Bioactive polysaccharides from the stems of the Thai medicinal plant Acanthus ebracteatus: their chemical and physical features

• Published in: Carbohydrate research Vol. 339; no. 4; pp. 753 - 762
• Main Authors: Hokputsa, Sanya, Harding, Stephen E, Inngjerdingen, Kari, Jumel, Kornelia, Michaelsen, Terje E, Heinze, Thomas, Koschella, Andreas, Paulsen, Berit S
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 15.03.2004
• Subjects: 3- O-Methylgalactose; Acanthaceae - chemistry; Acanthus ebracteatus; bioactive properties; Chromatography, Gel; Chromatography, Ion Exchange; Complement Fixation Tests; Complement fixing activity; Complement System Proteins - drug effects; Gas Chromatography-Mass Spectrometry; Hemolysis - drug effects; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; medicinal plants; Molecular Weight; Pectin; pectins; Plant Stems - chemistry; Plants, Medicinal - chemistry; Polysaccharides - chemistry; Polysaccharides - isolation & purification; Polysaccharides - pharmacology; Refractometry; structure-activity relationships; Pectin; 3- O-Methylgalactose; Complement fixing activity; Acanthus ebracteatus
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/j.carres.2003.11.022

Graphic Crude water-soluble polysaccharides were isolated from Acanthus ebracteatus by hot water extraction followed by ethanol precipitation after pre-treatment with 80% ethanol. The crude polysaccharides were separated into neutral and acidic polysaccharides by anion-exchange chromatography. The neutral polysaccharide (A1001) was rich in galactose, 3- O-methylgalactose and arabinose, whereas the acidic polysaccharide (A1002) consisted mainly of galacturonic acid along with rhamnose, arabinose and galactose as minor components indicating a pectin-type polysaccharide with rhamnogalacturonan type I (RG-1) backbone. 3- O-Methylgalactose is also present in the acidic fraction. Both neutral and acidic fractions showed potent effects on the complement system using pectic polysaccharide PM II from Plantago major as a positive control. A small amount of 3- O-methylgalactose present in the pectin seemed to be of importance for activity enhancement in addition to the amount of neutral sugar side chains attached to RG-1. The relationship between chemical structure and effect on the complement system of the isolated polysaccharides is considered in the light of these data. The presence of the rare monosaccharide 3- O-methylgalactose may indicate that this can be used as a chemotaxonomic marker. The traditional way of using this plant as a medical remedy appears to have a scientific basis.