Isolation of p=Aminoisobutyric Acid from Bulbs of Iris tingitana var. Wedgewood

In the course of paper chromatographic analysis of the free amino acids in bulbs of Wedgewood iris (Iris tingitana) a ninhydrin-reacting compound which occupied a spot corresponding to that of P-aminoisobutyric acid (Spot 11, Fig. 1) was observed. The compound was resistant to acid hydrolysis and did not form a copper complex, because it moved through a barrier of copper carbonate (1) on paper chromatograms. This indicated that it was not an a-amino acid. The RF values in several solvent systems corresponded with those for authentic p-aminoisobutyric acid. @-Aminoisobutyric acid was first synthesized by Clemo and Melrose (2) in 1942 as the ethyl ester and as the free acid by Pollack (3) in the following year. Subsequently, it was isolated from normal human urine by Crumpler et ~2. (4) and also independently established by Fink et aZ. (5) as a urinary constituent in man both normally and in patients with neoplastic disease. In a review of the nitrogenous compounds in plants, Steward et al. (6) had indicated that the occurrence of p-aminoisobutyric acid in plants had not been established. The present report describes the isolation and identification of this substance from the bulbs of Wedgewood iris.