"One-pot" synthesis and antimalarial activity of formamidine derivatives of 4-anilinoquinoline

Copper(II)-N-hydroxy-N,N'-diarylformamidine complexes: Synthesis, crystal structures, antibacterial and molecular docking studies

A series of Cu(II) complexes were synthesized by using N-hydroxy-N,N'-diarylformamidine ligands: N-hydroxy-N,N'-(phenyl)formamidine (L1), N-hydroxy-N'-(4-methylphenyl)formamidine (L2), N-hydroxy-N,N'-(2,6-dimethylphenyl)formamidine (L3), N-hydroxy-N,N'-(2,6-diisopropylphenyl)formamidine (L4). Reaction of ligands L1-L4 with hydrated copper acetate furnished mononuclear Cu(II) complexes 1-4 with general formula [Cu-(L)₂]. The molecular structures of complexes 3 and 4, as determined by single crystal X-ray diffraction, showed both to have square planar geometry with a near C₂ symmetry. The antimicrobial potency of all four complexes was evaluated against three gram-(-) bacteria (S. typhimurium, P. aeruginosa, and E. coli) and two gram-(+) bacteria (Methicillin-resistant S. aureus (MRSA) and S. aureus), with ciprofloxacin as the reference drug. All tested complexes were inactive against gram-(+) bacteria strains except for complex 1, which displayed excellent activity when compared to the reference. Molecular docking studies showed that hydrogen bonding, pi-sigma and van der Waals interactions are prominent complex-protein connections, with complex 2 displaying good binding affinities with the studied biological targets.

Nanoporous TiO2 containing an ionic liquid bridge as an efficient and reusable catalyst for the synthesis of N,N′-diarylformamidines, benzoxazoles, benzothiazoles and benzimidazoles

Nanoporous TiO₂ modified with an ionic liquid was used for efficient coupling of amines, 1,2-phenylene diamines, 2-aminophenol and 2-aminothiophenol with orthoesters.

Prediction and characterization of halogen bonds involving formamidine and its derivatives

Ab initio calculations have been carried out for the complexes of formamidine (FA) and some representative halogenated molecules XY (X=Cl, Br, and I; Y=F, CCH, CF3, CN, and NC). The FA-(Z) complex combines with the halogenated molecule through a halogen bond, while the FA-(E) complex is stabilized jointly by both a halogen bond and a X⋯H interaction. The FA-(E) complex is more stable than the FA-(Z) counterpart, with the interaction energy of -3.4 to -23.4kcal/mol, indicating that FA is a good electron donor in halogen bonding. The methyl substituent particularly one at the imino nitrogen atom of FA has an enhancing effect on the strength of halogen bond. The similar effect is found for the phenyl and pyridyl substituents, depending on the FA conformation and substitution position of pyridyl. The stability of stronger halogen bonding is mainly attributed to electrostatic and polarization energies, which is different from the weak one with an electrostatic nature.

Synthesis and antimalarial activity of new analogues of amodiaquine

In order to determine the real significance of the 4'-phenolic group in the antimalarial activity and/or cytotoxicity of amodiaquine (AQ), analogues for which this functionality was shifted or modified were synthesized. Good in vitro antimalarial activity was obtained for compounds unable to form intramolecular hydrogen bond. Among the compounds synthesized, new amino derivative 5 displayed the greatest selectivity index towards the most CQ-resistant strain tested and was active in mice infected by Plasmodium berghei.

Effects of homeopathic medications Eupatorium perfoliatum and Arsenicum album on parasitemia of Plasmodium berghei-infected mice

Malaria is one of the most important parasitic diseases in the world and a major public health problem because of emerging drug-resistant strains of Plasmodium. A number of synthetic and natural compounds are now being analysed to develop more effective antimalarial drugs. We investigated the effect of homeopathic preparations of Eupatorium perfoliatum and Arsenicum album on parasitemia using a rodent malaria model. We found significant inhibitory effect on parasite multiplication with both medications with a level of 60% for Eupatorium perfoliatum at a 30 CH potency. Arsenicum album 0/6 gave 70% inhibition but this was less stable than Eupatorium perfoliatum. The number of schizonts was higher in animals treated with homeopathic medications. Although the mechanism of action is unknown, these agents would be good candidates as alternative or complementary medications in the treatment of malaria.