To enhance the hypoglycemic effects of inulin, banana condensed tannins (BCT) were grafted onto inulin via a free radical method to synthesize the novel BCT grafted inulin (BCT-g-inulin) complex. Spectroscopic methods, XRD, TGA, ¹H NMR, GPC and morphology analyses were utilized to characterize the structural properties of the BCT-g-inulin complex, and our results confirmed the conjugation of BCT and inulin. The conjugation possibly occurred between the hydroxyl group attached at the C₆ position of inulin and the C₆/C₈ position of flavon-3-ol units of BCT. The grafting ratio and grafting efficiency of the BCT-g-inulin complex were 357.54 ± 2.98 g kg⁻¹ complex and 74.57 ± 1.44%, respectively. The data of the antioxidant assays indicated that the BCT-g-inulin complex showed a significantly higher antioxidant activity than native inulin. Also, the grafting reaction remarkably improved the in vitro anti-diabetic activity of inulin. The glucose adsorption capacity and glucose dialysis retardation index of the BCT-g-inulin complex were remarkably higher than those of inulin, while the BCT-g-inulin complex showed much stronger inhibitory effects against α-amylase and α-glucosidase compared with inulin. Notably, the inhibition of both α-amylase and α-glucosidase by the BCT-g-inulin complex occurred through mixed-competitive mode. On the basis of fluorescence spectroscopy, the fluorescence of α-amylase and α-glucosidase could be quenched by the BCT-g-inulin complex through a static quenching mechanism. Hence, the BCT-g-inulin complex might have the potential to be developed as an effective anti-diabetic agent.

中文翻译：

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香蕉浓缩单宁-菊粉结合物的制备，表征及体外降血糖活性。

为了增强菊粉的降血糖作用，香蕉浓缩单宁（BCT）通过自由基方法嫁接到菊粉上，合成了新型BCT嫁接菊粉（BCT-g-菊粉）复合物。利用光谱法，XRD，TGA，¹ H NMR，GPC和形态分析来表征BCT-g-菊粉复合物的结构特性，我们的结果证实了BCT和菊粉的结合。在菊粉的C ₆位上的羟基与BCT的flavon-3-ol单元的C ₆ / C ₈位上的羟基之间可能发生共轭。BCT-g-菊粉复合物的接枝率和接枝效率为357.54±2.98 g kg ^-1复杂度为74.57±1.44％。抗氧化剂测定的数据表明，BCT-g-菊粉复合物显示出比天然菊粉显着更高的抗氧化剂活性。另外，接枝反应显着改善了体外菊粉的抗糖尿病活性。BCT-g-菊粉复合物的葡萄糖吸附能力和葡萄糖透析阻滞指数显着高于菊粉，而BCT-g-菊粉复合物对α-淀粉酶和α-葡萄糖苷酶的抑制作用比菊粉强得多。值得注意的是，BCT-g-菊粉复合物对α-淀粉酶和α-葡萄糖苷酶的抑制都是通过混合竞争模式发生的。在荧光光谱学的基础上，BCT-g-菊粉复合物可以通过静态猝灭机制猝灭α-淀粉酶和α-葡萄糖苷酶的荧光。因此，BCT-g-菊粉复合物可能具有被开发为有效的抗糖尿病药的潜力。