Abstract
The effects of herbal remedies aiding digestion are well known, but the underlying mechanisms remain poorly understood. Notably, many of these preparations are bitter, and bitter-tasting phenolic food constituents have been shown to induce digestive processes by activating extra-oral bitter taste receptors (TAS2Rs). This study examined the effects of a commercially available herbal mixture preparation used to aid digestive discomfort and nine solvent extracts thereof on proton secretion of immortalized human parietal cells (HGT-1). The bitter taste of the preparation was sensorially evaluated, and its impact on the gene expression of the polyphenol-related receptors TAS2R4, TAS2R5, and TAS2R39 was analyzed. Functional TAS2R involvement was validated using CRISPR-Cas9 knock-out and siRNA knock-down approaches. Total polyphenol content was quantified using Folin-Ciocalteu reagent. The bitter-tasting herbal mixture preparation and several of its solvent extracts stimulated proton secretion by HGT-1 cells concentration-dependently. Four extracts exhibited high total polyphenol content and induced strong secretory responses, whereas five extracts showed lower content and weaker effects (p < 0.01). Reduced responses were observed in TAS2R4ko, TAS2R5kd, and TAS2R39ko cells. In conclusion, bitter-tasting plant extracts can stimulate TAS2R-mediated digestive processes depending on their total polyphenol content, thereby supporting their use as promising remedies for alleviating digestive discomfort.