魔芋葡甘露寡糖的制备、化学结构及对胰岛NO自由基释放量的影响

The Preparation and Chemical Structure of Amorphophallus albus Konjac Oligosaccharides and Their Effects on NO Free Radical Release from the STZ-induced Diabetic Islets

魔芋精粉经 β 甘露聚糖酶酶解成寡糖后 ,用活性炭柱进行分离纯化 ,以不同浓度 (5 % ,10 % ,2 0 % )的乙醇洗脱 .研究不同洗脱组分对链脲佐菌素 (STZ)诱导糖尿病模型的胰岛NO自由基释放量的影响 .发现 1mg ml以 5 %乙醇洗脱的寡糖可以使胰岛培养液中的NO自由基释放量平均下降2 5 4 % (P <0 0 5 ) ,0 1mg ml以 5 %乙醇洗脱的寡糖使NO自由基水平下降 2 0 % (P <0 0 5 ) .结果表明 ,5 %乙醇洗脱的魔芋寡糖对保护胰岛免受链脲佐菌素 (STZ)的破坏有一定的作用 .用凝胶色谱、红外光谱、元素分析、核磁共振光谱、质谱等方法初步分析了 5 %乙醇洗脱的魔芋寡糖的化学结构 .发现该糖是一种四糖 ,分子量为 6 6 6 .其推测性结构式为 :β D Man(1→ 4 ) β D Man(1→ 4 ) β D Glc(1→ 4 )α D Man ,β D Man(1→ 4 ) β D Glc(1→ 4 ) β D Man(1→ 4 )α D Man或 β D Glc(1→ 4 ) β D Man(1→4 ) β D Man(1→ 4 )α D Man .

Amorphophallus albus Konjac glucomannan was enzymatically hydrolyzed to oligosaccharides by β mannase After removing protein, the oligosaccharides were purified in activated charcoal column by fractional elution with 5%,10%,20% ethanol. The elution products were named as KOS1,KOS2,KOS3, respectively. Effects of KOS1,KOS2 and KOS3 on nitric oxide (NO) free radical release from STZ induced diabetic islets were studied. NO was decreased by 25 4% and 20% when 1 mg/ml and 0 1 mg/ml KOS1 were added to the medium, respectively. The results indicated that KOS1 could protect the islets from being destroyed by streptozotocin in some degree. Sephadex G\|50 column chromatography, FTIR, elemental analysis, NMR and MALDI TOF mass spectrametry were used to analyze the physicochemical properties and structure of KOS1.The results suggest that KOS1 is a tetrasaccharide with molecular weight 666.Its conjectural chemical structures are as follows: β D Man(1→4)β D Man(1→4)β D Glc(1→4)α D Man,β D Man(1→4)β D Glc(1→4)β D Man(1→4)α D Man or β D Glc(1→4)β D Man(1→4)β D Man(1→4)α D Man.