title: Inhibition of α-amylase and glucoamylase by tannins extracted from cocoa, pomegranates, cranberries, and grapes.
abstract: Proanthocyanidins and ellagitannins, referred to as "tannins", exist in many plant sources. These compounds interact with proteins due to their numerous hydroxyl groups, which are suitable for hydrophobic associations. It was hypothesized that tannins could bind to the digestive enzymes α-amylase and glucoamylase, thereby inhibiting starch hydrolysis. Slowed starch digestion can theoretically increase satiety by modulating glucose "spiking" and depletion that occurs after carbohydrate-rich meals. Tannins were isolated from extracts of pomegranate, cranberry, grape, and cocoa and these isolates tested for effectiveness to inhibit the activity of α-amylase and glucoamylase in vitro. The compositions of the isolates were confirmed by NMR and LC/MS analysis, and tannin-protein interactions were investigated using relevant enzyme assays and differential scanning calorimetry (DSC). The results demonstrated inhibition of each enzyme by each tannin, but with variation in magnitude. In general, larger and more complex tannins, such as those in pomegranate and cranberry, more effectively inhibited the enzymes than did less polymerized cocoa tannins. Interaction of the tannins with the enzymes was confirmed through calorimetric measurements of changes in enzyme thermal stability.
authors.affiliation: PORT/Combat Feeding Directorate, US Army Natick Soldier Research, Development & Engineering Center (NSRDEC), Natick, Massachusetts 01760-5018, United States. ann.h.barrett.civ@mail.mil
authors.forename: Ann
authors.initials: A
authors.lastname: Barrett
authors.forename: Tshinanne
authors.initials: T
authors.lastname: Ndou
authors.forename: Christine A
authors.initials: CA
authors.lastname: Hughey
authors.forename: Christine
authors.initials: C
authors.lastname: Straut
authors.forename: Amy
authors.initials: A
authors.lastname: Howell
authors.forename: Zifei
authors.initials: Z
authors.lastname: Dai
authors.forename: Gonul
authors.initials: G
authors.lastname: Kaletunc
mesh_terms: D002099:Cacao / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D005087:Glucan 1,4-alpha-Glucosidase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006868:Hydrolysis; D047348:Hydrolyzable Tannins / Q000737:chemistry / Q000494:pharmacology*; D029561:Lythraceae / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D044945:Proanthocyanidins / Q000737:chemistry / Q000494:pharmacology*; D013213:Starch / Q000737:chemistry; D053719:Tandem Mass Spectrometry; D029799:Vaccinium macrocarpon / Q000737:chemistry; D027843:Vitis / Q000737:chemistry; D000516:alpha-Amylases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D047348:Hydrolyzable Tannins; D044945:Proanthocyanidins; D013213:Starch; D000516:alpha-Amylases; D005087:Glucan 1,4-alpha-Glucosidase