Purpose. To determine whether the N-alkyl analogs of the thalidomide are active and stable, their stabilities in buffer and their abilities to inhibit tumor necrosis factor alpha (TNF-α) in vitro in human peripheral blood mononuclear cell cultures were investigated.
Methods. TNF-α concentrations were determined with the aid of ELISA kits. Chemical stabilities of the compounds were determined in three phosphate buffer solutions (pH 6, 6.4, and 7.4) at 25 and 32°C by high-pressure liquid chromatography, and half-lives were calculated.
Results. The addition of N-alkyl groups to the glutarimide ring of the thalidomide molecule had little effect on the ability such compounds have to inhibit TNF-α production. There was no statistical difference between the activity of thalidomide and its N-alkyl analogs at a 95% confidence level. Like thalidomide, the N-alkyl analogs in this series inhibit an average of 60% of the TNF-α synthesis in lipopolysaccharide-stimulated peripheral blood mononuclear cell cultures. Thalidomide and its N-alkyl analogs are hydrolyzed at very similar rates, with half-lives ranging from 25 to 35 h at 32°C at pH 6.4 and an average rate constant of 2.35 × 10-2/h.
Conclusions. Alkylating thalidomide had little effect on its ability to inhibit the production of TNF-α in these cell cultures. All of the compounds tested seem to have some, perhaps comparable, therapeutic potential.