BIOACTIVE LONG-CHAIN N-ACYLETHANOLAMINES IN 5 SPECIES OF EDIBLE BIVALVE MOLLUSKS - POSSIBLE IMPLICATIONS FOR MOLLUSK PHYSIOLOGY AND SEAFOODINDUSTRY

Several long chain N-acylethanolamines, including the proposed endogen ous ligands of cannabinoid receptors, anandamide (N-arachidonoylethano lamine, C20:4 NAE) and N-palmitoylethanolamine (C16:0 NAE), as well as some of their putative biosynthetic precursors, the N-acyl-phosphatid ylethanolamines, were found in lipid extracts of five species of bival ve molluscs, including Mytilus galloprovincialis, commonly used as sea food. The amounts of these metabolites, the most abundant being C16:0 NAE and N-stearoylethanolamine, appeared to increase considerably whe n mussels were extracted 24h post-mortem, but were not significantly a ffected by boiling the tissue prior to extraction. In particulate frac tions of homogenates from Mytilus, where the existence of a highly sel ective cannabinoid receptor with an immunomodulatory function has been previously described, an enzymatic activity capable of catalyzing the hydrolysis of C20:4 NAE amide bond, and displaying similar pH depende ncy and inhibitor sensitivity profiles as the recently characterized ' fatty acid amide hydrolase' was found. The enzyme K-m and V-max for C2 0:4 NAE were 29.6 mu M and 73 pmol/mg protein/min, respectively. These findings support the hypothesis that C20:4 NAE, never reported before in the phylum Mollusca, may be a mollusc physiological mediator, and suggest that edible bivalves may be a dietary, albeit limited, source of C16:0 NAE, whose anti-inflammatory properties, when administered or ally in amounts higher than those reported here, have been previously reported. (C) 1998 Elsevier Science B.V.