아스코르빈산과 티올류 및 유기산이 폴리페놀 산화효오 활성에 미치는 영향

Effects of Ascorbic Acid, Thiols and Organic Acid on Polyphenol Oxidase Activity

The effects of ascorbic acid, thiols such as cysteine, n-acetyl-l- cyteine, glutathione, thiourea, 2-mercaptoethanol and dithiotreithol and organic acids such as magic acid, citric acid, glycolic acid, taurine and kojic acid on polyphenol oxidase (PPO) activity were studied in order to establish if it reacts with oxidized product an[Vor directly inhibits the enzyme. To investigate the mechanism, the quantiscation of t-butylcatechol and 4-methylcatechol (phenolic compounds) as substrates, their oxidized product and sul-phydryl colorless additional compounds were determined by high performance liquid chromatograph (HPLC) method. Chromatographic results indicate that ascorbic acid, organic acids and lower level of cgsteine reduced oxidized product of substrates back to their respective positions oleo-diphenols. On the other hand, other thiols and high level of cysteine reacted with oxidative product of o-diphenols and then produced sulphydryl colorless compounds. Cysteine apperars to have two types of mechanism of actions in the formation of oxidative products of substrates depending on its concentration; ascorbic acid-type and other thiols-types. The effect of ascorbic acid with thiols on polyphenol oxidase was determined by same method. Chromatographic results indicate that ascorbic acid was more reactive with oxidized product of substrates than thiols.