Characterization and Evaluation of Ternary Complexes of Ascorbic Acid with γ-Cyclodextrin and Poly(vinyl Alcohol)

Abstract

Ascorbic acid (AA) is a general antioxidant used in aqueous pharmaceutical formulations. However, in aqueous solutions, AA is unstable and easily oxidized when exposed to air, light and/or heat. Cyclodextrins are well known for their ability to form inclusion complexes with various compounds to improve their solubility and stability. Previous studies demonstrate that cyclodextrins preserve the antioxidant capacity of AA but data for γ-cyclodextrin (γCD) have not been reported. Poly(vinyl alcohol) (PVA) is a hydrophilic polymer widely used as a drug matrix in various pharmaceutical fields, but its application for drug stabilization is limited. This study aimed to investigate the protective ability of γCD on AA through the formation of ternary complexes with PVA. Binary (i.e., AA/γCD, AA/PVA and γCD/PVA) and ternary (i.e., AA/γCD/PVA) complexes were first confirmed. It was reported that those complexes were formed through interactions between the heterocyclic ring of AA, hydroxyl group of PVA and hydrophobic cavity of γCD. The hydrodynamic diameter of complexes was then studied. It was found that the diameter of γCD/PVA complexes increased with respect to the concentration of γCD. Higher γCD concentrations also resulted in increasing hydrodynamic diameters of the ternary complex. The presence of AA in ternary complexes interfered with the aggregation tendency of γCD/PVA binary complexes. Furthermore, the antioxidant capacity of AA in binary and ternary complexes was investigated. It was found that the presence of γCD preserved the antioxidant activity of AA, whereas PVA showed a contrasting effect. The influence of γCD and PVA concentration on antioxidant capacity was then studied through central composite design (CCD). Even though the concentration of γCD significantly affected the inhibition efficiency of the ternary complex, the insignificant influence of PVA could not be ignored. A promising protective ternary complex should consist of an optimized concentration of PVA and a high concentration of γCD.

Mechanochemical Approach to Obtaining a Multicomponent Fisetin Delivery System Improving Its Solubility and Biological Activity

“…The obtained results are consistent with the literature reports. Saokham et al [87] observed shifts in the spectra of ternary systems and associated them with interactions between individual components. Al-Burtomani et al [88] confirmed the formation of non-covalent bonds between the drug and cyclodextrin in the obtained ternary complexes.…”

“…[86]. The preparation of AChE/BChE and FIS utilized MGLTools 1.5.6 with AutoDock 4.2 (ADT; Scripps Research Institute, La Jolla, San Diego, CA, USA) [87]. AutoDockVina 1.1.2. was used to carry out the actual molecular docking.…”

Cyclodextrins and Their Derivatives as Drug Stability Modifiers

“…In addition, Saokham et al [ 54 ] studied the protection capacity of γCD for ascorbic acid through the formation of multicomponent complexes with the addition of polyvinyl alcohol. Based on the results, they determined that the complex formation with γCD and polyvinyl alcohol was able to protect ascorbic acid from the oxidation reaction in aqueous solutions when the optimal concentrations of γCD and polyvinyl alcohol were used.…”

Synthesis, Characterization, and Antimicrobial Activity of CoO Nanoparticles from a Co (II) Complex Derived from Polyvinyl Alcohol and Aminobenzoic Acid Derivative

“…These properties for PVA led to a wide range of applications in pharmaceutical, packaging, medical, cosmetic, and food industries [ 22 ]. There are groups that have investigated binary or mixed complexes between polyvinyl alcohol and metal ions [ 23 , 24 ]. Metal compounds with 4-aminobenzoic acid are among the most explored types of complexes in coordination chemistry and play an important role in catalysis, other materials science, and biochemistry [ 25 , 26 ].…”