Novel rapid method for the characterisation of polymeric sugars from macroalgae

S E Spicer,J M M Adams,D S Thomas,Ana L Winters,J A Gallagher

doi:10.1007/s10811-016-0995-0

Abstract

Laminarins are storage polysaccharides found only in brown seaweeds, specifically Laminarialaes and Fucales. Laminarin has been shown to have anti-apoptotic and anti-tumoural activities and is considered as a nutraceutical component that can positively influence human health. The structure is species dependent, generally composed of linear ß(1–3) glucans with intrachain β(1–6) branching and varies according to harvest season and environmental factors. Current methods for analysis of molar mass and DP length are technically demanding and are not widely available. Here, we present a simple inexpensive method which enables rapid analysis of laminarins from macroalgal biomass using high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) without the need for hydrolysis or further processing. This is based on the linear relationship observed between log10 DP and retention time following separation of laminarins on a CarboPac PA-100 column (Dionex) using standard 1,3-β-d-gluco-oligosaccharides ranging in DP from 2 to 8. This method was applied to analyse laminarin oligomers in extracts from different species harvested from within the intertidal zone on Welsh rocky shores containing laminarin polymers with different ranges of DP. The degree of polymerisation and extrapolated molar mass agreed well with values estimated by LC-ESI/MSn analysis and those reported in the literature.

Highlights

Marine algal biomass is both renewable and carbon neutral and an attractive alternative substrate for the production of biofuel and potential biorefinery products (Mazumdar et al 2014) including biologically active polysaccharides (Menshova et al 2014)
Species range from Laminaria hyperborea and L. digitata in the low intertidal zone where organisms are covered with seawater for all but the lowest of tides to Pelvetia canaliculata, which is found high on the shore and can survive for many days out of water (Fernandez-Marin et al 2011)
Analysis of laminarin fractions extracted from a range of brown seaweeds with the Dionex method described here yielded results which compared well the molecular size distribution determined by the LC-ESI/MSn method

Summary

Introduction

Marine algal biomass is both renewable and carbon neutral and an attractive alternative substrate for the production of biofuel and potential biorefinery products (Mazumdar et al 2014) including biologically active polysaccharides (Menshova et al 2014). Brown seaweeds of the phylum Ochrophyta include species that cover all intertidal zones. The most abundant polysaccharides of the brown algal species include laminarins, fucoidans and alginic acids which combined are reported to account for 40–80% of the dry defatted algal biomass (Zvyagintseva et al 2003). Laminarins ( known as laminarans or leucosin) (Alderkamp et al 2007) are a group of polysaccharides found in large quantities in brown algae. These storage carbohydrates are β(1,3) linked β-D-glucans with β(1–6) intrachain branching. Average degree of polymerisation (DP) is reported in the literature as 25 with a

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Conclusion