A Novel Method for the Analysis of Soluble Carbohydrates from Cistanche deserticola

Objective: A comprehensive monosaccharide quantifying method was developed in this article. Monosaccharides (including glucose, arabinose, galacturonic acid, galactose, mannose, rhamnose and xylose) were analyzed by RP-HPLC-DAD method. Meanwhile, mannitol and fructose were calculated based on peak areas obtained by HPIEC-RID and corresponding data obtained by RP-HPLC-DAD. Monosaccharide compositions of CDSC were analyzed, nine kinds of monosacchardes (glucose, arabinose, galctose, galacturonic acid, mannose, rhamnose, xylose, fructose and mannitol) in were quantified. Background: Cistanche deserticola Y. C. Ma, is a perennial holoparasite and mainly distributed in the desert region of northwestern China. It reported that C. deserticola soluble carbohydrate (CDSC) could prompt lymphocyte proliferation, modulate immunity, inhibit type 2 diabetes, anti-inflammation. For these reasons, it is very appealing to researchers to have a convenient method for monosaccharides analysis of the CDSC. However, previous researches have neglected the faultiness in monosaccharide composition analysis. Therefore, in this study we will focus on establishing a quantifying method of monosaccharides possibly found in C. deserticola. Methods: Soluble carbohydrates were hydrolyzed with trifluoroacetic acid, monosaccharides were labeled with 1-phenyl-3-methyl-5-pyrazolone (PMP), separated by HPLC system equipped with C18 column and detected with DAD (RP-HPLC-DAD). RP-HPLC-DAD method was used for quantitative analysis of glucose, arabinose, galacturonic acid, galactose, mannose, rhamnose and xylose. Meanwhile, hydrolyzates were separated by HPIEC system equipped with aminex HPX-87H ion exclusion column and detected by refractive index detector (HPIEC-RID). The quantity of mannitol and fructose can be calculated based on peak areas obtained by HPIEC-RID and corresponding data obtained by RP-HPLC-DAD. Results: Utilizing this method, monosaccharide compositions of CDSC with different molecular weight (CDCSA, CDCS-B, CDCS-C and CDCS-D) were analyzed, nine kinds of monosacchardes (glucose, arabinose, galctose, galacturonic acid, mannose, rhamnose, xylose, fructose and mannitol) in were found. Conclusion: Fructose and mannitol, which are abundant present in C. deserticola, cannot be analysis by normally PMP modify method, therefore, a comprehensive quantitative analysis method was developed in this research. Galacturonic acid was found out in macro-molecular polysaccharides from C.deserticola, which was not reported before. Galactose and galacturonic acid mainly exist in macro-molecular polysaccharide. Fructose and mannitol mainly exist in mini-molecule or exist in free form.