Antibacterial and enzyme inhibitory activities of flavan-3-ol monomers and procyanidin-rich grape seed fractions
Paola Solis Ares, Gautam Gaur, Benjamin P. Willing, Fabian Weber, Andreas Schieber, Michael G. Gänzle
Abstract
This study aimed to determine structure–function relationships of monomeric and oligomeric flavan-3-ols (procyanidins) with respect to their antimicrobial activity and their inhibition of digestive enzymes. Monomeric flacan-3-ols were purchased as reference compounds; oligomeric procyanidins were extracted from grape seeds, separated by high-performance counter-current chromatography and characterized by LC-MS/MS. The antimicrobial activity against a broad range of intestinal microorganisms increased in the order catechin = epicatechin > epigallocatechin and oligomeric procyanidins > epigallocatechin gallate. Facultative anaerobes were highly resistant while strict anaerobes including Allobaculum sp. and Ruminococcus gnavus were 10 – 100 times more sensitive. The inhibition of digestive enzymes from the rat small intestine increased in the order catechin < epicatechin and oligomeric procyanidins < epigallocatechin < epigallocatechin gallate. Trimeric and polymeric procyanidins were more inhibitory than dimeric procyanidins. Both the antimicrobial and enzyme-inhibitory activities of procyanidins and flavan-3-ols likely relate to their microbiome-modulating and health beneficial properties.