A polysaccharide fraction of shosaiko-to active in augmentation of natural killer activity by oral administration.

Shosaiko-to (Xiao-chai-hu-tang, SHO), which is a Kampo medicine prepared by decocting a prescription of 7 kinds of medical plants, has been used mainly to treat chronic hepatitis in Japan. Previously, we reported that an oral administration of SHO augmented natural killer (NK) activity in the peripheral blood. To characterize its active substance, SHO was fractionated. The high molecular weight fraction showed the ability to augment NK activity by oral administration, but the low molecular weight fraction did not. Furthermore, we obtained an active acidic polysaccharide from the high molecular weight fraction. This polysaccharide fraction, with a molecular weight of approximately 1.2 x 10(5), is probably responsible for the effect of the original Shosaiko-to. It contained no protein. The sugar moiety was composed of rhamnose, arabinose, mannose, galactose, glucose and galacturonic acid in molar ratios of 1:17:3:21:100:87.