Phenolic group on A-ring is key for dracoflavan B as a selective noncompetitive inhibitor of alpha-amylase

Toh Zhi Siang; Wang Hongyu; Yip Yew MunLu YuyunLim Benedict Jeffrey AngZhang DaiweiHuang Dejian

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Phenolic group on A-ring is key for dracoflavan B as a selective noncompetitive inhibitor of alpha-amylase

机译：Phenolic group on A-ring is key for dracoflavan B as a selective noncompetitive inhibitor of alpha-amylase

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A high throughput assay was applied to guide the isolation of a new pancreatic alpha-amylase inhibitor, dracoflavan B, from the dragon's blood resin from Daemonorops draco. Applying C18 column, we successfully isolated both diastereomers and their structures verified by H-1 NMR spectra in comparison with the literature values. Their activity in inhibition of pancreatic alpha-amylase with comparable IC50 values of 23 mu M (A type) and 27 mu M (B type) that are similar to that of acarbose. Dracoflavan B shows much weaker activity in inhibiting bacterial alpha-amylase and no activity towards fungal alpha-amylase. Moreover, both isomers show no inhibitory activity towards mammalian alpha-glucosidase. Kinetic analysis revealed that using starch as the substrate, dracoflavan B was a non-competitive alpha-amylase inhibitor with a K-i value of 11.7 mu M. Lack of alpha-amylase inhibition for proanthocyanidin A2 dimer demonstrated that dracoflavan B hydrophobic nature of the B, A', C' and B' rings are important for its alpha-amylase inhibition. In addition, selective chemical modification studies revealed that the phenolic group is also vital to dracoflavan B for its pancreatic alpha-amylase inhibition activity. Without the A ring phenolic hydrogen bond donor, the derivatives of dracoflavan B showed detrimental alpha-amylase inhibition. On the contrary, galloylation on the A ring phenolic OH group enhanced the activity as shown by the low IC50 (12 mu M) against alpha-amylase which is 56 more potent as compared to dracoflavan B. (c) 2015 Elsevier Ltd. All rights reserved.

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《Bioorganic and medicinal chemistry》 |2015年第24期|7641-7649|共9页
作者
Toh Zhi Siang; Wang Hongyu; Yip Yew MunLu YuyunLim Benedict Jeffrey AngZhang DaiweiHuang Dejian;
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作者单位

Natl Univ Singapore, Dept Chem, Food Sci & Technol Program, Singapore 117543, Singapore;

Div Chem & Biol Chem, Singapore 639798, Singapore;

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正文语种英语
中图分类药学;
关键词
Dracoflavan B; alpha-Amylase inhibitors; Daemonorops draco; Proanthocyanidins;

Phenolic group on A-ring is key for dracoflavan B as a selective noncompetitive inhibitor of alpha-amylase

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