[Chemistry and pharmacology of pyrane derivatives. XVII. Synthesis of substituted 2-(dialkylamino)-3-formylchromones and their tricyclic derivatives]

Substituted 2-(dialkylamino)-3-formylchromones (II) were obtained from the reaction of substituted 2-(dialkylamino)chromones (I) either with the N,N-dimethylformamide-POCl3 reagent [compounds (IIa-e)] or with dichloromethylmethylether in the presence of TiCl4 [compounds (IIf-i)]. By treating (IIa,f) with hydroxylamine the oximes (IIIa,f) were prepared, which in turn were converted into the nitriles (IVa,f) by treatment with acetic anhydride. Compound (IIa), selected for the smallest steric hindrance of the 2-dialkylamino substituent, by reaction with hydrazines afforded [1]benzopyrano [2,3-c]pyrazole derivatives (VI), whereas reaction of (IIa) with guanidine, benzamidine or S-methylisothiourea gave rise to the formation of 5H-[1]benzopyrano[2,3-d]pyrimidine derivatives (IX). Among the compounds tested for their antiallergic properties, (IIf) showed an appreciable activity, but also high toxicity.

Antiallergic effects of 4-[2-oxo-3-(1H-tetrazol-5-yl)-2H-chromen-8-yloxy]-bu tyric acid

Antiallergic effects of 4-[2-oxo-3-(1H-tetrazol-5-yl)-2H-chromen-8-yloxy]-buty ric acid (C4C) were studied. C4C is an active principal metabolite of an orally effective antiallergic agent, KP-136. C4C (0.2-1 mg/kg, i.v.) markedly inhibited the mast cell-mediated homologous PCA of rats and the experimental allergic asthma of rats and guinea pigs, although it had almost no effects on heterologous PCA and compound 48/80-induced cutaneous response in rats. C4C (0.2 mg/kg, i.v.) was scarcely effective on cutaneous responses induced by intradermal injection of histamine and serotonin which are principal chemical mediators of rat homologous PCA, and it blocked the decrease of skin histamine content after the PCA. In addition, C4C (0.01-0.5 micrograms/ml) inhibited the increase of 45Ca uptake of mast cells, the histamine release and the degranulation induced by the antigen-antibody interaction. These effects of C4C were much the same as those of KP-136. From the above findings, C4C is considered to be an antiallergic agent that inhibits the mast cell activation by blocking the calcium influx, and it shares similar pharmacological properties with KP-136.

Pharmacological profile of MDL 26,024GO: a novel antiasthmatic agent

MDL 26,024GO was shown to be an orally absorbed mediator release inhibitor in the rat PCA and PPA tests. In addition, the compound was shown to both elicit and inhibit elicitation of the Bezold-Jarisch reflex in the dog. MDL 26,024GO also significantly reduced Ascaris-induced changes in pulmonary mechanics in cynomolgus monkeys. The compound inhibited both early and late phase antigen induced-changes in Ascaris-sensitive sheep, as well as the increased airway hyperreactivity which normally follows antigen challenge. These results suggest the compound may have therapeutic potential in the treatment of asthma.

Synthesis of 2-hydroxyacetyl-7-acetyl-xanthone, a new xanthone derivative endowed with antianaphylactic, analgesic, and antiinflammatory activities

2-Hydroxyacetyl-7-acetylxanthone (V), a new xanthone derivative, was synthesized in four steps starting from xanthene, by two synthetic approaches. The new compound displayed antianaphylactic activity in the PCA test and in the anaphylaxis shock test in rats. It also displayed analgesic activity in the writhing test in mice, and antiinflammatory activity in the carrageenin edema test in rats. The activity of the new compound has been tentatively interpreted on the basis of its chemical and structural analogy with known drugs.

Synthesis and antiallergic activity of N-[4-(4-diphenylmethyl-1-piperazinyl)butyl]-1,4-dihydro-4-oxopyridine-3 - carboxamides

A new series of oxopyridinecarboxamide derivatives 3a--g and 5a were synthesized and evaluated for their antiallergic activity. 1,4-Dihydro-7-methyl-4-oxo-1,8-naphthyridine-3-carboxamides 3a and 5a exhibited potent antiallergic activity (inhibitory rates of 80.7 and 88.3%, respectively, at 20 mg/kg, p.o.) in the rat passive cutaneous anaphylaxis (PCA) test and also exhibited much more potent in vitro inhibitory activity than caffeic acid against the enzyme 5-lipoxygenase (5-LO). Their in vitro antihistamine activity, however, was weaker than that of ketotifen. Compounds 3a and 5a are viewed as promising candidates for antiallergic agents.

Acrylamide derivatives as antiallergic agents. III. Synthesis and structure-activity relationships of N-[4-(4-diphenylmethyl-1-piperazinyl)butyl]- and N-[4-(4-diphenylmethylene-1-piperidyl)butyl]-3-heteroarylacry lamides

A new series of 3-heteroarylacrylamides 2 and 4 was prepared and the inhibitory activities against the rat passive cutaneous anaphylaxis (PCA) reaction and the enzyme 5-lipoxygenase (5-LO) were tested. Most of the compounds exhibited an anti-PCA activity superior to or equivalent to ketotifen and had a 5-LO inhibitory activity. The 3-heteroarylacrylamide derivatives including 3-(3-pyridyl)acrylamides represent a new structural class of compound that exhibits not only an in vivo anti-PCA activity but also an in vitro 5-LO inhibitory activity.

Evaluation of anti-allergic effects of 1-substituted 2-n-butyl-methylenedioxy indenes

The effects of ten 1-substituted 2-n-butyl-5,6-methylenedioxyindenes on mice and guinea pigs were investigated for their allergic reactions in the development of a new anti-allergic drug. Anti-allergic effects were determined by testing the effect of agents on passive cutaneous anaphylaxis (PCA) in mice and Schultz-Dale reaction in guinea pig tracheal muscle. 2-Butyl-1-[N-methyl-N-[2-(N',N'-dimethylamino) ethyl]amino]5,6- methylenedioxyindene (1) indicated the most potent anti-allergic activity. Since our previous experiments indicated that 2-n-butyl 3-dimethyl amino-5,6-methylenedioxyindene (MDI-A) and its derivatives showed a potent anti-allergic effect by interfering with the calcium (Ca) movement in the allergic reaction in guinea pigs, the effect of 1 and MDI-A on allergic reaction and Ca-induced contraction of tracheal muscle in these animals were compared. The present data indicate the superiority of 1 in both reactions.

Acrylamide derivatives as antiallergic agents. 2. Synthesis and structure-activity relationships of N-[4-[4-(diphenylmethyl)-1-piperazinyl]butyl]-3-(3-pyridyl)acryl amides

A new series of 3-(3-pyridyl)acrylamides 16, 17, 19, and 26, and 5-(3-pyridyl)-2,4-pentadienamides 20-25 were prepared and evaluated for their antiallergic activity. Several of these compounds exhibited more potent inhibitory activities than the parent compound 1a [(E)-N-[4-[4-(diphenylmethyl)-1-piperazinyl]butyl]-3- (3-pyridyl)acrylamide] against the rat passive cutaneous anaphylaxis (PCA) reaction and the enzyme 5-lipoxygenase. Particularly, (E)-N-[4-[4-(diphenylmethyl)-1-piperazinyl]butyl]-3- (6-methyl-3-pyridyl)acrylamide (17p) showed an ED50 value of 3.3 mg/kg po in the rat PCA test, which was one-fifth of ketotifen and oxatomide. As compared with ketotifen and oxatomide, compound 17p (AL-3264) possessed a better balance of antiallergic properties due to inhibition of chemical mediator release, inhibition of 5-lipoxygenase, and antagonism of histamine.

Inhibitory effects of beta-adrenergic stimulants on increased vascular permeability caused by passive cutaneous anaphylaxis, allergic mediators, and mediator releasers in rats

The effects of isoproterenol, salbutamol, theophylline, and forskolin on IgE antibody-mediated homologous passive cutaneous anaphylaxis (PCA) and on skin reactions caused by allergic mediators and mediator releasers were investigated in rats. Isoproterenol and salbutamol dose-dependently inhibited the PCA and skin reactions caused by histamine, serotonin, and leukotriene C4 (LTC4), elicited at the same time in the same rat. These agents also dose-dependently inhibited the skin reactions caused by platelet-activating factor (PAF), leukotriene D4 (LTD4), compound 48/80 (48/80), and calcium ionophore A23187 (A23187). Propranolol overcame the inhibitory effect of isoproterenol on PCA and skin reactions in a dose-dependent manner. Theophylline and forskolin showed similar effects as the beta-adrenergic stimulants. These results indicate that beta-adrenergic stimulants inhibit the increased vascular permeability caused by allergic mediators, and suggest that this activity of beta-adrenergic stimulants might play an important role in their antiallergic actions. Inhibition of increased vascular permeability might be mediated via beta-receptors and may be related to the increase in intracellular cyclic AMP levels.

Synthesis and antiallergy activity of 4-(diarylhydroxymethyl)-1-[3-(aryloxy)propyl]piperidines and structurally related compounds

A series of 4-(diarylhydroxymethyl)-1-[3-(aryloxy)propyl]piperidines was synthesized and evaluated for antiallergy activity. Several analogues had potent activity in the passive foot anaphylaxis (PFA) assay, an IgE-mediated model useful in the detection of compounds possessing antiallergic activity. In particular 1-[4-[3-[4-[bis(4-fluorophenyl)hydroxymethyl]-1-piperidinyl] propoxy]-3-methoxyphenyl]ethanone (1, AHR-5333) was more potent than oxatomide and terfenadine in this assay.

An anti-inflammatory steroid inhibits tissue sensitization by IgE in vivo

An anti-inflammatory corticosteroid, dexamethasone, was found to be a potent suppressor of cell sensitization induced by IgE antibody in a model of type I allergic inflammation in vivo. Low doses (approximately less than 10(-10) mol) of dexamethasone, administered intradermally to rabbits 90 min before injection of IgE into the same sites, suppressed local oedema induced by a local challenge with antigen 72 h later. The effect was not due to anti-inflammatory activity persisting in the skin site for the 3 day period. This novel potent activity of the corticosteroid may be an important component of its anti-allergic effect in diseases such as asthma.

Pharmacological properties of YM-11124, a selective immunosuppressive agent for cell-mediated immunity

Effect of YM-11124 on cell-mediated immune responses, type I to type III allergic reactions and inflammatory reaction was determined in mice, rats and guinea pigs. YM-11124 inhibited picryl chloride- and methylated bovine serum albumin-induced delayed-type hypersensitivity reactions by the treatment during both the sensitization and the elicitation phases in mice. Bilateral adrenalectomy did not prevent the suppression of DTH response by YM-11124. YM-11124 significantly prolonged the survival time of allogenic skin grafts in mice. Furthermore, YM-11124 inhibited the passive Arthus reaction in guinea pigs and the reversed passive Arthus reaction in rats. However, YM-11124 did not affect the passive cutaneous anaphylaxis reaction in rats, Forssman shock in guinea pigs and paw edema in rats. These results indicate that YM-11124 suppresses not only cell-mediated immune responses (type IV allergic reactions) but also type III allergic reactions without influence on types I and II allergic reactions as well as acute inflammation.

[Individual differences in PCA response in the guinea pig]

Experiments were carried out to determine the cause of individual differences in the passive cutaneous anaphylaxis (PCA) response in guinea pigs. The intensity of 4-h homologous PCA produced by anti-penicillin G serum was not markedly different among eight reactive sites on the back of a specified animal, whereas considerable individual differences were observed in the PCA response, even at a specified reactive site. PCA was significantly inhibited by an antihistaminic agent, promethazine, and the tissue histamine content was significantly reduced after PCA, suggesting histamine release as a mediator. The intensity of PCA in individual animals was highly correlated with that of the histamine-induced cutaneous reaction elicited at a site adjoining the PCA but was unrelated to skin histamine content. These results suggest that the difference in susceptibility to histamine has a considerable effect on individual differences in the PCA response in guinea pigs.

[Derivatives of pyrimidine 1,2-condensate. IV. Synthesis and pharmacological properties of the N,N-disubstituted 4-amino-2H-pyrido(1,2-a)pyrimidin- 2-ones and 2-amino-4H-pyrido(1,2-a)pyrmidin-4-ones]

The N,N-disubstituted 4-amino-2H-pyrido[1,2-a]pyrimidin-2-ones (III) and isomer 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones (IV) were obtained from the reaction of 2-aminopyridine with the N,N-disubstituted ethyl malonamate/phosphorus oxychloride reagent (II), in refluxing 1,2-dichloroethane. 2-[(N-Benzyl, N-ethyl)amino]derivative (IV b) was also prepared in excellent yield by treating 2-chloro-4H-pyrido[1,2-a]pyrimidin-4-one (V) with N-ethylbenzylamine. Finally, hydrogenation (Raney Nickel) of 4-[(N-ethyl,N-phenyl)amino]-2H-pyrido[1,2-a]pyrimidin-2-one (III e) afforded 6,7,8,9-tetrahydroderivative (VI) which in turn was treated with potassium borohydride to give 1,6,7,8,9,9a-hexahydroderivative (VII). Several compounds described in the present paper, along with some other compounds (III) and (IV) previously synthesized by us (1,2), were tested for various pharmacological activities. The antiallergic activity (PCA in the rat), even though found in several compounds examined, turned out to be submaximal in any case, in spite of the high dose administered (500 mg/kg p.o. as a rule). The most active compound (the activity being estimated at 0.42 times that of thiaramide hydrochloride) was the 4-aminoderivative (III e). The 2-aminoderivatives (IV) series, was found to have marked antiinflammatory properties (carrageenin oedema in the rat); nevertheless, this activity was related to toxic symptoms with the exception of compound (IV b), almost asymptomatic at the administered dose (200 mg/kg p.o.). Moreover the 2-aminoderivatives (IV) generally showed weak adrenolitic activity in vitro (rat seminal vesicles), which was estimated to be from 100 to 1000 times less than that of phenoxybenzamine.

Immunopharmacological studies on TBX, a new antiallergic drug (1). Inhibitory effects on passive cutaneous anaphylaxis in rats and guinea pigs

The effects of 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one potassium salt (TBX), a new antiallergic drug, on passive cutaneous anaphylaxis (PCA) mediated by homologous IgE or IgG antibody were investigated in rats and guinea pigs. TBX (i.v. and p.o.) clearly inhibited IgE- and IgGa-mediated homologous PCAs in rats, without showing any inhibition of the skin reactions caused by histamine, serotonin and bradykinin in contrast to the inhibition of prostaglandin E1-induced skin reaction. Neither adrenalectomy nor propranolol treatment modified TBX's inhibition of the former PCA. With regard to tachyphylaxis to TBX, it was demonstrable in IgE-mediated homologous PCA in rats when they were pretreated with TBX (0.5 mg/kg, i.v.), followed 60 min later by a second dose of the drug (0.05 mg/kg, i.v.). There was no cross-tachyphylaxis between disodium cromoglycate (DSCG) and TBX. Homologous PCA caused by guinea pig IgE was also inhibited in a dose-dependent fashion by i.v. and p.o. administrations of TBX, although higher doses of TBX were needed to inhibit guinea pig PCA than the rat one. Interestingly, TBX showed more potent inhibition of both rat and guinea pig homologous PCAs than DSCG or tranilast. The results obtained indicate that TBX is an orally effective antiallergic agent displaying no antagonistic actions on the chemical mediators released.

[Antiallergic effects of mequitazine. 2. In vivo experiments]

Antiallergic effects of mequitazine were investigated in vivo and compared with those of ketotifen and disodium cromoglycate (DSCG). The results obtained were as follows: 1) Mequitazine in doses of 2 and 5 mg/kg given, p.o., 1 hr prior to antigen challenge inhibited dose-dependently the 48-hr passive cutaneous anaphylaxis in rats. Five mg/kg of mequitazine showed almost the same extent of inhibitory activity as that of 1 mg/kg of ketotifen. An i.v. administration of 1 mg/kg DSCG 1 min before antigen challenge also showed a marked inhibition. 2) The experimental asthma induced by challenge with an i.v. injection of antigen in passively sensitized guinea pigs was fairly inhibited by the pretreatment with 5 mg/kg of mequitazine administered p.o., although 2 mg/kg of this drug showed only a slight inhibition. 3) The experimental asthma induced by aerosolized antigen was also fairly inhibited by the pretreatment with 5 mg/kg of mequitazine given p.o.

[Antigenicity study of carboplatin in guinea pigs and mice]

Carboplatin and carboplatin-ovalbumin mixture were examined for their antigenicity in Hartley guinea pigs as well as BALB/c and C3H/He mice in comparison with ovalbumin (OVA) and 2,4-dinitrochlorobenzene (DNCB)-OVA conjugate. The results obtained were as follows: 1. When guinea pigs were sensitized with carboplatin or carboplatin-OVA emulsified with Freund's complete adjuvant (FCA), these animals showed negative reactions in active systemic anaphylaxis (ASA), active cutaneous anaphylaxis (ACA), passive cutaneous anaphylaxis (PCA), passive hemagglutination (PHA) and Schultz-Dale test. 2. When mice were sensitized with carboplatin or carboplatin-OVA adsorbed to alum, these animals revealed a negative reaction in PCA using rats. 3. As positive controls, guinea pigs were sensitized with OVA or DNCB-OVA emulsified with FCA, and mice with OVA or DNCB-OVA adsorbed to alum. As a result, these animals disclosed positive reactions in ASA, ACA, PCA, PHA and Schultz-Dale test. As shown above, carboplatin was considered to possess neither antigenic nor haptenic properties. In addition, the dose levels of carboplatin employed in the present experiment were confirmed not to suppress immune reactions.

[One-step synthesis of 2-aminothieno [2,3-d]thiazen-4-ones in some cases 5,6-anellated from ethyl 2-benzoylthioureidothiophen-3-carboxylates and evaluation of their anti-allergy activity]

The cyclization of ethyl 2-benzoylthioureidothiophen-3-carboxylates under basic conditions is known to give 2-thioxothieno[2,3-d]pyrimidin-4(1H, 3H)-ones. On the other hand, we have found that ethyl 2-benzoylthioureidothiophen-3-carboxylates 10-16 on treatment with concentrated sulphuric acid or polyphosphoric acid/ethanol undergo cyclization to give the new 2-aminothieno[2,3-d][1,3]thiazin-4-ones 17-23, in some cases 5,6-anellated. Reaction of 10-16, which are readily available from ethyl 2-aminothiophen-3-carboxylates 3-9 and benzoyl isothiocyante affords the title compounds 17-23 in good yields. Mass spectral fragmentation of 17-23 is discussed. A series of 2-aminothieno[2,3-d][1,3]thiazin-4-ones, which contain a free or substituted amino group was evaluated in the rat active cutaneous anaphylaxis test for anti-allergy activity. One compound, 23 had weak activity in the range of theophylline. Only high concentrations of this compound inhibited weakly the histamine release from rat peritoneal mast cells activated by protamine sulfate.

[Inhibitory effect of AD-1590, a non-steroidal anti-inflammatory drug, on allergic inflammation in mice and rats]

Effect of AD-1590 on allergic inflammations was investigated. AD-1590 and indomethacin at an oral dosage as high as 32 mg/kg did not show any significant inhibitory activity on rat passive cutaneous anaphylaxis, a type-I allergy, although prednisolone and cyproheptadine produced strong inhibition. Against rat adjuvant arthritis, type-III and -IV allergies, AD-1590 showed potent prophylactic (2 and 4 mg/kg/day) and therapeutic (0.4-1 mg/kg/day) effects when given orally once a day for 3 weeks beginning from just before and for 1 week starting from 14 to 18 days after adjuvant inoculation, respectively; however, its prophylactic and therapeutic potencies were about one-fourth and one-fifth, respectively, that of indomethacin. The arthritis was strongly inhibited with prophylactic treatment of prednisolone (1 mg/kg/day) or cyproheptadine (40 mg/kg/day). On the other hand, prednisolone (ED50 = 0.0119 mg/ear, topical) showed strong activity in inhibiting mouse contact hypersensitivity to oxazolone (ear edema), a type-IV allergy, but cyproheptadine only had weak activity. AD-1590 (0.318 mg/ear) and indomethacin (0.699 mg/ear) produced rather strong inhibition; in particular, AD-1590 produced almost complete inhibition at high dosages, whereas most of the non-steroidal anti-inflammatory drugs (NSAID) tested showed weak inhibition or a partial inhibition of about 50% even at the highest dosage. The oral potency of AD-1590 was about 2 and 100 times those of indomethacin and ibuprofen, respectively. These results demonstrate that in allergic inflammation, the pharmacological properties of AD-1590 are somewhat different from those of other NSAID and different from those of prednisolone and cyproheptadine.

Synthesis and oral antiallergic activity of carboxylic acids derived from imidazo[2,1-c][1,4]benzoxazines, imidazo[1,2-a]quinolines, imidazo[1,2-a]quinoxalines, imidazo[1,2-a]quinoxalinones, pyrrolo[1,2-a]quinoxalinones, pyrrolo[2,3-a]quinoxalinones, and imidazo[2,1-b]benzothiazoles

4H-Imidazo[2,1-c][1,4]benzoxazine-2-carboxylic acid (3) was found to possess potent activity in the IgE-induced rat passive cutaneous anaphylaxis model which may be predictive of clinical antiallergic activity. Compared to disodium cromoglycate (DSCG, 1), 3 was less active following iv administration but unlike DSCG showed very significant oral activity. To explore the structural requirements for this activity, a range of tricyclic compounds was prepared and their activities were measured. Individual 2-carboxylic acids derived from imidazo[1,2-a]quinolines, imidazo[1,2-a]quinoxalines, imidazo[1,2-a]quinoxalinones, pyrrolo[1,2-a]quinoxalinones, pyrrolo[2,3-a]quinoxalinones, and imidazo[2,1-b]benzothiazoles showed iv activities up to 10(3) times as potent as DSCG and many of them showed significant oral activity. From these, imidazo[1,2-a]quinoxaline-2-carboxylic acid 114 has been chosen for further development.

[Evaluation of the immunotoxicity of sulfanilamide, anti-inflammatory and antihistaminic preparations]

The effects of 15 widely used drugs on the production of IgE-antibodies and the development of anaphylactic sensitization of rat skin were studied. Some drugs were shown to be able to increasing antibody titres in the blood and prolonging skin sensitization.

The possibilities of predicting allergic effects of new antirheumatics

The new antirheumatic drugs Benzofenac and Flobufen were assessed for their possible influence on various immunological parameters. They were shown to enhance passive cutaneous anaphylaxis (PCA) to ovalbumin in rats and to suppress the numbers of helper and suppressor T-lymphocytes in mice. The effect of Benzofenac in the latter system was found to be more pronounced. The drugs had no effects in any of the other test systems, including the development of delayed hypersensitivity, mitogen-induced lymphocyte proliferation in vitro and the production of antisera (as tested by PCA).

Effects of FR50948, a new orally active antiallergic agent, in experimental allergic models

The antiallergic activity of sodium 10-(2,3-dimethyl pentanamido)-4-oxo-4H-pyrimido [1,2-C] quinazoline-3-carboxylate-hydrate (FR50948) was studied and compared with the activities of sodium cromoglycate (SCG) and lodoxamide. FR50948 had inhibitory effects on type I and type III allergic reactions, but not on type II and IV allergic reactions. FR50948 also had weak inhibitory effects on inflammation (carrageenin paw edema and adjuvant arthritis) and SRS release from rat neutrophils, but no antagonistic effects to histamine and serotonin. The inhibitory effect of FR50948 on IgE-mediated type I allergic reactions was essentially the same as those of SCG and lodoxamide, because FR50948 inhibited the histamine release from rat peritoneal mast cells and had cross tachyphylaxis with SCG in the rat PCA test. However, FR50948, like lodoxamide, had a stronger activity than SCG and was effective by the oral route, unlike SCG which was effective only by the parenteral route. Furthermore, the inhibitory effects of FR50948 on type III reactions and inflammatory reactions were much more potent than those of SCG and equal to those of lodoxamide, and the effect on IgG-mediated PCA was stronger than that of either reference drug. These results suggest that FR50948 will be beneficial in clinical use.