Metabolism of 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2 (1H)-one (L-696,229), an HIV-1 reverse transcriptase inhibitor, by rat liver slices and in humans.

Healthy subjects were administered single oral doses of 800 mg or 400 mg 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-o ne (L-696,229), a nonnucleoside inhibitor of the human immunodeficiency virus-type 1 (HIV-1) reverse transcriptase (RT). Plasma or urine samples were collected over a period of 48 hr. Pooled plasma (0.5-6 hr) and urine (0-24 hr) samples were analyzed by HPLC-UV and HIV-1 RT inhibition assay using poly rC.dG as a template primer. The parent compound and several common metabolites were detected in both samples. The metabolic profiles were also similar to those obtained from a rat liver slice incubation with [3H]L-696,229. The in vitro metabolites were identified by NMR and MS as 5 alpha-hydroxyethyl- (major), 5,6-dihydrodiol-, 6'-hydroxy-, 6-hydroxymethyl-, and 5-vinyl analogs, and a benzoxazole ring hydrolysis product. Most of the significant metabolites in human plasma and urine were found to be identical to the in vitro metabolites, as established by HPLC-UV and MS. Hydrolysis of the plasma and urine with beta-glucuronidase/sulfatase indicated the presence of significant amounts of conjugates of the parent compound and 5 alpha-hydroxyethyl metabolite. Most of the other primary metabolites were also present in conjugated forms, albeit in small quantities. In addition, two secondary metabolites were isolated and identified from the hydrolyzed urine as 5-acetyl-6'-hydroxy- and 5 alpha-hydroxyethyl-6-hydroxymethyl- analogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis and evaluation of 2-pyridinone derivatives as HIV-1-specific reverse transcriptase inhibitors. 4. 3-[2-(Benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-one and analogues.

A new series of potent specific 2-pyridinone reverse transcriptase (RT) inhibitors was developed based on the preliminary development lead 3-[(phthalmido)ethyl]-5-ethyl-6-methylpyridin-2(1H)-one (3), a non-nucleoside derivative which exhibited weak antiviral activity in cell culture against HIV-1 strain IIIB. One compound, 3-[(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-one (9,L-696,229), which was a highly selective antagonist of the RT enzyme (IC50 = 23 nM) and which inhibited the spread of HIV-1 IIIB infection by > 95% in MT4 human T-lymphoid cell culture (CIC95 = 50-100 nM), was selected for clinical evaluation as an antiviral agent.

5-chloro-3-(phenylsulfonyl)indole-2-carboxamide: a novel, non-nucleoside inhibitor of HIV-1 reverse transcriptase.

A series of highly potent, structurally novel, non-nucleoside RT inhibitors has been described. Low nanomolar concentrations of 5-chloro-3-(phenylsulfonyl)-indole-2-carboxamide (1) inhibit the HIV-1 RT enzyme in vitro and HTLVIIIb viral spread in MT-4 human T-lymphoid cells. Good oral bioavailability was observed in rhesus monkeys upon oral dosing of 1 as a suspension in methocel. When compared to other non-nucleoside inhibitors (e.g. 15-18), 1 possesses improved inhibitory potency with respect to the wild-type RT, as well as the K103N and Y181C mutant enzymes. Additional studies within this class of inhibitors are in progress.

Synthesis and evaluation of 2-pyridinone derivatives as specific HIV-1 reverse transcriptase inhibitors. 3. Pyridyl and phenyl analogs of 3-aminopyridin-2(1H)-one.

In an ongoing effort to develop novel nonnucleoside, specific human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) inhibitors, a series of 3-[(pyridylmethyl)amino]- and 3-[(phenylmethyl)amino]-2-pyridinone derivatives was synthesized and tested for HIV-1 RT inhibitory activity. The more potent compounds have a 2'-methoxy group and 4'- and/or 5'-aliphatic substituents on the pyridyl and phenyl rings. Several of the more potent compounds were also evaluated for antiviral activity in MT-4 cell culture. From this series of compounds, 3-[N-[(5-ethyl-2-methoxy-6-methyl-3-pyridyl)methyl]amino]-5-ethyl-6- methylpyridin-2(1H)-one (6) was selected for clinical evaluation.

Metabolism of a new HIV-1 reverse transcriptase inhibitor, 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-one (L-696,229), in rat and liver slices.

L-696,229 is a potent and specific inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase and is currently undergoing clinical evaluation. In vivo metabolism in rats was investigated using an intravenous bolus dose of 5 mg/kg [3H]L-696,229. The amount of radioactivity eliminated in bile and urine over a period of 6 hr was 60 and 22%, respectively. Radiochromatographic analysis of the bile and urine showed that L-696,229 was metabolized rapidly and completely to several common metabolites. Sequential oxidation at the alpha-position of the 5-ethyl group to an acetyl moiety, aromatic hydroxylation of the benzoxazole group (position C4', C6', or C7'), and subsequent sulfate conjugation were the major metabolic pathways as determined by the application of enzymatic hydrolysis, FAB-MS, and 1H- and 13C-NMR spectroscopies. The in vitro metabolism of this 2-pyridinone derivative with rat liver slices resulted primarily in hydroxylation at the 6-methyl and 5-ethyl groups. The 6-hydroxymethyl- and 5-alpha-hydroxyethyl analogs were also inhibitors of HIV-1 reverse transcriptase.

Synthesis and evaluation of 2-pyridinone derivatives as HIV-1-specific reverse transcriptase inhibitors. 2. Analogues of 3-aminopyridin-2(1H)-one.

A series of nonnucleoside 3-aminopyridin-2(1H)-one derivatives was synthesized and evaluated for HIV-1 RT inhibitory properties. Several analogs proved to be potent and highly selective antagonists with in vitro IC50 values as low as 19 nM in the enzyme assay using rC.dG as template-primer. Two compounds from this series, 3-[[(4,7-dimethylbenzoxazol-2-yl)methyl]-amino]-5-ethyl-6-methy lpyridin-2(1H)-one (34, L-697,639) and the corresponding 4,7-dichloro analogue (37, L-697,661) inhibited the spread of HIV-1 IIIb infection by 95% in MT4 cell culture at concentrations of 25-50 nM and were selected for clinical trials as antiviral agents.

Origin of monacolin L from Aspergillus terreus cultures.

In freshly harvested Aspergillus terreus cultures grown for the production of lovastatin (formerly called mevinolin), no monacolin L could be detected. However, during the isolation of lovastatin, significant quantities of monacolin L appeared. It has been discovered that a new metabolite structurally related to the members of the monacolin series is present. This metabolite is unstable and under mildly acidic conditions and elevated temperature, it converts to monacolin L. The subject metabolite is proven to be a hydroxylated derivative of dihydromonacolin L identified as 3 alpha-hydroxy-3,5-dihydromonacolin L. It seems that all monacolin L found later during various treatments of the broth and broth extracts is formed from that precursor via a dehydration reaction. The new metabolite was converted to its phenacyl ester, by means of extractive alkylation, for isolation and structure elucidation by chemical, chromatographic and spectroscopic methods. This ester, on standing, gradually formed the corresponding lactone.

Inhibitors of glycolic acid oxidase. 4-substituted 2,4-dioxobutanoic acid derivatives.

Fourteen new 4-substituted 2,4-dioxobutanoic acids have been synthesized. These compounds, all of which contain lipophilic 4-substituents, are potent inhibitors in vitro of porcine liver glycolic acid oxidase. The I50 value of the two most potent representatives, 4-(4'-bromo[1,1'-biphenyl]-4-yl)-2, 4-dioxobutanoic acid (8) and 4-[4'-[[(3,4-dihydro-3-hydroxy-2H-1, 5-benzodioxepin-3-yl)methyl]thio][1,1'-biphenyl]-4-yl]-2, 4-dioxobutanoic acid (13) is 6 X 10(-8)M.

Synthesis and receptor binding studies relevant to the neuroleptic activities of some 1-methyl-4-piperidylidene-9-substituted-pyrrolo[2,1-b][3]benzazepine derivatives.

The synthesis of a series of 1-methyl-4-(9-substituted-11H-pyrrolo[2,1-b]benzazepin-11-ylidene)piperidines (4a-f) and 1-methyl-4-(9-substituted-6,11-dihydro-5H-pyrrolo[2,1-b][3]benzazepin-11-ylidene)piperidines (4g-l) is described. As with th e 3-substituted cyproheptadine compounds 1b-e, atropisomerism exists in 4b-f, but unlike the enantiomers of 1b-e, the pyrrolobenzazepine enantiomers racemize at room temperature. Thus, the bromo compound (+)-4b has a half-life of 128 +/- 1 min at 25 degrees C, while the chloro compound (-)-4c has a half-life of 114 +/- 9 min at 25 degrees C. Compounds 4a-l have been examined for receptor binding affinities in assays that have been recognized as predictive for antipsychotic activity. The displacement of specifically bound tritiated ligands, comprising the dopamine antagonist [3H]spiperone, the dopamine agonist [3H]apomorphine, the muscarinic cholinergic antagonist [3H]quinuclidinyl benzilate (QNB), the alpha-adrenergic antagonist [3H]prazosin, the alpha-adrenergic agonist [3H]clonidine, the serotonin-1 binding agent [3H]serotonin, and the mixed serotonin agonist-antagonist [3H]lysergic acid diethylamide (LSD), by 4a-l has been measured utilizing membrane preparations of mammalian brain. Certain of the features of the receptor binding of these compounds have been shown to be common to several of the receptor sites. Data from these binding studies have been compared to corresponding data previously obtained for a series of chiral 3-substituted cyproheptadine analogues, and the receptor binding data of the two classes of compounds are discussed with respect to their molecular geometries.

Inhibitors of glycolic acid oxidase. 4-Substituted 3-hydroxy-1H-pyrrole-2,5-dione derivatives.

An extensive series of novel 4-substituted 3-hydroxy-1H-pyrrole-2,5-dione derivatives has been prepared and studied as inhibitors of glycolic acid oxidase (GAO). Compounds possessing large lipophilic 4-substituents are, in general, potent, competitive inhibitors of porcine liver GAO in vitro. Methylation of the nitrogen or the 3-hydroxy substituent reduced potency dramatically, indicating the requirement for the two acidic functions on the 1H-pyrrole-2,5-dione nucleus. In rat liver perfusion studies, with three representative compounds, concentration-dependent inhibition of the conversion of [1-14C]glycolate to [14C]oxalate was observed. Chronic oral administration to ethylene glycol fed rats of the 4-(4'-bromo[1,1'-biphenyl]-4-yl) derivative (83) was shown to effect a significant reduction in urinary oxalate levels over a 58-day period.

Urinary metabolites of timolol from humans and laboratory animals. Syntheses and beta-adrenergic blocking activities.

Syntheses are reported for three metabolites (2-4) of timolol (1) formed by oxidative metabolism of the morpholine ring. GLC-MS comparisons are presented which establish that the two metabolites whose structures were previously in question are identical with their synthetic counterparts 2 and 3. In 2, metabolic oxidation of the 4-morpholinyl group of 1 had occurred at the carbon next to oxygen to give the 2-hydroxy-4-morpholinyl moiety, whereas in 3, the morpholine of 1 has been oxidized one step further and then ring opened to produce the N-(2-hydroxyethyl)glycine substituent. Biological testing of synthetic samples of the three major metabolites from human urine (3, 4, and 6) indicated that only 4, in which the morpholine moiety has been degraded to a 2-hydroxyethylamino group, had significant beta-adrenergic blocking activity (one-seventh that of timolol in anesthetized dogs).

Inhibitors of indoleethylamine N-methyltransferase. Derivatives of 3-methyl-2-thiazolidinimine. In vitro, in vivo, and metabolic studies.

A variety of substituent groups has been attached to the exocyclic imine function of 2-imino-3-methylthiazolidine (1) in a search for metabolic precursors of this potent inhibitor of the enzyme indoleethylamine N-methyltransferase (INMT) which would exhibit superior pharmacodynamic properties in animals. It has been determined that chemically stable derivatives of 1 based on succinic, nicotinic, and N-acylated amino acids, although they lack in vitro efficacy, are potent inhibitors of INMT when administered orally or intravenously to rabbits. Metabolic studies carried out with 14C-labeled N,N'-bix(3-methyl-2-thiazolidinylidene)succinamide (3) have established that conversion of this compound to 1 occurs both in the whole rabbit and in the isolated rabbit liver. 1 itself has been shown to be metabolically inert in rabbits, being excreted primarily in the urine.

Quantitative structure-activity relationships involving the inhibition of glycolic acid oxidase by derivatives of glycolic and glyoxylic acids.

The enzyme glycolic acid oxidase oxidizes glycolate to glyoxylate and glyoxylate to oxalate. Three series of compounds related to the natural substrates, substituted glycolic, oxyacetic, and glyoxylic acids, have been investigated as inhibitors of this enzyme using the techniques of regression analysis and quantitative structure-activity relationships. The best overall correlation with inhibitory potencies was found with the Hansch hydrophobic parameter pi. The classical electronic parameters sigmap, sigmam, F, and R performed poorly. For the substituted glyoxylic acids, a dummy parameter relating to the presence of a nucleophilic group in close proximity to the alpha-carbonyl of the glyoxylate group was found to be highly significant. The syntheses of six novel glycolic and glyoxylic acids are described.

Cyclic amidine inhibitors of indolamine N-methyltransferase.

Syntheses of a large number of mono- and bicyclic, as well as a few tricyclic, amidine derivatives related to 2,3,4,6,7,8,-hexahydropyrrolo[1,2-a]pyrimidine (DBN) are reported. In vitro potencies for inhibition of the enzyme indolamine N-methyltransferase (INMT) from rabbit and human lung are presented. Four bicyclic amidine derivatives and 11 monocyclic derivatives were found to be equal or superior to DBN in in vitro potencies. With the bicyclic amidines, increasing ring size or introduction of substituents reduced activity. Among the monocyclic analogues, the most potent representatives were five- or six-membered systems with an exocyclic imino group, combined with methyl of ethyl substituents on the endocyclic nitrogen. Introduction of additonal substituents decreased inhibitory potency. 2,3,5,6-Tetrahydro-8H-imidazo[2,1-c][1,4]thiazine and 3-methyl-2-iminothiazolidine have been shown to cause inhibition of lung INMT when administered orally to rabbits.

Kojic amine--a novel gamma-aminobutyric acid analogue.

A series of compounds containing the 3-hydroxy-4H-pyran-4-one nucleus has been synthesized and tested as potential skeletal muscle relaxants. Reduction of 2-(azidomethyl)-5-hydroxy-4H-pyran-4-one (4) with HBr in HOAc--phenol yielded 2-(aminomethyl)-5-hydroxy-4H-pyran-4-one (kojic amine, 3) in 81% yield. Reaction of 2-[(tosyloxy)-methyl]-5-(benzyloxy)-4H-pyran-4-one (5) with NH3 gave a 40% yield of the O-benzyl ether of kojic amine, which was N-acylated with a series of carbobenzyloxy-protected amino acids. Complete deprotection with HBr--HOAc gave the following amino acid amides of kojic amine: glycyl (23), alpha-alanyl (24), beta-alanyl (25), gamma-aminobutyryl (26), and glycylglycyl (27). Among the analogues of kojic amine prepared was a series of one-carbon homologues: 2-[(methylamino)methyl]-5-hydroxy-4H-pyran-4-one (7a), 2-(1-aminoethyl)-5-hydroxy-4H-pyran-4-one (8), 6-(aminomethyl)-3-hydroxy-2-methyl-4H-pyran-4-one (12), and 2-(2-aminoethyl)-5-hydroxy-4H-pyran-4-one (16). Kojic amine (3) has been found to possess certain of the properties to be expected in a gamma-aminobutyric acid mimetic agent, notably skeletal muscle relaxant activity. In the chronic spinal cat preparation, ED70 values for reduction of flexor spasms of 2.2 and 4.0 mg/kg by iv and po routes of administration, respectively, were observed for kojic amine, which was the most potent of the various hydroxypyrone derivatives investigated.