2-Arylbenzimidazoles as antiviral and antiproliferative agents. Part 1.

Being involved in an anti-Flaviviridae Project, and because of the role played by benzimidazole derivatives as promising inhibitors of the HCV helicase and RNA polymerase, as well as of the Zn finger transcription factor, we synthesized a new series of 2-arylbenzimidazoles and evaluated them for antiviral activity, as well as for antiproliferative activity. Compounds were tested in cell-based assays against viruses representative of: i) two of the three genera of the Flaviviridae family, i.e. Flaviviruses and Pestiviruses; ii) other RNA virus families, such as Retroviridae, Picornaviridae, Paramyxoviridae, Rhabdoviridae and Reoviridae; iii) two DNA virus families (Herpesviridae and Poxviridae). Compounds 15, 28 and 29 resulted moderately active only against Yellow Fever Virus (a Flavivirus) (range 6-27 microM), whereas none of the title benzimidazoles showed any antiviral activity at concentrations not cytotoxic for the resting cell monolayers. Compounds were also tested for antiproliferative activity against a panel of exponentially growing cell lines derived from human haematological and solid tumors. Several new benzimidazoles turned out active. Among them, compound 27 was the most potent against human haematologic and solid tumor cells and turned out to be as potent as Etoposide and more potent than 6-mercaptopurine (6-MP), used as reference antitumor agents.

Synthesis and anti-picornaviridae in vitro activity of a new class of helicase inhibitors the N,N'-bis[4-(1H(2H)-benzotriazol-1(2)-yl)phenyl] alkyldicarboxamides.

A series N,N'-bis[4-(1H(2H)-benzotriazol-1(2)-yl)phenyl]alkyldicarboxamides (3a-f and 5a-j) were prepared starting from their already known (1a-d) and (4a-c) or new (4d) amine parents. Because of the antiviral activity of several N-[4-(1H(2H)-benzotriazol-1(2)-yl)phenyl]alkylcarboxamides previously reported, title compounds were evaluated in vitro for cytotoxicity and antiviral activity against viruses representative of Picornaviridae, [i.e. Enterovirus Coxsackie B2 (CVB-2) and Polio (Sb-1)] and of two of the three genera of the Flaviviridae [Bovine Viral Diarrhea Virus (BVDV) and Yellow Fever Virus (YFV)]. Furthermore, because of the in silico activity against the RNA-dependent RNA-helicase of Polio 1 previously reported, title compounds were evaluated against the 3D model of the Sb-1 helicase and against the 2D model of the CVB-2 helicase. As a reference we used the antiviral and in silico activities of an imidazo counterpart of the title compounds, N,N'-bis[4-(2-benzimidazolyl)phenyl]alkyldicarboxamides (III) that other authors reported to be able to inhibit the corresponding enzyme of Hepatitis C Virus (HCV). In cell-based antiviral assays, N,N'-bis[4-(1H-benzotriazol-1-yl)phenyl]alkyldicarboxamides (3a-f) resulted completely inactive whereas the bis-5,6-dimethyl-benzotriazol-2-yl derivatives (5d-f) exhibited good activity against the Enteroviruses, (EC(50)s ranged between 7 and 11 microM against CVB-2 and 19-52 against Sb-1). Interestingly, bis-5,6-dichloro-benzotriazol-2-yl derivatives (5h-j) showed very selective activity against CVB-2 (EC(50)s = 4-11 microM) whereas they resulted completely inactive against all the other viruses screened. In general, all title compounds showed a good cytotoxicity profile in MT-4 cells. Molecular modeling investigations showed that active compounds may interact with the binding site of the Sb-1 helicase and that their free binding energy values are in agreement with their EC(50)s values.

Chemistry, biological properties and SAR analysis of quinoxalinones.

Quinoxaline derivatives have received much attention in recent years owing to their both biological properties and pharmaceutical applications. In this review we focus the attention on quinoxalin-2(3)-ones and quinoxalin-2,3-diones. These derivatives are particularly interesting since some of them showed antimicrobial (against several bacteria, viruses, fungi, etc), or anticancer activities. Furthermore, others are reported to be potent no-NMDA glutamate receptor antagonists, endowed with anxiolytic, deconditioning, analgesic, antispastic, antiallergic, antithrombotic activities. In this article we also report SAR studies and the most important methods of synthesis of the quinoxalin-2(3)-(di)ones.

Synthesis and cytotoxicity of bis(benzo[g]indole-3-carboxamides) and related compounds.

A series of bis(benzo[g]indoles) bridged by CX-(CH2)nN(Me)(CH2)n-CX (X = O, S, H2; n = 2,3) was synthesized as bifunctional antitumor agents and evaluated for cytotoxic activity against diverse human cancer cell lines by the National Cancer Institute. The parent compounds 2a,b exhibited a good level of activity and derivates 2c-g,i,k demonstrated significant inhibitory effects, all with IC50 values in the low micromolar range. The thioamide analogue 2j showed less potency. It is interesting to note that introduction of substituents on the benzene ring of the benzo[g]indole portion of 2a,b did not affect activity, with the only exception of the 7,8-dichloro derivative 2h which became less potent. One member of this series, 2i, was then tested in the hollow fiber cell assay to evaluate, in a preliminary fashion, its in vivo antineoplastic activity. Molecular modelling studies were performed on amide 2a and thioamide 2j to explain the loss of activity of 2j as to 2a. Finally, compound 2a behaved as a typical DNA intercalating agent, as judged from viscosity measurements with Poly(dA-dT)...poly(dA-dT).

Quinoxaline chemistry. Part 13: 3-Carboxy-2-benzylamino-substituted quinoxalines and N-[4-[(3-carboxyquinoxalin-2-yl) aminomethyl]benzoyl]-L-glutamates: synthesis and evaluation of in vitro anticancer activity.

Among a new series of 28 3-carboxy or carbethoxy quinoxalines bearing a substituted benzylamino or N-[4-(aminomethyl)benzoyl]glutamate group on position 2 of the ring and various substituents at C-6, 7 positions, 21 were selected at the National Cancer Institute for evaluation of their in vitro anticancer activity. The results obtained seem to confirm that the carboxy or carbethoxy group on position 3 is not helpful, with a few exceptions, for the anticancer activity.

Quinoxaline chemistry. Part 11. 3-Phenyl-2[phenoxy- and phenoxymethyl]-6(7) or 6,8-substituted quinoxalines and N-[4-(6(7)-substituted or 6,8-disubstituted-3-phenylquinoxalin-2-yl)hydroxy or hydroxymethyl] benzoylglutamates. Synthesis and evaluation of in vitro anticancer activity and enzymatic inhibitory activity against dihydrofolate reductase and thymidylate synthase.

Twenty-four out of twenty-nine quinoxalines were selected at the National Cancer Institute, Bethesda, Md, USA, for in vitro anticancer screening. Among these, 10 derivatives exhibited high values of percent tumor growth inhibition at a concentration of 10(-4) M in all cancer cell lines. Four of these compounds maintained these values at 10(-5) M, whereas a certain number exhibited significant values of percent inhibition at the most diluted concentrations (10(-8)-10(-6) M). Inhibitory activity against dihydrofolate reductase (DHFR) (bovine and rat liver) was determined for the most active compounds. This test showed that this type of quinoxaline exhibited an appreciable activity in comparison with the previously described aza analogues. In the other test (Lactobacillus casei, thymidylate synthase (TS), human HTS) no or poor activity was detected in both series of compounds.

Quinoxaline chemistry. Part 9. Quinoxaline analogues of trimetrexate (TMQ) and 10-propargyl-5,8-dideazafolic acid (CB 3717) and its precursors. Synthesis and evaluation of in vitro anticancer activity.

Eighteen quinoxalines bearing a methyleneanilino or methyleneaminobenzoylglutamate group on position 6 of the ring and various lipophilic substituents on positions 2 and 3 were prepared in order to discover if their structural analogy with both trimetrexate (TMQ) and 10-propargyl-5,8-dideazafolic acid (CB 3717) might display in vitro anticancer activity. Among these, 12 compounds were selected at the National Cancer Institute, Bethesda, MD, USA; they exhibited moderate (4b,d,i,l,m and 8) to strong (4f,h and 5a,e) cell-growth inhibition at a concentration of 10(-4) M. Interesting selectivities were also recorded between 10(-8) and 10(-6) M. These analogues proved to be less potent inhibitors of tumor cells than other classical and non-classical antifolate analogues previously described by us.

Quinoxaline chemistry. Part 10. Quinoxaline 10-oxa-analogues of trimetrexate (TMQ) and of 5,8-dideazafolic acid. Synthesis and evaluation of in vitro anticancer activity.

Among twenty-eight novel compounds (twenty-two 2,3-disubstituted-6-[(substituted-phenoxy)methyl-quinoxalines and six 4-[(2,3-disubstituted-quinoxalin-6-yl)methoxy]benzoylglutamates ) only thirteen were selected at NCI for evaluation of their in vitro anticancer activity. The results have shown that compounds 3l,c,b,e and 4b were endowed with significantly high values of percent tumor growth inhibition on several tumor cell lines at 10(-4) M, while compound 3t was characterized by a high selectivity, being still strongly inhibiting on three cell lines at 10(-5) M. Comparison of the presently observed activity with that of the previously described aza-analogues confirms that the effected isosteric substitution is highly valuable in some cases.

Synthesis and in vitro anticancer activity evaluation of biscarbamic esters of 2,3-bis(hydroxymethyl)-1-methyl-7- and 7,8-substituted-benzo[g]indoles.

A series of various bis(hydroxymethyl) carbamate derivatives of 7-mono- and 7,8-disubstituted-1-methyl-benzo[g]indoles was prepared in order to evaluate their cytostatic and cytotoxic activities in vitro. Compounds 2a-h showed significant tumor growth inhibition activity and were more potent than the 4,5-dihydrobenzo[g]indole analogues previously described. Compound 2a was the most active in this series, showing high activity and selectivity for some human cancer cell lines in the National Cancer Institute screen.

Quinoxaline chemistry. Part 12. 3-Carboxy-2[phenoxy]-6(7)substituted quinoxalines and N-[4-(6(7) substituted-3-carboxyquinoxalin-2-yl)hydroxy] benzoylglutamates. Synthesis and evaluation of in vitro anticancer activity.

Thirty quinoxalines bearing a substituted phenoxy or hydroxybenzoylglutamate group on position 2, a carboethoxy or carboxy group on position 3 and a trifluoromethyl group on position 6 or 7 of the heterocycle were prepared in order to evaluate the in vitro anticancer activity. Screening over 21 compounds selected at the National Cancer Institute (Bethesda, MD) showed that only few derivatives exhibited a moderate growth inhibition activity on various tumor panel cell lines at 10(-4) molar concentration. The acid derivatives showed no growth inhibition activity. The results obtained in this series seem to indicate that in general carboxy or carboethoxy groups close to O-link with phenyl or benzoyl glutamates on position 2 are detrimental for anticancer activity.

Quinoxaline chemistry. Part 8. 2-[Anilino]-3-[carboxy]-6(7)-substituted quinoxalines as non classical antifolate agents. Synthesis and evaluation of in vitro anticancer, anti-HIV and antifungal activity.

Thirty quinoxalines bearing a substituted anilino group on position 2, a carboethoxy or carboxy group on position 3 and a trifluoromethyl group on position 6 or 7 of the heterocycle were prepared in order to evaluate in vitro anticancer activity. Preliminary screening performed at NCI showed that most derivatives exhibited a moderate to strong growth inhibition activity on various tumor panel cell lines between 10(-5) and 10(-4) molar concentrations. Interesting selectivities were also recorded between 10(-8) and 10(-6) M for a few compounds. One single compound exhibited good activity against Candida albicans.

Quinoxaline chemistry. Part 7. 2-[aminobenzoates]- and 2-[aminobenzoylglutamate]-quinoxalines as classical antifolate agents. Synthesis and evaluation of in vitro anticancer, anti-HIV and antifungal activity.

Thirty-three quinoxalines bearing an aminobenzoyl or aminobenzoylglutamate group on position 2 and various substituents on position 3,6,7 of the heterocycle were prepared in order to evaluate in vitro anticancer activity. Preliminary screening performed at NCI showed that most derivatives exhibited a moderate to strong growth inhibition activity on various tumor panel cell lines between 10(-5) and 10(-4) Molar concentrations. Interesting selectivities were also recorded between 10(-8) and 10(-6) M. Among the series examined one compound (29) which was the most active also exhibited both in vitro anti-HIV protection and antifungal activity while in other two (31, 37) the antifungal activity was prevailing.

Quinoxaline chemistry. Part 5. 2-(R)-benzylaminoquinoxalines as nonclassical antifolate agents. Synthesis and evaluation of in vitro anticancer activity.

Thirty-one quinoxalines bearing a substituted benzylamino group on position 2 and various substituents on position 3,6,7 and 8 of the heterocycle were prepared in order to evaluate in vitro anticancer activity. Preliminary screening performed at NCI on twenty-two compounds showed that most derivatives exhibited a moderate to strong growth inhibition activity on various tumor panel cell lines between 10(-5) and 10(-4) molar concentrations. Interesting selectivities were also recorded between 10(-8) and 10(-5) M.

Quinoxaline chemistry. Part 6--Synthesis and evaluation of antiulcer and gastroprotective activity of 2-[arylmethylmercapto-, arylmethylsulfinyl-, piperazinyl-3-R-substituted]quinoxalines.

Thirty compounds possessing quinoxaline structure bearing either substituted arylmethylmercapto-, arylmethylsulfinyl group or a piperazinyl moiety in position 2 were prepared in order to evaluate an antiulcer and gastroprotective activity in rat pylorus ligature, in comparison with omeprazole and ranitidine at the dose of 100 mg/kg after oral administration. Among the compounds of the first group one third showed a moderate activity being about half potent as omeprazole whereas in the second group compound 5b exibited an activity superior to that of ranitidine accompanied with the lowest incidence of lesions and mortality and another compound (5i) was equiactive as ranitidine.

Quinoxaline chemistry. Part 4. 2(R)-anilinoquinoxalines as nonclassical antifolate agents. Synthesis, structure elucidation and evaluation of in vitro anticancer activity.

Thirty-five quinoxalines bearing a substituted aniline group on position 2 and various substituents on positions 3,6,7 and 8 were prepared in order to evaluate in vitro anticancer activity. Structural elucidation of some isomeric quinoxalinones formed by ring closure of 4-substituted-1,2-diaminobenzenes with dicarbonyl compounds was achieved by comparison with one isomer coming from an unambiguous independent route. Preliminary in vitro screening at NCI showed that many compounds exhibited a moderate to strong growth inhibition activity on various cell lines between 10(-5) and 10(-4) molar concentrations.

Triazolo[4,5-f]quinolines. Part VI. Synthesis and evaluation of 9-aminoalkyl(aryl)-2-methyl-2H-[4,5-f]quinolines as anticancer agents. Preliminary results of in vitro screening.

9-Aminoalkyl(aryl)-2-methyl-2H-triazolo[4,5-f] quinolines were prepared in order to evaluate their in vitro antitumor activity. Some members of this series exhibited both cell selectivity and tumor growth inhibition activity at concentrations between 10(-8) and 10(-4)M. In particular, compounds Ia,c,m,o,p and q showed percent growth near zero at midpoint between 10(-5) and 10(-4)M in most cell lines.

Choleretic activity of 3-[ring substituted benzotriazol-1(2)-yl]alkanoic and alkenoic acids.

In order to investigate the influence of structural modifications on the high choleretic activity of 3-(benzotriazol-1-yl)butanoic acid, a set of new benzotriazolyl alkanoic and alkenoic acids was prepared and, together with some other acids previously described, tested in rats by i.v. administration at the dose of 0.5 mmol/kg. Most of the tested compounds exhibited a good choleretic activity comparable with or higher than that of the model acid and of dehydrocholic acid (+56% mean increase of bile volume during 4 hours). Influence of nature and position of substituents was shown in some cases: a moderate decrease of activity was observed for methoxy derivatives and for the introduction of a methyl group in position 6, while a trifluoromethyl group in the same position enhanced the activity (10). Activity was maintained after the introduction of unsaturation in the chain (17,18), but was completely suppressed when unsaturation was associated with a shortening of the alkenoic chain (16). Moving the butanoic chain from position 1 to position 2 in the case of the nitroderivative (15) produced a striking increase of activity (from +42 to +118 mean variation of bile volume during 4 hours), while the same change in the unsubstituted acid 1 abolished the activity.

Synthesis of 1-methyl-2,3-dimethyl-N(isopropyl)carbamates-4,5-dihydro-7-R'- 8-R-1H-benzo[g]indoles and evaluation of in vitro anticancer activity.

The synthesis of 7-mono or 7,8-disubstituted 4,5-dihydro-1-methyl-1H- benzo[g]indoles bearing a methyl-N-isopropylcarbamate group in position 2 or 2,3 of the pyrrole ring is described, in order to evaluate in vitro, anticancer activity. The preliminary results of this screening at the NCI of Bethesda showed a certain cellular subpanel selectivity between 10(-5) and 10(-4) molar concentrations.

Synthesis and evaluation of gastroprotective activity of omeprazole related benzimidazole, imidazo[4,5-b]pyridine and quinoxaline 2-substituted derivatives.

Twenty compounds possessing benzimidazole, imidazo[4,5-b]pyridine and quinoxaline structure bearing either a substituted arylmethylmercapto- or an arylmethylsulfinyl group in position 2 were prepared in order to evaluate an antiulcer and gastroprotective activity in rat pylorus ligature, in comparison with omeprazole at the dose of 50 mg/kg after i.m. administration. One third of these compounds showed a moderate activity, being about half potent as omeprazole.