Comparative structure-activity analysis of Millettia speciosa Champ polysaccharides and oligosaccharides in anti-inflammatory effects.

This study systematically isolated and purified water-soluble carbohydrates from Millettia speciosa Champ (MSCP), conducting a comparative analysis of high-molecular-weight polysaccharides (MSCPH) and their fractions (MSCPH1-3) against low-molecular-weight oligosaccharides (MSCPL) to elucidate anti-inflammatory activities and structure-activity relationships. Results demonstrated that MSCPL (100-400 μg/mL) exhibited significant dose-dependent anti-inflammatory activity, with inhibition of nitric oxide (NO), interleukin-1β (IL-1β), and interleukin-6 (IL-6) peaking at 400 μg/mL (21.20 %, 41.22 %, and 69.35 %, respectively), while lower concentrations (100-200 μg/mL) displayed moderate but progressive inhibitory effects. In contrast, MSCPH showed weak anti-inflammatory activity, with maximum inhibitions of 22.33 % for NO and 15.09 % for IL-1β at 200 μg/mL (no significant effect on IL-6). Purified fractions, MSCPH1-3, had further reduced anti-inflammatory activity, suggesting that component synergy within MSCPH is critical for its bioactivity, albeit weak. Structural characterization revealed that the anti-inflammatory activity of MSCPL correlated with its low molecular weight (0.92 kDa) and specific monosaccharide composition (41.50 mol% glucose and 58.50 mol% fructose), likely facilitating receptor binding and cellular uptake. These findings identify MSCPL as a key anti-inflammatory component, providing a molecular basis for developing inflammation-targeted functional foods.