Anti-human immunodeficiency virus type 1 agent alpha-hydroxy glycineamide enters the target cells via a mechanism of passive diffusion.

Objectives: Alpha-hydroxy glycineamide (αHGA) is the active antiviral metabolite of tri-peptide glycyl-prolyl-glycine-amide (GPG-NH2 ). αHGA inhibits the replication of HIV-1 in vitro by interfering with the capsid formation. It has also an effect on viral gp160 envelope protein. Since drug transport is an important aspect of drug function, we investigated the mechanism of [(14) C] αHGA uptake by a human T cell line.

Methods: H9 cells were incubated with defined amounts of radiolabelled αHGA for definite time durations. After harvesting the cells and removal of radiolabelled material, the radioactivity associated with the cells was assayed. Experiments were also designed to address the effect of metabolic inhibitors, temperature and extra unlabelled compound as potential competitor on the cellular uptake of αHGA.

Key Findings: Uptake of αHGA into H9 cells was time- and dose-dependent. The uptake properties showed a low temperature dependency (Q10  < 2). Moreover the uptake was not inhibited by increasing concentrations of cold competitors. There was no effect on cellular uptake of αHGA by known metabolic inhibitors, NaN3 and NaF.

Conclusions: Kinetic analysis of compound uptake, metabolic inhibition studies, saturation studies and the Q10 value of αHGA uptake indicate that the compound enters H9 cells by a mechanism of passive diffusion.