HIV-1 infectivity inhibition and cellular cytotoxicity associated with chloroform extracts of accessions or commercial cultivars of H. perforatum. The HIV infectivity studies are represented as the ratio of HIV infectivity in the presence of extract divided by the infectivity in the absence of extract. The cytotoxicity is represented as the cell viability as detected in an ATPLite assay in the presence of extract divided by the viability of cultures in the absence of extract. All cells were exposed to equivalent concentrations of DMSO, the extract solvent. All studies were performed three times in triplicate and shown are means and standard error of the means. *p = 0.05.