The effect-enhancing and toxicity-reducing activity of Hypericum japonicum Thunb. extract in murine liver cancer chemotherapy.

Chinese herbs are potential sources of antitumor drugs with immunoregulatory activity and few adverse effects. In the present study, we investigated whether the Hypericum japonicum Thunb. (HJT) extract enhanced the efficacy of 5-fluorouracil (5-FU) treatment in murine liver tumor xenografts and reduced toxicity of chemotherapy in hepatoma H22-bearing mice. Tumor weight and inhibition rate, thymus and spleen indices, as well as white blood cell (WBC) count were calculated. The phagocytic function of macrophages was assessed by observing peritoneal macrophages phagocytized chicken red blood cells (RBC). Body weight and toxic reactions of the chemotherapeutic and life prolongation rate were investigated in the mice. Results demonstrated that the HJT extract significantly enhanced the tumor inhibition rate of 5-FU, improved the immune function, reduced the toxic effects and prolonged the survival time in the tumor-bearing mice. Taken together, these results indicated that the HJT extract has a synergistic tumor-inhibiting effect with 5-FU, is able to reduce the toxic side effects and is likely to be safe and efficacious for use in antitumor therapy.