Anti-HIV activity of extracts and compounds from algae and cyanobacteria

The human immunodeficiency virus (HIV) is the retrovirus that causes the ac quired immune deficiency disease syndrome (AIDS), This review discusses the anti-HIV activity of extracts and compounds isolated from freshwater and m arine algae, and cyanobacteria (formerly called "blue-green algae"), Compou nds and extracts with anti-HIV activity are also active against other retro viruses such as herpes simplex virus (HSV), but the amount of antiviral act ivity varies with the compound and the virus. Most of the research has focu sed on sulfated homopolysaccharides and heteropolysaccharides. Sulfoglycoli pids, carrageenans, fucoidan, sesquiterpene hydroquinones, and other classe s of compounds with anti-HIV activity that have been isolated from algae ha ve received less attention. Most studies have used in vitro test systems, b ut a few in vivo studies have been carried out using compounds isolated fro m algae or analogs produced synthetically or isolated from other natural so urces. Sulfated homopolysaccharides are more potent than sulfated heteropol ysaccharides. The presence of the sulfate group is necessary for anti-HIV a ctivity, and potency increases with the degree of sulfation, Studies using nonsulfated and sulfated homo- and heteropolysaccharides isolated from alga e or other natural sources, or synthesized, have revealed the mechanisms of binding of drugs to the virion, and the mechanisms of viral binding to hos t cells. However, given the few classes of compounds investigated, most of the pharmacopeia of compounds in algae and cyanobacteria with antiretrovira l activity is probably not known. (C) 2000 Academic Press.