Abstract：
:The effects of green and black tea polyphenols on cyclooxygenase (COX)- and lipoxygenase (LOX)-dependent arachidonic acid metabolism in normal human colon mucosa and colon cancers were investigated. At a concentration of 30 microg/mL, (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), and (-)-epicatechin-3-gallate (ECG) from green tea and theaflavins from black tea inhibited LOX-dependent activity by 30-75%. The formation of 5-, 12-, and 15-LOX metabolites was inhibited to a similar extent. Tea polyphenols also inhibited COX-dependent arachidonic acid metabolism in microsomes from normal colon mucosa, with ECG showing the strongest inhibition. The formation of thromboxane (TBX) and 12-hydroxyheptadecatrienoic acid (HHT) was decreased to a greater extent than other metabolites. The inhibitory effects of tea polyphenols on COX activity, however, were less pronounced in tumor microsomes than in normal colon mucosal microsomes. Theaflavins strongly inhibited the formation of TBX and HHT, but increased the production of prostaglandin E(2) (PGE(2)) in tumor microsomes. The enhancing effect of theaflavins on PGE(2) production was related to the COX-2 level in the microsomes. Although theaflavin inhibited ovine COX-2, its activity in the formation of PGE(2) was stimulated by theaflavin when ovine COX-2 was mixed with microsomes, suggesting that theaflavin affects the interaction of COX-2 with other microsomal factors (e.g. PGE synthase). The present results indicate that tea polyphenols can affect arachidonic acid metabolism in human colon mucosa and colon tumors, and this action may alter the risk for colon cancer in humans.
journal_name
Biochem Pharmacoljournal_title
Biochemical pharmacologyauthors
Hong J,Smith TJ,Ho CT,August DA,Yang CSdoi
10.1016/s0006-2952(01)00767-5subject
Has Abstractpub_date
2001-11-01 00:00:00pages
1175-83issue
9eissn
0006-2952issn
1873-2968pii
S0006-2952(01)00767-5journal_volume
62pub_type
杂志文章abstract：:Phospholipase A2 activity was detected in 7-day-old carrageenin-induced inflammatory tissue of rats using a synthetic substrate. 1-acyl-2-[3H]arachidonyl-phosphatidylcholine. The inflammatory tissue was homogenized in saline containing 1 M KCl, and the 105,000 g supernatant fraction was placed on a Sephadex G-100 colu...
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pub_type： 杂志文章
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pub_type： 杂志文章
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pub_type： 杂志文章
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pub_type： 杂志文章
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pub_type： 杂志文章
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pub_type： 杂志文章
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pub_type： 杂志文章
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pub_type： 杂志文章
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
doi：10.1016/j.bcp.2010.07.030
更新日期：2010-11-15 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
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更新日期：1982-06-01 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章,评审
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更新日期：2018-09-01 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
doi：10.1016/0006-2952(92)90595-a
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pub_type： 杂志文章
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更新日期：2007-02-01 00:00:00
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pub_type： 杂志文章,评审
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
doi：10.1016/0006-2952(82)90594-9
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pub_type： 杂志文章,评审
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更新日期：1996-09-13 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
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更新日期：1987-08-15 00:00:00
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更新日期：2012-01-15 00:00:00
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pub_type： 杂志文章,评审
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更新日期：2012-08-01 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章,评审
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更新日期：2002-07-01 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
doi：10.1016/0006-2952(86)90653-2
更新日期：1986-11-01 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
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更新日期：2009-02-01 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
doi：10.1016/0006-2952(93)90069-9
更新日期：1993-01-26 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
doi：10.1016/0006-2952(92)90064-p
更新日期：1992-11-03 00:00:00
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journal_title：Biochemical pharmacology
pub_type： 杂志文章
doi：10.1016/0006-2952(92)90342-g
更新日期：1992-12-01 00:00:00
abstract：:The salt-induced condensation of chromatin has been studied with flow-linear dichroism technique using an intercalative dye (methylene blue) to selectively monitor the linker orientation. At low ionic strength both linkers and chromatosomes (with their flat faces) are oriented preferentially parallel to the chromatin ...
journal_title：Biochemical pharmacology
pub_type： 杂志文章
doi：10.1016/0006-2952(88)90459-5
更新日期：1988-05-01 00:00:00
