L-DABA hydrobromide (L-2,4-Diaminobutyric acid hydrobromide) is a potent GABA transaminase inhibitor with antitumor and anticonvulsant activity for the study of neurological disorders.

Incubation with 10 mM L-2,4-Diaminobutyric acid for 24 h at 37°C irreversibly and completely damages tumor cells. The cell-destructive effect caused by L-DABA hydrobromide is likely a result of osmotic lysis induced by the non-saturated intracellular accumulation of L-DABA hydrobromide. Concomitant incubation with L-alanine and L-methionine can abolish the harmful effect of L-DABA hydrobromide[1]. Kinetic studies indicate that L-DABA hydrobromide is a non-linear, non-competitive inhibitor of GABA transaminase activity. The elevation of GABA levels induced by L-DABA hydrobromide parallels the inhibition of GABA transaminase activity[2]. L-2,4-Diaminobutyric acid, an amino acid analogue, produces a cytolytic effect with a human glioma cell line, SKMG-1, and normal human fibroblasts. The concentrations of L-DABA hydrobromide necessary to reduce the cell count to 50% of control following a 24-h incubation at 37°C are 12.5 mM for the human fibroblasts and 20 mM for the glioma cell line[2].

Treatment with L-DABA hydrobromide results in a 43.4% reduction of tumor growth[1]. In vivo, L-DABA hydrobromide is a more effective inhibitor of GABA transaminase compared to its efficacy in vitro[3].