Isolation, identification and characterization of degradant impurities in Tolterodine tartrate formulation.

During the stability study of Tolterodine tartrate drug product, two unknown impurities (Impurities I and II) were detected by ultra performance liquid chromatography (UPLC). Both impurities were isolated by preparative liquid chromatography and were subjected to mass and NMR spectral studies. Based on the spectral data, the Impurities I and II were characterized as N-(3-(2-hydroxy-5-methylphenyl)-3-phenylpropyl)-N,N-diisopropyl hydroxyl ammonium trifluoro acetate and 3-(2-hydroxy-5-methylphenyl)-N-isopropyl-3-phenylpropane-1-amine oxide respectively.

1-(6-Fluoro-1,3-benzothia-zol-2-yl)-2-(1-phenyl-ethyl-idene)hydrazine.

The asymmetric unit of the title compound, C(15)H(12)FN(3)S, consists of two independent mol-ecules with comparable geometries. In one mol-ecule, the 1,3-benzothia-zole ring system (r.m.s. deviation = 0.011 Å) forms a dihedral angle of 19.86 (6)° with the phenyl ring. The corresponding r.m.s. deviation and dihedral angle for the other mol-ecule are 0.014 Šand 22.32 (6)°, respectively. In the crystal, mol-ecules are linked via N-H⋯N, C-H⋯F and C-H⋯N hydrogen bonds into a three-dimensional network. The crystal studied was a non-merohedral twin with a refined BASF value of 0.301 (2).

1-(6-Fluoro-1,3-benzothia-zol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde.

The asymmetric unit of the title compound, C(17)H(10)FN(3)OS, consists of two crystallographically independent mol-ecules. In one mol-ecule, the pyrazole ring makes dihedral angles of 6.51 (7) and 34.02 (9)°, respectively, with the terminal 1,3-benzothia-zole ring system and the phenyl ring, while in the other mol-ecule these values are 6.41 (8) and 23.06 (9)°. In the crystal, the molecules are linked by weak π-π [centroid-centroid distance = 3.7069 (10) Å] and C-H⋯π inter-actions.

7-Chloro-3-phenyl-benzo[4,5]thia-zolo[2,3-c][1,2,4]triazole.

In the title compound, C(14)H(8)ClN(3)S, the dihedral angle between the approximately planar triple-fused ring system (r.m.s. deviation = 0.065 Å) and the pendant phenyl ring is 62.25 (5)°. In the crystal, mol-ecules are linked into infinite chains along the c-axis direction by C-H⋯N hydrogen bonds. Aromatic π-π stacking inter-actions [centroid-centroid distances = 3.7499 (8) and 3.5644 (8) Å] and weak C-H⋯π inter-actions are also observed.

2-[5-(4-Meth-oxy-phen-yl)-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl]-6-methyl-1,3-benzothia-zole.

In the title compound, C(24)H(21)N(3)OS, the pyrazole ring makes dihedral angles of 5.40 (7) and 6.72 (8)° with the benzo[d]thiazole ring system and the benzene ring, respectively, and a dihedral angle of 85.72 (8)° with the meth-oxy-substituted benzene ring. In the crystal structure, the mol-ecules are linked by C-H⋯π inter-actions.

Synthesis and biological evaluation of delavayin-C.

The synthesis of a cyclic heptapeptide, delavayin-C, cyclo(gly-tyr-tyr-tyr-pro-val-pro) is described. The structure of this compound was established on the basis of analytical IR, (1)H NMR and FAB mass spectral data. The antibacterial and antifungal activities of this peptide are also described.

Investigation of enhancement of solubility of norfloxacin beta-cyclodextrin in presence of acidic solubilizing additives.

The present study is aimed at improving the solubility of a poorly water-soluble drug, norfloxacin by incorporating solubilizing additives such as ascorbic acid and citric acid into the beta-cyclodextrin complexes. Norfloxacin, being amphoteric in nature, exhibits a higher solubility at pH below 4 and above 8. Addition of substances like ascorbic acid and citric acid in beta-cyclodextrin complexes reduces the pH of the immediate microenvironment of the drug below pH 4. In the present work, beta-cyclodextrin complexes of norfloxacin were prepared along with solubilizing additives such as citric acid and ascorbic acid in various proportion and the dissolution profile was performed in both HCl buffer, pH 1.2 and phosphate buffer, pH 7.4. The results have shown an enhanced dissolution rate in both media. DSC and IR spectral studies performed on the solid complexes have shown that there is no interaction of the drug with the additives and beta-cyclodextrin. Disc diffusion studies have shown larger diameters of zone of inhibition indicating a greater diffusivity of the drug into the agar medium.

Synthesis and biological activity of a novel series of 4-[2'-(6'-nitro)benzimidazolyl]benzoyl amino acids and peptides.

A series of new 4-[2'-(6'-nitro)benzimidazolyl]benzoyl amino acids and peptides have been synthesized by coupling the 4-[2'-(6'-nitro)benzimidazolyl]benzoic acid with amino acid methyl esters/dipeptides using DCC as the coupling agent. All the synthesized compounds were found to exhibit potent anthelmintic activity along with moderate antimicrobial activity.

(Nitro) hymenamide A, unusual biologically active cyclic peptide.

A new biological active cyclic peptide (Nitro) Hymenamide A has been synthesized and the structure was established on the basis of analytical, IR, NMR and mass spectral data. The new compound was subjected to both antimicrobial and pharmacological studies.