LC/ESI-ITMS Detection of the Neurotoxic Amino Acids in Cultured Cyanobacterial Isolate Nostoc MAC PCC 8009

Abstract

The non-protein amino acid β-methylamino-L-alanine (BMAA), is a neurotoxic agent that is produced by various strain of cyanobacteria. 2,4-diaminobutyric acid (2,4-DAB), and N-(2-aminoethyl) glycine (AEG) are the common isomers of BMAA. 2,4-DAB exhibit neurotoxic properties like BMAA. Various studies have shown that cyanobacteria produce BMAA and DAB, however, no studies have shown the  detection of these amino acids using liquid chromatography-electrospray ionization ion trap mass spectrometry (LC/ESI-ITMS) method. This study aimed to assess the occurrence of BMAA and its isomer 2,4-diaminobutyric acid (DAB) in axenic laboratory culture of  cyanobacterial strain Nostoc MAC PCC 8009. Axenic laboratory cultures were harvested after 12 weeks of growth and non-protein amino acids were extracted by trichloroacetic acid (TCA) and methanol extraction. Liquid chromatography-electrospray ionization ion trap mass spectrometry (LC/ESIITMS) was employed to analyse the presence of BMAA and 2,4-DAB. Both BMAA and 2,4-DAB were detected in the axenic cultures, which confirms the production of these neurotoxic amino acids by cyanobacteria. Multiple stage mass analysis by ESI-ITMS using [M+H] + was useful to distinguish between the two isomers.