Involvement of conformational isomerism in the complexity of the crystal network of 1-(4-nitrophenyl)-1H-1,3-benzimidazole derivatives driven by C-H...A (A = NO2, Npy and π) and orthogonal Npy...NO2 and ONO...Csp2 interactions.

A detailed structural analysis of the benzimidazole nitroarenes 1-(4-nitrophenyl)-1H-1,3-benzimidazole, C13H9N3O2, (I), 1-(4-nitrophenyl)-2-phenyl-1H-1,3-benzimidazole, C19H13N3O2, (II), and 2-(3-methylphenyl)-1-(4-nitrophenyl)-1H-1,3-benzimidazole, C20H15N3O2, (III), has been performed. They are nonplanar structures whose crystal arrangement is governed by Csp2-H...A (A = NO2, Npy and π) hydrogen bonding. The inherent complexity of the supramolecular arrangements of compounds (I) (Z' = 2) and (II) (Z' = 4) into tapes, helices and sheets is the result of the additional participation of π-πNO2 and n-π* (n = O and Npy; π* = Csp2 and NNO2) interactions that contribute to the stabilization of the equi-energetic conformations adopted by each of the independent molecules in the asymmetric unit. In contrast, compound (III) (Z' = 1) is self-paired, probably due to the effect of the steric demand of the methyl group on the crystal packing. Theoretical ab initio calculations confirmed that the presence of the arene ring at the benzimidazole 2-position increases the rotational barrier of the nitrobenzene ring and also supports the electrostatic nature of the orthogonal ONO...Csp2 and Npy...NO2 interactions.

Attenuation of nonenzymatic glycation, hyperglycemia, and hyperlipidemia in streptozotocin-induced diabetic rats by chloroform leaf extract of Azadirachta indica.

BACKGROUND: The hypoglycemic effects of hexane, chloroform and methanol extracts of leaves of Azadirachta indica (AI) were evaluated by oral administration in streptozotocin-induced severe diabetic rats (SD). MATERIALS AND METHODS: The effect of chronic oral administration of the extract for 28 days was evaluated in streptozotozin diabetic rats. Lipid peroxidation, glycogen content of liver and skeletal muscles, insulin, superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), oxidized glutathione (GSSG) levels were determined. In addition, advanced glycation end product formation (AGEs) was evaluated. RESULTS: The most active extracts were obtained with chloroform. Chloroform extract from AI shows increased levels of SOD, GSH, GSSG and CAT, hepatic glycogen content, glucose-6-phosphatase and insulin plasma levels, which also decreased the glucokinase (GK), lipid peroxidation and insulin resistance. The chloroform extract exhibited significant inhibitory activity against advanced glycation end product formation with an IC(50) average range of 79.1 mg/ml. CONCLUSION: Azadirachta indica can improve hyperlipidemia and hyperinsulinema in streptozocin-induced diabetic rats and, therefore, AI can be potentially considered to be an antidiabetic-safe agent.

Nephroprotective activity of Prosthechea michuacana against cisplatin-induced acute renal failure in rats.

In Mexican traditional medicine the orchid Prosthechea michuacana is highly valued as a food and in the treatment of various human diseases, including drug-related renal disease. Methanol, hexane, and chloroform extracts of bulbs of P. michuacana were studied in the cisplatin-induced renal injury model in rats. Results showed that treatment with cisplatin induced significant elevations in concentrations of blood urea and serum creatinine and in lipid peroxidation. Treatments with methanolic extract (200, 400 and 500 mg/kg) increased levels of biochemical markers of renal injury like reduced glutathione, glutathione S-transferase, and superoxide dismutase and inhibited the increases in blood urea and serum creatinine concentrations and lipid peroxidation induced by cisplatin. Hexane and chloroform extracts did not show any effect. The results obtained in the present study indicate that this orchid can be a potential source of natural nephroprotective activity.