title: Simulated digestion of proanthocyanidins in grape skin and seed extracts and the effects of digestion on the angiotensin I-converting enzyme (ACE) inhibitory activity.
abstract: This study investigated the effect of in vitro gastrointestinal digestion on the stability and composition of flavan-3-ols from red grape skin and seed extracts (raw and purified, which are high in proanthocyanidins (PAs)). In addition, the effects of digestion on the angiotensin I-converting enzyme (ACE) inhibitory activities of these extracts were evaluated. The extracts were digested with a mixture of pepsin-HCl for 2 h, followed by a 2 h incubation with pancreatin and bile salts including a cellulose dialysis tubing (molecular weight cut-off 12 kDa) at 37°C with shaking in the dark and under N2. Under gastric conditions, the mean degree of polymerisation (mDP) of seed extracts, raw (mDP≈6, p<0.05), and purified (mDP≈10, p<0.05) was stable. The mDP of the raw skin extracts increased from 19 to 25 towards the end of the digestion. The PAs were significantly degraded (up to 80%) during the pancreatic digestion, yielding low-molecular-weight compounds that diffused into the serum-available fraction (mDP≈2). The overall mass transfer coefficient (K) of the seed extracts was 10(-7) m(2)/s. After simulated gastrointestinal digestion, over 80% of ACE inhibition by raw seed and skin extracts was preserved. However, the purified seed and skin extracts lost their ability to inhibit ACE after intestinal digestion.
authors.affiliation: Bioengineering Laboratory, Department of Chemical Engineering, Faculty of Engineering, Universidad de Concepción, Barrio Universitario s/n, Concepción, Chile. kfernandeze@udec.cl
authors.forename: Katherina
authors.initials: K
authors.lastname: Fernández
authors.forename: Javiera
authors.initials: J
authors.lastname: Labra
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000737:chemistry* / Q000378:metabolism; D004063:Digestion; D005638:Fruit / Q000737:chemistry / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D007703:Peptidyl-Dipeptidase A / Q000737:chemistry / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry* / Q000378:metabolism; D044945:Proanthocyanidins / Q000737:chemistry* / Q000378:metabolism; D012639:Seeds / Q000737:chemistry* / Q000378:metabolism; D027843:Vitis / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D010936:Plant Extracts; D044945:Proanthocyanidins; D007703:Peptidyl-Dipeptidase A