Structure and anti-complementary activity of pectic polysaccharides isolated from the root of Angelica acutiloba Kitagawa.
Four pectic polysaccharides (AR-2IIa-IId) with anti-complementary activity have been isolated from a hot-water extract of the root of Angelica acutiloba Kitagawa. Each of these polysaccharides contained a large proportion of GalA together with neutral sugars consisting mainly of Rha, Ara, and Gal. Digestion with endo-alpha-(1----4)-polygalacturonase indicated that AR-2IIa-IIc each contained a large proportion of enzyme-sensitive polygalacturonan regions, and that AR-2IId contained a large proportion of enzyme-resistant regions. When AR-2IId was de-esterified, it became sensitive to the enzyme. These polysaccharides also contained small proportions of enzyme-resistant regions (PG-1) which were rich in neutral sugars. Methylation analysis and base-catalysed beta-elimination studies suggested that each PG-1 contained a rhamnogalacturonan moiety in which 2,4-disubstituted Rha was attached to 4-substituted GalA through position 2 of Rha. Carboxyl-reduction and methyl- and de-esterification of these polysaccharides modulated their anti-complementary activities. Digestion with endo-alpha-(1----4)-polygalacturonase decreased the activities of AR-2IIa and -2IIb, but not those of AR-2IIc and -2IId. Although PG-1 fractions from AR-2IIa-IIc were more active than the original polysaccharides, oligogalacturonide fragments obtained by enzymic digestion had weak or negligible activity. AR-2IIa-IIc expressed their anti-complementary activities mainly via the classical pathway, but AR-2IId and each PG-1 expressed their activities via both the classical and alternative pathways.
Kiyohara
H
H
Oriental Medicine Research Center, Kitasato Institute, Tokyo, Japan.
Cyong
J C
JC
Yamada
H
H
D003167:Complement Activation / Q000187:drug effects*; D004951:Esterification; D006801:Humans; D008745:Methylation; D010084:Oxidation-Reduction; D010946:Plants, Medicinal; D011134:Polysaccharides / Q000032:analysis / Q000302:isolation & purification / Q000494:pharmacology
D011134:Polysaccharides