Preparation of Water-soluble Rutin/Hydroxypropyl-β-Cyclodextrin Inclusion Complex and Its Antioxidant Activity and Stability Studies

Rutin has a variety of pharmacological activities, in order to solve the application defects caused by its poor water solubility. In this paper, rutin/hydroxypropyl-beta-cyclodextrin (HPCD) inclusion complexes were prepared by solvent evaporation method and analysed for structure, solubility, antioxidant activity and stability. The analysis of the inclusion complex showed that HPCD could effectively encapsulate rutin in a molar ratio of 1:1, and its entrapment efficiency and drug loading were 89.33% and 26.67%, respectively. The solubility of the inclusion complex in water was 51 times higher than that of rutin. After complexation, the crystal diffraction peaks of rutin disappeared and the temperature of the maximum weight loss increased from 266 ℃ to 318 ℃ and solid inclusion complex forms showed an irregular sheet-like structures indicating a successful complexation of rutin by HPCD. The IC₅₀ of the inclusion complex for scavenging DPPH radicals and ABTS cationic radicals was significantly lower than that of rutin, and its ferric ion reduction capacity was 1.3 times that of rutin. The stability study also showed a higher retention rate of rutin in the inclusion complex after exposure to natural light for 6 days (31.80%, 66.70%) or heat treatment at 50 ℃ for 15 days (66.91%, 87.38%). The complexation of rutin by HPCD significantly improved its solubility, antioxidant activity and stability, which can be used in different environments to exert its health functions.