Two Natural Flavonoid Substituted Polysaccharides from : Structural Characterization and Anticomplement Activities.

Two novel natural flavonoid substituted polysaccharides (MBAP-1 and MBAP-2) were obtained from Lour. and characterized by HPGPC, methylation, ultra-high-performance liquid chromatography-ion trap tandem mass spectrometry (UPLC-IT-MS), and NMR analysis. The results showed that MBAP-1 was a homogenous heteropolysaccharide with a backbone of 4)-β-d-Glc-(1→ and →3,4,6)-β-d-Glc-(1→. MBAP-2 was also a homogenous polysaccharide which possessed a backbone of →3)-α-d-Glc-(1→, →4)-β-d-Glc-(1→ and →3,4)-β-d-Glc-2-OMe-(1→. Both the two polysaccharides were substituted by quercetin and exhibited anticomplement activities in vitro. However, MBAP-1 (CH: 0.075 ± 0.004 mg/mL) was more potent than MBAP-2 (CH: 0.249 ± 0.006 mg/mL) and its reduced product, MBAP-1R (CH: 0.207 ± 0.008 mg/mL), indicating that multiple monosaccharides and uronic acids might contribute to the anticomplement activity of the flavonoid substituted polysaccharides of . Furthermore, the antioxidant activity of MBAP-1 was also more potent than that of MBAP-2. In conclusion, these two flavonoid substituted polysaccharides from were found to be potential oxidant and complement inhibitors.