Acacia rigidula Benth., blackbrush, is a shrub found growing on rocky
ridges in west and southwest Texas and northern Mexico. Consumption of
blackbrush and a related species guajillo, Acacia berlandieri Benth., has
been associated with a locomotor ataxia known as limber leg. In an effort
to identify the mechanism of this toxicity, blackbrush was subjected to
rigorous chemical analysis. In addition to the four previously detected
amines, N-methyl-@b-phenethylamine, tyramine, N-methyltyramine, and
hordenine, 40 other alkaloids and amines were isolated and identified by
GC-MS. These alkaloids and amines included nicotine,
N,N-dimethyltryptamine, mescaline, several tetrahydroisoquinoline
alkaloids, and four amphetamines. A significant increase in the number and
relative quantities of these compounds was observed in late season foliage.