Antiproliferative and apoptotic activity of new indazole derivatives as potential anticancer agents.

To develop potent and selective anticancer agents, a series of novel polysubstituted indazoles was synthesized and evaluated for their in vitro antiproliferative and apoptotic activities against two selected human cancer cell lines (A2780 and A549). Several compounds showed an interesting antiproliferative activity, with IC50 values ranging from 0.64 to 17 µM against both cell lines. The most active indazoles were then tested in different pharmacological dilution conditions, adding five new cell lines (A2780, A549, IMR32, MDA-MB-231, and T47D) as targets, confirming their antiproliferative activity. Furthermore, selected compounds were able to trigger apoptosis to a significant extent and to cause, in part, a block of cells in the S phase of the cell cycle, with a concomitant decrease of cells in the G2/M and/or G0/G1 phases and the generation of hypodiploid peaks. However, molecule 7d caused a great increase of cells in G2/M and the appearance of polyploid cells. Altogether, our results suggest a good pharmacological activity for our selected polysubstituted indazoles, which are suggestive of a preferential mechanism of action as cell cycle-specific antimetabolites or as an inhibitor of enzyme activities involved in DNA synthesis, except for 7d, which, on the contrary, seems to have a mechanism involving the microtubule system.

A Suitable Functionalization of Nitroindazoles with Triazolyl and Pyrazolyl Moieties via Cycloaddition Reactions.

The alkylation of a series of nitroindazole derivatives with 1,2-dibromoethane afforded the corresponding N-(2-bromoethyl)- and N-vinyl-nitro-1H-indazoles. The Cu(I)-catalysed azide- alkyne 1,3-dipolar cycloaddition was selected to substitute the nitroindazole core with 1,4-disubstituted triazole units after converting one of the N-(2-bromoethyl)nitroindazoles into the corresponding azide. The reactivity in 1,3-dipolar cycloaddition reactions with nitrile imines generated in situ from ethyl hydrazono-α-bromoglyoxylates was studied with nitroindazoles bearing a vinyl unit. The corresponding nitroindazole-pyrazoline derivatives were obtained in good to excellent yields.

Synthesis and antitumor activity of some substituted indazole derivatives.

Some new N-[6-indazolyl]arylsulfonamides and N-[alkoxy-6-indazolyl]arylsulfonamides were prepared by the reduction of 2-alkyl-6-nitroindazoles with SnCl2 in different alcohols, followed by coupling the corresponding amine with arylsulfonyl chlorides in pyridine. The newly synthesized compounds were evaluated for their antiproliferative and apoptotic activities against two human tumor cell lines: A2780 (ovarian carcinoma) and A549 (lung adenocarcinoma). Preliminary in vitro pharmacological studies revealed that N-(2-allyl-2H-indazol-6-yl)-4-methoxybenzenesulfonamide 4 and N-[7-ethoxy-2-(4-methyl-benzyl)-2H-indazol-6-yl]-4-methyl-benzenesulfonamide 9 exhibited significant antiproliferative activity against the A2780 and A549 cell lines with IC50 values in the range from 4.21 to 18.6 µM, and also that they trigger apoptosis in a dose-dependent manner. Furthermore, both active compounds were able to cause an arrest of cells in the G2/M phase of the cell cycle, typical but not exclusive of tubulin interacting agents, although only infrequent interactions with the microtubule network were observed by immunofluorescence microscopy, while docking analysis showed a possible different behavior between the two active compounds.

Crystal structure of N-(1-allyl-3-chloro-4-eth-oxy-1H-indazol-5-yl)-4-meth-oxybenzene-sulfonamide.

In the title compound, C19H20ClN3O4S, the benzene ring is inclined to the indazole ring system (r.m.s. deviation = 0.014 Å) by 65.07 (8)°. The allyl and eth-oxy groups are almost normal to the indazole ring, as indicated by the respective torsion angles [N-N-C-C = 111.6 (2) and C-C-O-C = -88.1 (2)°]. In the crystal, mol-ecules are connected by N-H⋯N hydrogen bonds, forming helical chains propagating along [010]. The chains are linked by C-H⋯O hydrogen bonds, forming a three-dimensional network.

Crystal structure of N-(1-allyl-3-chloro-1H-indazol-5-yl)-4-methyl-benzene-sulfonamide.

The 3-chloro-1H-indazole system in the title mol-ecule, C17H16ClN3O2S, is almost planar, with the largest deviation from the mean plane being 0.029 (2) Šfor one of the N atoms. This system is nearly perpendicular to the allyl chain, as indicated by the C-C-N-N torsion angle of -90.1 (6)° between them. The allyl group is split into two fragments, the major component has a site occupancy of 0.579 (7). The indazole system makes a dihedral angle of 47.53 (10)° with the plane through the benzene ring. In the crystal, mol-ecules are connected by N-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional network.

Crystal structure of N-(3-chloro-1-methyl-1H-indazol-5-yl)-4-meth-oxy-benzene-sulfonamide.

In the title compound, C15H14ClN3O3S, the dihedral angle between the planes of the indazole ring system (r.m.s. deviation = 0.007 Å) and the benzene ring is 89.05 (7)°. The meth-oxy C atom deviates from its attached ring by 0.196 (3) Å. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds generate R 2 (2)(8) loops. The dimers are connected into [010] chains by C-H⋯O inter-actions.

1-(4-Methyl-phenyl-sulfon-yl)-5,6-di-nitro-1H-indazole.

In the title compound, C14H10N4O6S, the indazole ring system is almost perpendicular to the tosyl ring, as indicated by the dihedral angle of 89.40 (9)° between their planes. The dihedral angles between the indazole system and the nitro groups are 57.0 (3) and 31.9 (3)°. In the crystal, mol-ecules are linked by C-H⋯O inter-actions, forming chains running along [100].

N-(1-Allyl-3-chloro-4-eth-oxy-1H-indazol-5-yl)-4-methyl-benzene-sulfonamide.

In the title compound, C19H20ClN3O3S, the benzene ring is inclined to the indazole ring system by 51.23 (8)°. In the crystal, mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers which stack in columns parallel to [011]. The atoms in the allyl group are disordered over two sets of sites with an occupancy ratio of 0.624 (8):0.376 (8).

N-(3-Chloro-4-eth-oxy-1-methyl-1H-indazol-5-yl)-4-meth-oxy-benzene-sulfonamide.

The indazole ring system of the title compound, C17H18ClN3O4S, is almost planar (r.m.s. deviation = 0.0113 Å) and forms dihedral angles of 32.22 (8) and 57.5 (3)° with the benzene ring and the mean plane through the 4-eth-oxy group, respectively. In the crystal, mol-ecules are connected by pairs of N-H⋯O hydrogen bonds into inversion dimers, which are further linked by π-π inter-actions between the diazole rings [inter-centroid distance = 3.4946 (11) Å], forming chains parallel to [101].

Crystal structure of 2-(4-methyl-benzyl-idene)malono-nitrile.

The mol-ecule of the title compound, C11H8N2, is approximately planar (r.m.s.deviation for all non-H atoms = 0.023 Å). The malono-nitrile C-C-C angle is 113.54 (13)°. In the crystal, mol-ecules stack head-to-tail along [010]. There are no significant inter-molecular inter-actions present.

N-(3-Chloro-1-methyl-1H-indazol-5-yl)-4-methylbenzene-sulfonamide.

The asymmetric unit of the title compound, C15H14ClN3O2S, contains two independent mol-ecules showing different conformations: in one mol-ecule, the indazole ring system makes a dihedral angle of 51.5 (1)° with the benzene ring whereas in the other, the indazole unit is almost perpendicular to the benzene ring [dihedral angle 77.7 (1)°]. In the crystal, the mol-ecules are linked by N-H⋯N and N-H⋯O hydrogen bonds, forming a set of four mol-ecules linked in pairs about an inversion centre.

Ethyl 3-[7-(N-acetyl-4-meth-oxy-benzene-sulfonamido)-3-chloro-2H-indazol-2-yl]propionate.

In the title compound, C21H22ClN3O6S, the fused five- and six-membered ring rings are almost perpendicular to the planes through the atoms forming the acetyl and the propionic ester groups, as indicated by the dihedral angles of 80.3 (2) and 88.3 (7)°, respectively. The dihedral angle between the indazole system and the 4-meth-oxy-benzene-sulfonyl group is 13.76 (6)°. The carbonyl O atom is split over two positions in a 0.60 (5):0.40 (5) ratio. In the crystal, mol-ecules are linked by C-H⋯O and C-H⋯N inter-actions into a three-dimensional network.

N-(2-Allyl-4-eth-oxy-2H-indazol-5-yl)-4-methyl-benzene-sulfonamide.

The indazole ring system of the title compound, C19H21N3O3S, is almost planar (r.m.s. deviation = 0.0192 Å) and forms dihedral angles of 77.99 (15) and 83.9 (3)° with the benzene ring and allyl group, respectively. In the crystal, centrosymmetrically related mol-ecules are connected by pairs of N-H⋯O hydrogen bonds into dimers, which are further linked by C-H⋯O hydrogen bonds, forming columns parallel to the b axis.

Crystal structure of 3-{1-[(1-allyl-1H-indazol-6-yl)amino]-ethyl-idene}-6-methyl-2H-pyran-2,4(3H)-dione.

In the title compound, C18H17N3O3, the dihedral angle between the planes of the indazole ring system [maximum deviation = 0.012 (1) Å] and the pyran-2,4-dione ring is 54.03 (6)°. An intra-molecular N-H⋯O hydrogen bond closes an S(6) ring. The same H atom also participates in an inter-molecular N-H⋯O hydrogen bond, which generates an inversion dimer. The dimers are linked by weak C-H⋯O contacts, thereby forming a three-dimensional network.

6,6'-Di-nitro-1,1'-(ethane-1,2-di-yl)di(1H-indazole).

The mol-ecule of the title compound, C16H12N6O4, is built up from two fused five- and six-membered rings linked by an ethyl-ene group. The dihedral angle between the planes through the indazole ring systems is 39.74 (5)°. The nitro groups are tilted by 7.2 (2) and 8.5 (2)° with respect to planes of the fused-ring systems. In the crystal, mol-ecules are linked by C-H⋯N and C-H⋯O hydrogen bonds into chains running parallel to the c axis.

1-Methyl-2-methyl-sulfanyl-6-nitro-1H-benzimidazole.

The mol-ecule of the title compound, C9H9N3O2S, is built up from fused five- and six-membered rings connected to methyl-sulfanyl and nitro groups, respectively. The mean plane through the fused ring system is inclined slightly relative to the plane passing through the nitro group [dihedral angle = 3.6 (2)°]. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds and π-π inter-actions between imidazole rings [inter-centroid distance = 3.667 (3) Å], forming a three-dimensional network.

Synthesis, characterization, and inhibition effects of a novel eugenol derivative bearing pyrrole functionalities on the corrosion of mild steel in a HCl acid solution.

Semi-synthetic modifications of natural products have yielded numerous anti-cancer drugs, antimicrobials, and corrosion inhibitors. In this study, eugenol, a natural product, was synthetically modified to generate a novel heterocyclic compound: pyrrole, which forms crystals. The latter is the outcome of the condensation reaction between eugenol hydrazide and 2,5-hexanedione, conducted under reflux ethanol conditions, without a catalyst, achieving a 96% yield. This compound structure was characterized through spectroscopic methods, such as NMR and FTIR, and validated par the crystal's X-ray diffraction analysis. According to the findings of the electrochemical study, pyrrole demonstrated effective inhibition against the carbon steel's corrosion in a 1 M HCl acid solution.

Ethyl 3-[6-(4-meth-oxy-benzene-sulfon-amido)-2H-indazol-2-yl]propano-ate monohydrate.

In the title compound, C(19)H(21)N(3)O(5)S·H(2)O, the central indazole system is essentially planar (r.m.s. deviation = 0.012 Å), while both the benzene ring and the mean plane defined by the non-H atoms of the ethyl propionic ester unit (r.m.s. deviation = 0.087 Å) are nearly perpendicular to the indazole plane, as indicated by the dihedral angles of 82.45 (8) and 75.62 (8)°, respectively. Consequently, the mol-ecule adopts a U-shaped geometry. In the crystal, the water mol-ecule, which is linked to the indazole system by a strong O-H⋯N hydrogen bond, is also involved in two additional N-H⋯O and O-H⋯O inter-actions, which link the organic mol-ecules into chains along the b-axis direction.

5,11-Ditosyl-5H,11H-dibenzo[b,f][1,5]diazo-cine-6,12-dione acetic acid hemisolvate.

The mol-ecular structure of the title compound, C28H22N2O6S2·0.5CH3COOH, is built up from three fused rings, two six and one eight membered. The eight-membered ring shows a boat conformation and the dihedral angle between the two benzene groups attached thereto is 66.43 (11)°, resulting in a V-shaped geometry. Two tosyl substituents are bound to the N atoms. The planes through the tolyl rings are roughly perpendicular, as indicated by the dihedral angle of 82.44 (12)°. In the crystal, the mol-ecule and its inversion-related symmetry-equivalent are linked to the acetic acid solvent mol-ecule by non-classical O-H⋯O and C-H⋯O hydrogen bonds. Two half-occupied acetic acid solvent mol-ecules are disordered at the same site and linked by a center of symmetry.

N-(2-Allyl-4-chloro-2H-indazol-5-yl)-4-meth-oxy-benzene-sulfonamide hemi-hydrate.

The fused five- and six-membered rings in the title compound, C17H16ClN3O3S·0.5H2O, are practically coplanar, with the maximum deviation from the mean plane being 0.057 (3) Šfor the C atom bound to the exocyclic N atom. The indazole system makes a dihedral angle of 66.18 (12)° with the plane through the benzene ring, and it is nearly perpendicular to the allyl group, as indicated by the N-N-C-C torsion angle of 79.2 (3)°. In the crystal, the water mol-ecule, lying on a twofold axis, forms O-H⋯N and accepts N-H⋯O hydrogen bonds. Additional C-H⋯O hydrogen bonds contribute to the formation of a chain along the b-axis direction.