Table 5.

Summary of antiviral activity among various agaran and ulvan, with each respective proposed mechanism of action and remarks on molecular weight and sulfate content of the tested compound.

Sulfated Polysaccharide	Virus Strain	Antiviral Activities		Proposed Mechanism of Action	Toxicity (Cell)	Remarks on Molecular Weight and Sulfate Content	Refs.
		IC50 of Plaque Formation 2
Agaran (Bostrychia montagnei)	HSV-1	17–24%	13.1–25.7 µg/mL	multiple sulfate inhibits positive charge binding sites of the viral envelope glycoprotein, which is necessary for virus attachment onto cell surface	>1000 µg/mL Vero 1	higher molecular weight and sulfate content correlates with greater antiviral activity	[103,104]
		11.2–16.2%	>50 µg/mL
	HSV-2	17–24%	12.4–46.2 µg/mL
		11.2–16.2%	>50 µg/mL
Agaran (Acanthophora spicifera)	HSV-1	15.1–26.4%	0.6–0.8 µg/mL
		4.7–6.9%	>50 µg/mL
	HSV-2	15.1–26.4%	0.9–1.4 µg/mL
		4.7–6.9%	>50 µg/mL
		EAE	IC50
Ulvan (Ulva armoricana)	HSV-1	carbohydrases	320.9–373.0 µg/mL		>500 µg/mL		[105]
		proteases	>500 µg/mL
		inhibition of syncytia formation
Ulvan (Ulva clathrata)	NDV	51.54% at 0.1 µg/mL		inhibition of NDV replication cycle	810 µg/mL Vero 1		[92]
		JEV-infection inhibition
Ulva (Ulva lactuca)	JEV	70% at 0.03 µg/mL		inhibition of viruses from entering into cells	no toxicity was observed in tested mice	higher MW yielded better anti-JEV activity	[106]

HSV = herpes simplex virus; NDV = Newcastle disease virus; JEV = Japanese encephalitis virus; MW = molecular weight; EAE = enzyme-assisted extraction.¹ The Vero cell used is African green monkey kidney cells. ² The presented percentage values are the sulfate content range of the fractionated extract.