Structures and structure-activity relationships of three mitogenic and complement fixing pectic arabinogalactans from the malian antiulcer plants Cochlospermum tinctorium A. Rich and Vernonia kotschyana Sch. Bip. ex Walp.
Structures of three pectic arabinogalactans, one from Vernonia kotschyana (Vk2a) and two from Cochlospermum tinctorium (Ct50A1 and Ct50A2), and their complement fixation and induction of B cell proliferation in vitro were compared. The polysaccharide Vk2a expressed potent biological activity in both assays compared with Ct50A1 and Ct50A2. Vk2a possessed a very high molecular weight (1150 +/- 20 kDa) compared with Ct50A1 and Ct50A2 which both showed a polydisperse nature with the highest molecular weight polymers in each fraction estimated at approximately 105 kDa (Ct1a) and 640 +/- 100 kDa (Ct2a), respectively. The HMW polymers showed complement fixation in the same range as the native fractions. The arabinogalactan II content was low in Vk2a (2%) compared with that in Ct50A1 (23%) and Ct50A2 (12%). The high molecular weight polymers were subjected to digestion with a beta-d-(1, 3)-galactanase-rich fraction from Driselase, oligomers were isolated by HPAEC, and their finer structures were determined by MALDI- and ES-qoToF-MS, linkage, and monosaccharide composition analyses. Vk2a consists of both a galacturonan core and a rhamnogalacturonan core rich in neutral side chains. The backbones of both Ct-polysaccharides consist mainly of RG-I regions with numerous neutral side chains dominated by galactosyl residues, whereas the homogalacturonan regions seem to be small. Differences in the chain lengths of the 6-linked galacto-oligosaccharides attached to the 3-linked galactan core could not be related to the differences in the potencies of the biological activities observed.
Nergard
Cecilie Sogn
CS
Department of Pharmacognosy, School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, 0316 Oslo, Norway.
Kiyohara
Hiroaki
H
Reynolds
James C
JC
Thomas-Oates
Jane E
JE
Matsumoto
Tsukasa
T
Yamada
Haruki
H
Patel
Trushar
T
Petersen
Dirk
D
Michaelsen
Terje E
TE
Diallo
Drissa
D
Paulsen
Berit Smestad
BS
D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D000897:Anti-Ulcer Agents / Q000737:chemistry / Q000494:pharmacology; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D031212:Bixaceae / Q000737:chemistry*; D002478:Cells, Cultured; D003168:Complement Fixation Tests; D003165:Complement System Proteins / Q000187:drug effects* / Q000276:immunology*; D005260:Female; D005685:Galactans / Q000737:chemistry* / Q000494:pharmacology*; D006031:Glycosylation; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008934:Mitogens / Q000737:chemistry / Q000494:pharmacology*; D008938:Mitosis / Q000187:drug effects; D008970:Molecular Weight; D009005:Monosaccharides / Q000737:chemistry; D009792:Oceans and Seas; D010368:Pectins / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship; D035741:Vernonia / Q000737:chemistry*
D000596:Amino Acids; D000897:Anti-Ulcer Agents; D005685:Galactans; D008934:Mitogens; D009005:Monosaccharides; D010368:Pectins; D003165:Complement System Proteins; C005653:arabinogalactan