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About half of the world's population is infected with the bacterium Helicobacter pylori. For colonization, the bacterium neutralizes the low gastric pH and recruits immune cells to the stomach. The immune cells secrete cytokines, i.e. , the pro-inflammatory IL-17A, which directly or indirectly damage surface epithelial cells. Since (I) dietary proteins are known to be digested into bitter tasting peptides in the gastric lumen, and (II) bitter tasting compounds have been demonstrated to reduce the release of pro-inflammatory cytokines through functional involvement of bitter taste receptors (TAS2Rs), we hypothesized that the sweet-tasting plant protein thaumatin would be cleaved into anti-inflammatory bitter peptides during gastric digestion. Using immortalized human parietal cells (HGT-1 cells), we demonstrated a bitter taste receptor TAS2R16-dependent reduction of a H. pylori -evoked IL-17A release by up to 89.7 ± 21.9% (p ≤ 0.01). Functional involvement of TAS2R16 was demonstrated by the study of specific antagonists and siRNA knock-down experiments. [Display omitted] • Sweet-tasting thaumatin is cleaved into bitter peptides during gastric digestion. • Bitter peptides stimulate the proton secretion of immortalized human partial cells. • Native proteins of H. pylori induce increased IL-17A release in HGT-1 cells. • Bitter peptides reduce the release of IL-17A induced by H. pylori. • Stimulation of H+ secretion and reduction of IL-17A release are TAS2R16-mediated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Arabica-specific bitter tastant mozambioside degrades during coffee roasting. • Previously unknown pyrolysis products with higher bitter intensity are generated. • The structures of the new compounds are elucidated by NMR and HR-MS. • The new compounds are potent agonists for TAS2R43 and TAS2R46 (HEK 293T-Gα16gust44). • Molecular Docking simulations reveal their orientation within the bitter receptor. Arabica coffee contains the bitter-tasting diterpene glycoside mozambioside , which degrades during coffee roasting, leading to yet unknown structurally related degradation products with possibly similar bitter-receptor-activating properties. The study aimed at the generation, isolation, and structure elucidation of individual pyrolysis products of mozambioside and characterization of bitter receptor activation by in vitro analysis in HEK 293T-Gα16gust44 cells. The new compounds 17- O - β - d -glucosyl-11-hydroxycafestol-2-on, 11- O - β - d -glucosyl-16-desoxycafestol-2-on, 11- O -β- d -glucosyl- (S) -16-desoxy-17-oxocafestol-2-on, 11- O - β - d -glucosyl-15,16-dehydrocafestol-2-on, and 11- O - β - d -glucosyl- (R) -16-desoxy-17-oxocafestol-2-on were isolated from pyrolyzed mozambioside by HPLC and identified by NMR and UHPLC-ToF-MS. Roasting products 11- O -β- d -glucosyl- (S) -16-desoxy-17-oxocafestol-2-on, 11- O - β - d -glucosyl-15,16-dehydrocafestol-2-on, and 11- O - β - d -glucosyl- (R) -16-desoxy-17-oxocafestol-2-on had lower bitter receptor activation thresholds compared to mozambioside. Molecular docking simulations revealed the binding modes of the compounds 11- O - β - d -glucosyl-15,16-dehydrocafestol-2-on and 11- O - β - d -glucosyl- (R) -16-desoxy-17-oxocafestol-2-on and their aglycone 11-hydroxycafestol-2-on in the two cognate receptors TAS2R43 and TAS2R46. The newly discovered roasting products 17- O - β - d -glucosyl-11-hydroxycafestol-2-on, 11- O -β- d -glucosyl- (S) -16-desoxy-17-oxocafestol-2-on, 11- O - β - d -glucosyl-15,16-dehydrocafestol-2-on, and 11- O - β - d -glucosyl- (R) -16-desoxy-17-oxocafestol-2-on were detected in authentic roast coffee brew by UHPLC-ToF-MS and could contribute to coffee's bitter taste impression. [ABSTRACT FROM AUTHOR]

Highlights • Bitter peptide fraction had more positive charges, but less umami peptide residues. • HPH peptide fractions significantly inhibited quinine bitterness. • The least bitter peptide fractions had the most bitter-inhibitory effect. • HPH peptides are the blockers of human T2R4, T2R7, and T2R14. • HPH fraction is a rich T2R antagonist source. Abstract Bitter sensation is mediated by various bitter taste receptors (T2Rs), thus T2R antagonists are actively explored. Our objective was to look for novel T2R blockers in hen protein hydrolysate (HPH). We screened the least bitter HPH fractions using electronic tongue, and analyzed their peptide sequences and calcium mobilization in HEK293T cells expressing T2Rs. The results showed that the HPH fractions with higher bitterness intensity had higher hydrophobicity, more hydrophobic amino acids, and more positively charged peptides, but fewer known umami peptides. The peptide fractions from the least bitter HPH fraction significantly inhibited quinine bitterness (P < 0.05), and also significantly inhibited quinine- or diphenhydramine-dependent calcium mobilization of HEK293T cells expressing human T2R4, T2R7, or T2R14 (P < 0.05). Among them, the first eluted (least bitter) peptide fraction showed the strongest bitter-inhibitory effect. In conclusion, HPH peptides are the blockers of T2R4, T2R7, and T2R14. [ABSTRACT FROM AUTHOR]