金花葵多糖提取工艺优化及结构表征和抗氧化性研究

优化金花葵干花苞中多糖的提取工艺，并对其结构和抗氧化活性进行研究。本研究在单因素实验的基础上，通过正交试验优化水提醇沉法提取多糖的工艺，利用高效液相色谱(HPLC)法分析多糖的单糖组成，应用傅里叶红外光谱(FTIR)法和扫描电镜(SEM)观察对多糖官能团和外貌进行分析，并检测了多糖清除自由基的能力和还原力。结果表明，金花葵的干花苞多糖最佳提取工艺为：提取温度100℃、提取时间3 h和料液比1:50 g/mL。在此工艺条件下，多糖得率为17.23%±0.19%，多糖含量为27.87%±0.60%。其单糖组成及摩尔比为阿拉伯糖:半乳糖:鼠李糖:甘露糖:葡萄糖=0.97:1:0.23:0.05:0.43。表面呈不规则片状，并且证明具有糖醛酸、吡喃糖环官能团。此外，提取的多糖具有一定的清除DPPH自由基、ABTS⁺自由基能力，对自由基半数抑制对应浓度(IC₅₀)分别为1.22、4.43 mg/mL，表明具有良好的抗氧化活性。研究结果为金花葵花苞中多糖的化学结构解析和功能研究提供了研究基础与理论依据。

Optimization of Extraction Technology,Structure Characterization and Antioxidant Activity of Polysaccharide from Hibiseus manihot L.

To optimize the extraction technology of polysaccharides from Hibiseus manihot L. the dried flower buds, and study its structure and antioxidant activity. In this study, on the basis of single factor experiments, the orthogonal experimental design methodology the optimization of extraction process of polysaccharide of the dried flower buds was carried out by water extraction and alcoholic precipitation method. The crude polysaccharides composition was analyzed by high performance liquid chromatography (HPLC), the functional groups and external structure of the polysaccharide were analyzed by Fourier infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and the free radical scavenging ability and reducing power of the polysaccharides were also tested. The results showed that the optimal extraction conditions were as follows: Extraction temperature of 100 ℃, extraction duration of 3 h, solid-liquid ratio of 1:50 g/mL. Under this condition, the yield of polysaccharide was 17.23%±0.19% and the polysaccharide content was 27.87%±0.60%. The polysaccharide from the dried flower buds was composed of arabinose, galactose, rhamnose, mannose and glucose in molar ratios of 0.97:1:0.23:0.05:0.43. The obtained polysaccharide extract was found to be mainly composed of irregular lamellar structures with the functional groups of uronic acid and pyranose ring. The polysaccharides have certain ability of scavenging DPPH free radical, ABTS+ free radical, the corresponding half-inhibitory concentrations (IC₅₀) of polysaccharides against DPPH radicals and ABTS+ radicals were 1.22 and 4.43 mg/mL, respectively, it would prove that the polysaccharide had good antioxidant activity. The results would provide a theoretical basis for structural determination research of polysaccharides of Hibiseus manihot L..