Cardiovascular disease is the leading causes of death.However,the complications can be treated with heparin and heparinoids,such as heparin pentasaccharide Fondaparinux,dermatan sulfate,and PSS made from alginate extracted from brown seaweeds by chemical sulfation.Alginate is composed of a linear backbone of polymannuronate(PM),polyguluronate(PG),and alternate residues of mannuronic acid and guluronic acid.It is unknown if heparin and sulfated PG(PGS)/PM(PMS) have the same or different anticoagulant molecular targets.In the current study,the anticoagulant activities of PGS,PMS,and their oligosaccharides were directly compared to that of heparin,Fondaparinux,and dermatan sulfate by the activated partial thrombinplastin time(aP TT) assay using normal,antithrombin III(ATIII)-deficient,heparin co-factor II(HCII)-deficient,and ATIII-and HCII-double deficient human plasmas.Our results showed that PGS,PMS,and their oligosaccharides had better anticoagulant activity than that of Fondaparinux in all four human plasmas tested.As expected,heparin was the best anticoagulant in normal plasma.Moreover,PGS,PGS6,PGS12,PGS25,PMS6,PMS12,and PMS25 were better anticoagulants than dermatan sulfate in HCII-deficient plasma.Most strikingly,PGS,PGS12,PGS25,PMS6,PMS12,and PMS25 were better anticoagulants than that of heparin in ATIII-and HCII-double deficient human plasma.The results revealed for the first time that sulfated alginate had ATIII-and HCII-independent anticoagulant activities.Therefore,developing PGS and PMS-based anticoagulants might require to discover their major molecular targets and to develop target-specific anticoagulant assays. Cardiovascular disease is the leading causes of death. However, the complications can be treated with heparin and heparinoids, such as heparin pentasaccharide Fondaparinux, dermatan sulfate, and PSS made from alginate extracted from brown seaweeds by chemical sulfation. Alginate is composed of a linear backbone of polymannuronate (PM), and polyguluronate (PG), and alternate residues of mannuronic acid and guluronic acid. It is unknown if heparin and sulfated PG (PGS) / PM (PMS) have the same or different anticoagulant molecular targets. , the anticoagulant activities of PGS, PMS, and their oligosaccharides were directly compared to that of heparin, Fondaparinux, and dermatan sulfate by the activated partial thrombinplastin time (aP TT) assay using normal, antithrombin III (ATIII) -deficient, heparin co- factor II (HCII) -deficient, and ATIII-and HCII-double deficient human plasmas. Our results showed that PGS, PMS, and their oligosaccharides had better anticoagulant activity than that of Fondaparinux i n all four human plasmas tested. As expected, heparin was the best anticoagulant in normal plasma. Moreover, PGS, PGS6, PGS12, PGS25, PMS6, PMS12, and PMS25 were better anticoagulants than dermatan sulfate in HCII- deficient plasma. Host strikingly, PGS, PGS12, PGS25, PMS6, PMS12, and PMS25 were better anticoagulants than that of heparin in ATIII-and HCII-double deficient human plasma. The results revealed for the first time that sulfated alginate had ATIII-and HCII-independent anticoagulant activities. Therefore, developing PGS and PMS-based anticoagulants might require to discover their major molecular targets and to develop target-specific anticoagulant assays.