富硒西兰花中硒的赋存形态及其抗氧化性

Study on the Distribution and Combined Speciation of Selenium in Se-enriched Broccoli and Their Antioxidant Activity

西兰花硒富集能力很强,且有机硒为95.2%~96.5%。提取、检测富硒西兰花中含硒营养物质含硒核酸、多糖、粗蛋白、其他物质及其硒含量,发现硒主要赋存在含硒粗蛋白,约占90.2%~91.5%。用四种溶剂顺序提取水溶性、盐溶性、醇溶性和碱溶性粗蛋白,并分别检测其硒含量,发现水溶性蛋白中硒含量最高,约占57.9%。将原子荧光光谱仪与液相色谱联用分析分别四种溶性含硒粗蛋白的含硒氨基酸种类和含量,发现四种溶性粗蛋白中硒主要以硒代半胱氨酸(Secys)、硒代蛋氨酸(SeMet)、硒甲基半胱氨酸(SeMecys)形式存在,占总含硒粗蛋白硒总量的90%以上。采用D-脱氧核糖法和邻苯三酚自氧化法,比较4种溶性粗蛋白的清除自由基能力,发现其与粗蛋白存在较好的剂量-效应关系,其中水溶性蛋白对·OH和·O2^-的清除效果最好,IC50分别约为(0.42和0.81)mg/mL。

The broccoli enriches selenium,and by which 95.2%~96.5%of inorganic selenium is absorbed and transforms into organic selenium.This study mainly aimed to analyze species of selenium and their concentration in the Se-enriched broccoli.The Nucleonic acid,polysaccharide,crude protein and other substance of the Se-enriched broccoli was separated used by ultrasonic,centrifugation,dialysis etc.It was found that the selenium of broccoli was mainly protein-bound selenium,accounted for 90.2%~91.5%.Selenium of crude proteins of the Se-enriched broccoli were also sequentially extracted by ultrapure water,0.5mol/L NaCl,75%Ethyl alcohol and 0.1mol/L NaOH.The content of water-soluble protein binding selenium was the highest,up to 57.9%.Total Se concentration and selenium species of selenium of crude proteins were determined combinedly used by AFS and HPLC-AFS.The selenium species of selenium of crude proteins were mainly SeCys,SeMet,SeMetcys,achieved to 90%.Their antioxidant activity of protein-bound selenium extracted by four kind of solvents to scavenging·OH and·O2^- was determined by the methods of D-DNA and pyrogallol autoxidation method.The concentration of crude protein and scavenging rates of·OH and·O2^- showed better dose-response relationships.Water-soluble protein binding selenium had greatest ability to scavenging·OH and·O2^-,and IC50 were about 0.42 mg/mL and 0.81mg/mL,respectively.