Quantification of orally administered chondroitin sulfate oligosaccharides in human plasma and urine.

Chondroitin sulfate has been widely administered orally to improve knee osteoarthritis. Chondroitin sulfate also has various biological properties, such as anti-inflammatory, immunomodulatory, anti-oxidative, and antitumor activity. However, chondroitin sulfate absorption in the digestive system and bioavailability remains controversial owing to its large molecular weight. In this study, we aimed to evaluate the absorption of chondroitin sulfate oligosaccharides, depolymerized chondroitin sulfate with low molecular weight, in oral administration to humans. Four types of chondroitin sulfate with varying molecular weight [chondroitin sulfate tetrasaccharide (MW. 980), CSOS-1 (MW. 1,500), CSOS-2 (MW. 2,800), and HMWCS (MW. 70,000)] were orally administered and quantified in plasma and urine. Exogenous chondroitin sulfate in these samples was quantified using a high-performance liquid chromatography system equipped with a fluorescence detector. Quantitative changes of administered chondroitin sulfate tetrasaccharide showed similar patterns in plasma and urine, therefore it was presumed that the amount of exogenous chondroitin sulfate excreted in urine reflects its quantitative profile in blood. Considering urinary exogenous chondroitin sulfate as a parameter of intestinal chondroitin sulfate absorption, urinary contents of orally administered chondroitin sulfate with varying molecular weight were compared. Consequently, the amount of urinary exogenous chondroitin sulfate in 24 h after administration was higher in the chondroitin sulfate oligosaccharides group than that in the high molecular weight chondroitin sulfate group. Additionally, in the molecular weight distribution, urinary exogenous chondroitin sulfate after chondroitin sulfate oligosaccharides administration showed a lower content of chondroitin sulfate oligosaccharides with a higher molecular weight than that observed before administration. In summary, our results demonstrated for the first time that lower molecular weight of chondroitin sulfate is more efficiently absorbed through the digestive tract in human, and the improvement of its bioavailability is expected.

Detection and identification of furan fatty acids from fish lipids by high-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry.

Using high-performance liquid chromatography coupled to high-resolution electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC/ESI-Q-TOF-MS), we have developed a new method for detection and identification of furan fatty acids (F-acids), which are widely distributed in living organisms and foods as minor lipid components and are known to have antioxidant and anti-inflammatory effects. For this purpose, total fatty acids prepared from the testis lipids of Japanese chum salmon (Oncorhynchus keta) were examined without any concentration or isolation of F-acids. In negative ESI mode, F-acids gave a prominent [M-H]- ion, by which individual F-acids could be detected and identified. High-resolution extracted ion chromatograms clearly showed the occurrence of five major F-acid homologs as already reported by GC/MS. The method was successfully applied to several fish samples and revealed the occurrence of F-acids for the first time in the two New Zealand fish, hoki (Macruronus novaezelandiae) and school shark (Galeorhinus galeus).

Natural killer T cells from interleukin-4-deficient mice are defective in early interferon-gamma production in response to alpha-galactosylceramide.

Discovery of the natural killer (NK) T cell-specific ligand, alpha-galactosylceramide (alpha-GalCer) has enabled us to investigate the functional regulation of NKT cells. However, the detailed mechanism of cytokine production by NKT cells remains to be elucidated. Here we evaluated the role of interleukin (IL)-4 in the production of interferon (IFN)-gamma from NKT cells using IL-4-deficient C57BL/6 mice (IL-4(-/-) mice). Administration of alpha-GalCer into wild-type C57BL/6 mice caused the production of both IFN-gamma and IL-4 in serum or cytoplasm within 4 h of the injection. Unexpectedly, however, IL-4(-/-) mice-derived NKT cells did not produce any IFN-gamma at early phase after primary stimulation with alpha-GalCer. Because NKT cells from IL-4(-/-) mice produced IFN-gamma when they were stimulated secondarily with alpha-GalCer in vitro for 72 h, NKT cells from IL-4(-/-) mice were not completely genetically deficient for IFN-gamma production. To elucidate which cells, NKT cells or dendritic cells (DC), were responsible for the deficiency in IFN-gamma production in IL-4(-/-) mice, we carried out an add-back experiment using purified NKT cells and DC, which were prepared from either wild-type mice or IL-4(-/-) mice. NKT cells from wild-type mice produced IFN-gamma when they were cocultured with DC prepared from either wild-type or IL-4(-/-) mice, whereas NKT cells from IL-4(-/-) mice did not produce IFN-gamma by coculturing with DC from either wild-type or IL-4(-/-) mice. These results indicate that NKT cells, not DC, were responsible for the deficiency in IFN-gamma production in IL-4(-/-) mice. Thus, IL-4 is required for the activation of NKT cells to produce IFN-gamma in response to alpha-GalCer.