Stereospecific synthesis, assignment of absolute configuration, and biological activity of the enantiomers of 3-[[[3-[2-(7-chloroquinolin-2-yl)-(E)-ethenyl]phenyl] [[3-(dimethylamino)-3-oxopropyl]thio]methyl]thio]propionic acid, a potent and specific leukotriene D4 receptor antagonist.

The enantiomers of the leukotriene D4 antagonist 3-[[[3-[2-(7-chloroquinolin-2-yl)-(E)-ethenyl]phenyl] [[3-(dimethylamino)-3-oxopropyl]thio]methyl]thio]propionic acid (L-660,711)(MK-571) have been prepared, their absolute stereochemistry has been assigned as S for (+)-1 and R for (-)-1 by X-ray analysis of a synthetic intermediate (5), and the biological activity of the enantiomers has been explored. Unexpectedly, the enantiomers are both comparably biologically active with (+)-1 slightly more intrinsically active at the LTD4 receptor in vitro.

Substituted (pyridylmethoxy)naphthalenes as potent and orally active 5-lipoxygenase inhibitors; synthesis, biological profile, and pharmacokinetics of L-739,010.

Dioxabicyclooctanyl naphthalenenitriles have been reported as a class of potent and nonredox 5-lipoxygenase (5-LO) inhibitors. These bicyclo derivatives were shown to be metabolically more stable than their tetrahydropyranyl counterparts but were not well orally absorbed. Replacement of the phenyl ring in the naphthalenenitrile 1 by a pyridine ring leads to the potent and orally absorbed inhibitor 3g (L-739,010, 2-cyano-4-(3-furyl)-7-[[6-[3-(3-hydroxy-6,8-dioxabicyclo[3.2.1] octanyl)]-2-pyridyl]methoxy]naphthalene). Compound 3g inhibits 5-HPETE production by human 5-LO and LTB4 biosynthesis by human PMN leukocytes and human whole blood (IC50S of 20, 1.6, and 42 nM, respectively). Derivative 3g is orally active in the rat pleurisy model (inhibition of LTB4, ED50 = 0.3 mg/kg) and in the anesthetized dog model (inhibition of ex vivo whole blood LTB4 and urinary LTE4, ED50 = 0.45 and 0.23 microgram/kg/min, respectively, i.v. infusion). In addition, 3g shows excellent functional activity against ovalbumin-induced dyspnea in rats (60% inhibition at 0.5 mg/kg, 4 h pretreatment) and Ascaris-induced bronchoconstriction in conscious sheep (50% and > 85% inhibition in early and late phases, respectively at 2.5 micrograms/kg/min, i.v. infusion) and, more particularly in the conscious antigen sensitive squirrel monkey model (53% inhibition of the increase in RL and 76% in the decrease of Cdyn, at 0.1 mg/kg, po). In rats and dogs, 3g presents excellent pharmacokinetics (estimated half-lives of 5 and 16 h, respectively) and bioavailabilities (26% and 73% when dosed as its hydrochloride salt at doses of 20 and 10 mg/kg, respectively, in methocel suspension). Based on its overall biological profile, compound 3g has been selected for preclinical animal toxicity studies.

The derivation of an inbred line of rats which develop asthma-like symptoms following challenge with aerosolized antigen.

Sensitized Sprague-Dawley rats developed respiratory impairment after challenge with aerosolized antigen. The response to challenge was heterogeneous. A proportion of each group of rats developed dyspnea and other symptoms similar to asthma; the remainder developed apnea but no other symptoms. Selective breeding from rats which developed dyspnea increased the incidence from 44% in F0 to 55% in F1 and greater than 90% in F2 and F3. Inbreeding also produced a significant increase in the duration of antigen-induced dyspnea. The results from the selective inbreeding suggest antigen-induced dyspnea is controlled genetically, possibly by multiple gene loci. These inbred rats constitute a population which have a predictable response to aerosolized antigen challenge. They should have utility in investigating allergic asthma and evaluating potential new drugs.

Studies on the anti-allergic action of N-(3',4'-dimethoxycinnamoyl) anthranilic acid (N-5').

The effects of the anti-allergic compound (N-(3',4'-dimethoxycinnamoyl) anthranilic acid (N-5' or Tranilast) have been investigated upon antigen-induced contractions of respiratory smooth muscle in vitro and bronchoconstriction in vivo. N-5' (3.1 X 10(-5) M) in vitro had no significant effect upon antigen-induced contractions of the guinea pig trachea. However, when tested at concentrations of 9.2 and 3.1 X 10(-5) M, but not 0.9 X 10(-5), N-5' significantly inhibited antigen-induced contractions of the human parenchyma. In vivo N-5' (5 and 10 mg/kg p.o.) failed to inhibit antigen-induced dyspnea in hyperreactive rats. N-5' (20 mg/kg p.o.) also failed to inhibit the immediate bronchoconstriction following ascaris challenge of conscious squirrel monkeys but significantly attenuated the reduction in dynamic compliance during the pulmonary late phase response observed between 4 and 10 h after antigen challenge. It is suggested that N-5' does not act as a "cromoglycate-like" compound but may have novel mechanisms of action in human bronchial asthma.

Inhibition of allergen-induced bronchoconstriction in hyperreactive rats as a model for testing 5-lipoxygenase inhibitors and leukotriene D4 receptor antagonists.

Sensitized inbred hyperreactive rats showed reproducible episodes of dyspnea when exposed to aerosols of antigen. Following inhibition of the serotonin component of the response by pretreatment with methysergide, the model was shown to be useful for studying the oral activity of compounds that affect the production or action of leukotrienes. This was shown through inhibition of the duration of dyspnea by two selective 5-lipoxygenase inhibitors, L-651,392 and L-615,919, and two selective leukotriene D4 receptor antagonists, L-647,438 and L-649,923. Selectivity of the compounds could be demonstrated by reducing inhibition of the antigen response in the absence of methysergide and failure to inhibit serotonin-induced dyspnea. It is concluded that the model provides a reproducible method for screening large numbers of leukotriene inhibitors and antagonists and gives a measurement of their duration of biological activity.

Effects of a contractile prostaglandin antagonist (L-640,035) upon allergen-induced bronchoconstriction in hyperreactive rats and conscious squirrel monkeys.

The effects of an antagonist of contractile prostanoids, L-640,035 (3-hydroxymethyl-dibenzo[b,f]thiepin-5-dioxide) upon antigen-induced bronchoconstriction have been studied in inbred rats with non-specific bronchial hyperreactivity and in conscious squirrel monkeys. L-640,035 was a potent inhibitor of antigen-induced dyspnea (ED50 3.1 mg/kg p.o.) in inbred rats pretreated with methysergide (3 micrograms/kg i.v.) but produced no significant inhibition in untreated rats. Administration of L-640,035 (10 mg/kg p.o.) to conscious squirrel monkeys exposed to aerosols of ascaris antigen markedly inhibited changes in pulmonary resistance (RL) and dynamic compliance (CDYN). At a lower dose (1 mg/kg p.o.) the inhibition of changes in CDYN were similar but the effects on RL were reduced. It was concluded first that contractile prostanoids may be important mediators of antigen-induced bronchoconstriction and secondly that L-640,035 may be effective in human allergic asthma.

Saliva stimulation in dogs with permanent duct fistulae.

Saliva fluids were collected from catheters inserted in the duct openings of permanent paratid and sublingual duct fistulae prepared in dogs. In anesthetized dogs stimulants applied to the tongue had no effect on saliva output. In awake dogs topically applied sucrose (1.25%-20%) had no significant stimulating effect on salivary secertion when compared to water control responses. Citric acid (1.25%-20%), applied topically, resulted in dose-related fluid increases, with parotid volumes consistently higher than sublingual volumes. Pilocarpine (0.125 mg/kg, IV), elicited similar saliva volumes in awake and anesthetized animals; sublingual secretions were higher than parotid volumes. For comparing drug secretion or saliva composition in awake and anesthetized animals, use of the same, preferable an IV, stimulant administered on a milligram perper-kilogram basis is suggested.

The activity of synthetic leukotriene C-1 on guinea pig trachea and ileum.

The effects of synthetic leukotriene C-1 (LTC-1) on isolated guinea pig trachea and ileum have been determined and compared to histamine. LTC-1 produced a slow contraction of the trachea and the ileum with pD2 values of 8.7 +/- 0.1 (n = 14) and 8.5 +/- 0.1 (n = 13), respectively. In comparison, the pD2 values for histamine were 5.6 +/- 0.1 (n = 6) and 6.2 +/- 0.1 (n = 6), indicating LTC-1 was 2-3 orders of magnitude more potent. LTC-1 was antagonised by FPL 55712 with pA2 values of 6.9 +/- 0.1 (n = 5) and 6.4 +/- 0.1 (n = 7) on the trachea and ileum, respectively. Incubation with lipoxidase produced a time and enzyme dependent loss of biological activity and a concurrent shift in U.V. absorption spectrum.

The respiratory response of sensitized rats to challenge with antigen aerosols.

An experimental procedure was developed to evaluate the effects of challenging sensitized conscious rats with antigen aerosols. The challenge resulted in changes in the respiratory patterns which were antigen specific and mediated by IgE antibodies. The response was inducible in non-sensitized rats by passive administration of IgE-rich serum. Sprague-Dawley rats were heterogeneous with respect to the respiratory response. A proportion (20--70%) of each group had continuous dyspnoea and other symptoms similar to asthma; the other had only episodes of apnoea. Wistar and Long-Evans rats resembled Sprague-Dawley rats; Fischer 344 rats had apnoea only, even though they produced IgE antibodies. The type of response did not correlate with serum IgE levels. The respiratory responses were reduced by dexamethasone, disodium cromoglycate, epinephrine and theophylline. Rats that respond with dyspnoea may provide a useful experimental model of allergic asthma.

Respiratory responses to leukotrienes and biogenic amines in normal and hyperreactive rats.

The effects of leukotriene D4, serotonin, and methacholine were studied on respiratory smooth muscle in vitro and respiratory responses in vivo in three strains of rats. These were an inbred strain of hyperresponsive rats, Sprague Dawley rats, and Fischer rats. Trachea from inbred rats responded in vitro to serotonin and methacholine but not to leukotrienes or histamine. Parenchyma from inbred rats responded to serotonin, methacholine, and leukotrienes. In vivo respiratory responses in inbred rats were observed after aerosol administration of histamine and serotonin, methacholine, and leukotriene D4. When these in vitro and in vivo experiments were repeated in Sprague Dawley and Fischer rats, a clear correlation was observed between the responses of strains of rats to aerosolized antigen and responses to spasmogenic mediators. It is concluded that inbred rats have a nonspecific bronchial hyperreactivity that contributes to their sensitivity to aerosolized antigen and that they may be a useful model for human asthmatic conditions.

Effects of a selective phosphodiesterase IV inhibitor (CDP-840) in a leukotriene-dependent non-human primate model of allergic asthma.

The activity of CDP-840, a novel, selective phosphodiesterase IV inhibitor was determined in a leukotriene-dependent non-human primate model of allergic asthma. Measurements of specific airway resistance (sRaw) were recorded in a dual chamber plethysmograph for 1 h and 3-5 h after challenge of allergic conscious squirrel monkeys with an aerosol of ascaris antigen. Orally administered CDP-840 (10 mg/kg; 1 h before challenge) produced partial inhibition (41 and 45%, respectively) of both the acute (1 h post antigen) response and the late (3-5 h post antigen) response to antigen but failed to alter the response to an aerosol of leukotriene D4. In a second series of experiments, intravenous CDP-840 (5 mg/kg; 30 min before challenge) showed improved potency, producing 82% inhibition of the early and 51% inhibition of the late phase response. CDP-840 was inactive when tested intravenously at 1 mg/kg and was inactive against the 3-5 h response when administered after the early phase response (5 mg/kg; i.v. 60 min post antigen challenge). The novel phosphodiesterase IV inhibitor CDP-840 selectively inhibited antigen-induced bronchoconstriction in conscious squirrel monkeys. This effect appears to be independent of any direct bronchodilator action. It is concluded that the activity of CDP-840 in this model may be due to an inhibitory effect on mediator (e.g., leukotriene) release.

Differing mechanisms for leukotriene d4-induced bronchoconstriction in guinea pigs following intravenous and aerosol administration.

Leukotriene D4 (LTD4) when administered intravenously or by aerosol to guinea pigs produced changes in pulmonary mechanics including a decrease in dynamic compliance and an increase in pulmonary resistance. The effects of intravenous LTD4 (0.5 microgram kg-1) were short lived and abolished by pretreatment of the animal with either cyclooxygenase inhibitors, a thromboxane synthetase inhibitor (OKY 1555) or an SRS-A antagonist (FPL 55712). These findings suggest that bronchoconstriction produced by the intravenous infusion of LTD4 at 0.5 microgram kg-1 is due to the release of thromboxane A2. However, in animals treated with indomethacin, LTD4 at higher doses (greater than 0.8 microgram kg-1) still elicited a bronchoconstriction which could be blocked by FPL 55712. Nebulization of 0.1 - 1.0 microgram of LTD4 into the lung produced prolonged changes in pulmonary mechanics which were inhibited by FPL 55712 and were potentiated by indomethacin. LTD4, therefore, when administered by aerosol produced effects on the lung which were not mediated by cyclooxygenase products. Responses to nebulized rather than intravenous LTD4 in the guinea pig may more closely resemble those seen in human tissues.

Substituted indoles as potent and orally active 5-lipoxygenase activating protein (FLAP) inhibitors.

This paper reports on the SAR investigation of inhibitors of 5-lipoxygenase activating protein (FLAP) based on MK-0591. Emphasis was made on modifications to the nature of the link between the indole and the quinoline moieties, to the substitution pattern around the two heterocycles and to possible replacements of the quinoline moiety. Lead optimization culminated in (3-[1-(4-chlorobenzyl)-3-(t-butylthio)-5-(pyridin-2-ylmethoxy)-ind ol-2-yl]-2,2-dimethylpropanoic acid (18k), as a potent inhibitor of leukotriene biosynthesis that is well absorbed and active in functional models.