Antiviral carbohydrates from marine red algae
It is possible that heparin-like sulfated polysaccharides from red algae, or fractions thereof, might be found to be low-cost, broad-spectrum antiviral agents. The prevailing view among virologists has been that sulfated polysaccharides inhibit viral action by acting only at the surfaces of cells. This perception now is changing with the finding that both the herpes virus (containing DNA) and human immunodeficiency virus (containing RNA) are inhibited by sulfated polysaccharides that act within the cell as well as external to it. Aqueous extracts of many red algae are active against retroviruses. Carrageenan, a common cell wall polysaccharide from red algae, is co-internalized into infected cells with the Herpes simplex virus (HSV), inhibiting the virus. Carrageenan also interferes with fusion (syncytium formation) between cells infected with the human immunodeficiency virus (HIV) and inhibits the specific retroviral enzyme reverse transcriptase.