A-type procyanidin derivatives with antioxidant and much enhancedα-glucosidase inhibitor activities

A型原花青素衍生物的制备、抗氧化和α-葡萄糖苷酶抑制活性研究

Procyanidins are natural compounds with good biological activity.However,due to a large number of phenolic hydroxyl groups in the structure,they have high polarity and low bioavailability.The preparation of A-type proanthocyanidin derivatives is an effective way to change their polarity and biological activity.In this paper,a series of A-type procyanidin derivatives were designed and synthesized by two practical and safe methods,and two new dimeric A-type procyanidin derivatives,procyanidin A1-acetone conjugate(6)and procyanidin A2-cystein conjugate(9)were obtained and reported for the first time.Their structures were characterized and confirmed by ^(1)H NMR,^(13)C NMR,HMBC,^(1)H-^(1)H COSY and MS.All the compounds showed strong DPPH scavenging activities.Compound 6 showed inhibitory effects onα-glucosidase with an IC_(50) value of 8.7μg/mL,while its parental compound,procyanidin A1,had no inhibitory effects.Degradation of procyanidins from peanut skin by L-cystein was studied.The results showed that the main structural unit of procyanidins in peanut skin was A-type proanthocyanidins dimer.

原花青素是一类具有良好生物活性的天然化合物,但由于其结构中含有大量的酚羟基,造成其极性大、生物利用度较低的特点。制备A型原花青素衍生物是改变其极性和生物活性的有效手段。本文采用两种安全可靠的制备方法,合成了一系列A型原花青素衍生物,并通过^(1)H NMR、^(13)C NMR、H MBC、^(1)H-^(1)H COSY和MS对其结构进行鉴定,其中有两种新的原花青素A型二聚体衍生物:原花青素A1-丙酮缩合物(6)和原花青素A2-半胱氨酸衍生物(9)。活性测试结果表明所有化合物均具有较强的DPPH自由基清除活性。化合物6对α-葡萄糖苷酶有较强的抑制活性,IC_(50)值为8.7μg/mL,其前体化合物原花青素A1对α-葡萄糖苷酶无抑制作用。采用L-cystein对花生红衣中原花青素多聚体进行降解研究,实验结果表明花生红衣中原花青素多聚体的主要结构单元为A型原花青素二聚体。