4-HYDROXYPIPECOLIC ACID AND PIPECOLIC ACID IN ACACIA SPECIES - THEIR DETERMINATION BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY, ITS APPLICATION TO LEGUMINOUS PLANTS, AND CONFIGURATION OF 4-HYDROXYPIPECOLIC ACID

A new method for the determination of naturally occurring imino acids in plants was devised. This method comprises the formation of dinitrop henyl derivatives and their measurement by HPLC. The determination lim its were 100 pmol for 4-hydroxypipecolic acid (HPA) and proline (Pro) and 10 pmol for pipecolic acid (Pip). The recoveries of HPA, Pro, and Pip from leaf homogenate of an Acacia species were 95.9 +/- 2.8, 100.5 +/- 1.7, and 101.1 +/- 2.3%, respectively. HPA was found in leaves, s eeds, and roots of five kinds of Acacia but not in leaves of other mem bers of the legume family. The HPA content of Acacia dealbata Link lea ves was much higher in winter than in summer. From X-ray analysis, HPA was found to be hydrated by two water molecules that are situated in a vacant channel formed by the molecular arrangement of HPA. HPA had n o remarkable physiological or pharmaceutical activities.