Antioxidative Substances in the Green Fractions of the Lipids of Aonori (Enteromorpha sp.)

Abstract

Previously we reported that the lipid extracts with hexane/ethanol (79 : 21, v/v) from several edible seaweeds showed potent antioxidativity in linoleic acid-ethanol-water system. In the present study, the antioxidative components in the lipids of Aonori (Enteromorpha sp.) were isolated and identified by silica gel column chromatography, HPLC, NMR and FAB/MS. Among 12 fractions separated by the silica gel column chromatography with hexane, benzene, ether, ethyl acetate and methanol, fraction No. 6 (F6) has the strongest antioxidative activity on dark place with the thiocyanate method. F6-2 was the main antioxidative component in 3 peaks (F6-1, F6-2, F6-3) which were isolated from F6 by the HPLC analysis. From the assignment of chemical shift parameters of 1H-NMR and ¹³C-NMR, it was considered that the main antioxidative component in F6-2 was derivative of chlorophyll a. According to the molecular ion (872 MH⁺) of the FAB/MS analysis, it was found that the main antioxidative component in lipids of Aonori was pheophytin a, one of the Mg-free chlorophylls.