Anti-herpes simplex virus substances produced by the marine green alga, Dunaliella primolecta

Among 106 microalgae tested, the cytopathic effect (CPE) upon Vero cells of herpes simplex virus, Type 1 (HSV-1) was inhibited by four methanol extrac ts of Dunnliella bioculata C-523, D. primolecta C-525, Lyngbya sp. M-9 and Lyngbya aerugineo-coerulea M-12. The green alga, D. primolecta, had the hig hest anti HSV-1 activity, since 10 mu g mL(-1) of extract from this alga co mpletely inhibited the CPE. This activity was similar to that of acyclovir at the same concentration. We compared anti-viral activities against adeno virus, herpes simplex virus-2 (HSV-2), Japanese Encephalitis and Polio viru ses. Only the CPE of HSV-2 was inhibited. Thus, the factor was specific aga inst HSV. The antiviral activity was apparently excited during HSV adsorpti on and invasion of the cells. We optimized the conditions for anti HSV-1 ac tivity by prolonging the exposure of HSV-1 to the extract. After 2 h, the C PE of even a high titer of HSV-1 (10(6) TCID50/0.1 mL) was completely inact ivated. By use of various chromatographic techniques, three green substance s having anti-HSV activity were purified from the algal mass of D. primolec ta, and 5 mu g mL(-1) of this purified substances completely inhibited the CPE. From the analysis of NMR and MS, the chemical structures of the active substances were identified as pheophorbide-like compounds.