The increasing incidence of human immunodeficiency virus (HIV) infection and the associated acquired immune deficiency syndrome (AIDS) mortality rates as well as the sometimes severe side effects of highly active anti retroviral therapy (HAART) warrants the continuous search for new, less toxic drug candidates. The anti-HIV activity (inhibition of reverse transcriptase-RT and protease-PR in direct enzyme assays) of eleven gold(I) phosphine compounds are reported here. Uptake of the compounds by peripheral blood mononuclear cells (PBMCs) was demonstrated by inductively coupled plasma atomic emission spectroscopy (ICP-AES) while the effect of the compounds on cell viability was assessed using flow cytometry with annexin V and propidium iodide (PI). Of the 11 gold compounds tested, 7 significantly (p o 0.05) inhibited RT activity at concentrations of 25 and 250 mM while 3 compounds significantly inhibited its activity at 6.25 mM. In the anti-protease assay, 4 of the compounds significantly inhibited the enzyme (p o 0.05) at 100 mM. All of the compounds were taken up by PBMCs (demonstrated by
ICP-AES) and were non toxic to these cells at clinically tolerable concentrations. The potential of these novel gold(I) phosphine compounds as anti-HIV agents is therefore promising and worthy of further investigation.