Encapsulation of ciprofloxacin, sparfloxacin, and ofloxacin drugs with α- and β-cyclodextrins: spectral and molecular modelling studies

Abstract

Inclusion complexation of ciprofloxacin (CIP), sparfloxacin (SPA), and ofloxacin (OFL) drugs with α-CD and β-CD was studied by UV-visible, fluorescence, time-resolved fluorescence, Fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (¹HNMR), scanning electron microscopy (SEM), and molecular modelling techniques. Changes in the absorbance and fluorescence intensities and fluorescence lifetime of the drugs in the cyclodextrin (CD) solutions suggest the formation of inclusion complexes. Carbonyl stretching frequency moved to higher wave numbers and broadening of the N–H stretching band indicated the formation of inclusion complex. Cyclohexane ring protons of the drugs show remarkable upfield or downfield shift in the ¹HNMR spectrum, indicating that the cyclohexane part of the guest molecule is entrapped inside CD cavities. SEM images of CIP/CD, SPA/CD, and OFL/CD complexes have a crystal structure with different morphology from the isolated CIP, SPA, OFL, and CDs. Investigations of the energetic, thermodynamic, and electronic properties of parametric model number 3 computational calculations confirmed the stability of the inclusion complex.

Keywords:

• Ciprofloxacin; sparfloxacin; ofloxacin
• cyclodextrins
• inclusion complex
• molecular modelling

Additional information

Funding

This work was supported by the Council of Scientific Industrial Research, New Delhi, India [No. 01(2549)/12/ EMR-II], and University Grants Commission, New Delhi, India [F. No. 41-351/2012 (SR)].