Anti-hepatoma activity of the stiff branched β- d -glucan and effects of molecular weight

exhibited the highest inhibition ratio of ∼77% against H22 tumour, even significantly higher than the positive control of cytoxan. The immunohistochemical and western blot analyses revealed that the AF1 glucans triggered cell apoptosis, indicated by the activation of caspase 3/9 and down-regulated tumour angiogenesis factors of VEGF and CD31. The underlying antitumor mechanism was suggested to induce tumour cell apoptosis and to inhibit angiogenesis in tumour tissues via enhancement of the immune-response. Taken together, the AF1 β-glucan was a potent natural drug candidate with high anti-cancer activities and less cytotoxicity, and the AF1 sample with a moderate molecular weight existed in aqueous solution as a more extended chain conformation, which plays an important role in activating immune responses.