Native (F2) and carboxyl-reduced (R) ulvans from Ulva fasciata were sequentially oxidized with periodate-chlorite affording the polycarboxyl ulvans C1, C2 and C3 (1.20, 1.41 and 1.81 mmol g^-1 of COOH, respectively; 19.7, 21.3 and 21.0% of NaSO₃, respectively) and R-C3 (1.86 mmol g^-1 of COOH; NaSO₃ = 22.7%), respectively. APTT assay (polysaccharide fractions at 150 µg mL^-1) showed clotting time of 45.6 s for F2 fraction. For polycarboxyl ulvans C1, C2, C3 and R-C3 the clotting times were 101.0, 122.2, 222.0 and 227.0 s, respectively. Comparison of the APTT assay results using ulvans chemically modified by carboxyl-reduction, desulfation, periodate oxidation and/or chlorite oxidation showed the anticoagulant activity of polycarboxyl ulvans is dependent of the sulfate groups present in the native polymer. In addition, the increase of the anticoagulant activity was accompanied by the increasing of the carboxyl groups and the content of this acidic substituent seems to be more important than its positioning.

依次用高碘酸盐-亚氯酸盐氧化来自Ulva fasciata的天然（F2）和羧基还原的（R）ulvans，分别得到多羧基ulvans C1，C2和C3（分别为1.20、1.41和1.81 mmol g ^-1的COOH；19.7、21.3和19.7分别为21.0％的NaSO ₃和R-C3（1.86 mmol g ^-1的COOH； NaSO ₃ = 22.7％）。APTT分析（150 µg mL ^-1的多糖级分）显示F2分数的凝结时间为45.6 s。对于多羧基ulvans C1，C2，C3和R-C3，凝血时间分别为101.0、122.2、222.0和227.0 s。使用通过羧基还原，脱硫，高碘酸盐氧化和/或亚氯酸盐氧化化学修饰的ulvans对APTT分析结果的比较表明，多羧基ulvans的抗凝活性取决于天然聚合物中存在的硫酸根基团。另外，抗凝活性的增加伴随着羧基的增加，并且该酸性取代基的含量似乎比其位置更重要。