Drying and extraction effects on three edible brown seaweeds for metabolomics
Metabolomics is often used to comprehensively elucidate the metabolites in organisms like seaweed. Amino acids hydrolysed from proteins and certain targeted metabolites in seaweed have been investigated. However, water-soluble metabolites like free amino acids, organic acids, and sugars have seldom been comprehensively analysed. Metabolomics are valuable tools for these studies, but they require optimisation of pre-treatment methodology. Here, we evaluated various pre-treatment drying and extraction methods for brown seaweed metabolomics. Three edible brown seaweeds (Cladosiphon okamuranus [Mozuku], Saccharina japonica [Kombu], and Undaria pinnatifida [Wakame]) were used. Freeze-drying and oven-drying at both 40 and 80 °C were investigated. Methanol-water extracts with and without chloroform were compared. Metabolites were evaluated and quantified using liquid chromatography-mass spectrometry and capillary electrophoresis-mass spectrometry. The results showed that metabolite profiling was determined mainly by seaweed species identity rather than pre-treatment method. Freeze-drying yielded higher metabolite concentrations than oven-drying at either 40 or 80 °C. The effects of extraction with and without chloroform on metabolite concentration varied with seaweed species.
KeywordsPhaeophyceae Metabolomics Brown seaweed Drying methods Extraction methods
The authors thank Dr. Tatsuki Ogura and Mr. Yujin Ashio (Institute for Advanced Biosciences, Keio University, Japan) for their helpful suggestions.
This study was funded by the Yamagata prefectural government and by the city of Tsuruoka. It was also supported by a scholarship from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan, for an international student (Hamid, S.S).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
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