Discovery of <i>N</i>-<scp>l</scp>-Lactoyl-<scp>l</scp>-Trp as a Bitterness Masker via Structure-Based Virtual Screening and a Sensory Approach

Abstract

N - Lactoyl-amino acid derivatives ( N - Lac-AAs) are of increasing interest as potential taste-active compounds. The complexity and diversity of N - Lac-AAs pose a significant challenge to the effective discovery of taste-active N - Lac-AAs. Therefore, a structure-based virtual screening was used to identify taste-active N -Lac-AAs. Virtual screening results showed that N -lactoyl-hydrophobic amino acids had a higher affinity for taste receptors, specifically N - l -Lac -l -Trp. And then, N - l -Lac -l -Trp was synthesized in yields of 22.3% by enzymatic synthesis in the presence of l -lactate and l -Trp, and its chemical structure was confirmed by MS/MS and one-dimensional (1D) and two-dimensional (2D) NMR. Sensory evaluation revealed that N - l -Lac -l -Trp had a significant taste-masking effect on quinine, d -salicin, caffeine, and l -Trp, particularly l -Trp and caffeine. N - l -Lac -l -Trp had a better masking effect on the higher concentration of bitter compounds. It reduced the bitterness of caffeine (500 mg/L) and l -Trp (1000 mg/L) by approximately 20 and 26%, respectively. The result of the ligand–receptor interaction and a quantum mechanical analysis showed that N - l -Lac -l -Trp increased the binding affinity to the bitter receptor mainly through hydrogen bonding and lowering the electrostatic potential.

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