Plant amino acids beta-N-oxalylamino-L-alanine (L-BOAA, present in Lathyrus sativus) and beta-N-methylamino-L-alanine (L-BMAA, present in Cycas circinalis) have been implicated in the pathogenesis of human neurological disorders lathyrism and amyotrophic lateral sclerosis-Parkinson's dementia