甘薯叶片中多酚类物质的提取及抗氧化活性研究

Study on the extraction and antioxidant activity of polyphenols from sweetpotato leaves

研究不同溶剂(水、体积分数70%乙醇、甲醇、丙酮和正丁醇)对烘干和晒干两种干燥方式下甘薯叶片多酚、黄酮类化合物得率的影响,分析不同溶剂提取物DPPH(1,1-二苯基-2-三硝基苯肼)自由基清除能力和总抗氧化能力的差异,并对活性物质的得率与抗氧化能力进行相关性分析.结果表明:两种干燥方式中,体积分数70%乙醇溶剂提取多酚和黄酮类物质得率均为最高,其中多酚在烘干和晒干样中分别为(31.47±0.10)mg/g和(35.12±0.17)mg/g,黄酮则分别为(15.59±0.40)mg/g和(14.36±0.40)mg/g.不同溶剂中以甲醇提取物的DPPH清除能力最强,而体积分数70%乙醇提取物的总抗氧化能力为最强.相关性分析表明,甘薯叶片中多酚含量、DPPH自由基清除率与总抗氧化能力分别呈极显著(P<0.01)和显著(P<0.05)正相关,而黄酮与总抗氧化能力之间也呈显著正相关,但与DPPH自由基清除率之间无显著相关性.

The effects of different solvents （water, 70% ethanol, methanol, acetone, and n-butanol） on the yield of polyphenols and flavonoids in leaves of sweetpotato under different drying conditions were studied, the differences in DPPH（1,1-diphenyl-2-trinitrophenylhydrazine） free radical scavenging capacity and total antioxidant capacity of different extracts were analyzed, and the correlation analyses between the content of active substances and the antioxidant capacity were also made. The results showed that the yields of polyphenols and flavonoids were all the highest in 70% ethanol in both drying methods. Polyphenol contents in oven drying samples and sun drying samples were （31.47±0.10） mg/g and （35.12±0.17） mg/g respectively, while the flavonoid contents were （15.59±0.40） mg/g and （14.36±0.40） mg/g respectively. The DPPH ftee radical scavenging ability of methanol extracts was the strongest among different solvent extracts and the total antioxidant capacity was the strongest with 70% ethanol extract. Correlation analysis showed that the content of polyphenols in leaves of sweetpotato was extraordinary （P 〈0.01） and significant （P〈0.05） positively correlated with DPPH clearance and total antioxidant capacity, respectively. There was also a significant positive correlation （P〈0.05） between flavonoids and total antioxidant capacity, but there was no significant correlation with the DPPH clearance rate.