Lipophilic and hydrophilic extracts from approximately 600 strains of cultured cyanophytes, representing some 300 species, were examined for antiviral activity against three pathogenic viruses. Approximately 10% of the cultures produced substances that caused significant reduction in cytopathic effect normally associated with viral infection. The screening program identified Chroocococcales as commonly producing antiviral agents. Key index words: antiviral, cyanobacteria, cyanophyte, herpes virus, HIV-1, HIV-2, human immunodeficiency virus, natural products, pharmaceutical, respiratory syncytical virus.

Sulfoglycolipids from blue-green algae exhibit strong antiviral properties. Helper T-cells exposed to blue-green algae-sulfoglycolipids were protected from HIV-1 infection in in vitro studies.

Several glycolipids were isolated from spirulina by systematic fractionation with different solvents. Structural investigation using methylation, GC-MS and enzymatic techniques indicated four major glycolipids. Main fatty acid components of these glycolipids were identified as palmitic acid and linoleic or linolenic acid. Based on this fatty acid composition, spirulina glycolipids were compared with those in higher plants.