Physicochemical properties and antimicrobial activity of fluoroquinolone complexes with cyclodextrin derivatives and polymeric carriers for aquaculture applications

Abstract

Fluoroquinolones (ciprofloxacin and levofloxacin) are broad-spectrum antibiotics, but their use is limited by low solubility, toxicity, and the risk of resistance. The use of cyclodextrins and polymeric carriers is a promising approach to overcome these limitations. In this work, we systematically studied the complexation of ciprofloxacin (CF) with β-cyclodextrin derivatives — 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), methyl-β-cyclodextrin (M-β-CD), and sulfobutyl ether β-cyclodextrin (SBE-β-CD) — using IR and UV spectroscopy, equilibrium dialysis, and solubility assays. The most stable complex is formed with HP-β-CD (Kdis = 1.7 × 10−4 M), which increases the solubility of CF by 20% (pH 4.0) and 64% (pH 7.4) and provides sustained release. Based on these data, two types of polymeric complexes of levofloxacin (LF) with enterosgel, and silica gel/HP-β-CD were developed for aquaculture. Influence of dihydroquercetin on physicochemical parametres of complexes has been studied. The complexes showed high loading efficiency (85–95%) and sorption capacity up to 1.0 mg/mg. The solubility of LF complexes was reduced by 6 times compared to the free drug, and release was prolonged up to 3 days. The synthesized complexes antimicrobial activity against E. coli and B. subtilis was higher than that of the commercial drug "Antibak". The developed complexes represent a promising environmentally safe strategy for aquaculture.