# Therapeutic Potential of Seaweed-Derived Bioactive Compounds for Cardiovascular Disease Treatment
## 3 Seaweed-Derived Polysaccharides with Therapeutic Potential against CVD  
In terms of economic value, seaweed polysaccharides are the most important products derived from seaweeds. Several studies have demonstrated the pharmacological activities of polysaccharides obtained from seaweeds. They are the multi-component mixtures made up of one or more monosaccharides linked by one, three, or four glycosidic linkages distributed between and inside seaweed cells [89]. In recent years, the most famous polysaccharides such as ulvan (sulfated glucuronoxylorhannans), fucoidan (L-fucose and sulfate ester groups), and carrageenan (sulfated galactans) extracted from green, brown, and red seaweeds, respectively, have been extensively investigated for their health-promoting effects [90; 91; 92; 93]. Among the risk factors for cardiovascular disease, seaweed-derived polysaccharides have been the focus of anti-diabetic research, and studies using fucoidan are the most widely reported. Fucoidan derived from _Sargassum wighti_, _Sargassum thumbergii_, _Sragassum honeri_, _Sargassum ringgoldianum_, _Sargassum_, _siliquastrum_, _Sargassum graminifolium_, _Sargassum kjellmanium_, _Fucus vesicolus_, _Ascophyllum nodosum_, _Saccharina longicurris_, _Cystoseira crinite_, _Ecklonia maxima_, and _Turbinaria conoides_ exhibit anti-diabetic activity through the inhibition of \(\alpha\)-amylase and \(\alpha\)-glucosidase alone or both enzymes [94; 95; 96; 97; 98; 99; 100; 101; 102] (Table 2). Interestingly, [PERSON] et al. revealed that the \(\alpha\)-amylase and \(\alpha\)-glucosidase inhibition of fucoidan differed depending on the species from which the fucoidan was extracted and by the month and year of collection [98]. In addition, the oral administration of _Sargassum fusiforme_-derived fucoidan decreased the fasting blood glucose levels in high-fat diet/streptozotocin-induced diabetic mice model and reduced diabetes-related intestinal bacteria, which may potentially aid diabetes [103; 104; 105]. Many studies have demonstrated cardioprotection by polysaccharides. Sulfated polysaccharides from _Padina tetrastromatica_ exerted cardioprotective effects by activating the PI3K/Akt/Nrf2 signaling pathway in in vitro and Sprague Dawley rat models [106]. Fucoidan is a well-known l-fucose-enriched sulfate. Low molecular weight fucoidan (MW = 7000 Da) produced from _Laminaria japonica_ (L. _japonica_) could induce endothelium-dependent vasodilation via the eNOS expression upregulation in cerebral microvascular endothelial cells and effectively improve blood pressure and local blood flow in rats [107]. _Cystoseira crinite_-derived fucoidan exhibits ACE inhibitory activity in vitro and in vivo [108]. In addition, [PERSON] et al. suggested that fucoidan (100 mg/kg/day) from _Undaria pimmatifida_ prevents vascular dysfunction through PI3K/Akt/eNOS-dependent mechanisms in a hypertensive rat model [109]. Furthermore, continuous feeding with kappa-carrageenan produced from _Kappanlycus albarezii_ or iota-carrageenan from _Sarcoma filiform_ to high-fat diet-fed rats attenuated the parameters defining cardiovascular and metabolic health such as body weight, abdominal and liver fat, systolic blood pressure, plasma total cholesterol concentrations, and the plasma activities of alanine transaminase and aspartate transaminase [110]. In green seaweeds, ulvan is one of the major polysaccharide structures isolated from _Ulva pertusa_ which had anti-hyperlipidemic effects via the modulation of lipid levels and the mRNA expression of FXR, LXR, and PPARy in an in vivo rat model [111]. However, the anti-hypertensive effect of ulvan is not clear. Thus, further detailed investigations are required. These functional compounds from seaweed protect the muscle and platelets and stimulate blood vessel dilatation [112]. In human trials, one previous report demonstrated that daily fucoidan consumption from _L. japonica_ could remarkably suppress thrombus formation and further protect cardiovascular health [113].