Synthesis of 6-Fluoro-7-cyclic Amino-substituted Dicarboxylic Acid Quinolones and their Antibacterial Activity

A Combination of Pharmacophore-Based Virtual Screening, Structure-Based Lead Optimization, and DFT Study for the Identification of S. epidermidis TcaR Inhibitors

The transcriptional regulator (TcaR) enzyme plays an important role in biofilm formation. Prevention of TcaR-DNA complex formation leads to inhibit the biofilm formation is likely to reveal therapeutic ways for the treatment of bacterial infections. To identify the novel ligands for TcaR and to provide a new idea for drug design, two efficient drug design methods, such as pharmacophore modeling and structure-based drug design, were used for virtual screening of database and lead optimization, respectively. Gemifloxacin (FDA-approved drug) was considered to generate the pharmacophore model for virtual screening of the ZINC database, and five hits, namely ZINC77906236, ZINC09550296, ZINC77906466, ZINC09751390, and ZINC01269201, were identified as novel inhibitors of TcaR with better binding energies. Using structure-based drug design, a set of 7a–7p inhibitors of S. epidermidis were considered, and Mol34 was identified with good binding energy and high fitness score with improved pharmacological properties. The active site residues ARG110, ASN20, HIS42, ASN45, ALA38, VAL63, VAL68, ALA24, VAL43, ILE57, and ARG71 are playing a promising role in inhibition process. In addition, we performed DFT simulations of final hits to understand the electronic properties and their significant role in driving the inhibitor to adopt apposite bioactive conformations in the active site. Conclusively, the newly identified and designed hits from both the methods are promising inhibitors of TcaR, which can hinder biofilm formation.

Synthesis and In vitro Antibacterial, Antitubercular Studies of Novel Fluoroquinolones Analogs Containing 4-substituted Sec Amine

Background:

Tuberculosis is a contagious, air borne disease and second leading cause of death among infectious diseases worldwide. Fluoroquinolones are well-known antibacterial agents and they were recommended as second-line of antitubercular drugs.

Method:

A series of novel fluoroquinolone analogs 6-24 was effectively synthesized. An attempt was made by tagging the substituted pyrazole on to fluoroquinolones for the first time at C-7 position. The newly synthesized compounds were characterized by FTIR, 1HNMR, ESI-MS, HR-MS and elemental analysis. The in vitro antibacterial activity of all the title compounds was investigated against various gram positive, gram negative bacterial organisms and in vitro antitubercular activity against Mycobacterium Tuberculosis H37Rv strain.

Result:

Most of the synthesized compounds showed comparable activity against the entire gram positive and gram negative bacterial organisms. Fluoroquinolone 16 showed enhanced activity against both type of bacterial strains and compound 11showed promising activity against MTB-H37Rv strain.

Conclusion:

Some of the novel fluoroquinolone analogs (11, 16) showed potent antibacterial, antitubercular activity.