Effect of partial desulfation and oversulfation of sodium spirulan on the potency of anti-herpetic activities

The aim of the present study is to evaluate the effect of partial desulfation and oversulfation of sodium spirulan (Na-SP) isolated from Spirulina platensis on the exhibition of anti-herpes simplex viruses type 1 and 2 (HSV-1 and -2) activities. Partially desulfated (PDS-SPs) and oversulfated derivatives (OS-SPs) were obtained by solvolytic desulfation and sulfation with dicyclocarbodiimide-sulfuric acid, respectively. When PDS-SPs were subjected to anti-HSV-1 assay, antiviral potency was dependent on their sulfate content, and PDS-SPs with lower sulfate content than 8.6% were found to be inactive. Some derivatives showing anti-HSV-1 effect also showed anti-HSV-2 activity. Anti-HSV-1 effect of OS-SPs was equivalent to that of Na-SP when they were added to the medium during viral infection and throughout the incubation thereafter, while they were enhanced as compared with Na-SP when they were added to the medium immediately after viral infection. The results of time-of-addition experiments suggested that the most sensitive phase of OS-SP-2 and -5 might be the early steps of viral adsorption and penetration.