Design, synthesis, spectroscopic characterization, in-vitro antibacterial evaluation and in-silico analysis of polycaprolactone containing chitosan-quercetin microspheres

Abstract

Aim of present study was to synthesize a novel chitosan-quercetin (CTS-QT) complex by making a carbodiimide linkage using maleic anhydride as cross-linker and to investigate its enhanced antibacterial and antioxidant activities as compare to pure CTS and QT. Equimolar concentration of QT and maleic anhydride were used to react with 100 mg CTS to form CTS-QT complex. For this purpose, three bacterial strains namely E. Coli, S. Aureus and P. Aeruginosa were used for in-vitro antibacterial analysis (ZOI, MIC, MBC, checker board and time kill assay). Later molecular docking studies were performed on protein structure of E. Coli to assess binding affinity of pure QT and CTS-QT complex. MD simulations with accelerated settings were used to explore the protein-ligand complex’s binding interactions and stability. Antioxidant profile was determined by performing DPPH• radical scavenging assay, total antioxidant capacity (TAC) and total reducing power (TRP) assays. Delivery mechanism to CTS-QT complex was improved by synthesizing polycaprolactone containing microspheres (CTS-QT-PCL-Levo-Ms) using Levofloxacin as model drug to enhance their antibacterial profile. Resulted microspheres were evaluated by particle size, charge, surface morphology, in-vitro drug release and hemolytic profile and are all were found within limits. Antibacterial assay revealed that CTS-QT-PCL-Levo-Ms showed more than two folds increased bactericidal activity against E. Coli and P. Aeruginosa, while 1.5 folds against S. Aureus. Green colored formation of phosphate molybdate complexes with highest 85 ± 1.32% TAC confirmed its antioxidant properties. Furthermore, molecular docking and dynamics studies revealed that CTS-QT was embedded nicely within the active pocket of UPPS with binding energy greater than QT with RSMD value of below 1.5. Conclusively, use of maleic acid, in-vitro and in-silico antimicrobial studies confirm the emergence of CTS-QT complex containing microspheres as novel treatment strategy for all types of bacterial infections.

Communicated by Ramaswamy H. Sarma

Keywords:

• Antibacterial
• antioxidant
• chitosan-quercetin-complex
• E. Coli
• gastroenteritis
• microspheres
• molecular docking
• molecular dynamics

Acknowledgment

Authors are very much thankful to the Department of Pharmaceutics, Faculty of Pharmacy, Baha-Uddin -Zakariya University Multan for providing research facilities, Department of Chemistry, Faculty of Women, Ain Shams University, Heliopolis, Cairo, Egypt for computational analysis, Department of Applied Biology and Biotechnology for providing facilities for antibacterial analysis and Higher Education Commission (HEC) Pakistan for providing funding of the project.

Disclosure statement

No potential conflict of interest was reported by the authors.

Statement and declarations

Competing interests

The authors reported in the manuscript has no any conflict of interest.

Consent for publication

All authors have agreed with the content of the manuscript.

Data availability statement

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.

Author’s contribution

A = Study design

B = Manuscript preparation

C = Lab work

D = Data interpretation

E = DFT, Docking, Simulations

F = Funds

G = Characterization

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Additional information

Funding

This work was funded by Higher Education Commission of Pakistan under the grant number 518-74010-2MD5-115 and author Muhammad Azeem has received the funds.