title: Use of experimental design methodology to prepare Maillard reaction products from glucose and cysteine inhibitors of polyphenol oxidase from eggplant (Solanum melongena).
abstract: Polyphenol oxidase (PPO) from eggplant was extracted and partially purified by a two-step fractionation-precipitation using ammonium sulfate and phenylsepharose hydrophobic interaction chromatography. The eggplant PPO extract was characterized concerning its kinetic properties. Optimal conditions to obtain Maillard reaction products (MRPs) with a maximal inhibitory potency (IP) toward PPO activity were determined using the surface response methodology and a four-factor and five-level experimental design. The MRPs were prepared from cysteine (0.25 M) and glucose (0-1 M), at several initial pH values (2-6) and at differing heating times (3-19 h) and temperatures (95-115 degrees C). The maximal IP was obtained after heating a model system of glucose/cysteine (1/0.25 M) at pH 2 for 3 h 20 min at 115 degrees C. The soluble part of this MRP, called MRP(IPmax), was a noncompetitive inhibitor toward eggplant PPO. The IP of MRP(IPmax) on PPO activity was very potent as compared to that displayed by benzoic, p-coumaric, and t-cinnamic acids, as well as sorbic acid and 4-hexylresorcinol. The activity of preincubated PPO at 0 degrees C with MRP(IPmax) was only slightly restored after dialysis or gel filtration.
authors.affiliation: Conservatoire National des Arts et Métiers, Chaire de Biochimie Industrielle et Agro-Alimentaire, UMR SCALE 1211, 292 Rue Saint Martin, Case 306-75141 Paris Cedex 03, France.
authors.forename: Sophie C
authors.initials: SC
authors.lastname: Cheriot
authors.forename: Catherine
authors.initials: C
authors.lastname: Billaud
authors.forename: Jacques
authors.initials: J
authors.lastname: Nicolas
mesh_terms: D019817:Benzoic Acid / Q000494:pharmacology; D004156:Catechol Oxidase / Q000037:antagonists & inhibitors*; D002934:Cinnamates / Q000494:pharmacology; D003373:Coumaric Acids / Q000494:pharmacology; D003545:Cysteine / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D005947:Glucose / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D015416:Maillard Reaction; D011422:Propionates; D032323:Solanum melongena / Q000201:enzymology*; D013011:Sorbic Acid / Q000494:pharmacology; D013997:Time Factors
chemical_list: D002934:Cinnamates; D003373:Coumaric Acids; D004791:Enzyme Inhibitors; D011422:Propionates; C029010:cinnamic acid; D019817:Benzoic Acid; D004156:Catechol Oxidase; C495469:p-coumaric acid; D005947:Glucose; D003545:Cysteine; D013011:Sorbic Acid