藤茶二氢杨梅素茶氨酸复合物的制备及抗氧化活性研究

二氢杨梅素在天然藤茶中含量高达25.6%,具有多种生理功能,受到广泛关注。但二氢杨梅素常温水溶性差,生物利用度较低,限制了其应用范围,为了提高二氢杨梅素的水溶性,对二氢杨梅素进行分子修饰,制备了二氢杨梅素-茶氨酸复合物,利用紫外光谱、红外光谱、质谱和核磁共振氢谱对复合物进行了结构表征,测定了复合物的理化性质,并考察了复合物的抗氧化活性。通过结构分析,二氢杨梅素分子中C3-OH、C5-OH、C7-OH、C3′-OH、C5′-OH与茶氨酸的活泼氢通过氢键结合形成复合物;复合物清除·OH自由基的能力均强于二氢杨梅素和Vc,清除O2-·自由基和DPPH自由基的能力和二氢杨梅素相当,比Vc强。二氢杨梅素和茶氨酸的复合,不仅提高其水溶性,在抗氧化活性方面也起到了强化的作用。

Synthesis of Dihydromyricetin-theanine Complex and Its Antioxidant Activity

Dihydromyricetin is currently attracting extensive scientific attention because of its various physiological functions. Although the content of dihydromyricetin in Ampelopsis grossedentata is up to 25.6%, its poor water solubility at room temperature and low bioavailability limit the scope of its application. In order to improve the water solubility of dihydromyricetin, its structure was modified and a dihydromyricetin-theanine complex was prepared. The structure was characterized by UV, IR, MS, and 1HNMR spectra, its physical and chemical properties were measured, and the antioxidant activity of the complex was investigated. Based on structural analysis, the complex was found to be formed via hydrogen bonding interactions between C3-OH, C5-OH, C7-OH, C3'-OH, and C5'-OH in dihydromyricetin and active hydrogens in theanine. The scavenging capacity of the complex against hydroxyl free radicals was stronger than that of dihydromyricetin and Vc, and was equivalent to that of dihydromyricetin against superoxide and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, but was better than that of Vc. It is therefore considered that the complexation of dihydromyricetin with theanine not only improved the water solubility of dihydromyricetin but also enhanced its antioxidant activity.