A water-soluble glucan, NLC-A, from the roots of Rhamnus heterophyllus Olive was obtained as a homogeneous component as determined by HPLC. NLC-A was shown to compose of D-glucose, and its MW was estimated to be 1.2 x 10(4). Methylation analysis, peroxidation analysis, Smith degradation and reaction with I2-KI showed that NLC-A is a (1----4) linked alpha-D-glucan to which are attached glucosyl side chains at 0-6 of the glucosyl residues of the main chain.