イケチョウガイ卵のセラミド2-アミノエチルホスホネートについて
1975 年 24 巻 3 号 p. 181-184
詳細
1975 年 24 巻 3 号 p. 181-184
Ceramide 2-aminoethylphosphonate (CAEP) was found to be the principal phospho-sphingolipids in the shellfish. The presence of CAEP as a major lipid constituent in these organism is unique, since this phospholipid has been not found or only trace in all other animals investigated so far.
In this paper authors report the isolation and characterization of CAEP from ova of a fresh-water bivalve, Hyriopsis schlegelii. Total lipid (0.5g) from the ova was subjected to alkaline methanolysis according to a modified procedure of Dawson. An alkali-stable lipid fraction (200mg) was fractionated on a silicic acid column with chloroform-methanol mixture. CAEP (32mg) was eluted from the column with 350ml of chloroform-methanol (80 : 20, by vol) and the homogeneity of the isolated CAEP was determined on thin-layer plates developed in chloroform-methanol-water (65 : 25 : 4, by vol) and chloroform-methanol-acetic acid-water (100 : 20 : 12 : 5, by vol). Enzymatic degradation of CAEP by phospholipase C from Cl. perfringens yielded ceramide and 2-aminoethylphosphonic acid, and the former was purified by chromatography on a silicic acid column using chloroform, chloroform-methanol (98 : 2, by vol). The chloroform-methanol eluate contained only one component as revealed by thin-layer chromatography.
Acid hydrolysis of ceramide derived from CAEP was performed by heating for 18hr at 70°C in aqueous 1N-methanolic HCl. The fatty acid methyl esters produced by the acid hydrolysis were extracted with n-hexane and estimated by gas-liquid chromatography at 160°C on a 15% DEGS column. The fatty acids identified were C14 : 0, C15 : 0, C16 : 0 (predominant), C17 : 0 and C18 : 0. After removal of fatty acid components by extraction with n-hexane the remaining aqueous solution was adjusted to pH 11.0 by adding 1N-NaOH. The long-chain bases were extracted with diethyl ether from the remaining solution, converted to their trimethylsilyl derivatives and analyzed by gas-liquid chromatograph-mass spectrometer at 200°C on a 1% OV-1 column. Octadeca-4-sphingenine (predominant), and presumable branched octadeca- and nonadeca-4-sphingenine were the principal long-chain bases of CAEP.
To determine 2-aminoethylphosphonic acid obtained as one of the enzymatic hydrolyzates, a small portion of the hydrolyzates was converted to a trimethylsilyl derivative with bis (trimethylsilyl) acetamide-pyridine-trimethyl chlorosilane (1hr, 60°C), and analyzed by gas-liquid chromatograph-mass spectrometer. 2-Aminoethylphosphonic acid was identified by a reference to the mass spectrum of the synthetic compound.
The occurrence of CAEP in nature is well documented. However, this is the first finding of this compound in the lipids of shellfish ova.
