Synthesis and antiallergic activities of 1,3-oxazolo[4,5-h]quinolines.

A series of new 1,3-oxazolo[4,5-h]quinolines has been prepared. These compounds were tested as inhibitors of antigen-induced release of histamine (AIR) in vitro from rat peritoneal mast cells (RMC) and as inhibitors of IgE-mediated passive cutaneous anaphylaxis in the rat (PCA). After several modifications of the original lead, the most potent compound of the series was determined to be 5-chloro-1,3-oxazolo[4,5-h]quinoline-2-carboxylic acid methyl ester (4a). It has an IC50 of 0.3 microM in the RMC assay and an ED50 (intraperitoneal) of 0.1 mg/kg in the PCA test, which is 10 times and 60 times more potent than disodium cromoglycate (DSCG), respectively. Of greater importance, it is orally active (ED50 = 0.5 mg/kg) as an inhibitor of the PCA test.

1,2,4-Triazolo[4,3-a]quinoxaline-1,4-diones as antiallergic agents.

A series of new 1,4-dihydro-1,2,4-triazolo[4,3-]quinoxaline-1,4-diones has been prepared. These compounds were tested as inhibitors of antigen-induced release of histamine (AIR) in vitro from rat peritoneal mast cells (RMC) and as inhibitors of IgE-mediated rat passive cutaneous anaphylaxis (PCA). Most of this new class of antiallergic agents showed good activity in the RMC and PCA tests. The most potent compound, 2-acetyl-7-chloro-5-n-propyl-1,2,4-triazolo[4,3-a]quinoxaline-1,4-dione (1x), with an I50 value of 0.1 microM, is 30 times more potent than disodium cromoglycate (DSCG) in the RMC assay.

[1,4]Benzoxazine-2,3-diones as antiallergic agents.

The synthesis of a series of [1,4]benzoxazine-2,3-diones and a new class of compounds, benzobisoxazinetetrones, is described. These compounds were evaluated for their effect in the rat mast cell (RMC) test passively sensitized in vitro with rat antiovalbumin serum and for their effect in inhibitory passive cutaneous anaphylaxis (PCA) in the rat. Some of these compounds are of the same potency level as disodium cromglycate in the RMC test and some are effective orally in PCA.

Pyrido[3',2':4,5]thieno[3,2-d]-N-triazines: a new series of orally active antiallergic agents.

A new series of orally active mediator release inhibitors, pyrido[3',2':4,5]thieno[3,2-d]-N-triazines, was synthesized and evaluated for antiallergic activity. Several products showed high activity as inhibitors or wheal information in the rat passive cutaneous anaphylaxis screen and as inhibitors of histamine release from passively sensitized rat mast cells. Many compounds were orally active in the PCA test. The most potent compound, 7-phenylpyrido-[3',2':4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)- one (10) with an I50 value of 0.05 microM, was 60 times more potent than disodium cromoglycate (DSCG) in the RMC assay.

In vivo anti-allergic and bronchopulmonary pharmacology of REV 3164 in rats and guinea-pigs.

REV 3164 has been evaluated in a variety of intact rodent models to reveal potential utility in the prophylactic treatment of asthma. REV 3164 was found a potent, orally active inhibitor of rat (IgE) passive cutaneous anaphylaxis (PCA, ED50 = 0.9 mg/kg). By contrast, at 50-200 mg/kg p.o., it did not affect guinea-pig (IgG1) PCA. In PCA rats, both REV 3164, 1-36 mg/kg i.p., and the known inhibitor of mast cell mediator release, disodium cromoglycate (DSCG), 2-54 mg/kg i.p., blocked cutaneous wheals caused by i.v. antigen challenge but not by intradermal serotonin or histamine. Neither REV 3164 (0.1-10 mg/kg i.p.) nor DSCG (2-54 mg/kg i.p.) affected Compound 48/80-induced wheals. REV 3164 (0.01-1 mg/kg i.v. or 10 mg/kg i.p.) abolished rat (IgE) passive lung anaphylaxis (PLA, ED50 = 0.05 mg/kg i.v. for inhibition of elevated airway resistance). At 10 mg/kg i.p., REV 3164 did not affect active lung anaphylaxis in guinea-pigs pharmacologically manipulated to enhance the production and action of slow reacting substance of anaphylaxis (SRS-A), nor did it exhibit anticholinergic activity in the rat. REV 3164 (100 mg/kg i.p.) did not protect conscious guinea-pigs from histamine aerosol-induced collapse. It is concluded that REV 3164 is an oral inhibitor of IgE-dependent immediate hypersensitivity in the rat with biological activities in rats and guinea-pigs similar to DSCG.

Synthesis of 2-(2,3-dihydro-2-oxo-1,3,4-oxadiazol-5-yl) benzo heterocycles. A novel series of orally active antiallergic agents.

A series of new 2-(2,3-dihydro-2-oxo-1,3,4-oxadiazol-5-yl) benzo heterocycles has been prepared. These compounds were tested as inhibitors of antigen-induced release of histamine (AIR) in vitro from rat peritoneal mast cells (RMC) and as inhibitors of IgE-mediated rat passive cutaneous anaphylaxis in the rat (PCA). Most of this new class of antiallergic agents showed good activity in the RMC assay. The most potent compound, 3-chloro-2-(2,3-dihydro-2-oxo-1,3,4-oxadiazol-5-yl)benzo[b]thiophe ne (6t), with an I50 value of 0.2 microM, is 15 times more potent than disodium cromoglycate (DSCG) in the RMC assay. Many compounds were orally active in the PCA test, and several of these compounds showed higher potency when given in this way to that shown by DSCG when given intraperitoneally.

In vitro and in vivo immunopharmacologic properties of a new antiallergic agent RHC 3414.

The antiallergic activity profile of RHC 3414 (7-phenylpyrido (3', 2': 4, 5)-thieno (3.2-d)-1, 2, 3-triazine-4(3H)-one) has been compared with that of disodium cromoglycate (DSCG) in several in vitro and in vivo models of anaphylaxis and inflammation. RHC 3414 was approximately 50 times more potent than DSCG as an inhibitor of antigen-induced release of histamine (AIR) from rat mast cells (RMC) in vitro. As an inhibitor of mediator release, the activity profile of RHC 3414 was identical to that of DSCG in the following respects: inhibition of IgE-mediated release of histamine from RMC but not human basophils (HUB), rapid loss of inhibitory activity as a function of time prior to antigen challenge, inability to inhibit the release of histamine from RMC stimulated by non-immunologic secretagogues as well as IgG1-mediated histamine release from guinea-pig lung slices. In vivo, given orally the sodium salt of RHC 3414 (RHC 3414-Z) was a potent inhibitor of passive cutaneous anaphylaxis (PCA) in the rat. Administered intraperitoneally, RHC 3414-Z was approximately 30 times as potent as DSCG as an inhibitor of IgE-mediated PCA in the rat without any antihistaminic or antiserotonin activity. RHC 3414-Z also inhibited adjuvant-induced inflammatory responses in the rat but had no effect on carrageenan-induced edema formation in vivo or on phospholipase A2 or cyclooxygenase activity in vitro. We conclude that RHC 3414 is a potent antiallergic agent with a mechanism of action similar to that of DSCG. In addition, RHC 3414 may possess the ability to inhibit chronic inflammatory processes, an attribute which should prove useful in the prophylactic treatment of asthma.