女贞子多酚对自由基的清除效果及其影响因素分析

摘要

Natural water-soluble free radical scavengers include phenols,vitamins,sugars,and peptides,a-mong which the phenols have the strongest free radical scavenging ability.The polyphenol extracted from fresh Ligustrum lucidum can be easily oxidized and has significant free radical scavenging effects.We studied the free radical scavenging effect of Ligustrum lucidum polyphenol by a DPPH method,and investigated the effects of Ligustrum lucidum polyphenol concentration,reaction temperature,and reaction time on the DPPH scavenging rate.The results indicate that the DPPH scavenging rate increases with the increase of polyphenol concentra-tion,reaction temperature,and reaction time.The DPPH scavenging rate reached 100% under the conditions as follows:the Ligustrum lucidum polyphenol concertration is 0.035 mg·mL-1,the reaction temperature is 30℃,and the reaction time is 2 h.The DPPH scavenging abilities of Ligustrum lucidum polyphenol and other common antioxidants are in the following order:gallic acid,Ligustrum lucidum polyphenol,ascorbic acid,and reduced glutathione.The free radical scavenging abilities of Ligustrum lucidum polyphenol extracts in different months are significantly different.With the delay of collection time,the DPPH scavenging rate gradually de- creased.Among the Ligustrum lucidum polyphenol extracts collected in September to December,the free radical scavenging ability of the Ligustrum lucidum polyphenols extracts in September is the strongest.%天然水溶性自由基清除剂包括酚类、维生素类、糖类、肽类等,其中自由基清除能力最强的是酚类.从新鲜女贞子中提取到的女贞子多酚极易氧化,具有显著的自由基清除作用.采用 DPPH 法研究了女贞子多酚对自由基的清除效果,并探讨了女贞子多酚浓度、反应温度和反应时间对DPPH 清除率的影响.结果表明,随着女贞子多酚浓度的增加、反应温度得升高和反应时间的延长,DPPH 清除率逐渐升高;在女贞子多酚浓度为0.035 mg·mL-1、反应温度为 30℃、反应时间为 2 h时,女贞子多酚对DPPH 的清除率达 100%;女贞子多酚与 3 种常用氧化剂的 DPPH 清除能力大小为:没食子酸>女贞子多酚>抗坏血酸>还原型谷胱甘肽;不同月份女贞子多酚提取物对自由基的清除能力差异明显,随着采集时间的推迟,DPPH 清除率逐渐下降,在 9~12 月份采集的女贞子多酚粗提物中,9 月份采集的女贞子多酚提取物的自由基清除能力最强.