Structural characterization and anti-hypoxia activity of an exopolysaccharide isolated from fermentation broth of Lachnum sp.

Abstract

A novel exopolysaccharide (LEP-1) was isolated from the fermented broth of Lachnum YM268 through ethanol precipitation, deproteinization, decolorization and purification. The physicochemical properties of LEP-1 were determined by high performance gel permeation chromatography (HPGPC), field-emission scanning electron microscopy (SEM), fourier transform infrared spectrometry (FT-IR), gas chromatography-mass spectrometry (GC–MS), and 1D- and 2D-nuclear magnetic resonance spectroscopy (NMR). LEP-1 was a heteropolysaccharide with an average molecular weight of 473kDa, which consisted of glucose (Glc) and mannose (Man) in a molar ratio of 1.3:1.0. The backbone of LEP-1 was composed of →1)-α-Manp-(3,6→, →2)-α-Manp-(6→, →1)-α-Glcp-(6→ and →1)-β-Glcp-(6→, and its branches consisted of →1)-β-Glcp, →1)-α-Manp-(3,6→ and →2)-α-Manp-(6→. The analysis of the chain conformation showed that LEP-1 had no triple helical structure. The effects of LEP-1 on the hematological parameters and anti-hypoxia activities of the experimental mice were studied. The results showed that LEP-1 had strong ability to increase the red blood cell (RBC) amount and hemoglobin (HGB) concentrations, and could also prolong the survival times of mice in normobarie hypoxia and sodium nitrite tests. These suggest LEP-1 may be considered as a potential candidate for developing novel anti-hypoxia agents.