Fresh lamprey oil (F-La) is known to contain a large amount of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. When F-La was deodorized with steam at 280°C and 1 mmHg for 1 h, the contents of EPA and DHA were reduced and unidentified peaks were detected by gas-liquid chromatography. In male ddY mice, one week feeding of the lamprey oil deodorized at 280°C (H-La) remarkably decreased the serum triglyceride level and increased the liver weight 2.0-fold. H-La also lowered the corrected phagocytic index (α), which is an indicator of activities of reticuloendothelial system, but suppressed relatively little the antibody production against sheep red blood cells. It is suggested that H-La contains biologically active substances, which have potent hepatotoxic and serum triglyceride-reducing effects. This biologically active substances appear to be derived from long-chain polyunsaturated fatty acids under thermal deodorization conditions.
