Abstract
A polysaccharide extracted from the leaf of
Rhizophora apiculata (RAP) was assessed in cell culture systems, for its activity against human and simian immunodeficiency viruses. RAP inhibited HIV-1 or HIV-2 or SIV strains in various cell cultures and assay systems. It blocked the expression of HIV-1 antigen in MT-4 cells and abolished the production of HIV-1 p24 antigen in peripheral blood mononuclear cells (PBMC); the 50% effective concentration (EC
50) of RAP in HIV-1 infected MT-4 cells and in PBMC was 10.7 and 25.9 μg/ml, respectively. RAP (100 μg/ml) completely blocked the binding of HIV-1 virions to MT-4 cells. RAP also reduced the production of viral mRNA when added before virus adsorption. RAP inhibited syncytium formation in cocultures of MOLT-4 cells and MOLT-4/HIV-1
IIIB cells. RAP did not prolong activated partial thromboplastin time (APTT) up to 500 μg/ml. These properties may be advantageous should RAP be considered for further development.