Determination of biogenic amines in Acacia rigidula and its dietary supplements

Acacia rigidula (Leguminosae) is a shrub that grows in the southern part of Texas, USA. In an earlier published investigation, the presence of several toxic amines, alkaloids and many unexpected components as analyzed by GC-MS was reported. Currently, the leaf extract of this plant is used in several weight-loss and body-building products in the US market without published data on its biological effects. Further, there is lack of conclusive information on the identity and quantity of amines in the plant material and the products. In our chemical investigations on A. rigidula, we have established an LC-MS-MS method for the quantitative determination of several phenethylamine, tyramine and tryptamine derivatives. The separation of these amines was achieved on a reversed phase pentafluorphenyl (PFP) column in 15 minutes. To enrich these components and to reduce the matrix induced ion suppression during LC-MS, the extracts were subjected to cationic exchange clean-up. Heptylamine and isotope labeled compounds were used as internal standards for the quantitative analysis. The new method is rapid and sensitive and it enables simultaneous analysis of several amines in A. rigidula plant material. The content of biogenic amine of several dietary supplement products containing A.rigidula was also established.