Flavonoid constituents contribute to the low diastase activity of Triadica cochinchinensis honey through in vitro enzyme inhibition and in vivo transcriptional regulation.

Diastase activity is a key international criterion for assessing honey quality, indicative of freshness and the absence of excessive heat treatment. This study found that the diastase activity of Triadica cochinchinensis honey (TCH) was only 3.45, significantly lower than other 11 common honeys with range of 9.96 to 23.06. Furthermore, its diastase activity abnormally decreased during honey ripening. Flavonoids have been reported to effectively inhibit diastase activity. The underlying mechanisms were investigated in vitro and in vivo based on the characteristic flavonoids in TCH identified by LC-MS/MS, i.e. unique (-)-gallocatechin gallate (GCG) and high-content naringenin chalcone (NGC). In vitro enzymatic assays indicated that GCG and NGC inhibited α-amylase activity via mixed-type. The binding of GCG and NGC on α-amylase was further characterized by fluorescence quenching and molecular docking. In vivo studies revealed that dietary supplementation of GCG and NGC suppressed the α-amylase gene expression in the hypopharyngeal glands of honey-ripening bees (15-day-old) by 78.92% and 67.71%, respectively, and in foragers (25-day-old) by 91.14% and 56.48%, respectively. Network pharmacology analysis linked this suppression by interfering with four α-amylase-related pathways.