The effects of ethyl all-cis-5,8,11,14,17-icosapentaenoate (EPA-E), highly purified ethyl ester of icosapentaenoic acid (EPA), on rabbit platelets were studied. In in vitro, highly purified EPA (62.5-3000 microM) suppressed the platelet aggregation induced by collagen, arachidonic acid (AA) and adenosine diphosphate (ADP). In ex vivo, a single administration of EPA-E (300 and 1000 mg/kg, p.o.) and repeated administrations (30 and 300 mg/kg/d, p.o.) for 2 weeks showed no effects on collagen-, AA- and ADP-induced platelet aggregation. Repeated administrations (30 and 300 mg/kg/d, p.o.) for 4 weeks suppressed the collagen-induced platelet aggregation, but not the AA- and ADP-induced platelet aggregation. Repeated administrations for 4 weeks also suppressed thromboxane B2 (TXB2) formation induced by collagen, but a single administration and repeated administrations for 2 weeks failed to inhibit TXB2 formation. The EPA level in the platelet phospholipids increased slightly with a single administration, and increased markedly with repeated administrations for 2 and 4 weeks. The AA level in the phospholipids showed practically no changes with a single and repeated administrations. These results suggested that highly purified EPA-E could reduce platelet aggregability by the change of the EPA level in the platelet phospholipids and should allow for a reasonable period of administration.
Vitellogenesis has been extensively studied in oviparous vertebrates, including teleost fishes, while not much is known with regard to jawless hagfishes, modern representatives of the most primitive vertebrate class. This study aimed to characterize vitellogenin (Vtg) and yolk protein (YP) in the inshore hagfish (Eptatretus burgeri) as an initial step to understand vitellogenesis in this species. A putative Vtg fraction was purified from the serum of female hagfish by combinations of hydroxylapatite and ion-exchange chromatography, followed by gel filtration. The purified fraction appeared to contain two distinct Vtgs (Vtg1 and Vtg2) and exhibited biochemical properties resembling those previously reported for teleost Vtgs; these appeared to be female-specific serum proteins and high-molecular-weight proteins in gel filtration (~505 kDa as the mixture fraction of both Vtgs) and in SDS-PAGE (Vtg1 and Vtg2; ~210 kDa and ~195 kDa, respectively). A major YP was also purified from hagfish eggs by combinations of hydroxylapatite chromatography and gel filtration; the apparent native mass of the purified YP was unusually large (> 669 kDa). The purified YP consisted of four polypeptides in SDS-PAGE; the peptide pattern indicated that it consisted of two lipovitellins (Lv1 and Lv2) giving rise to two sets of heavy chains (~116 kDa and ~106 kDa, respectively) and two light chains (~32 kDa and ~28 kDa, respectively). Additional immunological analysis, Nterminal amino acid sequencing and cDNA cloning firmly confirmed the precursor-product relationship between hagfish Vtgs and Lvs.
We started to study on the development of EPA ethyl ester(EPA-E) for a drug in cooperation with doctors and pharmaceutical companies in 1979, and we were permitted to manufacture the drug for atherosclerosis obliterans named EPADEL in 1990. In this work, several methods were examined to purify EPA-E in fish oil ethyl ester mixture to pharmaceutical grade, and the distillation with mufti-tower system and cyclic process of urea adduction method were developed. By the combination of above two processes, 90% EPA-E was obtained from fish oil ethyl ester containing 18% EPA. Stability tests revealed that EPA-E in a closed container could be stored without any undesirable changes at room temperature for 2 years. Clinical studies clarified the effect of EPA-E on both atherosclerosis obliterans and hyperlipidemia.
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