Biotransformation and Epithelial Toxicity of Prenylated Phenolics from Licorice Roots (Glycyrrhiza spp.) in 3D Apical-Out Mucus-Producing Human Enteroids

Apical-out enteroids mimic the in vivo environment well due to their accessible apical surface and mucus layer, making them an ideal model for studying the impact of (bioactive) food compounds. Generated human ileal apical-out enteroids showed a fucose-containing mucus layer surrounding the apical brush border on their exposure side, indicating their physiological relevance. Effects on the mucosal epithelium of antibacterial prenylated phenolics (glabridin, licochalcone A, and glycycoumarin) from licorice roots were investigated for cytotoxicity, cell viability, barrier integrity, and biotransformation. At concentrations up to 500 μg mL^-1, licochalcone A and glycycoumarin did not significantly affect apical-out enteroids, with cytotoxicities of −6 ± 2 and −2 ± 2% and cell viabilities of 77 ± 22 and 77 ± 13%, respectively (p > 0.05). Conversely, 500 μg mL^-1 glabridin induced significant cytotoxicity (31 ± 25%, p < 0.05) and reduced cell viability (21 ± 14%, p < 0.01). Apical-out enteroids revealed differential sensitivities to prenylated phenolics not observed in apical-in enteroids and Caco-2 cells. Both enteroid models showed phase II biotransformation but differed in the extent of glucuronide conversion. The apical mucus layer of apical-out enteroids likely contributed to these differential interactions, potentially due to differences in electrostatic repulsion. This study underscores the relevance of 3D apical-out enteroid models and highlights the promise of prenylated phenolics for antimicrobial applications.