HIV reverse transcriptase inhibitors of natural origin

Inhibitors of HIV reverse transcriptase (RT) are important drugs for the treatment of acquired immuno-deficiency syndrome (AIDS). One approach to identify novel inhibitors of HIV-1-RT is the screening of natural compounds. Many natural products have been shown to be active as RT inhibitors. These compounds belong to a wide range of different structural classes, e.g., coumarins, flavonoids, tannins, alkaloids, lignans, terpenes, naphtho- and anthraquinones, and polysaccharides. The life forms from which the bioactive compounds were isolated are as equally diverse and comprise terrestrial and marine plants, micro-organisms, and marine animals. From the most extensive screening effort, carried out by the NCl, calanolide A, isolated from the terrestrial plant Calophyllum lanigerum (Guttiferae), has been discovered as the most interesting natural RT inhibitor. The promise of this natural product probably relates to a novel mechanism of action. The current review describes natural products from various sources that are able to inhibit HIV-RT.