Structural features and anti-HIV-1 activity of novel polysaccharides from red algae Grateloupia longifolia and Grateloupia filicina

Abstract

Since sulphated polysaccharides have antiviral activity <i>in vitro</i>, we examined the structure and antiretroviral activity of native sulphated galactans extracted from the red algae, <i>Grateloupia filicina</i> (GFP) and <i>Grateloupia longifolia</i> (GLP). The sulphate contents of GFP and GLPE (the 1,4-α-d-glucan-glucanohydrolase digest of GLP) were 25.7 and 18.5%, respectively. The sulphate ester groups were located at carbon 2 for GFP and at carbon 2 and 6 for GLPE. Antiretroviral activity was investigated with a primary isolate (PI) of HIV-1 and human peripheral blood mononuclear cells (PBMCs) rather than T-cell line adapted (TCLA) HIV-1 and T-cell lines because it is more representative of the in vivo situation. Both compounds and their derivatives had potent anti-HIV-1 activity when added at the time of infection, and 2 h post-infection (EC_50s 0.010–0.003 μM, EC_90s 0.87–0.33 μM) and low cytotoxicity. Their potential medical application as virucidal vaginal formulations is discussed.