Choline Esters, their Precursors and Metabolites in the Hypobranchial Gland of Prosobranchiate Molluscs, <em>Concholepas concholepas</em> and <em>Thais chocolata</em>.

Extracts of the hypobranchial body of two prosobranchiate molluses of the Muricidae family were examined for their content of choline esters, as well as of precursors and metabolites of these esters. The hypobranchial gland of Concholepas concholepas contained, in addition to large amounts of urocanylcholine (murexine) and senecioylcholine, appreciable amounts of free choline, free urocanic acid and ethyl urocanate. All these compounds, and especially the choline esters, were predominantly located in the dye-secreting area of the hypobranchial gland. As much as 3% of the wet weight of the purple area was accounted for by murexine and seneciocylcholine. The only choline ester found in the hypobranchial body of Thais cholate was senecioylcholiine; derivatives of urocanic acid were lacking. The occurrence of ethyl urocanate in the hypobranchial gland of Concholepas concholepas demonstrates that not only choline but also other alcohols may be esterified by urocanic acid. [ABSTRACT FROM AUTHOR]