Antiviral activities against HSV-1, HCMV, and HIV-1 of rhamnan sulfate from Monostroma latissimum

Rhamnan sulfate (RS), a natural sulfated polysaccharide isolated from Monos troma latissimum, showed potent inhibitory effects on the virus replication of herpes simplex virus type 1 (HSV-1), human cytomegalovirus (HCMV), and human immunodeficiency virus type 1 (HIV-1) in vitro. The antiviral action of RS was not only due to the inhibition of virus adsorption, but also migh t involve the later steps of viral replication in host cells on the basis o f the results of time-of-addition experiments. Furthermore, RS and 3'-azido -3'-deoxythymidine (AZT) were synergistic in their anti-HIV-l activities. T hese data indicate that RS is a potent antiviral substance against HSV-1, H CMV, and HIV-1.