title: Inhibitory effects of propyl gallate on tyrosinase and its application in controlling pericarp browning of harvested longan fruits.
abstract: Tyrosinase (EC 1.14.18.1), also known as polyphenol oxidase (PPO), is a key enzyme in pigment biosynthesis of organisms. The inhibitory effects of propyl gallate on the activity of mushroom tyrosinase and effects of propyl gallate on pericarp browning of harvested longan fruits in relation to phenolic metabolism were investigated. The results showed that propyl gallate could potently inhibit diphenolase activity of tyrosinase. The inhibitor concentration leading to 50% activity lost (IC50) was determined to be 0.685 mM. Kinetic analyses showed that propyl gallate was a reversible and mixed type inhibitor on this enzyme. The inhibition constants (K(IS) and K(I)) were determined to be 2.135 and 0.661 mM, respectively. Furthermore, the results also showed that propyl gallate treatment inhibited activities of PPO and POD in pericarp of harvested longan fruits, and maintained higher contents of total phenol and flavonoid of longan pericarp. Moreover, propyl gallate treatment also delayed the increases of browning index and browning degree in pericarp of harvested longan fruits. Therefore, application of propyl gallate may be a promising method for inhibiting tyrosinase activity, controlling pericarp browning, and extending shelf life of harvested longan fruits.
authors: Institute of Postharvest Technology of Agricultural Products, College of Food Science, Fujian Agriculture and Forestry University , Fuzhou, Fujian 350002, China.
authors: Yi-Fen
authors: YF
authors: Lin
authors: Yong-Hua
authors: YH
authors: Hu
authors: He-Tong
authors: HT
authors: Lin
authors: Xuan
authors: X
authors: Liu
authors: Yi-Hui
authors: YH
authors: Chen
authors: Shen
authors: S
authors: Zhang
authors: Qing-Xi
authors: QX
authors: Chen
mesh_terms: D004156:Catechol Oxidase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005519:Food Preservation / Q000379:methods*; D005638:Fruit / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D007700:Kinetics; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D010940:Plant Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D011435:Propyl Gallate / Q000494:pharmacology*; D029631:Sapindaceae / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology*
chemical_list: D004791:Enzyme Inhibitors; D010940:Plant Proteins; D011435:Propyl Gallate; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase