Synthesis of 1-/2-substituted-[1,2,3]triazolo[4,5-g]phthalazine-4,9-diones and evaluation of their cytotoxicity and topoisomerase II inhibition

Studies on antitumor heterocyclic quinones containing nitrogens revealed that the number and position of nitrogens on the heterocyclic ring have significance on cytotoxicity of quinones. In our continuous effort to find more cytotoxic quinone compounds, we designed triazolophthalazine analogues in order to introduce more nitrogens on the heterocyclic quinones. 1-/2-Substituted-[1,2,3]triazolo[4,5-g]phthalazine-4,9-diones were synthesized by 1,3-dipolar addition of phthalazine-5,8-dione and 4-methoxybenzyl azide by modification of previously reported method. The cytotoxicity of the synthesized compounds was evaluated by a SRB (sulforhodamine B) assay against nine types of human cancer cell lines and inhibition against topoisomerase II (Topo II) of them was assessed by a decatenation assay. Most of the synthesized compounds showed considerably higher cytotoxicity than that of doxorubicin. Also, topoisomerase II inhibitory activity of the tested compounds was higher than that of etoposide and IC(50) values of the compounds were 19.4-64.5 microM.     

Cytotoxicity and DNA topoisomerase inhibitory activity of benz[f]indole-4,9-dione analogs

A series of benz[f]indole-4,9-diones, based on the antitumor activity of 1,4-naphthoquinone, were synthesized and evaluated for their cytotoxic activity in cultured human cancer cell lines A549 (lung cancer), Col2 (colon cancer), and SNU-638 (stomach cancer), and also for the inhibition of human DNA topoisomerases I and II activity in vitro. Several compounds including 2-amino-3-ethoxycarbonyl-N-methyl-benz[f]indole-4,9-dione showed a potential cytotoxic activity judged by IC50<20.0 microg/ml in the panel of cancer cell lines. Especially, 2-hydroxy-3-ethoxycarbonyl-N-(3,4-dimethylphenyl)-benz[f]indole-4,9-dione had potential selective cytotoxicity against lung cancer cells (IC50=0.4 microg/ml)) compared to colon (IC50>20.0 microg/ml) and stomach (IC50>20.0 microg/ml) cancer cells. To further investigate the cytotoxic mechanism, the effects of test compounds on DNA topoisomerase I and II activities were used. In a topoisomerase I-mediated relaxation assay using human placenta DNA topoisomerase I and supercoiled pHOTI plasmid DNA, 2-amino-3-ethoxycarbonyl-N-(4-fluorophenyl)-benz[f]indole-4,9-dione had the most potent inhibitory activity among the compounds tested. However, most of the compounds showed only weak inhibition of the DNA topoisomerase II-mediated KDNA (Kinetoplast DNA) decatenation assay, except for 2-amino-3-ethoxycarbonyl-N-(4-methylphenyl)-benz[f]indole-4,9-dione and 2-amino-3-ethoxycarbonyl-N-(2-bromoehtyl)-benz[f]indole-4,9-dione with a moderate inhibitory activity. These results suggest that several active compounds had relatively selective inhibitory activity against toposiomearse I compared to toposiomerase II. No obvious correlation was observed between the cytotoxicity of the individual compound and the inhibitory activity of DNA relaxation and decatenation by topoisomerase I and II, respectively, in vitro.     

Cytotoxicity and DNA Topoisomerase Inhibitory Activity of Benz[f]indole-4,9-dione Analogs

A series of benz[f]indole-4,9-diones, based on the antitumor activity of 1,4-naphthoquinone, were synthesized and evaluated for their cytotoxic activity in cultured human cancer cell lines A549 (lung cancer), Col2 (colon cancer), and SNU-638 (stomach cancer), and also for the inhibition of human DNA topoisomerases I and II activity in vitro. Several compounds including 2-amino-3-ethoxycarbonyl-N-methyl-benz[f]indole-4,9-dione showed a potential cytotoxic activity judged by IC₅₀<20.0 μg/ml in the panel of cancer cell lines. Especially, 2-hydroxy-3-ethoxycarbonyl-N-(3,4-dimethylphenyl)-benz[f]indole-4,9-dione had potential selective cytotoxicity against lung cancer cells (IC₅₀=0.4 μg/ml)) compared to colon (IC₅₀>20.0 μg/ml) and stomach (IC₅₀>20.0 μg/ml) cancer cells. To further investigate the cytotoxic mechanism, the effects of test compounds on DNA topoisomerase I and II activities were used. In a topoisomerase I-mediated relaxation assay using human placenta DNA topoisomerase I and supercoiled pHOTI plasmid DNA, 2-amino-3-ethoxycarbonyl-N-(4-fluorophenyl)-benz[f]indole-4,9-dione had the most potent inhibitory activity among the compounds tested. However, most of the compounds showed only weak inhibition of the DNA topoisomerase II-mediated KDNA (Kinetoplast DNA) decatenation assay, except for 2-amino-3-ethoxycarbonyl-N-(4-methylphenyl)-benz[f]indole-4,9-dione and 2-amino-3-ethoxycarbonyl-N-(2-bromoehtyl)-benz[f]indole-4,9-dione with a moderate inhibitory activity. These results suggest that several active compounds had relatively selective inhibitory activity against toposiomearse I compared to toposiomerase II. No obvious correlation was observed between the cytotoxicity of the individual compound and the inhibitory activity of DNA relaxation and decatenation by topoisomerase I and II, respectively, in vitro.     

Synthesis and cytotoxicity evaluation of 6,11-dihydro-pyridazo- and 6,11-dihydro-pyrido[2,3-b]phenazine-6,11-diones

The 6,11-dihydro-pyridazo[2,3-b]phenazine-6,11-dione and 6,11-dihydro-pyrido[2,3-b]phenazine-6,11-dione derivatives were synthesized from 6,7-dichloro-5,8-phthalazinedione and 6,7-dichloro-5,8-quinolinedione, respectively, producing a series of new anticancer drugs. The cytotoxic activities of the prepared compounds were evaluated by a SRB (Sulforhodamine B) assay against the following tumor cell lines: A459 (human lung), SK-OV-3 (human ovarian), SK-MEL-2 (human melanoma), XF498 (human CNS), and HCT 15 (human colon). Almost all the derivatives of the 6,11-dihydro-pyridazo[2[,3-b]phenazine-6,11-dione and 6,11-dihydro-pyrido[2,3-b]phenazine-6,11-dione, tetracyclic heteroquinone analogues with four or three nitrogen atoms, exhibited excellent cytotoxicity on almost all the human tumor cell lines tested. Specifically, 6,11-dihydro-pyridazo[2,3-b]phenazine-6,11-dione (4a) exhibited potent activity against all the tumor cell lines, and in particular, its cytotoxic effect against HCT 15 (ED(50)=0.004 microg/mL) was 25 times greater than that of doxorubicin (ED(50)=0.093 microg/mL).     

Cytotoxic activity toward KB cells of 2-substituted naphtho[2,3-b]furan-4,9-diones and their related compounds

We investigated the cytotoxic activity of 2-substituted naphtho[2,3-b]furan-4,9-diones. We have previously synthesized 33 types of 2-substituted and related compounds, and the cytotoxic activity of these compounds was then examined by a KB cell culture assay. 2-(3-Furanoyl)benzoic acids and 1,4-naphthoquinones had no activity. 2-Acetyl-4,9-dimethoxynaphtho[2,3-b]furan 4 showed low activity. However, parent naphtho[2,3-b]furan-4,9-dione 2 and most 2-substituted derivatives exhibited cytotoxic activity. The parent structure was therefore for cytotoxicity. 2-Formylnaphtho[2,3-b]furan-4,9-dione 11 had particularly potent activity (ED50=0.09 microg/ml).     

Synthesis of pyridino[2,3-f]indole-4,9-dione and 6,7-disubstituted quinoline-5,8-dione derivatives and evaluation on their cytotoxic activity

We report upon the synthesis of the following derivatives: N-substituted-pyridino[2,3-f]indole-4,9-dione, and 6-(alpha-diethoxycarbonyl-methyl)-7-substituted-amino-quinoline-5,8-dione, which contain the active quinoline-5,8-dione (VII) moiety. The cytotoxic activities of these compounds have been tested in SRB (SulfoRhodamine B) assays against the cancer cell lines of A-549 (human lung cancer), SK-MEL-2 (human melanoma cancer), SK-OV-3 (human ovarian cancer), XF-498 (human brain cancer) and HCT 15 (human colon cancer). The compound, N-benzyl-3-ethoxycarbonyl-2-hydroxy-pyridino[2,3-f]indole-4,9-dione (A-9), also showed higher activity than cis-platin. The highest level of cytotoxic activity in these human tumor cell lines was observed in the compound 6-(alpha-diethoxycarbonyl-methyl)-7-(2-methyl-phenylamino)-quinoline-5,8-dione (B-3).     

Synthesis, and cytotoxic activity of some novel indolo[2,3-b]quinoline derivatives: DNA topoisomerase II inhibitors

A series of new 5H-indolo[2,3-b]quinoline derivatives bearing methoxy and methyl groups at C-2 and C-9 was synthesized (according to the modified Graebe-Ullmann reaction). These compounds were evaluated for their antimicrobial and cytotoxic activity and tested as inhibitors of DNA topoisomerase II. Lipophilic and calf thymus DNA binding properties of these compounds were also established. In the SAR studies we used quantum-mechanical methodology to analyze the molecular properties of the drugs. All of the 5H-indolo[2,3-b]quinolines tested were found to inhibit the growth of gram-positive bacteria and pathogenic fungi at MIC ranging between 2.0 and 6.0 microM. They showed also cytotoxic activity in vitro against several human cancer cell lines of different origin (ID50 varied from 0.6 to 1.4 microM), and stimulated the formation of topoisomerase-II-mediated pSP65 DNA cleavage at concentration between 0.2 and 0.5 microM. The most active indolo[2,3-b]quinolines which had the greatest contribution to the increase in the Tm of DNA displayed also the highest DNA binding constants and the highest cytotoxic activity. The differences in DNA binding properties and cytotoxic activity seem to be more related to steric than electrostatic effects.     

New benzo[g]isoquinoline-5,10-diones and dihydrothieno [2,3-b]naphtho-4,9-dione derivatives: synthesis and biological evaluation as potential antitumoral agents

Novel antitumoral agents with quinonic structure were synthesized and evaluated for their in vitro cytotoxic activities. This study examines the cytotoxic activities of several aryl benzo[g]isoquinoline-5,10-dione derivatives and a number of aminoacyl dihydrothieno[2,3-b]naphtho-4,9-dione (DTNQ) derivatives containing amino acids in position 3 of the ring system. Compound 6 showed remarkable cytotoxic activity at submicromolar concentration not only against several human leukaemia and solid tumour cell lines, but also toward sensitive and resistant human cell lines.     

Synthesis, cytotoxicity, DNA interaction and topoisomerase II inhibition properties of tetrahydropyrrolo[3,4-a]carbazole-1,3-dione and tetrahydropyrido-[3,2-b]pyrrolo[3,4-g]indole-1,3-dione derivatives.

Three tetrahydropyrrolo[3,4-a]carbazole-1,3-diones (6--8) and two tetrahydropyrido[3,2-b]pyrrolo[3,4-g]indole-1,3-diones (11--12) have been synthesized. Their interaction with DNA was probed by absorption and thermal melting studies. Compounds 8 and 12 both equipped with a hydroxyethyl-aminoethyl side-chain demonstrated higher affinities for poly(dA-dT)(2) than compounds 6, 7 and 11 bearing a dimethylaminoethyl side-chain. Circular and electric linear dichroism measurements showed that all five drugs behave as typical DNA intercalating agents. A plasmid cleavage assay was used to evaluate the capacity of the drugs to inhibit human topoisomerase II. Compounds 8 and 12 which bind strongly to DNA were found to stabilize DNA-topoisomerase II covalent complexes but their topoisomerase II inhibitory properties do not correlate with their cytotoxic potential. Compounds 6 and 7 are essentially inactive whereas compounds 8, 11 and 12 exhibit a high toxicity to P388 murine leukemia cells and provoke a marked accumulation in the G2/M phase of the cell cycle. These compounds form a new class of DNA-targeted antitumor agents.     

Biological evaluation of isothiazoloquinolones containing aromatic heterocycles at the 7-position: In vitro activity of a series of potent antibacterial agents that are effective against methicillin-resistant Staphylococcus aureus

We synthesized a diverse series of 9H-isothiazolo[5,4-b]quinoline-3,4-diones containing heteroaromatic groups at the 7-position via palladium-catalyzed cross-coupling. Many of these compounds demonstrated potent antistaphylococcal activity (MICs 2 microg/mL) against a multi-drug-resistant strain (ATCC 700699) and low cytotoxic activity (CC(50)>100 microM) against the human cell line Hep2 (laryngeal carcinoma).     

Synthesis and biological evaluation of novel naphthoquinone fused cyclic aminoalkylphosphonates and aminoalkylphosphonic monoester

A series of novel naphthoquinone fused cyclic alpha-aminophosphonates, 2-alkoxy-3,4-dihydro-2H-naphtho[2,3-e][1,4,2]oxazaphosphinane-5,10-dione 2-oxide 3-17 and naphthoquinone fused cyclic alpha-aminophosphonic monoester 18 were synthesized for the first time. These cyclic alpha-aminophosphonates were evaluated for antitumor activity on four human tumor cell lines, and three of them showed significant cytotoxicity (IC(50): 0.019-5.15 microM) comparable to that of the reference drug doxorubicin. Furthermore, inhibition assays for topoisomerase II-mediated relaxation of supercoiled DNA indicated that the naphthoquinone fused cyclic aminophosphonates were catalytic inhibitors of topoisomerase II.     

Synthesis and in vitro evaluation of 7-dialkylaminomethylbenzo[g]quinoxaline-5,10-diones

A series of benzo[g]quinoxaline-5,10-dione derivatives carrying a 7-dialkylaminomethyl substituent was synthesized and their in vitro cytotoxic activities were evaluated against four human cancer cell lines (HCT-15, SK-OV-3, MD-MB-468 and T-47D). The most active compound 9d showed cytotoxic activity comparable to that of doxorubicin against HCT-15 cancer cell line.     

Synthesis of some new [1,2,4]triazolo[3,4-b][1,3,4]thiadiazines and [1,2,4]triazolo[3,4-b][1,3,4] thiadiazoles starting from 5-nitro-2-furoic acid and evaluation of their antimicrobial activity

New series of fused 1,2,4-triazoles such as, 6-(aryl)-3-(5-nitrofuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 4-8, 6-(alkyl/aryl amino)-3-(5-nitrofuran-2-yl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 9-13 and 6-(4-substituted phenyl)-3-(5-nitrofuran-2-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines 14-18 have been synthesized via the reaction of 4-amino-5-(5-nitrofuran-2-yl)-4H-1,2,4-triazole-3-thiol 3 with various reagents such as hetero aromatic aldehydes, alkyl/aryl isothiocyanates and 4-substituted phenacyl bromides, respectively. The structures of the newly synthesized compounds have been confirmed on the basis of elemental analysis and spectral studies. The newly synthesized triazolo derivatives have been investigated for their in vitro antibacterial activity. Most of the tested compounds showed interesting antibacterial activity against Staphylococcus aureus. Furthermore, the most potent antibacterial compounds 11-13 were evaluated for their in vitro cytotoxic activity against human cancer cell lines. It was found that compounds 11 and 13 showed higher cytotoxicity against Hep-G2 cell line as compared to standard.     

Synthesis and cytotoxicity of 1-substituted 2-methyl-1H-imidazo[4,5-g]phthalazine-4,9-dione derivatives

A series of 1-substituted 2-methyl-1H-imidazo[4,5-g]phthalazine-4,9-dione derivatives 8 was synthesized from 6,7-dichlorophthalazine-5,8-dione 5 and evaluated for in vitro cytotoxicity against several human tumor cell lines. Most of the tested compounds showed potential cytotoxic activity considerably higher than that of the reference compounds, ellipticine and doxorubicin.     

Synthesis and cytotoxic activity of pyridazino[1',6':1,2]pyrido[3,4-b]indol-5-inium derivatives as anti-cancer agents

Several new pyridazino[1',6':1,2]pyrido[3,4-b]indol-5-inium derivatives were synthesised from beta-carboline derivatives and their cytotoxic activity and effect on the cell cycle were evaluated against L1210 cancer cells.     

Synthesis and cytotoxic evaluation of analogues of the marine pyridoacridine amphimedine

4-Substituted-7H-pyrido-[4,3,2-de][1,8] or [1,9]-phenanthroline-7-ones and 9-methyl-1,4-diazanaphtacene-3,10-dione, analogues of the marine pyridoacridine amphimedine were synthesised from isoquinoline-5,8-dione. The first compounds were obtained starting from a Diels-Alder reaction whereas the synthesis of the last compound was initiated by a reaction of condensation with 2-aminoacetophenone. The different tetra- and pentacyclic compounds were evaluated for in vitro cytotoxic activities against six distinct human cancer cell lines. All the compounds exhibit cytotoxic activity with IC(50) values (i.e., the drug concentration inhibiting the mean growth value of the six cell lines by 50%)<10(-7)M for two of them.     

Synthesis, cytotoxicity, QSAR, and intercalation study of new diindenopyridine derivatives

Seven new derivatives of diindenopyridine were synthesized by Hantsch pyridine synthesis. Their biological activity to inhibit cell proliferation was assessed by MTT assay on seven cell lines. 11-(4-Fluoro-phenyl)-diindeno[1,2-b;2',1'-e]pyridine-10,12-dione and 11-(2-nitro-phenyl)-diindeno[1,2-b;2',1'-e]pyridine-10,12-dione were active on K-562 cell line with IC50 values of 79.66 and 78.2 microM, respectively. Effect of structural parameters on the cytotoxicity was evaluated by quantitative structure activity relationship (QSAR) analysis and a linear relationship was found between the -logIC15 of these compounds and their surface area and molar refractivity. To model the DNA-intercalator complex, force field molecular mechanic calculation was employed and the binding energy of the reaction between the intercalating agent and each reasonable double base pairs of DNA was calculated. It was found that these molecules could intercalate into the DNA. Also, it was observed that 11-(2-nitro-phenyl)-diindeno[1,2-b;2',1'-e]pyridine-10,12-dione, which showed the highest activity in K-562 cell line, produced the most negative binding energy with a moderate selectivity toward A-G/T-C double base pairs.     

Identification of antitumour activity of novel derivatives of 8-aryl-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-dione and 8-aryl-4-imino-2,3,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3(6H)-one

The series of 8-aryl-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-diones (11-20) and 8-aryl-4-imino-2,3,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3(6H)-ones (21-25) were designed and their in vitro cytotoxic activities against human LS180, HeLa, T47D, A549 and RPMI 8226 carcinoma cells are presented. In the crystalline state molecule 12 exists as the predominant tautomeric 3-oxo form, whereas the second possible 3-hydroxy tautomer is not observed. Compound 19 revealed a strong affection to LS180 cancer cells at lower tested concentration (37.9 microM) and simultaneously was found to be non-toxic towards the normal cell line investigated--GMK cells. Furthermore, this compound was proved to possess the efficiency for DNA strand breakage of the examined cancer cell lines. However, imidazotriazin-3,4-dione 20 was able to cause significant viability decreases in human RPMI 8226 peripheral blood myeloma cells. Compound 22 has exhibited remarkable inhibitory effects against LS180 and A549 carcinoma cells, whereas 24 revealed the highest growth inhibition against A549 cell line. Simultaneously, at lower tested concentration these compounds were proved to be completely non-toxic for GMK cells. Moreover, cytotoxic and antibacterial properties of starting, tautomeric 1-aryl-2-hydrazonoimidazolidines (1-6 and 8-9) are presented. Six of them (1-2, 4-6 and 9) proved active as antimicrobials. All these compounds revealed MIC values in the range of 15.0-78.6 microM. Their activities were compared to those of ampicillin and chloramphenicol.     

Synthesis and evaluation of pyrazolo[3,4-b]pyridines and its structural analogues as TNF-alpha and IL-6 inhibitors

In the present article, we have synthesized three different series of pyrazolo[3,4-b]pyridines and their structural analogues using novel synthetic strategy involving one-pot condensation of 5,6-dihydro-4H-pyran-3-carbaldehyde/2-formyl-3,4,6-tri-O-methyl-D-glucal/chromone-3-carbaldehyde with heteroaromatic amines. All synthesized compounds were evaluated for their anti-inflammatory activity against TNF-alpha and IL-6. Out of 28 compounds screened, 40, 51, 52 and 56 exhibited promising activity against IL-6 with 60-65% inhibition at 10 microM concentration. Amongst these, 51, 52 and 56 showed potent IL-6 inhibitory activity with IC(50)'s of 0.2, 0.3 and 0.16 microM, respectively. Compound 56 was not cytotoxic in CCK-8 cells up to the concentration of >100 microM.     

Synthesis of new indeno[1,2-e]pyrimido[4,5-b][1,4]diazepine-5,11-diones as potential antitumor agents

Novel racemic indeno[1,2-e]pyrimido[4,5-b][1,4]diazepine-5,11-diones 3-29 were obtained regioselectivily from the reaction of 5,6-diamino-3,4-dihydropyrimidin-4-ones 1 and 2-arylideneindandiones 2 as reagents. These compounds have been evaluated at the US National Cancer Institute (NCI) for their ability to inhibit approximately 60 different human tumor cell lines, where 5 and 6 presented remarkable activity against 57 and 48 cancer cell lines, respectively, with the most important GI(50) values ranging from 0.49 to 1.46 microM, in vitro assay.