Synthesis, Molecular Structure, Anticancer Activity, and QSAR Study of N-(aryl/heteroaryl)-4-(1H-pyrrol-1-yl)Benzenesulfonamide Derivatives.

A series of N-(aryl/heteroaryl)-4-(1H-pyrrol-1-yl)benzenesulfonamides were synthesized from 4-amino-N-(aryl/heteroaryl)benzenesulfonamides and 2,5-dimethoxytetrahydrofuran. All the synthesized compounds were evaluated for their anticancer activity on HeLa, HCT-116, and MCF-7 human tumor cell lines. Compound 28, bearing 8-quinolinyl moiety, exhibited the most potent anticancer activity against the HCT-116, MCF-7, and HeLa cell lines, with IC50 values of 3, 5, and 7 µM, respectively. The apoptotic potential of the most active compound (28) was analyzed through various assays: phosphatidylserine translocation, cell cycle distribution, and caspase activation. Compound 28 promoted cell cycle arrest in G2/M phase in cancer cells, induced caspase activity, and increased the population of apoptotic cells. Relationships between structure and biological activity were determined by the QSAR (quantitative structure activity relationships) method. Analysis of quantitative structure activity relationships allowed us to generate OPLS (Orthogonal Projections to Latent Structure) models with verified predictive ability that point out key molecular descriptors influencing benzenosulfonamide's activity.

Synthesis and QSAR study of novel 6-chloro-3-(2-Arylmethylene-1-methylhydrazino)-1,4,2-benzodithiazine 1,1-dioxide derivatives with anticancer activity.

A series of new 6-chloro-3-(2-arylmethylene-1-methylhydrazino)-1,4,2-benzodithiazine 1,1-dioxide derivatives were effectively synthesized from N-methyl-N-(6-chloro-1,1-dioxo-1,4,2-benzodithiazin-3-yl)hydrazines. The intermediate compounds as well as the products, were evaluated for their cytotoxic effects toward three human cancer cell lines. All compounds shown moderate or weak cytotoxic effects against the tested cancer cell lines, but selective cytotoxic effects were observed. Compound 16 exhibited the most potent cytotoxic activity against the HeLa cell line, with an IC50 value of 10 µM, while 14 was the most active against the MCF-7 and HCT-116 cell lines, affording IC50 values of 15 µM and 16 µM, respectively. The structure-activity relationship was evaluated based on QSAR methodology. The QSAR MCF-7 model indicated that natural charge on carbon atom C13 and energy of highest occupied molecular orbital (HOMO) are highly involved in cytotoxic activity against MCF-7 cell line. The cytotoxic activity of compounds against HCT-116 cell line is dependent on natural charge on carbon atom C13 and electrostatic charge on nitrogen atom N10. The obtained QSAR models could provide guidelines for further development of novel anticancer agents.

Synthesis of a new series of N4-substituted 4-(2-aminoethyl)benzenesulfonamides and their inhibitory effect on human carbonic anhydrase cytosolic isozymes I and II and transmembrane tumor-associated isozymes IX and XII.

A series of novel N(4)-substituted 4-(2-aminoethyl)benzenesulfonamides 5-17 have been synthesized and investigated as inhibitors of four isoforms of zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), that is the cytosolic CA I and II, and tumor-associated isozymes CA IX and XII. Against the human CA I investigated compounds displayed KI values from 96.3 to 3520 nM, toward hCA II at range of 18.1-2055 nM, while against hCA IX ranging from 5.9 to 419 nM and against hCA XII in the range of 4.0-414 nM. The very good inhibitory activity against tumor-associated hCA IX and hCA XII was found. The six new compounds displayed a powerful inhibitory potency toward hCA IX (K(I) = 5.9-10.7 nM) in comparison with the clinically used CAIs AAZ, MZA, EZA, DCP and IND (24-50 nM). The most potent hCA IX and hCA XII inhibitors 11 and 12 (K(I): 5.9 and 6.2 nM for hCA IX and 4.3 and 4.0 nM for hCA XII, respectively) belonged to the compounds with cationic character and presented meaningful affinity to the transmembrane isoforms hCA IX and XII than to physiologically dominant isozymes hCA I and II with the selectivity ratios hCA IX versus hCA II and hCA XII versus hCA II for 11 and 12 in the range of 10-15.

Synthesis of a new series of biologically interesting 6'-chloro-1',1'-dioxospiro[4H-benzo[d][1,3,7]oxadiazocine-4,3'(2'H)-[1,4,2]benzodithiazine]-2,6(1H,5H)dione derivatives.

ABSTRACT: A series of 6'-chloro-1',1'-dioxospiro[4H-benzo[d][1,3,7]oxadiazocine-4,3'(2'H)-[1,4,2]benzodithiazine]-2,6(1H,5H)dione derivatives have been synthesized from isatoic anhydride and 3-(R2-amino)-1,4,2-benzodithiazine 1,1-dioxides. Some synthetic limitations are discussed on the basis of quantum chemical calculations performed by use of the Hartree-Fock method.

Carbonic anhydrase inhibitors. Regioselective synthesis of novel series 1-substituted 1,4-dihydro-4-oxo-3-pyridinesulfonamides and their inhibition of the human cytosolic isozymes I and II and transmembrane cancer-associated isozymes IX and XII.

A series of novel 1-substituted 1,4-dihydro-4-oxo-3-pyridinesulfonamides 4-6, 9-17 and 21-31 have been synthesized and investigated as inhibitors of four isoforms of zinc enzyme carbonic anhydrase (CA.EC 4.2.1.1), that is the cytosolic CA I and II, and cancer-associated isozymes CA IX and XII. Against the human isozymes hCA I the new compounds showed K(I)s in the range of 224-4830 nM, whereas toward hCA II, K(I)s = 318-873 nM. Isozyme hCA IX was inhibited with K(I)s = 11.8-93.4 nM, and hCA XII with 23.5-82.3 nM. Compounds 12-14, 27 and 29-31 have an activity against hCA I (K(I)s = 224-889 nM) which is comparable to the clinically used sulfonamide DCP (K(I)s = 1200 nM). Several of new compounds, including 9, 10, 21, 24, 26-28 and 30 have an activity against hCA IX (K(I)s = 11.8-38.6 nM) which is comparable or more effective than the clinically used sulfonamides AAZ, MZA, EZA, DCP and IND (K(I)s = 24-50 nM). Compounds 9, 10, 13, 21-23, 26 and 27 were also very effective hCA XII inhibitors, with inhibition constants ranged from 23.5 to 47.2 nM comparable or more effective than sulfonamides EZA (K(I)s = 22 nM) or DCP (K(I)s = 50 nM), respectively.

Carbonic anhydrase inhibitors. Synthesis, molecular structures, and inhibition of the human cytosolic isozymes I and II and transmembrane isozymes IX, XII (cancer-associated) and XIV with novel 3-pyridinesulfonamide derivatives.

A series of novel 3-pyridinesulfonamide derivatives (2-5, 9-11 and 13-15) have been synthesized and investigated as inhibitors of five isoforms of zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), that is, the cytosolic ubiquitous CA I and II, and isozymes CA IX and XII (cancer-associated), and XIV. Against the human isozyme hCA I the new compounds showed K(I)s in the range of 0.089-251 µM, whereas toward hCA II, K(I)s = 50.5-487 nM. Isozyme hCA IX was inhibited with K(I)s in the range of 5.2-18.3 nM, while hCA XII with K(I)s = 6.0-16.4 nM, and hCA XIV with K(I)s = 76.4-152.0 nM. All of the new compounds 2-5, 9-11 and 13-15 showed excellent hCA IX inhibitory efficacy, with K(I)s = 5.2-18.3 nM, being much more effective as compared to the clinically used AAZ, MZA, EZA, DCP and IND (K(I)s = 24-50 nM).

Carbonic anhydrase inhibitors. Regioselective synthesis of novel 1-substituted 1,4-dihydro-4-oxo-3-pyridinesulfonamides and their inhibition of the human cytosolic isozymes I and II and transmembrane cancer-associated isozymes IX and XII.

A series of 1-substituted 1,4-dihydro-4-oxo-3-pyridinesulfonamide (2-16) have been synthesized and investigated as inhibitors of four isoforms of zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), that is the cytosolic ubiquitous CA I and II, and cancer-associated isozymes CA IX and XII. Against the human isozymes hCA I the new compounds showed inhibition constants in the range of 1.09-12.1 microM, against hCA II in the range of 50.5-172 nM, against hCA IX in the range of 5.2-118 nM, and against hCA XII in the range of 8.7-381 nM, respectively. Compounds 2, 3, 5-9, 11, 13 and 14 showed excellent hCA IX inhibitory efficacy, with K(I)s = 5.2-11.0 nM, being much more effective as compared to the clinically used sulfonamides AAZ, MZA, EZA, DCP and IND (K(I)s = 24-50 nM). Compounds 2, 3, 5-9, 11 and 13 were also very effective hCA XII inhibitors (K(I)s = 8.7-45.2 nM) which are comparable or more effective than those clinically used EZA and DCP (K(I)s = 22 and 50 nM), respectively.

Carbonic anhydrase inhibitors: synthesis and inhibition of the human cytosolic isozymes I and II and transmembrane isozymes IX, XII (cancer-associated) and XIV with 4-substituted 3-pyridinesulfonamides.

A series of novel 4-substituted-3-pyridinesulfonamides (2-27 and 31-33) have been synthesized and investigated as inhibitors of five isoforms of zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), that is, the cytosolic, ubiquitous isozymes CA I and II, and transmembrane isozymes CA IX, XII (cancer-associated) and XIV. Against the human isozymes hCA I, the new compounds showed inhibition constants in the range of 0.078-11.7 microM, against hCA II in the range of 9.9-140 nM, against hCA IX in the range of 4.6-313 nM, against hCA XII in the range of 3.4-21.6 nM, and against hCA XIV in the range of 50.9-160 nM, respectively. Compounds 4, 6, 7, 9, 11-14, 19, 20, 22-24, 26, 27, 31 and 32 showed excellent hCA IX inhibitory efficacy, with inhibition constants of 4.6-12.0 nM, being much more effective as compared to the clinically used sulfonamides AAZ, MZA, EZA, DCP and IND. 4-[N'-(6-chloro-7-cyano-1,1-dioxo-1,4,2-benzodithiazin-3-yl)hydrazino]-3-pyridinesulfonamide (31) is the prominent of the compounds due to its remarkable inhibitory activity toward hCA I (KIs=0.078 microM), hCA IX (KIs=7.2 nM) and hCA XII (KIs=3.4 nM).

Synthesis and anti-HIV-1 integrase activities of 3-aroyl-2,3-dihydro-1,1-dioxo-1,4,2-benzodithiazines.

A series of novel 3-aroyl-2,3-dihydro-1,1-dioxo-1,4,2-benzodithiazines 15-28 as potential HIV-1 integrase (IN) inhibitors have been synthesized by the reduction of 3-aroyl-1,1-dioxo-1,4,2-benzodithiazines 1-14 with benzenesulfonyl hydrazide. All the compounds 15-28 inhibited IN mediated strand transfer reaction with IC(50) values ranging from 3 to 30 microM. The 3-(4-bromobenzoyl)-6-chloro-7-methyl-2,3-dihydro-1,1-dioxo-1,4,2-benzodithiazine 17 with the IC(50) values of 4+/-1 and 3+/-1 microM for 3'-processing and strand transfer, respectively, was the most potent. Compound 17 as well its analogues were 5-20-fold less potent in Y99S and H114A mutants, implicating these residues as potential drug-binding site. This is a first report implicating Y99S and H114A of IN core domain in drug-binding interactions.

Carbonic anhydrase inhibitors: inhibition of human cytosolic isozymes I and II and tumor-associated isozymes IX and XII with S-substituted 4-chloro-2-mercapto-5-methyl-benzenesulfonamides.

A series of S-substituted 4-chloro-2-mercapto-5-methyl-benzenesulfonamides has been investigated as inhibitors of four isoforms of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), that is, the cytosolic, ubiquitous isozymes CA I and II, as well as the transmembrane, tumor-associated isozymes CA IX and XII. The new derivatives were inefficient inhibitors of isoform I (K(I)s in the range of 2.7-18.7 microM) but generally had low nanomolar affinity for the inhibition of the other three isoforms (K(I)s in the range of 2.4-214 nM against hCA II; 1.4-47.5 nM against hCA IX, and 1.7-569 nM against hCA XII, respectively). Some selectivity for the inhibition of the tumor-associated versus the cyctosolic isoform II with some of these compounds has also been evidenced. As CA IX is an important marker of tumor hypoxia and its predictive, prognostic, and druggability potentials for designing antitumor therapies were recently validated, detection of selective, potent CA IX inhibitors may be relevant in the fight against cancers overexpressing CA isozymes.

Synthesis, anti-HIV-1 integrase, and cytotoxic activities of 4-chloro-N-(4-oxopyrimidin-2-yl)-2-mercaptobenzenesulfonamide derivatives.

Several 4-chloro-N-(4-oxopyrimidin-2-yl)-2-mercaptobenzenesulfonamide derivatives 13-28 and 35-44 have been synthesized and tested as potential HIV-1 integrase (IN) inhibitors. Compounds 15-17, 19, 21-28, 36 and 41 inhibited IN with IC(50) values in the range of 3.3-63.0 microM. The compounds 13, 15, 16, 21-24 and 26-28 were further tested at the US National Cancer Institute for their in vitro activity against a panel of 53-57 human tumor cell lines. The compounds 26-28 were inactive, whereas the other compounds exhibited high or reasonable activity (GI(50)<0.01-20.0 microM) against one or more human tumor cell lines.

Synthesis of novel 3-amino-2-(4-chloro-2-mercaptobenzenesulfonyl)-guanidine derivatives as potential antitumor agents.

Novel 3-amino-2-(4-chloro-2-mercaptobenzenesulfonyl)guanidine derivatives have been synthesized as potential anticancer agents. The in vitro antitumor activity of these compounds has been evaluated in the US National Cancer Institute (NCI), and relationships between structure and antitumor activity are discussed. The prominent compound was 1-allyl-2-[4-chloro-5-(4-chlorophenylcarbamoyl)-2-methylthiobenzenesulfonyl]-3-(5-nitrofurfurylideneamino)guanidine (8) with remarkable activity against 21 human tumor cell lines representing leukemia, lung, colon, melanoma, ovarian, renal, prostate and breast (GI(50)=0.3-3.0microM), and selectivity toward leukemia RPMI-8226 cell line (GI(50)=0.3microM, TGI=1.4microM).

Synthesis, structural characterization, and in vitro antitumor activity of novel N-(6-chloro-1,1-dioxo-1,4,2-benzodithiazin-3-yl)arylsulfonamides.

A new series of N-(6-chloro-1,1-dioxo-1,4,2-benzodithiazin-3-yl)arylsulfonamides 23-48 have been synthesized as potential anticancer agents. All compounds were screened for their cytotoxic activity against six human tumor cell lines. The selected compounds 23-27, 30, 31, 33, 35, 38, 42, 45, and 46 were further tested at the US National Cancer Institute for their in vitro activities against a panel of 53-59 human tumor cell lines. The compounds 23-26, 30, 31, 33, 38, 42, 45, and 46 showed 50% growth inhibitory activity in low micromolar concentration (GI(50)=0.03-4.9 microM) against one or more human tumor cell lines (Table 3). The prominent compound with remarkable activity (GI(50)=0.03 microM, TGI=1.3 microM) and selectivity toward melanoma UACC-257 cell line was N-(6-chloro-7-cyano-1,1-dioxo-1,4,2-benzodithiazin-3-yl)-N-(phenyl)-5-bromothiophene-2-sulfonamide 46.

Carbonic anhydrase inhibitors. Selective inhibition of human tumor-associated isozymes IX and XII and cytosolic isozymes I and II with some substituted-2-mercapto-benzenesulfonamides.

A series of 2-mercapto-substituted-benzenesulfonamides has been prepared by a unique two-step procedure starting from the corresponding 2-chloro-substituted benzenesulfonamides. Compounds bearing an unsubstituted mercapto group and the corresponding S-benzoyl derivatives were investigated as inhibitors of four isoforms of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), i.e., the cytosolic, ubiquitous isozymes CA I and II, as well as the transmembrane, tumor associated isozymes CA IX and XII. These derivatives were medium potency hCA I inhibitors (K(I)s in the range of 1.5-5.7 microM), two derivatives were strong hCA II inhibitors (K(I)s in the range of 15-16 nM), whereas the others showed weak activity. These compounds inhibited hCA IX with inhibition constants in the range 160-1950 nM and hCA XII with inhibition constants in the range 1.2-413 nM. Some of these derivatives showed a certain degree of selectivity for inhibition of the tumor-associated over the cytosolic isoforms, being thus interesting leads for the development of potentially novel applications in the management of hypoxic tumors which overexpress CA IX and XII.

Synthesis and anti-HIV-1 activity of a novel series of 1,4,2-benzodithiazine-dioxides.

Previously, we discovered a series of novel benzodithiazines-dioxides with both antiviral and anticancer activities. In order to design compounds with distinct antiviral properties, we prepared new compounds with modifications on the imidazole and pyrimidine rings. Herein, we present the synthesis and antiviral activity of 8-chloro-2,3-dihydroimidazo[1,2-b][1,4,2]benzodithiazine 5,5-dioxides (22, 23, 30, and 31) and 9-chloro-2,3,4-trihydropyrimido[1,2-b][1,4,2]benzodithiazine 6,6-dioxides (14, 24, 25, and 27). We successfully identified a lead compound with remarkable anti-HIV-1 activity (EC(50)=0.09microM). These compounds showed minimal cytotoxicity and are therefore suitable for antiviral development.

Carbonic anhydrase inhibitors. Inhibition of the cytosolic human isozymes I and II, and the transmembrane, tumor-associated isozymes IX and XII with substituted aromatic sulfonamides activatable in hypoxic tumors.

Some 2-mercapto-substituted-benzenesulfonamides and their disulfides/sulfones were prepared and investigated as inhibitors of four isoforms of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), that is, CA I and II (cytosolic enzymes), and the tumor-associated CA IX and XII. Some mercaptans led to a consistent increase of inhibitory power (52.8- to 243-fold) over the corresponding oxidized (S-S type) derivatives, acting as potential hypoxia-activatable drugs.

Synthesis, antiviral, and anti-HIV-1 integrase activities of 3-aroyl-1,1-dioxo-1,4,2-benzodithiazines.

HIV-1 integrase (IN) is an essential enzyme for effective viral replication and is an attractive target for selective blockade of viral infection. Previously, we identified a series of sulfones, sulfonamides, and mercaptosalicylhydrazides (MBSAs) as IN inhibitors with antiviral activities in cell-based assays. In an effort to optimize a series of our active site directed lead compounds, we designed and synthesized novel benzodithiazines starting from MBSAs. In contrast to all reported IN inhibitors benzodithiazines are essentially nontoxic. Significant antiviral potency was only observed at concentration exceedingly higher than that required to inhibit purified IN.

2-Amino-6-(1-imidazolylmethyl)-4-(3,5,5-trimethyl-2-pyrazolin-1-yl)-1,3,5-triazine and 2-amino-6-(1-benzimidazolylmethyl)-4-(3,5,5-trimethyl-2-pyrazolin-1-yl)-1,3,5-triazine hemihydrate.

The two title compounds, C(13)H(18)N(8) and C(17)H(20)N(8).0.5H(2)O, possess similar molecular shapes, with the pyrazoline moiety and s-triazine ring located approximately in one plane, and the imidazole or benzimidazole ring nearly perpendicular to the s-triazine nucleus. In both crystal structures, despite there being a large number of accessible hydrogen-bond acceptor sites, only one H atom from the NH(2) group is involved in hydrogen bonding; the molecules are assembled into discrete centrosymmetric dimers via a pair of nearly linear N-H.N hydrogen bonds.

Synthesis, structural characterization and in vitro antitumor activity of 4-dimethylaminopyridinium (6-chloro-1,1-dioxo-1,4,2-benzodithiazin-3-yl)methanides.

Previously, we have described a novel series of low molecular weight cancer-specific antitumor agents with aminium N-(1,1-dioxo-1,4,2-benzodithiazin-3-yl)arylsulfonamidate structure. In an attempt to determine some of the structural features that account for the cytotoxic activity of such aminium salts, a novel series of 4-dimethylaminopyridinium (1,1-dioxo-1,4,2-benzodithiazin-3-yl)methanides (6-19) has been synthesized by the reactions of 3-methylthio-1,4,2-benzodithiazine1,1-dioxides with 4-DMAP and some active methylene compounds. The in vitro antitumor activity of these compounds has been tested in the National Cancer Institute (NCI), and relationships between structure and antitumor activity are discussed. Among the aminium salts 4-dimethylamino-pyridinium 4-chlorobenzoyl cyano (6-chloro-7-methyl-1,1-dioxo-1,4,2-benzodithiazin-3-yl)methanide (9) was superior to other pyridinium salts in terms of both remarkable activity (log GI50 and logTGI<-8.00) and high selectivity for the lung HOP-92 and melanoma UACC-257 cell lines.

Synthesis, structural characterization and in vitro antitumor activity of novel 6-chloro-1,1-dioxo-1,4,2-benzodithiazie derivatives.

A series of nonconventional aminium N-(6-chloro-7-R-1,1-dioxo-1,4,2-benzodithiazin-3-yl)arylsulfonamidates 7-15 have been synthesized by the reactions of 6-chloro-7-R-3-methylthio-1,4,2-benzodithiazine 1,1-dioxides with 4-dimethylaminopyridine or Et(3)N and some arylsulfonamides. The free N-(6-chloro-7-methyl-1,1-dioxo-1,4,2-benzodithiazin-3-yl)benzenesulfonamides 16-18 were obtained by treatment of their aminium salts with H(2)SO(4) in boiling acetic acid. The in vitro antitumor activity of the compounds 9, 11-14 and 16-18 has been tested in the antitumor screening of the National Cancer Institute (NCI), and relationships between structure and antitumor activity are discussed. 4-Dimethylaminopyridinium 4-chloro-N-(6-chloro-7-methyl-1,1-dioxo-1,4,2-benzodithiazin-3-yl)benzenesulfonamidate 9 is the prominent of the compounds due to its remarkable activity (log GI(50)<-8.00, log TGI=-5.50) and selectivity for the leukemia SR cell line. For that reason experimental and theoretical analysis of the geometric and electronic properties of 9 was carried out.