Construction of cinnamic acids derived β-cyclodextrins and their emodin-based inclusions with enhanced water solubility, excellent antioxidant and antibacterial activities

Abstract

β-Cyclodextrin (β-CD) is a natural macromolecule which has been regarded as a promising biomaterial and drug carrier. However, the poor water solubility and less functions of β-CD severely hinder its potential applications. Herein, we modified the β-CD with three cinnamic acid derivatives (ADs) of ferulic acid (FA), p-coumaric acid (p-CA) and caffeic acid (CA) by sulfonylation, amination and amidation. The resulted β-CD-ADs are β-CD-FA, β-CD-p-CA and β-CD-CA, which were confirmed by proton nuclear magnetic resonance (1H NMR) and high resolution mass spectrometry (HRMS). Compared to β-CD, the β-CD-ADs show enhanced water solubility (>600 mg/mL) and excellent antioxidant property in scavenging DPPH radicals. Furthermore, the inclusion complex of between emodin (ED) and β-CD-ADs were prepared and characterized by 1H NMR, fluorescence spectroscopy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The ED/β-CD-ADs inclusions had antioxidant activity because of chemical modification of cinnamic acid derivatives, especially for ED/β-CD-CA, which had the highest DPPH radical scavenging rate. The three ED/β-CD-ADs inclusions showed excellent antibacterial activity against S. aureus with the bactericidal rates beyond 97 %. Additionally, the ED/β-CD-ADs inclusions exhibited good blood compatibility by in-vitro hemolysis assay. This work provides an efficient way to modify β-CD with enhanced water solubility and more functional that could facilitate the application of β-CD in medicine and cosmetic.