Mulberry stem bark extract stimulates in vitro immunomodulatory response in mouse spleen lymphocytes

Abstract

We separated an aqueous extract of Morus alba stem bark by gel filtration chromatography, ammonium sulfate fractionation, and chromatography on Superdex 200 10/300GL and Mono Q 5/50GL columns. The resultant water-soluble fraction significantly increased total lymphocyte proliferation up to 3-fold (at 10μg/ml) and stimulated the proliferation of isolated B cells (at 5, 10, and 20μg/ml), similar to the positive control (lipopolysaccharide). This fraction, with an apparent high molecular weight of ≥ 200k, consisted of 55.3% proteins and 9.6% sugars. The bioactive fraction treated with trypsin and pre-incubated either alone or with 2-mercaptoethanol and glycopeptitase F significantly reduced lymphocyte proliferation. These results suggest that a water-soluble glycoprotein-like complex of M. alba stem bark has therapeutic potential to boost immunity.