A tryptophan derivative, N-acyl-N1-glucosyltryptophan, was isolated from Puerariae Flos (flowers of Pueraria lobata (WILLD.) OHWI, an important oriental crude drug used to ameliorate crapulence). In the preceding paper, two triterpenoidal glycosides of sophoradiol glucuronides and six known aromatic compounds (kakkalide, daidzin, genistin, rutin, robinin, nicotiflorin) were described. This paper deals with the tryptophan derivative tentatively named PF-P. PF-P (1), an amorphous powder with [α]D + 19.7° (dimethyl sulfoxide), was isolated by MCI-gel CHP 20P (solvent: H2O-MeOH) and silica gel (solvent: CHCl3:MeOH:H2O = 7:3:0.5) column chromatographies from the aqueous layer. Its molecular formula was C23H32N2O8·2H2CO3. The IR spectrum showed absorptions due to νOH (3400 cm-1) and νC=O and δN-H (1640-1580 cm-1); the UV spectrum exhibited a characteristic curve (ε 25800 at 223 nm, ε 5500 at 273 nm, ε 5400 at 279 nm, ε 4300 at 290 nm) due to an indole skeleton. Negative FAB-MS gave a cluster ion (M - H)- at m/z 463. 1H-1H and 1H-13C COSY NMR spectra revealed three partial structures: a caproic acid moiety, a β-D-glucopyranosyl moiety, and a tryptophan moiety. The linkage of the glucosyl moiety to N-1 of tryptophan was determined by 13C-1H long-range COSY spectrum (long-range coupling between the anomeric proton of the glucosyl moiety and C-2 of tryptophan). PF-P (1) is the first example of a tryptophan derivative combined with sugar and an organic acid. Tryptophan and its derivatives were also obtained from other Leguminosae plants (seeds of Dolichos lablab L., Phaseolus radiatus L., Psophocarpus tetragonolobus (L.) DC. and whole plants of Abrus cantoniensis HANCE), suggesting they might be characteristic substances in Leguminosae plants.