Separation and quantification of microalgal carbohydrates

Abstract

Structural carbohydrates can constitute a large fraction of the dry weight of algal biomass and thus accurate identification and quantification is important for summative mass closure. Two limitations to the accurate characterization of microalgal carbohydrates are the lack of a robust analytical procedure to hydrolyze polymeric carbohydrates to their respective monomers and the subsequent identification and quantification of those monosaccharides. We address the second limitation, chromatographic separation of monosaccharides, here by identifying optimum conditions for the resolution of a synthetic mixture of 13 microalgae-specific monosaccharides, comprised of 8 neutral, 2 amino sugars, 2 uronic acids and 1 alditol (myo-inositol as an internal standard). The synthetic 13-carbohydrate mix showed incomplete resolution across 11 traditional high performance liquid chromatography (HPLC) methods, but showed improved resolution and accurate quantification using anion exchange chromatography (HPAEC) as well as alditol acetate derivatization followed by gas chromatography (for the neutral- and amino-sugars only). We demonstrate the application of monosaccharide quantification using optimized chromatography conditions after sulfuric acid analytical hydrolysis for three model algae strains and compare the quantification and complexity of monosaccharides in analytical hydrolysates relative to a typical terrestrial feedstock, sugarcane bagasse.

Green Extraction of Bioactive Compounds from Microalgae

“…However, establishing the relationship between the chemical structure of the polysaccharides and their biological activity is not an easy task due to the huge complexity of microalgal carbohydrates, characterized by highly branched heteropolymers with a high diversity in their monosaccharide composition and distribution as well as in their glycoside bonds [30,33]. Therefore, the exhaustive characterization of microalgal carbohydrates presents some analytical limitations making more complex their analysis as the size of the carbohydrates increases [29]. Regarding the extraction of these compounds, the great majority of the applications consist of a concentration step using low temperatures followed by precipitation with a variety of organic solvents.…”

“…Nevertheless, little information is available about the classes of polysaccharides present in most microalgal species, with the exception of some β-glucans and spirulans [29,30]. However, microalgal carbohydrates, and mainly their structure and physico-chemical properties, are responsible for the different and important healthpromoting properties such as anti-inflammatory, antitumor, anti-adhesive, antiviral or antibacterial activities [30].…”

Quality control of sweet medicines based on gas chromatography-mass spectrometry

“…Derivatization methods of aminoglycosides have been reviewed before (49). Alditol acetates have been widely used for determination of neutral and basic monosaccharides simultaneously (50-52) however failed in uronic acids detection without forming methyl esters (52). The derivatization procedure including silylation, acetylation, oximation + acetylation and oximation + silylation have been compared for the analysis of iminosugars (DNJ and fagomine) and other low molecular weight carbohydrates.…”

Low cost ionic liquid–water mixtures for effective extraction of carbohydrate and lipid from algae

“…Previous studies on the carbohydrate content of algal biomass showed that the two most abundant monomeric sugars present in C. vulgaris are D-galactose and Dglucose (49 wt% and 35 wt% of total carbohydrate respectively). 43 The ACCU-CHEK Performa glucose meter used was responsive to both D-glucose and D-galactose. This is not unusual, for several glucose-meters have been reported to give unusually high readings in the presence of other sugars such as maltose or galactose.…”