An analog of valeric acid; inhibits class I HDACs (IC50s = ~2 mM); the number of axon branches in sensory neurons isolated from newborn rat dorsal root ganglia; inhibits amyloid-β deposition and neuritic plaque formation and decreases escape latency in the Morris water maze test in the APP23 transgenic mouse model of Alzheimer's disease; has anticonvulsant activity in the pentylenetetrazol seizure threshold test in mice (ED50 = 0.71 mmol/kg); induces neurotoxicity at ≥1.2 mmol/kg