The antiviral family is one of the widest families of bioactive compounds isolated from marine sources, or at least one of the most studied. In this group, there are compounds like polysaccharides, terpenoids, proteins, sulfated flavones, and fatty acids. When measuring the antiviral activity, the general trend is to treat well-known mammal cells with the extract and then monitor the viral infection with the micro­scope. Huheihel et al. [63] used green monkey kidney cells (vero cells) treated with polysaccharides extracted from Porphyridium sp., the cell culture was treated with herpes simplex viruses. Each day, the cultures were examined for evidence of the cytopathic effect, defined as areas of complete destruction of cells or of morpho­logically modified cells and expressed as the percentage of damaged cells in the inspected fi elds.

But similar test can be done in vivo, Huheihel et al. [63] applying locally (eyes and mouth) Porphyridium extracts in rabbits and rats; later, the animals were exposed to the virus. Inflammatory effects, illness, and weight changes were recorded over a period of 4 weeks posttreatment.