紫球藻胞外多糖酶解物的纯化、红外鉴定及其抗氧化活性

Purification,Infrared Spectrum Identification and Antioxidant Activity Enzymatic Preparation of Exopolysaccharide from Porphyridium cruentum

为了开发紫球藻藻资源,利用非洲大蜗牛(Lissachatina fulica)消化道混合酶酶解紫球藻胞外多糖(exopolysaccharide from Porphyridium cruentum,EPC)后以离子交换层析法对其酶解物进行分离纯化,并通过红外光谱法初步鉴定各纯化组分的结构,最后对其纯化前后的抗氧化活性进行研究.结果表明:EPC酶解物经两次分级纯化后获得8个纯度较高的多糖组分,其总糖和硫酸基含量均在30%和3%以上.8个多糖组分中均含有多糖的特征吸收峰,多糖结构为吡喃糖,糖链中的糖苷键为β-构型,并携带硫酸基团.EPC酶解物纯化前后抗氧化活性与总糖浓度呈正相关,纯化后的EPC_(Ⅱ)对·OH、DPPH·、ABTS·^(+)和O_(2)^(-)·4种自由基清除率的IC_(50)值分别为0.032、0.439、0.311、4.091 mg·mL^(-1),相比于EPC酶解物和EPCⅠ其清除能力显著提高.EPC_(Ⅱ)纯化后EPC_(Ⅱ)-QⅠ的ORAC值高达1523.98μmol·g-1,分别是EPC酶解物、EPCⅠ和EPC_(Ⅱ)的3.21、14.62和2.69倍.EPC酶解物经分级纯化后可获得高抗氧化活性的多糖组分.

In order to explore the structure and antioxidant activity of exopolysaccharide from Porphyridium cruentum(EPC),the algal resources of Porphyridium cruentum are developed and utilized.The EPC was enzymolized by mixed enzymes from the digestive tract of Lissachatina fulica and purified by ion exchange chromatography,and the structure of each purified component was preliminatively identified by infrared spectrum.Finally,the antioxidant activities before and after purification were studied.The results showed that the total sugar and sulfate contents of the 8 high-purity polysaccharide fractions of the EPC enzymatic preparation after two fractional purifications were higher than 30%and 3%.The 8 polysaccharide fractions were all pyran polysaccharides carrying sulfate groups,the glycosidic bonds in the sugar chain were inβ-configuration,and they had the general structural characteristics of sugar substances.The antioxidant activity of the EPC enzymatic preparation and purified fractions showed an obvious dose-effect relationship with the total sugar concentration,and the polysaccharide fraction EPC_(Ⅱ)with high antioxidant activity and its secondary purified fraction EPC II-Q I were obtained by separation and purification.The IC_(50)values of EPC_(Ⅱ)for the scavenging rates of the scavenging rates of·OH,DPPH·,ABTS·^(+)and O_(2)^(-)·were 0.032,0.439,0.311,4.091 mg·mL^(-1),respectively,the scavenging ability was significantly better than that of EPC enzymatic preparation and EPCⅠ.The ORAC value of EPC_(Ⅱ)-QⅠwas 1523.98μmol·g-1,which was 3.21,14.62 and 2.69 times of EPC enzymatic preparation,EPCⅠand EPC_(Ⅱ),respectively.