A NATURAL SULFATED POLYSACCHARIDE, CALCIUM SPIRULAN, ISOLATED FROM SPIRULINA-PLATENSIS - IN-VITRO AND EX-VIVO EVALUATION OF ANTI-HERPES SIMPLEX VIRUS AND ANTI-HUMAN-IMMUNODEFICIENCY-VIRUS ACTIVITIES

A sulfated polysaccharide named calcium spirulan (Ca-SP) has been isol ated from a sea alga, Spirulina platensis, as an antiviral component, The anti-human immunodeficiency virus type 1 (HIV-1) and anti-herpes s implex virus type 1 (HSV-1) activities of Ca-SP were compared with tho se of dextran sulfate (DS) as a representative sulfated polysaccharide , Anti-HIV-1 activities of these agents were measured by three differe nt assays: viability of acutely infected CD4-positive cells, or a cyto pathology assay; determination of HIV-1 p24 antigen released into cult ure supernatants; and inhibition of HIV-induced syncytium formation, A nti-HSV-l activity was assessed by plaque yield reduction, In addition , their effects on the blood coagulation processes and stability in th e blood were evaluated, These data indicate that Ca-SP is a potent ant iviral agent against both HIV-1 and HSV-1, Furthermore, Ca-SP is quite promising as an anti-EW agent because even at low concentrations of C a-SP an enhancement of virus-induced syncytium formation was not obser ved, as was observed in DS-treated cultures, Ca-SP had very low antico agulant activity, and showed a much longer half-life in the blood of m ice when compared with that of DS, Thus, Ca-SP can be a candidate agen t for an anti-HIV therapeutic drug that might overcome the disadvantag es observed in many sulfated polysaccharides, When the role of chelati on of calcium ion with sulfate groups was examined by removing calcium or its replacement by sodium, the presence of calcium ion in the mole cule was shown to be essential for the dose-dependent inhibition of cy topathic effect and syncytium formation induced by HIV-1.