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

Dendrobium denneanum Kerr, Dendrobium denneanum 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 D. denneanum 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.