Conversion of a cyclooxygenase (CO) inhibitor into a 5-lipoxygenase (LO) inhibitor: a general route to novel orally active anti-inflammatory and anti-allergy drugs.

Previously, the conversion of a CO inhibitor, naproxen, into an orally active 5-LO inhibitor, Wy-50,295, by covalent attachment of a quinoline group was reported. The authors now report the extension of this transformation to other CO inhibitors. Replacement of an existing substituent or a hydrogen in sulindac, etodolac, carprofen, diclofenac, oxaprozin, des-alpha-methyl-ketoprofen, or des-alpha-methyl-flurbiprofen by a methoxyquinoline group afforded new hybrid structures which were orally active 5-LO inhibitors in the rat RPAR (reverse passive Arthus reaction) assay. In contrast to Wy-50,295 which is a selective 5-LO inhibitor, some of these new hybrids were dual inhibitors of 5-LO and CO. For example, the quinoline-etodolac hybrid WAY-120,739, (1,8-diethyl-1,3,4,9-tetrahydro-6-(2-quinolinylmethoxy)pyrano [3,4-b]indole-1-acetic acid) was a dual inhibitor of 5-LO and CO (91% and 47% inhibition, respectively at 10 microM, rat PMN). In contrast, the quinoline-flurbiprofen hybrid WAY-121,006, (3-fluoro-4'-(2-quinolinylmethoxy)-[1,1'-biphenyl]-4-acetic acid), the quinoline-oxaprozin hybrid, WAY-120,460, (5-phenyl-4-[4-(2- quinolinylmethoxy)phenyl]-2-oxazolepropanoic acid) and the quinoline-carprofen hybrid WAY-120,429 (alpha-methyl-6-(2-quinolinylmethoxy)-9-(2-quinolinylmethoxy)-9H- carbazole-2-acetic acid) were purely 5-LO inhibitors (100%, 96% and 92% inhibition of 5-LO at 10 microM, rat PMN, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

N-phenyl-2-pyridinecarbothioamides as gastric mucosal protectants.

A series of substituted 2-pyridinecarbothioamides was synthesized and evaluated for gastric mucosal protectant activity in the rat. Out of this investigation N-(3,5-difluorophenyl)-2- pyridinecarbothioamide (23, AY-31,574) was identified. This compound was much more potent than sucralfate and ranitidine against ethanol-induced lesions. Compound 23 was equipotent with ranitidine against gastric injury caused by stress. Unlike ranitidine, 23 was found to be devoid of antisecretory activity in the pylorus-ligated rat model, making it a selective mucosal protectant. Such a potent selective mucosal protectant may provide a novel clinical approach in treating ulcers.

Structure-activity relationships among analogues of pemedolac, cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indo le-1-a cetic acid, a potent analgesic agent.

The syntheses of analogues of pemedolac (cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indol e-1-acetic acid), a potent analgesic, are described. They were tested for analgesic and antiinflammatory effects in vivo and for inhibition of prostaglandin production in vitro. Analysis of structure-activity relationships shows that analgesic activity in this series is associated with 1S-cis stereochemistry, the presence of a pi-system (allyl or benzyl) at position 4, and a log P value greater than 4.0.

Etodolac, a novel antiinflammatory agent. The syntheses and biological evaluation of its metabolites.

The syntheses of five metabolites of the antiinflammatory drug etodolac (1,8-diethyl-1,3,4,9-tetrahydropyrano-[3,4-b]indole-1-acetic acid) are described, viz. 6-hydroxyetodolac, N-methyletodolac, 4-ureidoetodolac, 8-(1'-hydroxy)etodolac, and 4-oxoetodolac. These syntheses were used to confirm the identities of the metabolites. The metabolites themselves, as well as the previously reported metabolite 7-hydroxyetodolac, were tested in a rat adjuvant edema model and in vitro for their capacity to block prostaglandin production in chondrocyte cells. All either were inactive or possessed only marginal activity. The isolation of N-methyletodolac and 4-oxoetodolac from human and rat urine, respectively, is also described.

Synthesis and analgesic activity of pemedolac (cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]ind ole-1- acetic acid).

The synthesis of cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indole -1-acetic acid, pemedolac (USAN), is described. This compound has been found to be a potent analgesic agent in primary screening. Pemedolac has been resolved and the active (+)-enantiomer assigned a 1S,4R absolute configuration on the basis of a crystallographic analysis of its (S)-(-)-borneol ester.

Etodolac (1,8-diethyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid): a potent antiinflammatory drug. Conformation and absolute configuration of its active enantiomer.

The active (+) enantiomer of the antiinflammatory agent etodolac (1,8-diethyl-1,3,4,9-tetrahydropyrano[3,4-b]-indole-1-acetic acid) has been assigned an S absolute configuration on the basis of a crystallographic analysis of the (S)-(-)-borneol ester of (-)-etodolac, and the conformation of etodolac has been determined by a crystallographic analysis of (+/-)-etodolac. Analyses of the solid-state conformation, as well as energy-minimized conformations obtained by molecular mechanics calculations, have failed to provide a basis for identifying a probable receptor-site conformation.

Disposition and biotransformation of 14C-etodolac in man.

Four human subjects were given a capsule containing 200 mg of 14C-etodolac. At the peak (two hours after dosing), most of the radioactivity in serum was due to etodolac; subsequently, metabolites gradually appeared. The elimination half-life of etodolac from serum averaged six hours. Etodolac was greater than 99% bound to human serum proteins. An average of 73% of the dose was excreted in the urine and 14% in faeces within seven days, with 61% appearing in the urine during the first 24 h. Microbial transformation of etodolac was employed to biosynthesize sufficient amounts of two urinary metabolites to facilitate structure elucidation. Five metabolites, representing 65% of the radioactivity in urine collected 0-24 h after dosing (61% of the dose was excreted in urine within 24 h), were isolated and characterized by t.l.c., g.c., h.p.l.c., n.m.r (1H and 13C) and m.s. Most of the identified urinary components were conjugates of etodolac and three hydroxylated metabolites (6-hydroxyetodolac, 7-hydroxyetodolac and 8-(1-hydroxyethyl)etodolac). Two metabolites were identified as glucuronyl ester conjugates of etodolac and 7-hydroxyetodolac; the former represented about 20% of the urinary radioactivity. False positive tests for bilirubin in urine of patients treated with etodolac were found to be due to the two phenolic metabolites.

Resolution of etodolac and antiinflammatory and prostaglandin synthetase inhibiting properties of the enantiomers.

Etodolac, 1,8-diethyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid, a clinically effective analgesic and antiinflammatory agent, has been resolved via a chromatographic separation of its diastereoisomeric esters with (-)-borneol. The effects of the enantiomers were studied in vitro on prostaglandin synthetase and on adjuvant-induced arthritis in rats. The biochemical and pharmacological results show that virtually all of the effects of etodolac are due to the (+) enantiomer.

Etodolic acid and related compounds. Chemistry and antiinflammatory actions of some potent di- and trisubstituted 1, 3, 4, 9-tetrahydropyrano[3, 4-b]indole-1-acetic acids.

A series of 37 1-ethyl- and 1-n-propyl-1, 3, 4, 9-tetrahydropyrano[3, 4-b]indole-1-acetic acids bearing one, or two, substituents on the benzene ring has been synthesized via the acid-catalyzed condensation of a substituted tryptophol with ethyl propionylacetate or ethyl butyrylacetate. Antiinflammatory and ulcerogenic effects were examined and the results show that 1, 8-diethyl-1, 3, 4, 9-tetrahydropyrano[3, 4-b]indole-1-acetic acid (etodolic acid, USAN) is a potent agent, particularly active against a chronic rat model of inflammation (ED50 0.7 + 1-0.1 mg/kg po in the adjuvant arthritis model) and which has a relatively low acute ulcerogenic potential in the same species.

3,4-Dihydro-1H-1,4-oxazino[4,3-a]indoles as potential antidepressants.

A series of 3,4-dihydro-1H-1,4-oxazino[4,3-a]indoles bearing basic side chains has been synthesized by a novel chemical process. These compounds have been screened for potential antidepressant activity. One of these derivatives, 3,4-dihydro-1,10-dimethyl-1-(3-methylaminopropyl)-1H-1,4-oxazino[4,3-a]indole (AY-23,673), was particularly potent in the prevention of reserpine ptosis test in mice, with an ED50 of 0.5 mg/kg ip.

Chemistry and antiinflammatory activities of prodolic-acid and related 1,3,4,9-tetrahydropyrano[3,4-b]indole-1-alkanoic acids. 1.

The synthesis and antiinflammatory activities of a series of 23 novel 1,3,4,9-tetrahydropyrano[3,4-b]indole-1-alkanoic acids are described and some relationships between structure and activity are discussed. One of these compounds, 1,3,4,9-tetrahydro-1-propylpyrano[3,4-b]indole-1-acetic acid (prodolic acid, USAN), has been selected for further studies.