Identification of D-Cysteamide in European Flat Oyster

Abstract

An unknown substance co-eluted with taurine on an amino acid autoanalyzer was found in the aqueous ethanol extract of the oyster Ostrea edulis. The compound wasextracted from 100g of soft parts from 13 specimens, isolated using Dowex 50 (H⁺ form) and Amberlite CG 400 (OH^-form)columns, and crystallized from hot 50% aqueous ethanol. The yield was 16mg as colorless needles. Its chemical and stereochemical structure was determined to be D-cysteamide [(S)-2-amino-3-sulfopropanamide] by FAB mass, ¹H and ¹³C NMR, IR, and CD spectra and elemental analysis.
In order to confirm the assigned structure, L-cysteamide was synthesized from L-cysteine methyl es-ter hydrochloride in a crystalline form. The synthetic compound was identical with a natural one in mobilities on the amino acid autoanalyzerand TLC and in FAB mass, ¹H and ¹³C NMR spectra but showed a reverse Cotton effect in the CD spectrum.