New agents for lowering blood sugar found in a common flowering garden plant

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New agents for lowering blood sugar found in a common flowering garden plant

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The complex plant flavonol glycoside montbretin A is a potent (K-i = 8 nM) and specific inhibitor of human pancreatic alpha-amylase with potential as a therapeutic for diabetes and obesity. Controlled degradation studies on montbretin A, coupled with inhibition analyses, identified an essential high-affinity core structure comprising the myricetin and caffeic acid moieties linked via a disaccharide. X-ray structural analyses of the montbretin A-human alpha-amylase complex confirmed the importance of this core structure and revealed a novel mode of glycosidase inhibition wherein internal pi-stacking interactions between the myricetin and caffeic acid organize their ring hydroxyls for optimal hydrogen bonding to the alpha-amylase catalytic residues D197 and E233. This novel inhibitory motif can be reproduced in a greatly simplified analog, offering potential for new strategies for glycosidase inhibition and therapeutic development.
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