Marco Ghia

1,8-Naphthyridines IV. 9-Substituted N,N-dialkyl-5-(alkylamino or cycloalkylamino) [1,2,4]triazolo[4,3-a][1,8]naphthyridine-6-carboxamides, new compounds with anti-aggressive and potent anti-inflammatory activities

The title compounds (8) were synthesized through the cyclocondensation of the corresponding N-substituted 4-amino-2-chloro-1,8-naphthyridine-3-carboxamides (4) with the proper hydrazides, in order to evaluate their anti-inflammatory and anti-aggressive properties. Several compounds 8 exhibited high anti-inflammatory activity (carrageenin-induced paw edema assay in the rat) along with appreciable anti-aggressive properties (isolation-induced aggressiveness test in mice). With respect to anti-inflammatory activity, the most active compounds (8n and 8c) produced a 61% edema inhibition at the 25 mg/kg dose, and 50 or 35% inhibition, respectively, at the 12.5 mg/kg dose. The structure-activity relationships are discussed.

Effect of aspirin on incidence and growth of aberrant crypt foci induced in the rat colon by 1,2-dimethylhydrazine

The aim of this work was to investigate if the possible chemopreventive effect of aspirin (ASA) on rat colon carcinogenesis could be detected with a medium-term assay. The end-point chosen was the inhibition of incidence and growth of putative preneoplastic lesions, the aberrant crypt foci (ACF) induced in the rat colon by two administrations of 1,2-dimethylhydrazine (DMH, 25 mg/kg p.o.). At both 4 and 8 weeks after the starting of the carcinogenic treatment the incidence of total ACF was reduced of 60% in rats receiving ASA (10 mg/kg/day p.o.) for 12 consecutive days during the initiation treatment with DMH. Also the number of the larger foci (with 3 or more crypts) was significantly lower in ASA-treated rats at both time-points (about 70% reduction). Moreover, concomitant ASA treatment determined a significant decrease of the mean number of crypts per focus at week 8. These results indicate that the chemopreventive effect of ASA on chemically-induced rat colon carcinogenesis observed in long-term studies may be detected in this relatively short assay.

1,5-Benzodiazepines IX. A new route to substituted 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amines with analgesic and/or anti-inflammatory activities

Abstract A new two-step synthetic pathway to substituted 4 H -[1,2,4]triazolo[4,3- a ][1,5]benzodiazepin-5-amines 2a–p is described. The cyclocondensation of (dimethylamino)benzodiazepinone 1a with hydrazides afforded triazolobenzodiazepinones 5 which in turn reacted with suitable primary or secondary amines, in the presence of titanium tetrachloride, to give the desired 5-amino-derivatives 2a–p . When compounds 5 were treated with the Lawessons reagent thiolactams 6 were obtained, which then reacted with sodium hydride and proper alkyl halides to yield 5-(alkylthio)derivatives 7a–d . Compounds 2a–h, j–p , and 7a–d were tested for their analgesic and anti-inflammatory activities, as well as for their acute toxicity and gross behavioral effects. The analgesic activity appeared noteworthy in the writhing test, where fifteen compounds were more effective than both the reference drugs acetylsalicyclic acid and dipyrone, but was less evident in the hot plate test. An anti-inflammatory activity, lower than that of indomethacin but reaching the level of statistical significance, was displayed in the carrageenin-induced edema assay by five of the nineteen test compounds.

Evaluation of the potential carcinogenic activity of Senna and Cascara glycosides for the rat colon

Anthraquinone glycosides of Senna and Cascara were investigated for their ability to induce aberrant crypt foci (ACF) in the rat colon mucosa, which are considered putative preneoplastic lesions. Dietary exposure to high doses of these glycosides for 56 successive days did not cause the appearance of ACF or increase in incidence of ACF induced by 1,2-dimethyl-hydrazine (DMH). However, in rats treated with both DMH and the highest dose of glycosides, the average number of aberrant crypts per focus, considered a consistent predictor of tumor outcome, was higher than in rats given DMH alone. These findings suggest that Senna and Cascara glycoside might behave as weak promoters in rat colon carcinogenesis.

Induction and promotion of γ-glutamyltranspeptidase-positive foci in the liver of female rats treated with ethinyl estradiol, clomiphene, tamoxifen and their associations

The objective of the present study was to determine whether a short exposure (6 weeks) to high doses of ethinyl estradiol (EE) could not only promote but also initiate hepatocarcinogenesis, and whether two antiestrogens, clomiphene (C) and tamoxifen (T), could influence EE activity. 2-Acetylaminofluorene (AAF), which has been shown to produce rat liver hyperplastic lesions characterized by the presence of estrogen receptors, was used either as a promoter to test for initiating activity, or as an initiator to test for promoting activity. Putative preneoplastic lesions were identified by means of a positive gamma-glutamyltranspeptidase (GGT) reaction. The results revealed that when administered alone in female Sprague-Dawley rats, not only E, but also C and T were clearly active in both initiating and promoting the development of GGT-positive foci. Moreover, in rats of the same strain treated with EE + C or EE + T a significant increase in the incidence of GGT foci demonstrated the occurrence of an additive effect in terms of both initiating and promoting activity. Fischer 344 rats were more susceptible than Sprague-Dawley rats to promotion by EE, C and T, but any substantial evidence of an additive effect was absent when the two anti-estrogens were administered in association with the estrogen.

Cinnamaldehyde-induced micronuclei in rodent liver

Cinnamaldehyde, a widely used flavoring agent, has so far been subjected to a limited range of genotoxicity tests, mainly carried out in vitro, which produced contradictory results. Therefore we have examined cinnamaldehyde using additional in vivo genotoxicity end-points. In Sprague-Dawley rats, a single oral dose equal to 1/2 LD50 did not induce DNA fragmentation in liver and gastric mucosa as evaluated by the alkaline elution technique, increased the frequency of micronucleated hepatocytes but not of bone marrow micronucleated polychromatic erythrocytes, and gave rise to a significantly higher incidence of total nuclear anomalies but not of micronucleated cells in forestomach mucosa. In Swiss mice, the equitoxic dose of cinnamaldehyde caused the same clastogenic effect in the liver, whilst a negative response was observed in both bone marrow and forestomach mucosa. Finally, in rats initiated with N-nitrosodiethylamine the administration of 500 mg/kg/day cinnamaldehyde for 14 successive days produced a modest but statistically significant increase of the average diameter and area of gamma-glutamyltranspeptidase-positive foci that, together with changes observed in other parameters, might be considered indicative of a potential promoting activity. Taken as a whole, these findings confirm that high doses of cinnamaldehyde may induce genetic alterations at the chromosomal level, and suggest that the liver is the preferential target of its undesirable effects.

1,5-Benzodiazepines VIII Novel 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepine derivatives with analgesic or anti-inflammatory activity

The reaction of N,N-disubstituted 4-(methylthio)-3H-1,5-benzodiazepin-2-amines 8 with formylhydrazine, acetylhydrazine or benzoylhydrazine afforded the expected N,N-disubstituted 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amines 9, along with lower yields of tetracyclic compounds 10. A number of compounds 9 and 10 were tested for their analgesic, anti-inflammatory and anticonvulsant activities, as well as for their acute toxicity and gross behavioral effects. Dipyrone, indomethacin and phenobarbital were used as reference drugs. Some compounds 9 showed statistically significant analgesic or anti-inflammatory properties, depending on the structure.

1,5-Benzodiazepines XI. 5-(Dialkylamino) or 5-(alkylthio) substituted 8-chloro-6-phenyl-6H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepines with anticonvulsant activity

Abstract The cyclocondensation of (dimethylamino)benzodiazepinones 3a,b with hydrazides yielded triazolobenzodiazepinones 4 which were treated with Lawessons reagent to give thiolactams 5. The phase-transfer catalyzed (TEBA) alkylation of compounds 5 with suitable alkyl halides afforded 5-(alkylthio)-6-phenyl-6H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepines 6a-f. The desired N,N-dialkyl-6-phenyl-6H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amines 7a-k were finally obtained from the reaction of the (methylthio)derivatives 6a-d with proper dialkylamines. Compounds 6b-f and 7a-e, g-k were screened for anticonvulsant activity after a preliminary evaluation of their gross behavioral effects and acute toxicity. Nine of the 15 triazolobenzodiazepines tested exerted a clear-cut anticonvulsant effect associated with low acute toxicity. In particular, the most active compounds 6e, f and 7h showed LD50/ED50 ratios that were notably higher than that of phenobarbital and ranging from 50% to 20% of that of diazepam, the latter used as reference drugs.

A study of the potential genotoxicity of cimetidine using human hepatocyte primary cultures: discrepancy from results obtained in rat hepatocytes.

The genotoxicity of cimetidine, a drug widely used in the treatment of peptic ulcer, was examined in human hepatocyte primary cultures. No induction of unscheduled DNA synthesis, as detected by autoradiography, or of DNA fragmentation, as measured by alkaline elution, was seen in metabolically competent human hepatocytes exposed for 20 h to cimetidine concentrations ranging from 0.33 to 9 mM. These findings, which are in contrast with the previously observed capability of cimetidine to induce DNA damage and repair in rat hepatocyte primary cultures, suggest that for some chemicals the rat hepatocyte model might be an inappropriate predictor of potential genotoxic effects in the analogous human cells.

Evaluation of flutamide genotoxicity in rats and in primary human hepatocytes

Flutamide, an effective competitive inhibitor of the androgen receptor used orally for palliative treatment of prostatic carcinoma and regulation of prostatic hyperplasia was evaluated for its genotoxic effects in the intact rat and in primary cultures of human hepatocytes. Negative responses were obtained in all the in vivo assays as well as in the in vitro assay. In rats given a single oral dose of 500 mg/kg flutamide, fragmentation and repair of liver DNA were absent, and no increase was observed in the frequency of micronucleated hepatocytes. In the liver of rats given flutamide as initiating agent at the dose of 500 mg/kg/week for 6 successive weeks, gamma-glutamyltraspeptidase-positive foci were detected only in 3 of 10 rats. There was no evidence of a promoting effect on the development of aberrant crypt foci in rats given 100 mg/kg flutamide on alternate days for 8 successive weeks. In primary cultures of human hepatocytes from one male and one female donor DNA fragmentation as measured by the Comet assays, and DNA repair synthesis as revealed by quantitative autoradiography, were absent after a 20 hr exposure to flutamide concentrations ranging from 18 to 56 microM. Taken as a whole, our results seem to indicate that flutamide is a non-genotoxic drug.