Comparative studies of the effects of Tabebuia avellanedae bark extract and β-lapachone on the hematopoietic response of tumour-bearing mice

The effects of Tabebuia avellanedae (TACE), traditionally prescribed in the treatment of cancer, and the naphtoquinone β-lapachone (β-lap) on the growth and differentiation of granulocyte and macrophage progenitor cells (CFU-GM) were studied in Ehrlich ascites tumour-bearing mice. Myelosuppression concomitant with increases in spleen CFU-GM and in serum colony-stimulating activity (CSA) were observed in these animals. Treatment with TACE (30–500 mg/kg) and β-lap (1–5 mg/kg) reversed these effects in a dose-dependent manner. The optimal biologically active doses of 120 mg/kg TACE and 1 mg/kg β-lap prolonged life span of tumour-bearing mice, both producing the same rate of extension in the duration of survival. Toxic manifestations were produced by the higher doses of β-lap in normal and tumour-bearing mice. In spite of similarities between treatments, TACE concentrations used to treat the animals presented no traces of β-lap, as measured by TLC and HPLC analyses. Our findings suggest that the antitumour effect of TACE and β-lap, acting synergistically with other factors, such as specific cytokines, may result from enhanced macrophage activation against tumour cells. In addition, it is clear from our results that hematopoietic disorders produced by tumours are an important pathological condition that must be considered in drug development.