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

A high throughput assay was applied to guide the isolation of a new pancreatic α-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 (1)H NMR spectra in comparison with the literature values. Their activity in inhibition of pancreatic α-amylase with comparable IC50 values of 23μM (A type) and 27μM (B type) that are similar to that of acarbose.