蒲公英多糖乙酰化修饰、体外抗氧化及抑菌作用研究

目的:以蒲公英多糖为原料，使用乙酸酐法修饰得到乙酰化蒲公英多糖，对其结构特征、体外抗氧化性以及抑菌效果进行研究。方法:采用水提醇沉法等制备蒲公英纯化多糖，选择乙酸酐法修饰得到乙酰化蒲公英多糖。利用红外光谱、扫描电镜、X-射线粉末衍射等测定蒲公英纯化多糖和乙酰化蒲公英多糖的结构特征。在此基础上，应用体外化学模型法评估多糖对清除1,1-二苯基-2-三硝基苯肼（1,1-Diphenyl-2-picrylhydrazyl，DPPH）自由基、超氧阴离子自由基、羟自由基和还原力的能力，并对其通过纸片法进行抑菌试验。结果:蒲公英纯化多糖的多糖含量为68.75%，红外光谱、扫描电镜、X-射线粉末衍射等结构表征证实乙酰化蒲公英多糖修饰成功，而且化学结构修饰后的乙酰化多糖，并未改变结构骨架。在浓度范围0.1~2.0 mg/mL内，改性前后的蒲公英纯化多糖对DPPH自由基IC₅₀值分别为5.393±0.941和2.153±0.093 mg/mL；对超氧阴离子自由基IC₅₀值分别为6.513±0.500和2.092±0.825 mg/mL；对羟自由基IC₅₀值分别为0.626±0.034和0.322±0.010 mg/mL；对还原力最大吸光度值为0.138±0.019和0.239±0.022。随多糖浓度的递增，经修饰后蒲公英纯化多糖的抗氧活性逐渐增强。此外，乙酰化蒲公英多糖抑菌能力强于蒲公英纯化多糖，且随多糖浓度的增加抑菌能力也随之增大。结论:蒲公英多糖经乙酰化修饰后，可显著提高体外抗氧化性和抑菌效果。

Antioxidant and Anti-bacteria Effects of Acetylated Taraxacum mongolicum Polysaccharide

Objective: To prepare acetylated Taraxacum mongolicum polysaccharide from Taraxacum mongolicum Hand.-Mazz, and study its structural characteristics, antioxidant activity and antibacterial activity. Methords: The structure of the polysaccharide extracted by water extraction and then alcohol precipitation method was modified by acetic anhydride method to obtain its acetylated. Infraed spectroscopy, scanning electron microscope and X-ray powder diffraction were used to structural characteristics of the polysaccharide and its acetylated. On the basis, the antioxidant activities were evaluated by 1,1-Dipheny1-2-picrylhydrazyl (DPPH) free radicals, superoxide anion free radicals, hydroxyl free radicals and reducing power scavenging abilities using chemical model method, and the anti-bacteria tests was evaluated through the paper method in vitro. Results: The extraction yield of purified dandelion polysaccharide was 68.75%. Infraed spectroscopy, scanning electron microscope and X-ray powder diffraction of characterization confirmed the successful synthesis of acetylated. The basic structure framework of polysaccharide was not changed after being modified with acetylated. In the concentration range of 0.1～2.0 mg/mL, IC₅₀ values were 5.393±0.941 and 2.153±0.093 mg/mL for pure polysaccharide and acetylated polysaccharides against 1,1-dipheny1-2-picryl-hydrazyl (DPPH) free radicals, respectively, 6.513±0.500 and 2.092±0.825 mg/mL against superoxide anion, respectively, 0.626±0.034 and 0.322±0.010 mg/mL against hydroxyl radical, respectively, and the maximum scanning rates were 0.138±0.019 and 0.239±0.022 reducing power, respectively. As the concentration increased, the antioxidant activity of acetylated polysaccharides increased gradually. In addition, the antibacterial airyctivity of the acetylated polysaccharides was stronger than the unmodified polysaccharides, and the antibaterial activity with the increase of polysaccharide cincentration. Conclusion: The structural stability of purified Taraxacum mongolicum polysaccharide was increased after being modified with acetylated, leading to a significant increase in the antioxidant activity and antibiacterial in vitro.