アサリエキス中のウナギ誘引物質-II : 天然エキスの分画による有効物質の検索

概要

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Succeeding to the previous study, in which attractants for eels, Anguilla japonica, were surveyed by the omission test using synthetic extracts, the present investigation was conducted to locate stimulating constituents by a stepwise fractionation of the natural extracts. (1) The aqueous ethanolic extracts of the soft part of short-necked clam, Tapes japonica, were defatted with ether without any decrease in activity. The extracts were then fractionated into basic, acidic and neutral fractions by passing columns of Dowex 50W (H+) and Dowex 2 (OH-) resins successively. Among them, only the basic fraction was found to be effective (Table 1). (2) The basic fraction was further divided into two, strongly and weakly basic fractions, with a column of Dowex 50W (NH4+) resin. As shown in Table 2, the non-adsorbed, weakly basic fraction was active, while the other not. (3) The weakly basic fraction was then fractionated by paper chromatography or chromatopile. As shown in Table 4, stimulating components were concentrated mostly in a fraction ranging from Rf 0.3 to 0.6. (4) Amino acid analysis of the above active fraction revealed the presence of seven amino acids (Table 5). A mixture of the authentic reagents of these amino acids was confirmed to be stimulating to eels, although weaker than the original extracts.