Experimental and theoretical structure characterization of two isoniazid derivatives: 2,4-Difluoro-N′-isonicotinoylbenzohydrazide and 2,4-dichloro-N′-isonicotinoylbenzohydrazide hydrochloride

New isoniazid derivatives with improved pharmaco-toxicological profile: Obtaining, characterization and biological evaluation

Tuberculostatic drugs are the most common drug groups with global hepatotoxicity. Awareness of potentially severe hepatotoxic reactions is vital, as hepatic impairment can be a devastating and often fatal condition. The treatment problems that may arise, within this class of medicines, are mainly of two types: adverse reactions (collateral, toxic or hypersensitive reactions) and the initial or acquired resistance of Mycobacterium tuberculosis to one or more antituberculosis drugs. Prevention of adverse reactions, increase treatment adherence and success rates, providing better control of tuberculosis (TB). In this regard, obtaining new drugs with low toxicity and high tuberculostatic potential is essential. Thus, in this work, we have designed or synthesized new derivatives of isoniazid (INH), such as new Isonicotinoylhydrazone (INH-a, INH-b and INH-c). These derivatives demonstrated good biocompatibility, antimicrobial property similar to that of parent isoniazid and last but not least, a significantly improved Pharmacotoxicological profile compared to that of isoniazid.

Computational and spectral studies of 6-phenylazo-3-(p-tolyl)-2H-chromen-2-one

6-Phenylazo-3-(p-tolyl)-2H-chromen-2-one 4 was prepared and characterized by IR, (1)H, and (13)C NMR spectral studies. The optimized structure of the chromen-2-one 4 was investigated by the Gaussian 03 B3LYP density functional method calculations at 6-31G(d,p) basis set. The gauge-independent atomic orbital (GIAO) (13)C and (1)H chemical shift calculations for the synthesized chromen-2-one in CDCl3 were also made by the same method. The computed IR frequencies of the chromen-2-one and the corresponding vibrational assignments were analyzed by means of potential energy distribution (PED%) calculation using vibrational energy distribution analysis (VEDA) program. The first order hyperpolarizability (βtot), polarizability (α) and dipole moment (μ) were calculated using 6-311G(d,p) basis set and the nonlinear optical (NLO) properties are also addressed theoretically. Stability of the chromen-2-one 4 molecule has been analyzed by calculating the intramolecular charge transfer using natural bond order (NBO) analysis. The molecular electrostatic potentials, HOMO-LUMO energy gap and geometrical parameters were also computed. Topological properties of the electronic charge density in chromen-2-one 4 were analyzed employing the Bader's Atoms in Molecule (AIM) theory which indicated the presence of intramolecular hydrogen bond in the molecule.

In vitro anti-mycobacterial activity of (E)-N'-(monosubstituted-benzylidene) isonicotinohydrazide derivatives against isoniazid-resistant strains

A series of twenty-three N-acylhydrazones derived from isoniazid (INH 1-23) have been evaluated for their in vitro antibacterial activity against INH- susceptible strain of M. tuberculosis (RG500) and three INH-resistant clinical isolates (RG102, RG103 and RG113). In general, derivatives 4, 14, 15 and 16 (MIC=1.92, 1.96, 1.96 and 1.86 µM, respectively) showed relevant activities against RG500 strain, while the derivative 13 (MIC=0.98 µM) was more active than INH (MIC=1.14 µM). However, these derivatives were inactive against RGH102, which displays a mutation in the coding region of inhA. These results suggest that the activities of these compounds depend on the inhibition of this enzyme. However, the possibility of other mechanisms of action cannot be excluded, since compounds 2, 4, 6, 7, 12–17, 19, 21 and 23 showed good activities against katG-resistant strain RGH103, being more than 10-fold more active than INH.

Synthesis, structure, and tuberculostatic activity of dimethyl benzoylcarbonohydrazonodithioates

ABSTRACT

New dimethyl benzoylcarbonohydrazonodithioates were obtained by CS2 addition to arylcarboxylic acid hydrazides and methylation of the formed adduct. The new derivatives were tested for their activity against Mycobacterium tuberculosis. Some compounds exhibited high activity toward sensitive and resistant strains.

GRAPHICAL ABSTRACT

Adsorption of isoniazid onto sepiolite-palygorskite group of clays: An IR study

The adsorption of isoniazid (INH) on sepiolite, loughlinite (natural Na-sepiolite) and palygorskite from Anatolia was investigated by FT-IR spectroscopy. Experimental results indicated that INH molecules, adsorbed on sepiolite-palygorskite group of clays, are coordinated to surface hydroxyls by H-bonding interaction through the pyridine ring nitrogen lone pairs. Moreover, some of the adsorbed INH molecules may enter the interior channels of the sepiolite-palygorskite structure and involve H-bonding interaction with zeolitic water. Some intensity and frequency changes in the OH stretching band of surface hydroxyls (Si-OH) of the INH-treated sepiolite and loughlinite were observed. However, this band is found to be less affected by the adsorption of isoniazid in the case of palygorskite, probably because the surface Si-OH groups in palygorskite appear to be less abundant than in sepiolite or loughlinite.

Benzyl N-((S)-2-hydr-oxy-1-{N'-[(E)-2-methoxy-benzyl-idene]hydrazinecarbon-yl}eth-yl)carbamate from synchrotron data

A U-shaped conformation is found in the title compound, C(19)H(21)N(3)O(5), with the benzene rings lying to the same side of the mol-ecule; the dihedral angle between them is 10.83 (16)°. The dihedral angle formed between the hydrazinecarbonyl and carbamate residues is 68.42 (13)°. The carbonyl groups lie approximately at right angles to each other [O-C⋯C-O pseudo torsion angle of 107.7 (3)°], and the conformation about the C12=N3 bond [1.279 (4) Å] is E. An intra-molecular N(cb)-H⋯O(hy) (cb = carbmate and hy = hydr-oxy) hydrogen bond occurs, generating an S(6) loop. In the crystal, inter-molecular O(h)-H⋯O(ca) (ca = carbon-yl) and N(hz)-H⋯O(ca) (hz = hydrazine) hydrogen bonds lead to the formation of a supra-molecular chain, two mol-ecules thick, which propagates along the a axis; these are connected by C-H⋯O(ca) contacts.

N'-(2-Fluoro-benzo-yl)benzohydrazide

In the crystal structure of the title compound, C(14)H(11)FN(2)O(2), the molecule is centrosymmetric. The F atom is disordered over four positions, on the two ortho positions of each ring, with occupancies of 0.287:0.213 (5). In the crystal structure, mol-ecules are linked by inter-molecular N-H⋯O and C-H⋯O hydrogen bonds.