Stizolobic Acid: a New Amino-Acid in Stizolobium hassjoo

Abstract

TWO new amino-acids have been found in the sap exuded from the cut surface of the epicotyl tips of etiolated seedlings of Stizolobium hassjoo, all parts of which turn black on dying owing to the oxidation of 3,4-dihydroxyphenylalanine. The exudate contains 3,4-dihydroxyphenylalanine and two new amino-acids, as shown by paper chromatography. The R_F values of the latter amino-acids coincided with no amino-acids already known, and it is proposed that these compounds be named stizolobic acid and stizolobinic acid, respectively. Stizolobic acid gives rise to an orange spot with ninhydrin (R_F = 0.16 in phenol/water (8 : 2 w/w), 0.11 in n-butanol/acetic acid/water (4 : 1 : 2 v/v)), while stizolobinic acid gives a brown spot (R_F = 0.24 in phenol/water, 0.14 in n-butanol/acetic acid/water).