George Y. Lesher

An efficient and novel synthesis of fused thiazol-2(3H)-ones

Reaction of o-bromo aromatic amines (2, 4, 7, 10, 15) with ethyl potassium xanthate gave the corresponding fused thiazol-2(3H)-thiones (16, 19, 22) which in turn were first alkylated with methyl iodide and then treated with sodium methoxide to produce fused thiazol-2(3H)-ones (18, 21, 24). Treatment of 4-(4-pyridinyl)-benzenamine dihydrobromide (1) with DMSO gave 2-bromo-4-(4-pyridinyl)benzenamine (2). Reduction of 4-(4-bromo-3-nitrophenyl)-pyridine (3) with stannous chloride gave 2-bromo-5-(4-pyridinyl)-benzenamine (4)

In vitro and in vivo activities of a new quinolone, WIN 57273, possessing potent activity against gram-positive bacteria.

The antibacterial activity of a new 7-dimethylpyridinyl quinolone, WIN 57273, was assessed by using in vitro and in vivo models. Agar inclusion and broth dilution in vitro tests revealed broad-spectrum activity against gram-positive and selected gram-negative organisms, with the greatest potency observed against the staphylococci. The MIC for 90% of coagulase-positive strains tested (MIC90) was less than or equal to 0.002 micrograms/ml; for the coagulase-negative strains the MIC90 was 0.008 micrograms/ml. Against enterococci the MIC90 was 0.06 micrograms/ml, with comparable activity observed against group A and group B streptococci as well as against the pneumococci. In general, the MIC90s for the gram-negative bacteria were less than or equal to 1 micrograms/ml. Exceptions were Serratia marcescens (MIC90, 16 micrograms/ml), Citrobacter freundii (MIC90, 4 micrograms/ml), and Pseudomonas aeruginosa (MIC90, 8 micrograms/ml). The greatest potency was observed against Haemophilus spp. and Neisseria spp., with MIC90s of 0.06 and 0.016 micrograms/ml, respectively. Broad-spectrum activity was also observed against anaerobes, with MIC90s ranging from 0.125 to 0.5 micrograms/ml among the species tested. The in vivo efficacy was determined by using a murine model by calculating the 50% protective doses against a lethal bacterial infection caused by strains of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, Listeria monocytogenes, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The staphylocci were most susceptible, with 50% protective doses for all strains ranging from 0.1 to 0.7 mg/kg. With the exception of the Pseudomonas infection, which was refractory to treatment, animals that were part of the other infection models responded to less than 10 mg/kg. Equivalent activity was seen with the subcutaneous or the oral route of drug administration. WIN 57273 was significantly more potent than ciprofloxacin in treating gram-positive bacterial infections (2- to 20-fold) but was significantly less effective at treating gram-negative bacterial infections (30- to 300-fold).

Synthesis of Aza Analogs of Amrinone

The aldol condensation product (4) of 4- acetylpyridine (2) and diethyl mesoxalate (3) was converted to pyridazine- carboxylic acid hydrazide (6). Curtius reaction of 6 gave aminopyridazinone (7). The condensation of (4-pyridinyl)glyoxal (17) with aminomalonamide (9) yielded pyrazinecarboxamide (18) which was transformed to aminopyrazinone (19) by the Hofmann reaction. Curtius reaction of 1,2,4-triazinone-5-carboxylic acid (21b) gave aminotriazinone (22). Demethylation of methoxypyridine (29) prepared from methyl 2-methoxyformylacetate (25) and isonicotinamidine (26) gave pyrimidinol (30)

Relationship of structure of bridged (2,6-dimethyl-4-pyridinyl)quinolones to mammalian topoisomerase II inhibition☆

Abstract Several enantiomerically pure (2,6-dimethyl-4-pyridinyl)quinolones, previously shown to be potent inhibitors of bacterial DNA gyrase, exhibit topoisomerase II inhibitory activity. Among these and other analogues, topoisomerase II inhibitory potency was found to be a sensitive function of the size and substitution of the bridge spanning the 1- and 8-positions of the quinoline ring. The 6-fluoro group was required for activity.

Pharmacologic and Pharmacodynamic Effects of the Selective Low Km Cyclic AMP Phosphodiesterase III Inhibitors WIN 63291 and WIN 62582

Summary We describe the biochemical, pharmacologic, and in vivo pharmacodynamic profiles of two novel inhibitors of the cyclic GMP-inhibitable, low Km cyclic AMP phosphodiesterase (PDE) III; WIN 63291, a 6-qui-nolinyl analogue of the prototypic PDE III inhibitor milrinone and WIN 62582, an imidazopyridinone. Both WIN 62582 and WIN 63291 competitively inhibit PDE HI from rat, dog, and human heart and from rat and canine aorta with IC50 values of 5–37 and 55–80 nM, respectively; the IC50 values for milrinone ranged from 300 to 520 nM. WIN 62582 and WIN 63291 are at least 1,000-fold selective for PDE III relative to inhibition of PDE isozymes I, II, IV, and V. We evaluated WIN 62582 and WIN 63291 in conscious rats and dogs after intravenous (i.v.) and oral (p.o.) administration. The dose of WIN 62582 required to reduce mean arterial blood pressure (MAP) by 20% (ED20) in rats was 1.8 mg/kg, with a pharmacodynamic duration of action of ±2 h. In comparison, the estimated i.v. ED20 for WIN 63291 in rats was 0.4 mg/kg, with a pharmacodynamic duration of action >6 h. In conscious dogs, the i.v. doses of WIN 62582 and 63291 required to increase left ventricular (LV) dP/dtmax significantly were 0.1 and 0.01 mg/kg, respectively. In dogs, WIN 63291 0.1 mg/kg p.o. increased LVdP/dtmax by 86% in 30 min; LVdp/dtmax remained increased by 60% for at least 6 h. In comparison, WIN 62582, 0.3 mg/kg p.o., increased LVdP/dt by 56% in 30 min and remained increased by 40% at 6 h. These data suggest that WIN 62582 and WIN 63291 are potent, selective, orally active inhibitors of PDE III and have a relatively long duration of action in vivo. Although WIN 62582 is 10-fold more potent than WIN 63291 as an inhibitor of PDE III in vitro, WIN 63291 is a slightly more potent cardiovascular agent in vivo after i.v. and p.o. administration to conscious rats and dogs.