Biological properties of pyrroloquinoline and pyrroloisoquinoline derivatives

In this review, we summarize pyrroloquinoline and pyrroloisoquinoline derivatives (PQs and PIQs) that act on a broad spectrum of biological targets and are used as bacteriostatic, antiviral, plasmodial, anticancer, antidiabetic and anticoagulant agents. Many of these compounds play important roles in the study of DNA and its interactions, the regulation of the cell cycle and programmed cell death. This review involves twenty-five types of skeletally analogical compounds bearing pyrrole and (iso)quinoline scaffolds with different mutual annelations.

4-Quinolone derivatives and their activities against Gram positive pathogens

Gram-positive bacteria are responsible for a broad range of infectious diseases, and the emergency and wide spread of drug-resistant Gram-positive pathogens including MRSA and MRSE has caused great concern throughout the world. 4-Quinolones which are exemplified by fluoroquinolones are mainstays of chemotherapy against various bacterial infections including Gram-positive pathogen infections, and their value and role in the treatment of bacterial infections continues to expand. However, the resistance of Gram-positive organisms to 4-quinolones develops rapidly and spreads widely, making them more and more ineffective. To overcome the resistance and reduce the toxicity, numerous of 4-quinolone derivatives were synthesized and screened for their in vitro and in vivo activities against Gram-positive pathogens, and some of them exhibited excellent potency. This review aims to outlines the recent advances made towards the discovery of 4-quinolone-based derivatives as anti-Gram-positive pathogens agents and the critical aspects of design as well as the structure-activity relationship of these derivatives. The enriched SAR paves the way to the further rational development of 4-quinolones with a unique mechanism of action different from that of the currently used drugs to overcome the resistance, well-tolerated and low toxic profiles.

Heterocycles [h]-fused to 4-oxoquinoline-3-carboxylic acid. Part XI: Synthesis and antibacterial activity of 4-fluoro-6-oxoimidazo[4,5-h]quinoline-7-carboxylic acids

A series of 2-hetaryl-4-fluoro-9-cyclopropyl-6-oxo-1H-imidazo[4,5-h]quinoline-7-carboxylic esters (3a–f) and their corresponding acids 4a–f have been prepared via microwave-assisted cyclocondensation reaction with some hetarene carboxaldehydes. The structures for these new esters and acids are based on spectral (IR, MS, and NMR) data. The in vitro antimicrobial assay of 4a–f hetaryl derivatives, their aryl analogues 1d–g, and the imidazo-unsubstituted acid 1a showed that all of these tricyclic heterocycles possess a good level of antibacterial activity. Among them, compound 1a exhibited the highest effect against both, Gram-positive (minimum inhibitory concentrations [MICs] 0.15–3.0 μg mL–1) and Gram-negative bacteria (MICs 0.7–3.0 μg mL–1). An excellent activity was recorded also for the halo-phenyl derivatives 1f,g and for the furan derivatives 4e,f, especially toward Gram-positive strains and Bacillus subtilis and Haemophilus influenzae, respectively.

Combinatorial synthesis of pyrrolo[3,2-f]quinoline and pyrrolo[3,2-a]acridine derivatives via a three-component reaction under catalyst-free conditions

A combinatorial synthesis of pyrrolo[3,2-f]quinoline and pyrrolo[3,2-a]acridine derivatives is described as a three-component reaction of aromatic aldehyde, 1H-indol-5-amine, and 1,3-dicarbonyl compounds under catalyst-free conditions. The 1,3-dicarbonyl compounds include 5,5-dimethylcyclohexane-1,3-dione, cyclopentane-1,3-dione, and 2H-indene-1,3-dione. It is interesting that the designed reactions gave aromatized or unaromatized products, which depend on the reaction temperature and reactants of 1,3-dicarbonyl compounds.