Inhibitory Effects of Oolong Tea Polyphenols on Pancreatic Lipase in Vitro

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• 作者：Masaaki Nakai ; Yuko Fukui ; Sumio Asami ; Yoshiko Toyoda-Ono ; Takashi Iwashita ; Hiroshi Shibata ; Tohru Mitsunaga ; Fumio Hashimoto ; and Yoshinobu Kiso
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2005
• 出版时间：June 1, 2005
• 年：2005
• 卷：53
• 期：11
• 页码：4593 - 4598
• 全文大小：106K
• 年卷期：v.53,no.11(June 1, 2005)
• ISSN：1520-5118

文摘

Fifty-four polyphenols isolated from tea leaves were evaluated for their inhibitory activities againstpancreatic lipase, the key enzyme of lipid absorption in the gut. (-)-Epigallocatechin 3-O-gallate(EGCG), which is one of major polyphenols in green tea, showed lipase inhibition with an IC₅₀ of0.349 M. Moreover, flavan-3-ol digallate esters, such as (-)-epigallocatechin-3,5-digallate, showedhigher activities of inhibition on lipase with an IC₅₀ of 0.098 M. On the other hand, nonesterifiedflavan-3-ols, such as (+)-catechin, (-)-epicatechin, (+)-gallocatechin, and (-)-epigallocatechin,showed zero and/or the lowest activities against pancreatic lipase (IC₅₀ > 20 M). These datasuggested that the presence of galloyl moieties within the structure was required for enhancement ofpancreatic lipase inhibition. It is well-known that flavan-3-ols are polymerized by polyphenol oxidaseand/or heating in a manufacturing process of oolong tea. Oolonghomobisflavans A and B andoolongtheanin 3'-O-gallate, which are typical in oolong tea leaves, showed strong inhibitory activitieswith IC₅₀ values of 0.048, 0.108, and 0.068 M, respectively, even higher than that of EGCG. Theoolong tea polymerized polyphenols (OTPP) were prepared for the assay from oolong tea extract,from which the preparation effectively subtracted the zero and/or less-active monomeric flavan-3-olsby preparative high-performance liquid chromatography. The weight-average molecular weight (Mw)and number-average molecular-weight (Mn) values of OTPP were 2017 and 903, respectively, byusing gel permeation choromatography. OTPP showed a 5-fold stronger inhibition against pancreaticlipase (IC₅₀ = 0.28 g/mL) by comparison with that of the tannase-treated OTPP (IC₅₀ =1.38 g/mL). These data suggested that the presence of galloyl moieties within their chemicalstructures and/or the polymerization of flavan-3-ols were required for enhancement of pancreaticlipase inhibition.Keywords: Oolong tea; flavan-3-ol; polymerized polyphenol; lipase inhibition