In vitro anti-HIV activity of sulfated cell-wall polysaccharides from gametic, carposporic and tetrasporic stages of the Mediterranean red alga Asparagopsis armata

The gametic, carposporic and tetrasporic reproductive stages from the Medit erranean red alga Asparogopsis armata contain peculiar sulfated galactans w ith galactose:3.6-anihydrogalactose:sulfates molar ratio of 1:0.01:1.23, 1: 0.04:0.47 and 1:0.01 :1.13, respectively. These water-soluble polysaccharid es were studied for their in vitro activity against the human immunodeficie ncy virus (HIV-1). Gametic and tetrasporic galactans inhibit HIV replicatio n at 10 and 8 mug/ml, respectively, as measured by HIV-induced syncitium fo rmation as well as reverse transcriptase activity in cell-free culture supe rnatant. The carposporic polysaccharide is ineffective, even at 100 mug/ml. The maximal antiviral effect involves the presence of the polysaccharides after or during infection but not before infection. This time of action sug gests an inhibition of an early step of HIV infection.