Several pharmacological activities have been observed in pectic
polysaccharides which were isolated from Chinese herbs containing
Kampo medicines. We found two different bioactive pectic
polysaccharides, bupleuran 2IIb and 2IIc, from the roots of Bupleurum falcatum. These bioactive pectic
polysaccharides were comprised of an alpha (1-->4) linked
galacturonan region, a ramified region that consists of a rhamnogalacturonan core substituted neutral
sugar chains as the side chains and a
rhamnogalacturonan II (RG II)-like region containing unique
sugars such as 3-deoxy-manno-2-octulosonic
acid (KDO). In order to understand the pharmacological activity of pectic
polysaccharides on the molecular level, we have elucidated the essential
carbohydrate structure for the expression of each pharmacological activity and their mode of actions. The ramified region in bupleuran 2IIb induced
Fc receptor up-regulation in macrophages by a mechanism dependent on an increase of intracellular Ca2+, followed by the enhancement of
immune complex clearance, whereas
bupleuran 2IIc, which mainly consists of a partially branched
galacturonan region, showed potent anti-
ulcer activity. The major mechanism of its mucosal protection was suggested to be due to anti-secretory activity on
acid and
pepsin, its ability to provide a protective coating and radical scavenging effect. The future problems were also discussed in order to develop pectic
polysaccharides as medicines.