 0.03. High-performance liquid chromatography (HPLC) results showed that these polysaccharides were mainly composed of mannose (Man) and glucose (Glc) with a small amount of galactose (Gal) and arabinose (Ara), and the monosaccharide ratios of different <i>Dendrobium</i> species were different. High-performance size exclusion chromatography-multi angle light scattering-refractive index detector (HPSEC-MALS-RID) showed that the molecular weight (Mw) of all <i>Dendrobium</i> polysaccharides was >1 × 10⁵ Da; <i>D. huoshanense</i> had the lowest molecular weight. Subsequently, an ethanol injured GES-1 cell model was constructed to evaluate the gastric mucosal protective potential of polysaccharides from eight different <i>Dendrobium</i> species. The results showed that the protective effect of the low concentration 50 μg/mL DHP treatment group was similar to that of the control group (<i>p</i> > 0.05), and the cell viability could reach 97.32% of that of the control group. Based on the polysaccharide composition, different kinds of <i>Dendrobium</i> have different degrees of migration and repair effects on GES-1 damaged cells, and the effect of DHP is slightly better than that of other varieties (83.13 ± 1.05%). Additionally, <i>Dendrobium</i> polysaccharides alleviated ethanol-induced oxidative stress and inflammatory response in gastric mucosal cells by enhancing the activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase) and reducing the levels of malondialdehyde and reactive oxygen species. Overall, DHP can most effectively protect gastric mucosa. These findings enhance our understanding of the relationship between the structure and biological activity of <i>Dendrobium</i> polysaccharides, providing a foundation for the quality control of <i>Dendrobium</i>. Furthermore, these findings offer theoretical support for the development of <i>Dendrobium</i> polysaccharides as nutraceuticals to treat digestive system diseases.