Abstract:[Objective] The extraction efficiency of different methods and the effects of these methods on the composition of mannoproteins extracted from yeast cell walls were compared. Furthermore, the anti-inflammatory activities of the extracted mannoprotein were evaluated. [Method] Three yeast mannoproteins (MP-W, MP-B, and MP-E) were extracted via high-temperature water, alkali, and enzyme-assisted extraction methods and purified via ethanol precipitation. The identification of monosaccharide composition and amino acid composition, distribution of relative molecular mass, and Fourier transform infrared spectroscopy were employed to analyze the composition and chemical structures of yeast mannoproteins. A cell experiment was carried out to examine the anti-inflammatory activity. [Result] The yields of yeast mannoproteins extracted by the three methods were 9.7%, 11.5%, and 23.1%, respectively. The yield of MP-E was significantly higher than those of MP-W and MP-B. The yeast mannoproteins obtained were composed of mannose, glucose, and glucosamine, and the peak area proportion of glucose in MP-E was significantly higher than those in MP-W and MP-B. MP-E had significantly lower mass fractions of total amino acids and aspartate (Asp) and significantly higher mass fraction of threonine (Thr) than MP-W and MP-B. The weight-average molecular weights of the extracted yeast mannoproteins were 103 493, 106 579, and 118 286, respectively. Fourier transform infrared spectroscopy showed that all the three yeast mannoproteins were glycoproteins, with no significant difference in the main functional groups. At the mass concentration of 150 μg/mL, MP-E extremely outperformed MP-W (P<0.001) and MP-B (P<0.001) in increasing interleukin-10 secretion and inhibiting tumor necrosis factor-α secretion in RAW264.7 cells. [Conclusion] There is no significant difference in the main functional groups of yeast mannoproteins obtained by the three extraction methods. However, the enzyme-assisted extraction method can significantly improve the yield of yeast mannoprotein, and the obtained yeast mannoprotein shows higher anti-inflammatory activity. The findings provide a theoretical basis for the development and application of yeast mannoproteins.
