DABA's main action is being an inhibitor of GABA transaminase, an enzyme that converts GABA back to glutamate. When the enzyme is inhibited, this conversion cannot happen, therefore, GABA levels are elevated.[1]
It has also been observed that 2,4-diaminobutyric acid is a GABA reuptake inhibitor.[2] This action further elevates levels of GABA.
Toxicity
In addition to being a neurotoxin, DABA can also cause liver damage.
Its potential as an anticonvulsant is unclear, it has been shown to have anticonvulsant properties against picrotoxin, but over the long term, it could paradoxically cause convulsions.[2][3]