Formation of Tryptophol Galactoside and an Unknown Tryptophol Ester in Euglena gracilis.

The unicellular alga Euglena gracilis Klebs ;Z' converted exogenous indole-3-ethanol (trytophol) to two major metabolites: tryptophol galactoside and an unknown compound, and to minor amounts of indole-3-acetic acid, tryptophol acetate, and tryptophol glucoside. The unknown was hydrolyzed to tryptophol by methanolic ammonia and should therefore be a tryptophol ester. The galactoside was identified as 2-(indol-3-yl)ethyl-beta-d-galactopyranoside. This structure was established by comparison with an authentic standard involving chromatographic methods, ultraviolet and mass spectroscopy, enzymic and acid hydrolysis, and identification of the galactose in the hydrolysate. By forming tryptophol galactoside, Euglena differs from the higher plants examined so far, for which the corresponding glucoside is the only sugar conjugate of tryptophol detected.