Preparation, characterization, and biological activity of the inclusion complex of dihydroquercetin and β-Cyclodextrin

Dihydroquercetin (DHQ) is a natural occurring dihydroflavonol that has strong antioxidant and antibacterial activities. However, its application is limited due to its poor solubility. This study aims to improve the aqueous solubility of DHQ by complexing DHQ with β-cyclodextrin (β-CD) to boost its biological activity. DHQ was encapsulated with β-CD by freeze drying at a 1:1-M ratio. The structure of DHQ/β-CD complex prepared was elucidated by using Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and 1 H nuclear magnetic resonance ( 1 H NMR). In addition, molecular docking further revealed two energetically favorable conformations of the DHQ/β-CD complex, in which DHQ interacted with β-CD via hydrogen bonds. Experimental results showed that the solubility of the DHQ increased 22.63-fold by encapsulating with β-CD. Also the dissolution rate, antioxidant activity and antibacterial activity of the DHQ were significantly improved by encapsulating. The encapsulating with β-CD solves the problem of the poor aqueous solubility of DHQ, and broadens the path for a more optimal use of the health promoting effect of DHQ in pharmaceutical and food products.