Li Ke, Yao Fan, Xue Qiang, Fan Hang, Yang Lingguang, Li Xiang, Sun Liwei, Liu Yujun
National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Biotechnology, Beijing Forestry University, Qinghuadonglu No. 35, Haidian District, Beijing, 100083, China.
Chem Cent J. 2018 Jul 12;12(1):82. doi: 10.1186/s13065-018-0445-y.
A flavonoids-rich extract of Scutellaria baicalensis shoots and its eight high content flavonoids were investigated for their inhibitory effects against α-glucosidase and α-amylase. Results show that abilities of the extract in inhibiting the two enzymes were obviously higher than those of acarbose. Moreover, inhibitory abilities of all the eight individual flavonoids against the two enzymes show exactly a same order (i.e., apigenin > baicalein > scutellarin > chrysin > apigenin-7-O-glucuronide > baicalin > chrysin-7-O-glucuronide > isocarthamidin-7-O-glucuronide), and their structure-activity relationship could be well-interpretated by the refined assign-score method. Furthermore, based on the inhibitory abilities and their contents in the extract, it was found that the eight flavonoids made predominant contributions, among which baicalein and scutellarin played roles as preliminary contributors, to overall inhibitory effects of the extract against the two enzymes. Beyond these, contributions of the eight flavonoids to the overall enzyme inhibitory activity were compared with those to the overall antioxidant activity characterized in our recent study, and it could be inferred that within the basic flavonoid structure the hydroxyl on C-4' of ring B was more effective than that on C-6 of ring A in enzyme inhibitory activities while they behaved inversely in antioxidant activities; scutellarin and apigenin contributed more to the overall enzyme inhibitory activity, and baicalin and scutellarin, to the overall antioxidant activity of the extract; and flavonoids of the extract, apart from directly inhibiting enzymes, might also be conducive to curing type 2 diabetes via scavenging various free radicals caused by increased oxidative stresses.
研究了黄芩嫩枝富含黄酮类化合物的提取物及其8种高含量黄酮类化合物对α-葡萄糖苷酶和α-淀粉酶的抑制作用。结果表明，该提取物对这两种酶的抑制能力明显高于阿卡波糖。此外，所有8种单一黄酮类化合物对这两种酶的抑制能力呈现出完全相同的顺序（即芹菜素＞黄芩素＞黄芩苷＞白杨素＞芹菜素-7-O-葡萄糖醛酸苷＞黄芩苷＞白杨素-7-O-葡萄糖醛酸苷＞异刺槐素-7-O-葡萄糖醛酸苷），并且它们的构效关系可以通过精细的赋值评分法得到很好的解释。此外，基于抑制能力及其在提取物中的含量，发现这8种黄酮类化合物对提取物对这两种酶的总体抑制作用起主要贡献，其中黄芩素和黄芩苷起初步贡献作用。除此之外，将这8种黄酮类化合物对总体酶抑制活性的贡献与我们最近研究中表征的总体抗氧化活性的贡献进行了比较，可以推断，在基本黄酮类结构中，B环C-4'位的羟基在酶抑制活性方面比A环C-6位的羟基更有效，而在抗氧化活性方面则相反；黄芩苷和芹菜素对提取物的总体酶抑制活性贡献更大，黄芩苷和黄芩苷对提取物的总体抗氧化活性贡献更大；提取物中的黄酮类化合物除了直接抑制酶外，还可能通过清除由氧化应激增加引起的各种自由基而有助于治疗2型糖尿病。
