相对低分子质量海带岩藻聚糖硫酸酯的制备及其对纤溶系统的影响

Preparation of relative low molecular mass fucoidan from Laminaria japonica and its effect on the fibrinolytic system

目的研究自由基氧化降解得到的相对低分子质量岩藻聚糖硫酸酯化学性质以及对新西兰大白兔体内纤溶系统的影响。方法采用H2O2-Cu2+自由基氧化结合分步超滤法,制备了重均分子量为7.68 kD和3.89 kD的两个相对低分子质量岩藻聚糖硫酸酯组分。采用静脉注射的方式研究两个相对低分子质量岩藻聚糖硫酸酯组分对新西兰大白兔的纤溶系统的影响。结果与结论4.5%H2O2与铜离子产生的羟基自由基可以有效地将海带岩藻聚糖硫酸酯降解,经分步超滤得到重均分子量分别为7.68 kD和3.89 kD的相对低分子质量组分,硫酸根含量分别为30.32%和32.48%,糖环上的硫酸根主要在4位。重均分子量7.68 kD组分主要由岩藻糖和半乳糖以2∶1的比例组成,其岩藻糖含量显著高于3.89 kD组分。相对低分子质量岩藻聚糖硫酸酯,尤其是重均分子量为7.68 kD的组分能够缩短全血凝块溶解时间和优球蛋白溶解时间,并能够显著升高家兔血清中t-PA活性,提高t-PA/PAI的百分比,但是对u-PA的活性没有显著影响,表明相对低分子质量岩藻聚糖硫酸酯对纤溶途径有一定的激活作用。

Objective To investigate relationship of the chemical character and fibrinolytic activity of relative low molecular mass fucoidan from Laminaria japonica.Methods Two relative low molecular mass fucoidan fractions were obtained by radical depolymerization and ultrafiltration of a crude fucoidan from Laminaria japonica.The effects of relative low molecular mass fucoidan on the fibrinolytic system in rabbit were evaluated by euglobulin lysis time,plasma clot dissolution time and activities of u-PA,t-PA and PAI-1.Results and Conclusion Two highly sulfated fucoidan from Laminaria japonica with weight-average molecular mass（Mw） 7.68kD and 3.89kD were obtained by hydroxyl radical generated from copper-catalyzed decomposition of H2O2 and step-by-step ultrafiltration.Fucoidan fraction with Mw of 7.68 kD was mainly composed of fucose and galactose,and its sulfate group content was 30.32%,which was lower than that of fraction with molecular mass of 3.89kD（32.4%）.The analysis of FT-IR showed that the sulfate group was mainly on the C4.Euglobulin lysis time and plasma clot dissolution time in rabbit blood were effectively shortened by relative low molecular mass fucoidan intravenously.Relative low molecular mass fucoidan could effectively enhance the activity of t-PA and inhibit the activity of PAI-1,but had no influence on u-PA.Fucoidan fraction with Mw of 7.68kD exhibited better effect on euglobulin lysis time and t-PA.The results showed that relative low molecular mass fucoidan from L.japonica had good fibrinolytic activity.