Antibacterial and antioxidant properties of hesperidin: β-cyclodextrin complexes obtained by different techniques

The purpose of this study was to investigate the influence of beta-cyclodextrin on aqueous solubility of hesperidin. The inclusion complexes were prepared by different methods (kneading, co-evaporation and lyophilization) and were tested for their antimicrobial and antioxidant activities. Solubility diagrams were drawn at four temperatures (20, 25, 37 and 40 degrees C) and the corresponding stability constants were calculated. The solubility diagrams obtained were of A(L) type and the stoichiometric ratio was 1:1. Moreover, the thermodynamic parameters of the complexation reaction were calculated: Gibbs free energy change, free energy change, enthalpy change and entropy change. The results showed that the complexation reaction is more effective with the increase in temperature and in cyclodextrin concentration. The inclusion process is endothermic and spontaneous and the interactions between hesperidin and beta-cyclodextrin are hydrophobic. UV-Vis, FTIR, (HNMR)-H-1, methods provided valuable information about complex formation. Antibacterial activity was investigated by the agar diffusion method, against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Candida albicans ATCC 10231. The results revealed that all the prepared compounds display a higher antibacterial activity compared to hesperidin. Also, the inclusion compounds presented an improved antioxidant activity, demonstrated by the determination of inhibition of lipoxygenase activity, DPPH radical scavenging activity and determination of reducing capacity. In vitro dissolution tests demonstrated that the inclusion compounds have an improved dissolution, compared to free hesperidin. The enhancement in the solubility, antibacterial and antioxidant activities depend on the method of preparation.