Pigment alterations in the brown mussel Perna perna

Potential sex and/or gametogenic stage differences in the metabolism of chlorophyll-a and carotenoids in the brown mussel Perna perna of southern Brazil were studied using high performance liquid chromatography (HPLC). Carotenoids derived directly from diet (phytoplankton) were fucoxanthin plus diatoxanthin (diatoms), alloxanthin (cryptophytes) and zeaxanthin (mainly cyanobacteria). Females accumulated carotenoid-diols and epoxides (similar to 3-4 mg/g-dry wt.) while males had much lower concentrations (similar to 0.7 mg/g-dry wt.). An antioxidant/free radical scavenging role is proposed for carotenoids in females. Mean ratios of chlorophyll plus derivatives (Chins-a) to carotenoids for male and female P. perna were 50:1 and 4:1, respectively. The higher ratio in males relates to both higher carotenoid contents in females plus higher total Chlns-a in males (similar to 22 mg/g-dry wt.), relative to the females (similar to 4 mg/g-dry wt.). Chlorophyll-a metabolism in both sexes followed two distinct pathways. First, cyclization of pyropheophorbide-a gave 132, 17(3)-cyclopheophorbide-a-enol (CPPaE) which was further oxidized to hydroxy-chlorophyllone. Second, chlorophyll-a derivatives retaining the 13(2)-carbomethoxy moiety were oxidized to purpurin-18 which was hydrolyzed to chlorin-p(6). In both cases, metabolism of dietary chlorophyll-a was oxidative and derivatives could either serve as antioxidants or merely be the results of non-specific digestive processes. (c) 2008 Elsevier Inc. All rights reserved.