Identification\nof 4′-Demethyl-3,9-dihydroeucomin\nas a Bitter-Masking Compound from the Resin of Daemonorops\ndraco

Masking the bitter taste of foods is one of the key strategies\nto improve their taste and palatability, particularly in the context\nof clean labeling, where natural compounds are preferred. Despite\nthe demand, the availability of natural bitter-masking compounds remains\nlimited. Here, we identified the bitter-masking compound 4′-demethyl-3,9-dihydroeucomin\n(<b>DMDHE</b>) isolated from the resin of Daemonorops\ndraco by means of an activity-guided in vivo (sensory\nbitterness rating of quinine) and in vitro (cell-based bitter response\nassays) approach. First, a mean bitter-masking effect of −29.6\n± 6.30% on the bitterness perceived from quinine [10 ppm] was\ndemonstrated for an organic solvent extract of the resin of D. draco (= DD [500 ppm]) in a sensory trial. The\nresults were verified in a cell-based bitter assay in which the bitter\ntaste receptor (TAS2R)-dependent proton secretion serves as an outcome\nmeasure of the cellular bitter response in parietal HGT-1 cells. By\nmeans of preparative RP-18 high-performance liquid chromatography\n(HPLC) analysis combined with activity-guided sensory evaluations,\nthe most potent bitter-masking fractions were identified. Subsequent\nquantitative liquid chromatography/high-resolution mass spectrometry/charged\naerosol detection/ultraviolet (LC-HRMS/CAD/UV), NMR analysis, followed\nby gram-scale synthesis, led to the characterization of <b>DMDHE</b> as bitter-masking homoisoflavanone. <b>DMDHE</b> decreased\nthe sensory bitterness of quinine by 14.8 ± 5.00%. Functional\ninvolvement of TAS2R14 was demonstrated by means of a CRISPR-Cas9\napproach, which revealed a reduction of the <b>DMDHE</b>-evoked\nbitter-masking effect by 40.4 ± 9.32% in HGT-1 <i>TAS2R14ko</i> versus HGT-1 wt cells.