Structure-activity relationships for inhibition of inosine monophosphate dehydrogenase by nuclear variants of mycophenolic acid.

Structure-activity relationships in the region of the phthalide ring of the inosine monophosphate dehydrogenase inhibitor mycophenolic acid have been explored. Replacement of the lactone ring with other cyclic moieties resulted in loss of potency, especially for larger groups. Replacement of the ring by acyclic substituents also indicated a strong sensitivity to steric bulk. A phenolic hydroxyl group, with an adjacent hydrogen bond acceptor, was found to be essential for high potency. The aromatic methyl group was essential for activity; the methoxyl group could be replaced by ethyl to give a compound with 2-4 times the potency of mycophenolic acid in vitro and in vivo.

Synthesis and biological activity of a series of diaryl-substituted alpha-cyano-beta-hydroxypropenamides, a new class of anthelmintic agents.

A series of alpha-cyano-beta-hydroxypropenamides was prepared and tested for anthelmintic activity. alpha-Cyano-beta-hydroxy-N-[4- (trifluoromethyl)phenyl]-3-[4-(trifluoromethyl)phenyl]propenamide (1) showed good activity against the nematode Nematospirodes dubius in a mixed parasite infection in mice; several of the analogues were also effective against the cestode Hymenolepis nana. In sheep trials, 1 caused 100% reduction of the hematophagous nematode Haemonchus contortus after a single dose of 20 mg/kg but did not show satisfactory control of Trichostrongylus colubriformis or Ostertagia circumcincta. Against the liver fluke Fasciola hepatica, 1 suppressed egg production but only temporarily, suggesting that the adult flukes were not eliminated. Mechanism of action studies on 1 using Ascaris mitochondria showed it to be an uncoupler of oxidative phosphorylation.

Synthesis and anthelmintic activity of 3'-benzoylurea derivatives of 6-phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole.

Reaction of 3-amino derivatives of the nematocides tetramisole and levamisole with variously substituted benzoylisocyanates gave a series of benzoylureas I which were tested for activity against helminths and ectoparasites. Compounds bearing 2,6-difluoro and 4-trifluoromethyl substituents had potent nematocidal activity in both mice and sheep. No antiectoparasitic activity was observed.

Synthesis and immunosuppressive activity of some side-chain variants of mycophenolic acid.

The syntheses and immunosuppressive bioassays of 12 side-chain variants of mycophenolic acid are described. The compounds were made either from mycophenolic acid itself or from 5-(chloromethyl)-1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-3-oxoisoben zofuran, a versatile intermediate for the synthesis of diverse side-chain variants. Replacement of the methylated E double bond of the natural product with a triple bond, a Z double bond, a saturated bond, or a sulfur atom, with overall chain lengths equal to or greater than that of mycophenolic acid, produced compounds devoid of significant activity. Replacement of the side-chain double bond with difluoro, dibromo, or unsubstituted cyclopropane rings also removed most activity. Replacement of the double bond with an allenic linkage yielded a compound with about one-fifth of the immunosuppressive activity of mycophenolic acid. Some possible causes for the unusual specificity of structure and activity are discussed.

Bioavailability improvement of mycophenolic acid through amino ester derivatization.

The potential bioavailability improvement of mycophenolic acid (MPA), 1, through ester derivatization was evaluated in monkeys at a dose of 20 mg/kg in this study. The acetyl solketal ester 3 was found to have excellent partition properties but poor aqueous solubility. Thus, even though it can be converted rapidly to MPA by plasma and liver enzymes, it showed poor oral bioavailability (56% of MPA) in monkeys. The bioavailability of the morpholinoethyl ester 4 and the acetyl morpholinoethyl ester 5, on the other hand, was found to be 236 and 150% that of MPA, respectively. Since ester 5 has greater aqueous solubility, but similar chemical stability and enzymatic hydrolysis rates compared to ester 4, the better bioavailability of ester 4 may result from its greater partitioning into the gastrointestinal membranes.

Antiinflammatory and aldose reductase inhibitory activity of some tricyclic arylacetic acids.

A number of dibenztropone, dibenzsuberone, dibenzoxepin, and dibenzthiepin acetic acids were synthesized and tested for antiinflammatory/analgesic activity and also for their ability to inhibit rabbit lens aldose reductase (AR). It was found that the structural requirements for antiinflammatory/analgesic activity, believed to be mediated by inhibition of cyclooxygenase, were much more stringent than were those for AR inhibition. For example, the introduction of a hydroxyl group into positions 1, 4, 6, 7, or 8 on dibenzsuberone-2-acetic acid (1a) had relatively little effect on AR inhibition, but caused wide variations in antiinflammatory/analgesic activity.

Risk of complications during intravenous heparin therapy.

The records of all patients to whom heparin was dispensed by the pharmacy of the University of California Medical Center, San Diego, during the year 1979 were reviewed. A total of 131 patients above age 15 met the inclusion criteria-they had received more than 10,000 units of heparin per 24 hours for at least 24 hours. All 131 patients were administered heparin by continuous intravenous infusion by peristaltic pump. All heparin was porcine heparin from a single commercial source. The daily mean minimum dose averaged 19,700 units, the maximum, 25,600 units. The activated partial thromboplastin time, usually measured once a day, was the only test used to monitor the dose. Major complicating events occurred in 13 patients (10 percent), and minor complicating events occurred in 10 patients (7.6 percent). All major complicating events occurred in patients with serious concurrent diseases. In subpopulations of 58 patients without concurrent disease, and of 24 in whom heparin was initiated for suspicion of thromboembolism that was not confirmed, no major complicating events occurred. These data indicate that continuous, intravenous administration of heparin is associated with minimal risk, and that risk is concentrated among older patients with serious concurrent disease.

Mono- and diaryl-2-quinuclidinylcarbinols with local anesthetic and antiarrhythmic activity.

The reaction between 2-carboethoxyquinuclidine and various aryl- and heteroarylithium reagents gave mixtures of aryl 2-quinuclidinyl ketones and diaryl-2-quinuclidinylcarbinols. Diborane reduction of the ketones gave the erythro-carbinols, stereochemically analogous to quinidine. Several of the mono- and diarylcarbinols exhibited potent local anesthetic and antiarrhythmic activity, in some cases greater than that of quinidine. Diphenyl-2-quinuclidinylcarbinol and a (bromomethoxyphenyl)(methoxyphenyl)-2-quinuclidinylcarbinol were particularly active in reverting ouabain-induced arrhythmia in dogs, showing a potency and duration of action equal to or greater than that of propranolol.

Dibenzotropone- and dibenzosuberonecarboxylic acids with bronchodilator activity.

The syntheses of 44 5H-dibenzo[a,d]cyclohepten-5-one derivatives bearing a carboxyl gropu at the 1, 2, 3, or 10 position and various substituents at the 7, 8, or 9 position are described. Some of the compounds showed significant bronchodilator activity in guinea pigs and protected the animals against a histamine challenge administered either by aerosol or intravenously. The most active compounds were 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-one-2-carboxylic acids bearing a methyl or halogen substituent at the 9 position. These compounds were approximately as active as aminophylline by intraperitoneal administration.

3-[(1,2,3-Thiadiazol-5-ylthio)methyl]cephalosporins.

The syntheses of ten 3-](1,2,3-thiadiazol-5-ylthio)methyl]cephalosporins, made by displacement of the 3'-acetoxy group by the novel thiol derivatives, potassium 1,2,3-thiadiazole-5-thiolate and dipotassium 1,2,3-thiadiazole-4-carboxylate-5-thiolate, are described. Several of the compounds showed good in vitro antibacterial activity against both Gram-positive and Gram-negative organisms. The subcutaneous in vivo activities against Staphylococcus aureus were generally less than that of cafazolin. Four of the compounds were administered orally and all were active; the 7 beta-(thiophen-2-acetamido) and 7 beta-(D-2-amino-2-phenylacetamido)-3-[(1,2,3-thiadiazol-5-ylthio)methyl] compounds were equally active by either route, with a PD50 of ca. 1 mg/kg.

Synthesis and antiinflammatory activity of 6,11-dihydro-11-oxodibenzo[b,e]thiepinalkanoic acids and related compounds.

Acetic acid derivatives of tricyclic systems, such as 6,11-dihydro-11-oxodibenzo[b,e]thiepin, 4,10-dihydro-4-oxo-thieno[2,3-c][1]benzothiepin, dibenzo[b,f]thiepin, dibenz[b,f]oxepin, etc., were synthesized and assayed for antiinflammatory activity. One of the compounds, 6,11-dihydro-11-oxodibenzo[b,e]thiepin-3-acetic acid (52), was chosen for evaluation in man on the basis of high antiinflammatory activity in both short- and long-term animal assays and a low gastric irritation liability in rats and dogs.

Dibenztroponeacetic and -propionic acids. Potent new antiinflammatory agents.

The syntheses and antiinflammatory assays of some dibenztroponeacetic and -propionic acids and derivatives are described. The most potent compound, d-2-(5H-dibenzo[a,d]cyclohepten-5-on-2-yl)propionic acid, has a potency of ca, 70 times phenylbutazone in the rat carrageenan paw assay and two to three times indomethacin in long-term animal assays. Some beta-dialkylaminoethyl esters of this compound also show high antiinflammatory activity.

Synthesis and antiinflammatory activity of some 1,6-methano[10]annuleneacetic acids.

Some new approaches to the 1,6-methano[10]annulene system are described. The routes were used to prepare 1,6-methano[10]annulene-3-acetic acid and the alpha-methyl analog. The compounds showed antinflammatory and analgesic activity, though less than that of corresponding naphthalene compounds; the possible effect of the chirality of the annulene on the observed biological activity is discussed.