Novel Dual Inhibitors of 5-Lipoxygenase and Thromboxane A2 Synthetase: Synthesis and Structure-Activity Relationships of 3-Pyridylmethyl-Substituted 2-Amino-6-hydroxybenzothiazole Derivatives
作者:Shigeki Hibi、Yasushi Okamoto、Katsuya Tagami、Hirotoshi Numata、Naoki Kobayashi、Masanobu Shinoda、Tetsuya Kawahara、Manabu Murakami、Kiyoshi Oketani
DOI:10.1021/jm00045a011
日期:1994.9
As part of our search for novel antiinflammatory drug candidates, we have designed and synthesized a series of 3-pyridylmethyl-substituted 2-amino-6-hydroxybenzothiazoles. Introduction of a 3-pyridylmethyl group into the 2-amino group (type-A) or the benzene ring (type-B) of 2-amino-6-hydroxybenzothiazoles imparted dual inhibitory activity against the production by glycogen-induced peritoneal cells of rat (in vitro) of leukotriene B-4 (LTB(4)) and thromboxane A(2) (TXA(2)), while not significantly inhibiting that of prostaglandin E(2) (PGE(2)). The observed inhibition of the former two arachidonic acid metabolites was indicated to be the result of a direct action on 5-Lipoxygenase and TXA(2) synthetase by a cell-free in vitro assay. On the other hand, the inhibitory activities against PGE(2) production were for most compounds very weak, indicating that they did not inhibit cyclooxygenase. Structure-activity relationship studies concerning the position of the 3-pyridylmethyl group revealed that type-B compounds generally showed about 10-fold stronger inhibitory activity against TXA(2) synthetase than type-A compounds. The position of the 3-pyridylmethyl group played an important role in TXA(2) synthetase inhibition. When some of these compounds (8, 13a, 26a (E3040), 26b, 27b, and 28b) were orally administered in the rat TNB/ethanol-induced chronic colitis model (100 mg/ kg), the production of both LTB(4) and TXB(2) in the rat colon was reduced (ex vivo). In addition, one type-B compound, 6-hydroxy-5,7-dimethyl-2-(methylamino)-4 zole (26a), demonstrated a therapeutic effect at treatments of 100 mg/kg po once daily for 11 days and showed almost comparable activity to sulfasalazine at a dose of 500 mg/kg, the reference drug for inflammatory bowel diseases, in this in vivo model.