Carotenoid Decomposition in Chum Salmon Oncorhynchus keta Liver Tissue during Spawning Migration

Abstract

Appreciable amounts of carotenoid in chum salmon were decomposed during spawning migration, although muscle carotenoid accumulated in the integument and ovaries. This decomposition of carotenoid was considered to occur in the liver tissue. The liver extracts with 0.5M KCl bleached astaxanthin in the presence of linoleic acid in vitro. The astaxanthin bleaching activity was closely related to the size of the liver tissue. This activity in liver tissue was not completely lost by heating at 100°C for 10min. The liver extracts showed an absorption maximum at 410-415nm, along with two broad ones at 540-545 and 575-580 nm. These results suggested that carotenoids transported from muscle to liver by serum lipoproteins are decomposed by heme proteins of the liver tissue.