Antiviral properties of a mangrove plant, Rhizophora apiculata Blume, against human immunodeficiency virus

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 v arious 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 (EC50) of RAP in HIV-1 infected MT-4 cells and in PBMC was 10.7 and 25.9 mu g/ml, respectively. RAP (100 mu g/ml) completely blocked the binding of HI V-1 virions to MT-4 cells. RAP also reduced the production of viral mRNA wh en added before virus adsorption. RAP inhibited syncytium formation in cocu ltures of MOLT-4 cells and MOLT-4/HIV-1(IIIB) cells. RAP did not prolong ac tivated partial thromboplastin time (APTT) up to 500 mu g/ml. These propert ies may be advantageous should RAP be considered for further development. ( C) 1999 Published by Elsevier Science B.V. All rights reserved.