Anti-HIV-1 activity of compounds derived from marine alga Canistrocarpus cervicornis

This paper describes the inhibition of human immunodeficiency virus-type 1 (HIV-1) virus replication in tumor cell lines by marine dolastanes (1-3) and secodolastane diterpenes (2) isolated from brown alga, Canistrocarpus cervicornis. Cells were exposed to CXCR4-tropic HIV-1 and treated with different concentrations of the compounds. We observed that the compounds inhibit HIV-1 replication in a dose-dependent manner with EC50 values of 0.35, 3.67, and 0.794 mu M for diterpenes 1, 2, and 3, respectively. We demonstrate that these compounds present no cytotoxic effect with CC50 values ranging from 935 to 1910 mu M. We also analyzed the virucidal effect of these compounds and observed that dolastane diterpenes 1 and 3 present a potent effect on a HIV-1 infectivity of up to 99 and 87 %, respectively, at a concentration of 25 mu M. No virucidal effect was observed with secodolastane diterpene 2. Our results support further investigations on compounds 1 and 3 for pre-exposure prophylaxis (PrEP) and suggest that the microbicidal compounds act before virus penetration into target cells. We propose that these marine diterpenes could be considered as a potential HIV-1 therapy.