naringenin

Naringenin is the flavanone aglycone (the basic structure with sugar removed) of the bitter glycoside naringin found in citrus; it is released when naringinase hydrolyzes the neohesperidose moiety. A 2014 degree thesis (a chapter corresponding to a 2013 JAFC paper) tested a library of flavonoid and isoflavonoid compounds in a cell assay with bitter taste receptors hTAS2R14 and hTAS2R39 expressed. It has been reported that naringenin activated both of these receptors, with detection thresholds of 16 and 8 micromolar, respectively, and EC50 (half-maximal effective concentration) of 36.2 and 32.9 micromolar, respectively.

The same test compound set did not include naringin itself, which is a glycoside. A 2013 paper that forms a pair with this reported, for a broader compound set, 68 compounds activating hTAS2R14 and 70 compounds activating hTAS2R39 (of which 58 activated both), with activation thresholds ranging from 0.12 to 500 micromolar. However, the abstract of this paper does not list individual compound names. Modeling in the same research indicates that when sugar is added (glycosidation), hTAS2R14 activation is impaired, indicating that sugar addition from naringenin to naringin may change the receptor's susceptibility to activation.

Within the scope of the abstract, according to evaluation by a trained sensory panel, complex formation with bovine lactoferrin reduced naringenin's maximum bitterness intensity by approximately 27% and overall bitterness perception by approximately 33%. Isothermal titration nanocalorimetry, molecular docking, and molecular dynamics simulation characterized this complex formation as entropy-driven binding to hydrophobic sites.