Spirocyclic sulfonamides with carbonic anhydrase inhibitory and anti-neuropathic pain activity.

A novel series of 4-oxo-spirochromane bearing primary sulfonamide group were synthetized as Carbonic Anhydrase inhibitors (CAIs) and tested for their management of neuropathic pain. Indeed, CAs have been recently validated as novel therapeutic targets in neuropathic pain. All compounds, here reported, showed strong activity against hCA II and hCA VII with KI values in the low or sub-nanomolar range. Two compounds (6d and 6l) showed good neuropathic pain attenuating effects and longer duration than drug reference acetazolamide in an animal model of oxaliplatin induced neuropathy.

Carbonic anhydrase inhibitors based on sorafenib scaffold: Design, synthesis, crystallographic investigation and effects on primary breast cancer cells.

Carbonic anhydrase inhibitors (CAIs) of the sulfonamide, sulfamate and coumarin classes bearing the phenylureido tail found in the clinically used drug Sorafenib, a multikinase inhibitor actually used for the management of hepatocellular carcinomas, are reported. All compounds were assayed on human (h) CA isoforms I, II, VII and IX, involved in various pathologies. Among the sulfonamides, several compounds were selective for inhibiting hCA IX, with KI values in the low nanomolar ranges (i.e. 0.7-30.2 nM). We explored the binding modes of such compounds by means of X-ray crystallographic studies on isoform hCA I in adduct with one sulfonamide and a sulfamate inhibitor. Antiproliferative properties of some sulfamates on breast tumor cell lines were also investigated.

Discovery of new organoselenium compounds as antileishmanial agents.

We report new organoselenium compounds bearing the sulfonamide moiety as effective inhibitors of the ß-isoform of Carbonic Anhydrase from the unicellular parasitic protozoan L. donovani chagasi. All derivatives were evaluated in vitro for their leishmanicidal activities against Leishmania infantum amastigotes along with their cytotoxicities in human THP-1 cells. Compounds 3e-g showed their activity in the low micromolar range with IC50 values spanning from 0.72 to 0.81 µM and selectivity indexes (SI) > 8 (for 3g SI > 30), thus much higher than those observed for the reference drugs miltefosine and edelfosine. This is the first study which reports new selenoderivatives with promising leishmanicidal properties and acting as Carbonic Anhydrase inhibitors too thus paving the way to the development of innovative agents for the treatment of neglected diseases such as leishmaniasis.

Synthesis 4-[2-(2-mercapto-4-oxo-4H-quinazolin-3-yl)-ethyl]-benzenesulfonamides with subnanomolar carbonic anhydrase II and XII inhibitory properties.

Condensation of substituted anthranilic acids with 4-isothiocyanatoethyl-benzenesulfonamide led to series of heterocyclic benzenesulfonamides incorporating 2-mercapto-quinazolin-4-one tails. These sulfonamides were investigated as inhibitors of the human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I and II (cytosolic isozymes), as well as hCA XII (a transmembrane, tumor-associated enzyme also involved in glaucoma-genesis). The new sulfonamides acted as medium potency inhibitors of hCA I (KIs of 28.5-2954nM), being highly effective as hCA II (KIs in the range of 0.62-12.4nM) and XII (KIs of 0.54-7.11nM) inhibitors. All substitution patterns present in these compounds (e.g., halogens, methyl and methoxy moieties, in positions 6, 7 and/or 8 of the 2-mercapto-quinazolin-4-one ring) led to highly effective hCA II/XII inhibitors. These compounds should thus be of interest as preclinical candidates in pathologies in which the activity of these enzymes should be inhibited, such as glaucoma (CA II and XII as targets) or some tumors in which the activity of isoforms CA II and XII is dysregulated.

Development of 3-(4-aminosulphonyl)-phenyl-2-mercapto-3H-quinazolin-4-ones as inhibitors of carbonic anhydrase isoforms involved in tumorigenesis and glaucoma.

A series of heterocyclic benzenesulfonamides incorporating 2-mercapto-3H-quinazolin-4-one tails were prepared by condensation of substituted anthranilic acids with 4-isothiocyanato-benzenesulfonamide. These sulfonamides were investigated as inhibitors of the human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I and II (cytosolic isozymes), as well as hCA IX and XII (trans-membrane, tumor-associated enzymes). They acted as medium potency inhibitors of hCA I (KIs of 81.0-3084 nM), being highly effective as hCA II (KIs in the range of 0.25-10.8 nM), IX (KIs of 3.7-50.4 nM) and XII (KIs of 0.60-52.9 nM) inhibitors. These compounds should thus be of interest as preclinical candidates in pathologies in which the activity of these enzymes should be inhibited, such as glaucoma (CA II and XII as targets) or some tumors in which the activity of three isoforms (CA II, IX and XII) is dysregulated.

Development of certain new 2-substituted-quinazolin-4-yl-aminobenzenesulfonamide as potential antitumor agents.

Carbonic anhydrases (CA I, II, IX and XII) are known to be highly expressed in various human malignancies. CA IX is overexpressed in colorectal cancer specifically in hereditary nonpolyposis colorectal cancer. Inhibition of CA activity by small molecular CA inhibitor like sulphonamides, sulphonamide derivative (SU.D2) or HIF1a inhibitor Chetomin leads to inhibition of tumorigenesis. Eighteen new quinazolin-4-sulfonamide derivatives were prepared and characterized by means of IR, NMR and mass spectra. Certain selected derivatives were tested for their ability to inhibit four isoforms of the metalloemzyme CA, namely, CA I, CA II, CA IX and CA XII. Compound 3c was found to be highly effective in inhibiting the cancer cell proliferation. 3c decreased cell viability of human HT-29 cells in dose and time dependent manner and with IC50 of 5.45 µM. Moreover, it was tested on metastatic colon cancer cell SW-620 where it was found to be equally effective on human SW-620 cells. This novel compound inhibited the CA IX and CA XII protein expression in HT-29 cells without affecting CA I and CA II expression. These findings indicate that 3c inhibits cellular proliferation in two human colon cancer cells by specifically targeting the CA IX and CA XII expression.

Benzenesulfonamides incorporating bulky aromatic/heterocyclic tails with potent carbonic anhydrase inhibitory activity.

Three series of sulfonamides incorporating long, bulky tails were obtained by applying synthetic strategies in which substituted anthranilic acids, quinazolines and aromatic sulfonamides have been used as starting materials. They incorporate long, bulky diamide-, 4-oxoquinazoline-3-yl- or quinazoline-4-yl moieties in their molecules, and were investigated for the inhibition of four physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the cytosolic human (h) hCA I and II, as well as the transmembrane hCA IX and XII. Most of the new sulfonamides showed excellent inhibitory effects against the four isoforms, with KIs of 7.6-322nM against hCA I, of 0.06-85.4nM against hCA II; of 6.7-152nM against hCA IX and of 0.49-237nM against hCA XII; respectively. However no relevant isoform-selective behavior has been observed for any of them, although hCA II and XII, isoforms involved in glaucoma-genesis were the most inhibited ones. The structure-activity relationship for inhibiting the four CAs with these derivatives is discussed in detail.

Inhibition studies of quinazoline-sulfonamide derivatives against the γ-CA (PgiCA) from the pathogenic bacterium, Porphyromonas gingivalis.

Carbonic anhydrases (CAs, EC 4.2.1.1) began to be investigated in detail in pathogenic bacteria, in the search for antibiotics with a novel mechanism of action, since it has been demonstrated that in many bacteria CAs are essential for the life cycle of the organism. The presence of CAs in pathogenic bacteria allows the development of anti-infectives with a new mechanism of action, less explored to date. Here, novel quinazoline derivatives crowned with sulfonamide functionality at position-2 were tested for their ability to inhibit the bacterial γ-CA (PgiCA), identified in the genome of Porphyromonas gingivalis. Six compounds were highly effective, nanomolar inhibitors of the pathogenic enzyme γ-PgCA. Three of them were also highly effective sub-nanomolar inhibitors of the cytosolic human isoform II (hCAII). The best γ-PgCA inhibitor was compound 8c, with a K(I) of 3.53 nM and selectivity ratio of 24.5 and 24.8 against hCA I and hCA II, respectively. Many of these new compounds showed a high selectivity for bacterial enzyme respect to the mammalian CA isoforms (hCAI and hCAII). These results suggest that sulfonamides with quinazoline scaffold could be considered as suitable candidates for further derivatization to better understand the role of bacterial CAs in pathogenesis.

Vibrational spectroscopic (FT-IR and FT-Raman) studies, HOMO-LUMO, NBO analysis and MEP of 6-methyl-1-({[(2E)-2-methyl-3-phenyl-prop-2-en-1-yl]oxy}methyl)-1,2,3,4-tetra-hydroquinazoline-2,4-dione, a potential chemotherapeutic agent, using density functional methods.

6-Methyl-1-({[(2E)-2-methyl-3-phenyl-prop-2-en-1-yl]oxy}methyl)-1,2,3,4-tetra-hydro quinazoline-2,4-dione was prepared via treatment of silylated 6-methylquinazoline-2,4-dione with bis-[(E)-2-methyl-3-phenylallyloxy]methane. FT-IR and FT-Raman spectra were recorded and analyzed. The vibrational wavenumbers were computed using DFT methods and are assigned with the help of potential energy distribution method. The first hyperpolarizability, infrared intensities and Raman activities also reported. The geometrical parameters of the title compound obtained from XRD studies are in agreement with the calculated (B3LYP) values. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. MEP was performed by the B3LYP method and from the MEP it is evident that the negative charge covers the CO group and the positive region is over the phenyl ring and NH group.

Inhibition of human carbonic anhydrase isozymes I, II, IX and XII with a new series of sulfonamides incorporating aroylhydrazone-, [1,2,4]triazolo[3,4-b][1,3,4]thiadiazinyl- or 2-(cyanophenylmethylene)-1,3,4-thiadiazol-3(2H)-yl moieties.

A series of benzenesulfonamides incorporating aroylhydrazone, piperidinyl, sulfone, [1,2,4]triazolo[3,4-b][1,3,4]thiadiazinyl- or 2-(cyanophenyl-methylene)-1,3,4-thiadiazol-3(2H)-yl moieties was investigated as inhibitors of four α-carbonic anhydrases (CAs, EC 4.2.1.1), the human (h) isoforms hCA I, II (cytosolic, offtarget enzymes) and hCA IX and XII (transmembrane, tumor-associated isoforms). Low nanomolar activity was observed against hCA II (KIs of 0.56-17.1 nM) with these sulfonamides, whereas the slow cytosolic isoform hCA I was less inhibited by these compounds (KIs of 86.4 nM-32.8 µM). Most of these sulfonamides significantly inhibited CA IX, with KIs in the range of 4.5-47.0 nM, although some of the derivatives incorporating bulkier bicyclic moieties, as well as 2-thienyl fragments, showed a weaker activity against this isoform (KIs in the range 50.1-553 nM). All the investigated compounds also inhibited CA XII with KIs in the range 0.85-376 nM. The best inhibitors were those incorporating bulky [1,2,4]triazolo[3,4-b][1,3,4]thiadiazinyl moieties and 1,3,4-thiadiazol-3(2H)-yl groups.

Quinazoline-sulfonamides with potent inhibitory activity against the α-carbonic anhydrase from Vibrio cholerae.

Thirteen novel sulfonamide derivatives incorporating the quinazoline scaffold were synthesized by simple, eco-friendly procedures. These compounds were tested for their ability to inhibit the α-carbonic anhydrases (CA, EC 4.2.1.1) from Vibrio cholerae (VchCA) as well as the human α-CA isoforms, hCA I and hCA II. Nine compounds were highly effective, nanomolar inhibitors of the pathogenic enzyme VchCA. Three of them were also highly effective sub-nanomolar inhibitors of the cytosolic isoform II. The best VchCA inhibitor had a KI of 2.7 nM. Many of these developed compounds showed high selectivity for inhibition of the bacterial over the mammalian CA isoforms, with one compound possessing selectivity ratios as high as 97.9 against hCA I and 9.7 against hCA II. Compound 9d was another highly effective VchCA inhibitor presenting a selectivity ratio of 99.1 and 8.1 against hCA I and hCA II, respectively. These results suggest that sulfonamides with quinazoline backbone could be considered suitable tools to better understand the role of bacterial CAs in pathogenesis.

Molecular structure and vibrational spectra of 2-Ethoxymethyl-6-ethyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione, a potential chemotherapeutic agent, by density functional methods.

In this work, the vibrational spectral analysis was carried out using FT-IR and FT-Raman spectroscopy for 2-Ethoxymethyl-6-ethyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione, which is a potential chemotherapeutic agent derivative. Theoretical calculations were performed by density functional methods. The complete vibrational assignments of the wavenumbers were made on the basis of potential energy distribution. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with the observed spectra. The frontier orbital energy gap and related properties of the molecule illustrates the high reactivity of the title compound. The first order hyperpolarizability, dipole moment and polarizability are also calculated. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Molecular electrostatic potential map is also constructed. The calculated geometrical parameters are in agreement with the XRD results.

Use of vibrational spectroscopy to study 4-benzyl-3-(thiophen-2-yl)-4,5-dihydro-1H-1,2,4-triazole-5-thione: A combined theoretical and experimental approach.

In this study, the experimental and theoretical vibrational frequencies of a newly synthesized potential anti-inflammatory agent namely, 4-benzyl-3-(thiophen-2-yl)-4,5-dihydro-1H-1,2,4-triazole-5-thione have been investigated. The experimental FT-IR (4000-400cm(-1)) and Laser-Raman spectra (4000-100cm(-1)) of the molecule in solid phase have been recorded. The theoretical vibrational frequencies and the optimized geometric parameters (bond lengths, bond angles and dihedral angles) have been calculated using density functional theory methods (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: the highly parameterized, empirical exchange correlation function) with 6-311++G(d,p) basis set by Gaussian 09W software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software program. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.

Structural and spectroscopic characterization of a novel potential anti-inflammatory agent 3-(adamantan-1-yl)-4-ethyl-1H-1,2,4-triazole-5(4H)thione by first principle calculations.

A comprehensive investigation on the molecular structure, electronic properties and vibrational spectra of the 3-(adamantan-1-yl)-4-ethyl-1H-1,2,4-triazole-5(4H)thione, a novel potential anti-inflammatory agent has been done with the hope that the results of present study may be helpful in the prediction of its mechanism of biological activity. The experimentally observed spectral data (FT-IR and FT-Raman) of the title compound was compared with the spectral data obtained by DFT/B3LYP method. The (1)H nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge Including Atomic Orbital method and compared with experimental results. The molecular properties like dipole moment, polarizability, first static hyperpolarizability, the molecular electrostatic potential surface, contour map have been calculated to get a better insight of the properties of the title molecule. Natural bond orbital (NBO) analysis has been applied to study stability of the molecule arising from charge delocalization. UV-Vis spectrum of the title compound was also recorded and the electronic properties, such as Frontier orbitals and band gap energies were calculated by TD-DFT approach. Global and local reactivity descriptors have been computed to predict reactivity and reactive sites on the molecule.

Inhibition of carbonic anhydrases from the extremophilic bacteria Sulfurihydrogenibium yellostonense (SspCA) and S. azorense (SazCA) with a new series of sulfonamides incorporating aroylhydrazone-, [1,2,4]triazolo[3,4-b][1,3,4]thiadiazinyl- or 2-(cyanophenylmethylene)-1,3,4-thiadiazol-3(2H)-yl moieties.

A series of new sulfonamides was prepared starting from 2-oxo-N'-(4-sulfamoylphenyl)-propanehydrazonoyl chloride, a sulfanilamide derivative, which was reacted with aroylhydrazides, amines, or thiols. A library of derivatives incorporating aroylhydrazone, [1,2,4]triazolo[3,4-b][1,3,4]thiadiazinyl- or 2-(cyanophenyl-methylene)-1,3,4-thiadiazol-3(2H)-yl moieties was thus synthesized. The new compounds were investigated as inhibitors of four α-carbonic anhydrases (CAs, EC 4.2.1.1), the human (h) isoforms hCA I and II, and the bacterial ones recently isolated from the extremophilic bacteria Sulfurihydrogenibium yellostonense (SspCA) and Sulfurihydrogenibium azorense (SazCA). Low nanomolar activity was observed against hCA II (KIs of 0.56-17.1 nM) whereas hCA I was less inhibited by these compounds (K(I)s of 86.4 nM-32.8 µM). The bacterial CAs were also effectively inhibited by these derivatives (K(I)s in the range of 0.77-234 nM against SazCA, and of 6.2-89.1 against SspCA, respectively), with several low nanomolar/subnanomolar inhibitors detected against both of them. As SspCA and SazCA are among the most thermostable and catalytically active CAs, it is of interest to find modulators of their activity for potential biotechnologic applications.

Synthesis and antimicrobial activity of novel 5-(1-adamantyl)-2-aminomethyl-4-substituted-1,2,4-triazoline-3-thiones.

The reaction of 5-(1-adamantyl)-4-substituted-1,2,4-triazoline-3-thione 5a,b and 10a,b with formaldehyde solution and various primary aromatic amines or 1-substituted piperazines yielded the corresponding N-Mannich bases 6a-o, 7a-g and 11a-i. The newly synthesized N-Mannich bases 6a-o, 7a-g and 11a-i were tested for in vitro inhibitory activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. The compounds 6j, 6l, 6m, 7a, 7b, 7c, 7d, 7f, 11a, 11b, 11c, 11d, 11e, 11f, 11h and 11i displayed moderate to good activity against the tested Gram-positive bacteria, while compounds 7c, 11c, 11d, 11f and 11h showed potent broad spectrum antibacterial activity. None of the newly synthesized compounds were proved to possess marked activity against C. albicans.

5-(Adamantan-1-yl)-N-methyl-1,3,4-thia-diazol-2-amine.

In the title compound, C13H19N3S, the methyl-amine substituent is coplanar with the thia-diazole ring to which it is attached [C-N-C-S torsion angle = 175.9 (2)°] and the amine H atom is syn to the thia-diazole S atom. Supra-molecular chains along [101], sustained by N-H⋯N hydrogen bonding, feature in the crystal packing.

3-(Adamantan-1-yl)-4-[(E)-(2,6-di-fluoro-benzyl-idene)amino]-1-[(4-ethyl-piperazin-1-yl)meth-yl]-4,5-di-hydro-1H-1,2,4-triazole-5-thione.

In the title compound, C26H34F2N6S, the triazole ring is linked to a benzene ring via an imine bond [N=C = 1.255 (2) Å; conformation: E], with a dihedral angle of 25.21 (11)° between the rings. The 4-ethyl-piperazinyl residue is folded away from the thione-S atom. In the crystal, helical supra-molecular chains propagating along [010] and sustained by weak C-S⋯π(triazole) inter-actions occur [S⋯centroid distance = 3.2872 (10) Å]. Links between these chains are of the type benzene-C-H⋯N(imine) and π-π [between centrosymmetrically related benzene rings with an inter-centroid distance of 3.9241 (15) Å] and result in a three-dimensional architecture.

3-(Adamantan-1-yl)-4-methyl-1-({4-[3-(tri-fluoro-meth-yl)phen-yl]piperazin-1-yl}meth-yl)-4,5-di-hydro-1H-1,2,4-triazole-5-thione.

In the title compound, C25H32F3N5S, two independent mol-ecules comprise the asymmetric unit and are related across a pseudo-centre of inversion. The piperazine rings have chair conformations with each N-bound substituent occupying an equatorial position so that the dihedral angles between the planes of the triazole and benzene ring are 78.20 (19) and 79.10 (19)° for the two independent mol-ecules, indicating that the mol-ecules have an L-shape. In the crystal, a three-dimensional architecture is stabilized by C-H⋯π inter-actions. The crystal studied was an inversion twin with the fractional contribution of the minor component being 0.27 (9).

5-(Adamantan-1-yl)-3-anilinomethyl-2,3-di-hydro-1,3,4-oxa-diazole-2-thione.

In the title compound, C19H23N3OS, the oxa-diazole and benzene rings are inclined at a dihedral angle of 50.30 (11)°, with the major twist between them occurring at the ring-methyl-ene N-C bond [N-N-C-N torsion angle = -101.2 (2)°]. In the crystal, helical supra-molecular chains along [010] are sustained by N-H⋯S hydrogen bonds. These are linked into layers lying parallel to (-101) by methyl-ene-phenyl C-H⋯π inter-actions.