Inhibition of reverse transcriptase activity by extracts of cultured blue-green algae (cyanophyta)

Lipophilic and hydrophilic extracts of over 900 strains of cultured blue-green algae (cyanophyta) were examined in vitro for their ability to inhibit the reverse transcriptases (RT) of avian myeloblastosis virus (AMV) and human immunodeficiency virus, type 1 (HIV-1). Eighteen (2.0%) aqueous extracts showed activity against AMV and HIV RTs. The maximal level of RT inhibition achieved by some of the active extracts was equivalent to that measured for 3'-azido-2',3'-di-deoxythymidine (AZT) at 668 ng/ml. Examination of partially purified fractions prepared by C18 column chromatography demonstrated that the RT inhibition observed could not be attributed entirely to the degradation of transcript DNA, template RNA, or enzyme protein in the reaction mixture. Thus, these results indicate that cultured blue-green algae may represent a novel source of compounds that inhibit RT activity, including that of HIV-1.