Studies on the extractive components of ascidians in Korea. II. Extractive nitrogenous constituents of two species of edible ascidians Styela clava and S. plicata.

Abstract

The muscles of two species of edible ascidians Styela clava and S. plicata cultured at the south coast of Korea, were analyzed for extractive nitrogen, free and combined amino acids, nucleotides and related compounds, quaternary ammonium bases, and guanidino compounds using specimens collected in December, 1988 and April, 1989, and compared with those of Halocynthia roretzi already reported. Taurine, proline, glutamic acid, glycine, and alanine were the major free amino acids in each sample. Among them, taurine was the most abundant, occupying 43-65% of total free amino acids. The content of glycinebetaine was also high in the April samples, being more than 300mg per 100g. As for nucleotides and related compounds, AMP was the principal constituent in all the samples. The composition of the major extractive components such as free amino acids, nucleotides and related compounds, and betaines in the muscles of both species was similar to that of H. roretzi, and many of those components seemed to exhibit the same seasonal variation, low in winter and high in spring, as observed for H. roretzi. The tunic of S. plicata was very poor in extractive components, but the amounts of combined amino acids were considerably higher than those in the muscle.