Aqueous extracts of P. vulgaris inhibit HIV-1 infectivity. A) DMSO, water extracts and ethanol extracts of P. vulgaris were diluted in media to 0.2% (water extracts: 66 μg/mL of Ames 27664, 42.2 μg/mL of Ames 27665, 59.6 μg/mL of Ames 27666, or 62.4 μg/mL of Ames 27748 and ethanol extracts: 66.8 μg/mL of Ames 27664, 69.2 μg/mL of Ames 27665, 64.2 μg/mL of Ames 27666, or 67.4 μg/mL of Ames 27748). Equivalent numbers of HIV-1 NL4-3 virions were added to each well of HeLa37 cells along with the diluted extracts. Forty hours following infection, cells were fixed and immunostained for viral antigens. Cell-viability studies were performed in parallel in uninfected HeLa37 cells and are shown by the hatched line. Cell viability and virus infectivity are shown as a ratio of the values in the presence of the extracts divided by the DMSO control. Shown are the averages and standard errors of three experiments performed in triplicate. B) The anti-HIV-1 dose response curve of 14 aqueous extracts of P. vulgaris accessions collected from the U.S. and the Republic of Georgia. All plant material was grown at NCRPIS, Ames, IA. Concentrations of the aqueous extracts noted were mixed with equivalent numbers of NL4-3 virions and added to HeLa37 cells as described in A. Cytotoxicity of the extracts are shown in parallel as the black line. Data are represented as the means and standard errors of the mean of two experiments performed in triplicate.