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The quantification of histidine-containing dipeptides (anserine, carnosine, and balenine) in serum might be a diagnostic tool to assess the health condition of animals. In this study, an existing reversed-phase ion-pair high-performance liquid chromatography (HPLC)-ultraviolet detection method was improved and validated to quantify serum anserine, carnosine, and balenine levels in the dolphin. The serum was deproteinized with trichloroacetic acid and directly injected into the HPLC system. Chromatographic separation of the three histidine-containing dipeptides was achieved on a TSK-gel ODS-80Ts (4.6 mm x 150 mm, 5 μm) analytical column using a mobile phase of 50 mmol/L potassium dihydrogen phosphate (pH 3.4) containing 6 mmol/L 1-heptanesulfonic acid and acetonitrile (96:4). The standard curve ranged from 0.1 μmol/L to 250 μmol/L. The average accuracy of the intra- and inter-analysis of anserine, carnosine, and balenine was 97-106%. The relative standard deviations of total precision (RSDr) of anserine, carnosine, and balenine in dolphin serum were 5.9%, 4.1%, and 2.6%, respectively. The lower limit of quantification of these compounds was 0.11-0.21 μmol/L. These results indicate that the improved method is reliable and concise for the simultaneous determination of anserine, carnosine, and balenine in dolphin serum, and may be useful for evaluation of health conditions in dolphins. Furthermore, this method can also be applied to other biological samples. [ABSTRACT FROM AUTHOR]

The potential of supercritical carbon dioxide (SC-CO2) extraction of "koku" enhancing compounds from dried herring fillet ("Migaki-nishin" in Japanese) and sturgeon liver was explored. "Koku" enhancing compounds from a water-soluble extract and a mixed water miscible SC-CO2 extract were isolated and evaluated for their effects on sensory perception. Results showed that only select compounds were found in the mixed water miscible SC-CO2 extract compared to the complicated composition of the water-soluble extract. A notable feature was that the mixed water miscible SC-CO2 extract contained "koku" enhancing compounds, e.g., nicotinamide, glycerol and creatine. This study revealed for the first time that these compounds were extracted by SC-CO2 extraction and that nicotinamide enhances "koku". We also extracted "koku" enhancing compounds from sturgeon liver using the SC-CO2 extraction technique. Instrumental analysis revealed that the sturgeon liver contained relatively large amounts of nicotinamide and glycerol. Thus, it is suggested that this technique might be applicable to the extraction of select compounds from fish and fishery by-products. [ABSTRACT FROM AUTHOR]