Isolation and partial characterization of biologically active polysaccharides from <i>Plantago major</i> L.

Abstract

Abstract Polysaccharide fractions were isolated from Plantago Major L. leaves by extraction with cold water, hot water and with dimethylsulphoxide (DMSO). Each of the three crude extracts obtained was further separated by ionexchange chromatography. Only the two acidic fractions from the 50°C crude extract were biologically active, demonstrated by in vitro testing of activation of the complement system and induction of tumour necrosis factor alpha (TNF‐α) production from human monocytes. One of the fractions, PM I 50 , contains polysaccharide material comprising arabinose, galactose and xylose with smaller proportions of galacturonic acid, glucose, mannose and rhamnose. This fraction was further fractionated by size exclusion chromatography to give three fractions PM I a , PM I b and PM I c . PM I a is probably an arabinogalactan and PM I b is mainly a 1,4‐linked xylan. The other biologically active fraction, PM II 50 is composed of 75% galacturonic acid, 3% rhamnose, 6% arabinose and 8% galactose. Structure analysis indicates that PM II 50 is a pectin type polysaccharide.