Gallotannins are uncompetitive inhibitors of pancreatic lipase activity

Inhibition of pancreatic lipase (PL) is used to treat dyslipidemias and obesity. Phenolic compounds are highly bioactive molecules that can inhibit various enzymes. Our aim was to evaluate the inhibitory activity of selected phenolic compounds of increasing molecular complexity, namely, phenolic acids, mangiferin, penta-O-galloyl-β-d-glucose (PGG) and tannic acid (TA) against porcine PL, according to in vitro and in silico methodologies. TA and PGG were effective inhibitors (IC₅₀ 22.4 and 64.6 μM, respectively), with strong affinity towards the enzyme-substrate complex (uncompetitive inhibition). Fluorescence quenching suggested phenolic-enzyme interactions, which may occur at the PL-colipase complex interface, according to molecular docking. Interactions are likely between hydroxyl groups and polar amino acid residues. We conclude that TA and PGG, but not simple phenolic acids, are effective PL inhibitors, likely due to their numerous hydroxyl groups, which promote phenolic-enzyme interactions. Thus, their consumption may exert health benefits derived from their effects on this digestive enzyme.

Keywords: Enzyme kinetics; Hydroxyl group; Molecular docking; Phenolic compound.