Structural studies of an immunostimulating gluco-arabinan from seeds of Caesalpinia bonduc

► A water-soluble gluco-arabinan (PS-II) was isolated from alkaline extract of seeds of Caesalpinia bonduc. ► The structure of this polysaccharide (PS-II) was established by chemical and 2D NMR studies. ► Comparison studies of immunostimulating properties between gluco-arabinan (PS-II) and arabinan (PS-I) were carried out.