PYC extract acts as an agonist of Toll-Like Receptor (TLR)1/2 and TLR2/6 and as a partial agonist of TLR5. HEK 293 cells expressing the receptors (A) TLR1/2, (B) TLR2/6, (C) TLR5, (D) TLR2, and (E) TLR4 were incubated for 24 h with different concentrations of PYC and catechin (CAT) or their known ligands as positive controls (PAM3, PAM2, flagellin, lipoteichoic acid (LTA), and LPS, resp.). All corresponding positive ligands induced TLR activation, confirming functionality of the assays. (F) HEK 293 cells expressing TLR5 were incubated for 24 h with different concentrations of PYC and CAT in combination with its known ligand as positive control (flagellin). Results are expressed as fold change of fluorescence intensity to unstimulated cells cultured in medium as control (n = 4 as technical replicates) All data are expressed as the mean ± SD. p-values < 0.05 are considered statistically significant, as analyzed with one-way ANOVA with Tukey post hoc comparison test (GraphPad Prism). Significant differences are indicated by asterisks: * p < 0.05; ** p < 0.01; *** p < 0.001.