A dimeric Phaseolus coccineus lectin with anti-oxidative, anti-proliferative and cytokine-inducing activities.

In the present study, a dimeric glucosamine binding lectin, designated as CHL, was purified from Phaseolus coccineus L. var. albonanus Bailey through three chromatographic steps. The molecular weight of CHL was approximately 66kDa. Its hemagglutinating activity toward rabbit erythrocytes was dependent on carbohydrates, especially glucosamine, and was stable at temperatures between 20 and 70°C, and at pH between 1 and 13. Intriguingly, further characterization showed that CHL served as a potent antioxidant to prevent erythrocytes from haemolysis induced by 2'-azobis (2-amidinopropane) dihydrochloride (AAPH) in a dose-dependent manner. Moreover, it exerted antitumor activity against human nasopharyngeal carcinoma CNE1 cells, hepatoma HepG2 cells, and breast cancer MCF7 cells but was devoid of antifungal activity. In addition, the CHL could bring about a significant dose-dependent increase in the production of mRNAs of pro-inflammatory cytokines including interferon-gamma and interleukin-2. These results suggest the potential therapeutic utility of CHL.