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Grant Abstract

Grant Number: 5R01AT006882-02
PI Name: Jiang
Project Title: Anti-inflammatory mechanisms, pharmacokinetics of novel metabolites of vitamin E

Abstract: DESCRIPTION (provided by applicant): Vitamin E supplementation has been commonly used as a CAM (Complementary and Alternative Medicine). Clinical studies on vitamin E have focused exclusively on 1-tocopherol (1T), but they have yielded disappointing results regarding potential health benefits. However, we and others have shown that other vitamin E forms and especially their novel metabolites have unique anti-inflammatory properties that are not possessed by 1T. In particular, we have demonstrated that 13'-carboxychromanol (4-13'-COOH), a long-chain metabolite derived from 4- tocopherol (4T), inhibits cyclooxygenases (COX-1 and COX-2) and 5-lipoxygenase (5-LOX) with potency similar to ibuprofen (a commonly used non-steroid anti-inflammatory drugs - NSAID) and zileuton (a clinically used 5-LOX inhibitor), respectively. Meanwhile, 3-tocopherol (3T) and 4T, but not 1T, inhibited COX-2-mediated prostaglandin E2 generation in cells and suppressed 5-LOX-mediated leukotriene B4 production in neutrophils by blocking calcium influx. In a preliminary study, we have found that 4T exhibited promising anti-arthritis effects. Since these vitamin E forms and metabolites inhibit both COXs- and 5-LOX-mediated pro-inflammatory pathways, we propose that these compounds may be superior to commonly used NSAIDs as anti-inflammatory and anti-arthritis agents because most NSAIDs only inhibit COX- catalyzed pathway. In addition, due to stronger inhibition of COXs and 5-LOX, we propose that 13'-COOH may be more effective than un-metabolized vitamins. To test these hypotheses, we will 1) investigate the effect and mechanism of long-chain carboxychromanols on COX-1/-2 and 5-LOX-catalyzed reactions in cell- and enzyme-based studies, 2) develop a new LC-MS-MS assay for vitamin E metabolites and characterize the pharmacokinetics of 4-13'-COOH, 3T and 4T, 3) translate the unique anti-inflammatory activity of 4-13'-COOH and vitamin E forms observed in vitro to a rat inflammation model and compare their anti-inflammatory efficacy to established NSAIDs, and 4) translate the anti-inflammatory actions to a disease relevant model by investigating anti-arthritis efficacy of 4-13'-COOH, 3T and 4T in the rat adjuvant-induced arthritis model. Our studies on these vitamin E forms and their novel metabolites may lead to discovery of a new class of anti-inflammatory agents that may be safer than some commonly used anti-inflammatory drugs and yet have similar or superior efficacy. The proposed studies will elucidate mechanisms of anti-inflammatory action and generate important preclinical data that are needed to insure maximally informative clinical efficacy studies on these compounds.

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