Lipopolysaccharide-Independent Limulus Amebocyte Lysate Activating, Mitogenic and Anti-Complementary Activities of Pectic Polysaccharides from Chinese Herbs

Abstract

Bioactive pectic polysaccharides from Chinese herbs were tested for the presence of lipopolysaccharide (LPS) or LPS-like substances by chromogenic Limulus amebocyte lysate (LAL)-assay. Pectic polysaccharides from BUPLEURUM FALCATUM, GLYCYRRIZA URALENSIS, and ANGELICA ACUTILOBA were LAL-positive at different rates. The fractions GR-2IIc/PG-1 (ramified region; rhamnogalacturonan core with neutral sugar side chains) from G. URALENSIS and AGIIb-1 (acidic arabinogalactan) from A. ACUTILOBA activated the endotoxin-mediated coagulation factor (factor C). When the pectin-like polysaccharide bupleuran 2IIc from B. FALCATUM was digested with ENDO-polygalacturonase or degraded with lithium, the resulting oligosaccharides still showed LAL-reactivity. Carboxyl-reduction of acidic polysaccharides increased the reactivity to the beta(1-->3)-glucan-mediated coagulation factor (factor G) but not the factor C. Bupleuran 2IIc and its PG-1 and PG-2 (rhamnogalacturonan II-like region, which contains 2-keto-3-deoxyocuturosonic acid) showed significant mitogenic activities even by using C3H/HeJ mice which are low responder mice to LPS. When the LAL-positive substance was removed from bupleuran 2IIc and its fraction PG-1 by phase separation using Triton X-114, the mitogenic and anti-complementary activities did not change. These results indicated that mitogenic and anti-complementary activity of bioactive pectic polysaccharides from B. FALCATUM were due to the action of pectic polysaccharides but not LPS.