Anti-Inflammatory and Antioxidant Effects of Crude Polysaccharides from Dendrobium denneanum (A Genuine Medicinal Herb of Sichuan) on Acute Gastric Ulcer Model in Rats

<i>Dendrobium denneanum</i> Kerr, <i>Dendrobium denneanum</i> Kerr, an orchid in the food-medicine homology catalog, is traditionally used for stomach-nourishing, yin-tonifying, and immunity-enhancing. While its preventive effect on acute gastric ulcers is confirmed, variations among genuine producing areas remain underexplored. This study comparatively analyzed components of <i>D. denneanum</i> from 22 habitats and their polysaccharides' (DDP) anti-inflammatory/antioxidant activities. Results showed habitat-dependent active components: total sugar (20-51.49%), crude polysaccharide yield (0.29-1.76%), and total phenol (~3%). In vitro, all extracts exhibited dose-dependent scavenging of DPPH (IC₅₀: 0.99-2.11 mg/mL), ABTS (0.61-1.62 mg/mL), and hydroxyl radicals (1.02-2.18 mg/mL), with Habitats 5 and 7 showing the strongest activity. GPC, ion chromatography, and FT-IR revealed DDP had a 5-11 kDa molecular weight, dominated by glucose (49.67-84.73%), plus mannose (8.29-12.25%) and galactose (0.96-16.41%), with shared hydroxyl (3400 cm^-1) and β-glycosidic bond (890 cm^-1) features. In ethanol-induced gastric ulcer rats, DDP exerted dose-dependent protection: low doses (100 mg/kg/d) reduced ulcer index, increased SOD/GSH-Px (1.5-1.8-fold), decreased MDA (30-35%), and elevated PGE₂; high doses (400 mg/kg/d) further inhibited serum TNF-α/IL-6 (25-40%) and improved histopathology. Conclusion: Despite habitat-dependent component variations, DDP maintains consistent structures. This study first confirms DDP protects gastric mucosa via antioxidant-anti-inflammatory synergism, supporting its development as a natural gastroprotectant. Future work may focus on standardized cultivation and clinical translation.