The Spectrum of Thiazolidinediones against Respiratory Tract Pathogenic Bacteria: An In Vitro and In Silico Approach

Abstract

Background and objectives: Drug design strategies to develop novel broad-spectrum antibacterial agents for the treatment of respiratory tract infections that can combat bacterial resistance are currently gaining momentum. 2,4-thiazolidinedione is a structural scaffold that contains pharmacophores similar to β-lactam and non- β-lactam antibiotics. The objective of the study was to synthesize newer 3,5-Disubstituted-2,4-Thiazolidinediones (DTZDs) and subject them to in vitro antibacterial screening against bacterial pathogens. Also, we performed in silico docking of selected compounds to penicillin-binding proteins and beta-lactamases.

Methods: Intermediate Schiff bases were prepared by the reaction between 2,4-thiazolidinedione and an appropriate aldehyde followed by acylation of the ring nitrogen with 3-brompropanoyl chloride resulting in DTZDs. Minimum inhibitory concentrations were determined against few bacteria infecting the respiratory tract by the broth tube dilution method. Zones of inhibitions against the bacteria were also determined using agar well diffusion technique. Molecular docking of the compounds to all types of Penicillin-Binding Proteins (PBPs) and β-lactamases was also carried out.

Results: Compounds DTZD12 and DTZD16 exhibited broad-spectrum antibacterial activity. The minimum inhibitory concentrations of the compounds were 175μg/100μL. Measurements of the zones of inhibitions indicated that compound DTZD12 was more active than DZTD16. E. coli was the most susceptible organism. Docking results established that both the compounds were able to interact with PBPs and β-lactamases through strong hydrogen bonds, especially the unique interaction with active serine residue of the PBP for inhibition of cell wall synthesis.

Conclusion: DTZD12 and DTZD16 can be developed into antibacterial drugs for respiratory tract infections to oppose bacterial resistance, or can also be used as leads for repurposing the existing 2,4- thiazolidinediones.

Keywords: Antibacterial susceptibility; docking; in silico; penicillin-binding protein; respiratory tract infections; thiazolidinediones; β-lactamase resistant.