Bioassay guided purification of an immunomodulatory polysaccharide from roots of Tinospora cordifolia

The interest of researchers in medicinal plants as natural sources has noticeably increased in the past 20 years. Further particular attention has been given to substances, which are used as folklore medicines. Plant polysaccharides have been extensively studied for their antitumor, antibacterial and antifungal properties. Certain polysaccharides from herbs possess immuno-enhancing effects, such as the augmentation of spleen lymphocyte functions. Hence the present investigation was carried out towards isolation and activity based purification of one such immunologically active polysaccharide (arabinogalactan) from the roots of Tinospora cordifolia (Menispermaceae). Fractionation of crude isolated polysaccharide was carried out using sephacryl S-400 GPC column followed by in vitro mitogenic stimulation of mice spleen lymphocytes. The cells were pulsed with ³H Thymidine (1µCi/well) and the amount of radioactivity incorporated into DNA was measured using liquid scintillation counter. Results revealed that fraction-II exhibited a higher stimulation index (S.I.=17) as compared to that of both fraction-I (S.I.=12) and crude (S.I.=11). Further, on structure elucidation of fraction-II by qualitative sugar analysis, ¹HNMR-spectroscopy and partial acid hydrolysis revealed predominantly, the presence of arabinogalactan in the pure fraction.

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