Oxalyldiaminopropionic acid
Oxalyldiaminopropionic acid (ODAP) is a structural analogue of the neurotransmitter glutamate found in the grass pea Lathyrus sativus. It is the neurotoxin responsible for the motor neuron degeneration syndrome lathyrism.
Source: Wikipedia — Oxalyldiaminopropionic acid (CC BY-SA 4.0)