Inhibition of growth of human immunodeficiency virus in vitro by crude extracts of Chinese medicinal herbs.

Twenty-seven medicinal herbs reputed in ancient Chinese folklore to have anti-infective properties were extracted by boiling under reflux. The extracts were tested for inhibitory activity against the human immunodeficiency virus in the H9 cell line at concentrations nontoxic to growth of the H9 cells. Using a significant reduction (greater than 3 S. D. below the mean) in the percentage of cells positive for specific viral antigens in three successive assays as indicative of activity against the virus, 11 of the 27 extracts were found to be active. One of the extracts (Viola yedoensis) was studied in greater depth. At a subtoxic concentration, this extract shut off completely the growth of HIV in virtually all experiments. It did not inactivate HIV extracellularly, did not induce interferon and did not inhibit the growth of herpes simplex, polio or vesicular stomatitis viruses in human fibroblast culture. Chinese medicinal herbs appeared to be a rich source of potentially useful materials for the treatment of human immunodeficiency virus infection.