Shridhar Malladi

Synthesis, characterization and anti-microbial studies of some novel 2,4-disubstituted thiazoles

In the present study a series of novel 2,4-disubstituted thiazole derivatives containing substituted pyrazole moiety was synthesized by the reaction of 3-Aryl-1H-pyrazole-4-carbaldehyde thiosemicarbazone with 6-Bromo/H-3-(bromoacetyl)-2H-chromen-2-one/phenacyl chloride. Structures of newly synthesized compounds were characterized by spectral studies. New compounds were screened for their antibacterial studies against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The results revealed that compounds 7c, 8e, and 8f having 2,5-dichlorothiophene substituent and 8c, 8d having 2,4-dichlorophenyl substituent showed significant antibacterial activity against all tested microorganisms.

Synthesis, characterization, anticancer, and antioxidant activity of some new thiazolidin-4-ones in MCF-7 cells

There are limited studies centring on the potential of thiazolidin-4-ones as anticancer agents. In this study, a new series of 2-(3-substituted-1H-pyrazol-4-yl)-3-(3-substituted-5-sulfanyl-1,2,4-triazol-4-yl)-1,3-thiazolidin-4-one (4a–o) have been synthesized by cyclo-condensation reaction of 5-substituted-4-[(3-substituted-1H-pyrazol-4-ylmethylidene)amino]-2H-1,2,4-triazole-3-thione (3a–o) and thioglycolic acid. The structures of all the synthesized compounds were confirmed by elemental analysis, spectral techniques like IR, 1H NMR, and mass spectroscopy. Few compounds exhibited dose-dependent cytotoxic effect in MTT assay in human breast cancer (MCF-7) cells. Apoptotic degradation of DNA due to action of potent thiazolidin-4-ones was analysed by agarose gel electrophoresis and visualized by ethidium bromide staining (comet assay). A concentration-dependent increase in tail length and olive tail moment was observed when treated with thiazolidin-4-ones. In vitro antioxidant studies like DPPH and ABTS-free radical scavenging assays-indicated moderate activity of thiazolidin-4-ones.

Synthesis and biological evaluation of aminoketones

A three-component Mannich reaction of different ketones with aromatic aldehydes and different amines in microwave irradiation under solvent free condition afforded corresponding β-amino carbonyl compounds in excellent yields. This method proved as a novel and improved modification of the reported three-component Mannich reaction in terms of milder reaction conditions, reaction times, clean reaction profiles, very small quantity of catalyst and simple workup procedure. Newly synthesized β-aminoketones were characterized by spectral studies. Structure of compound 4a was also confirmed by single-crystal X-ray analysis. All the compounds were screened for their antimicrobial activity by MIC method. Few of the molecules were found to be biologically potent.

Synthesis, characterization and antimicrobial activity of novel ethyl 1-(N-substituted)-5-phenyl-1H-pyrazole-4-carboxylate derivatives

In the present study, a novel series of Pyrazole derivatives (3a–m) were synthesized by condensing ethyl-3-(dimethylamino)-2-(phenylcarbonyl)prop-2-enoate with different aromatic and aliphatic hydrazines. These newly synthesized compounds were characterized by NMR, mass spectral, IR spectral studies as well as by C, H, and N analyses. All the newly synthesized compounds were screened for their antibacterial properties against Staphylococcus aureus,Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. Among the screened samples, 3c, 3f, 3k, and 3l have showed excellent antibacterial activity against all the tested bacterial strains as compared to the standard drug Ceftriaxone. Few of the compounds were found to be biologically potent. Molecular structure of compound 3i was confirmed by single crystal X-ray analysis.

(E)-1-(4-Fluorophenyl)ethan-1-one semicarbazone

In the title compound, C9H10FN3O, the semicarbazone group is nearly planar, with the maximum deviation of 0.044 (1) Å for one of the N atoms. The mean plane of semicarbazone group forms a dihedral angle of 30.94 (4)° with the benzene ring. The molecules are linked into a supramolecular chain by N—H⋯O hydrogen bonds formed along the c axis. The crystal structure is further stabilized by weak intermolucular C—H⋯π interactions; the closest C⋯Cg contact is 3.6505 (11) Å.

(E)-1-(4-Fluoro­phen­yl)ethan-1-one semicarbazone

In the title compound, C9H10BrN3O, the hydrazone portion and aliphatic chain are essentially coplanar [maximum deviation 0.057 (15) Å] and the mean plane makes a dihedral angle of 70.9 (6)° with the benzene ring. The main feature of the crystal structure is the intermolecular N—H⋯O hydrogen bond, which links molecules into zigzag chains along the a axis. These chains are further stacked along the b axis. The crystal structure features non-classical intermolecular C—H⋯O interactions. The crystal studied was a nonmerohedral twin, with a twin ratio of 0.505 (1):0.495 (1).

Synthesis and anti-inflammatory evaluation of some new 3,6-disubstituted-1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazoles bearing pyrazole moiety

In the present study, a new series of 3,6-disubstituted-1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazoles (4aj) have been synthesized by condensing 3-substituted-4-amino-5-mercapto-1,2,4-triazoles (1a–b) with various 3-substituted-pyrazole-4-carboxylic acids (3a–e) in the presence of POCl3. The structures of newly synthesized compounds were characterized by elemental analysis, IR, 1H NMR, 13C NMR, and mass spectroscopic studies. Structure of the compound 4b was also confirmed by recording the single crystal X-ray structure. All the synthesized compounds were screened for their anti-inflammatory activities by carrageenan induced paw edema method. Anti-inflammatory screening indicated that, compounds 4d, 4e, and 4h were found to be biologically active whereas remaining compounds showed poor anti-inflammatory activity. Also molecular docking studies were also performed for compounds which showed good anti-inflammatory activity.

2-(4-Methylphenoxy)acetohydrazide

In the title compound, C9H12N2O2, the acetohydrazide group is approximately planar [maximum deviation = 0.034 (2) Å]. In the crystal, molecules are linked via intermolecular N—H⋯O, N—H⋯N and C—H⋯O hydrogen bonds into infinite two-dimensional networks parallel to (001).

4-Amino-3-(1-naphthyl­oxymeth­yl)-1H-1,2,4-triazole-5(4H)-thione

In the title compound, C13H12N4OS, the dihedral angle between the triazole and naphthalene ring systems is 67.42 (5)°. In the crystal, adjacent molecules are linked via two pairs of intermolecular N—H⋯S interactions, forming R 2 2(8) and R 2 2(10) ring motifs. Weak C—H⋯S interactions generate infinite chains along [001] and the structure is further consolidated by C–H⋯π bonds and aromatic π⋯π stacking interactions [distance between the centroids of the triazole rings = 3.2479 (7) Å].

(E)-1-(2,4-Dichloro-phen-yl)-3-(1,3-diphenyl-1H-pyrazol-4-yl)prop-2-en-1-one.

In the title molecule, C24H16Cl2N2O, the dihedral angles between the pyrazole ring and its N- and C-bonded phenyl rings are 7.06 (10) and 53.15 (10)°, respectively. The dihedral angle between the two pendant rings is 52.32 (10)°. The molecule exists in a trans conformation with respect to the acyclic C=C bond. In the crystal, inversion dimers occur in which each molecule is linked to the other by two C—H⋯O hydrogen bonds to the same acceptor O atom. There are also short Cl⋯Cl contacts [3.3492 (9) Å] and C—H⋯π interactions.