In Vitro Assessment of Cytoprotective Effects of CANOVA against Cell Death Induced by the Anti-malarial Artesunate - A Preliminary Experiment.

BACKGROUND: Artesunate (ATS) is a semi-synthetic compound derived from artemisinin, which is widely accepted in the treatment of malaria. However, there is evidence that ATS, under certain in vitro conditions, induces several impairments to normal cell functions. Canova (CA) is a Brazilian homeopathic formulation indicated for patients with depressed immune system. CA shows both in vitro and in vivo protective effects against mutagenic/carcinogenic compounds. Therefore, we aimed to assess in vitro the cytoprotective effects of CA against the cytotoxicity of ATS in Vero cells. METHODS: Viability of Vero cells exposed to ATS was assessed by MTT assay, whereas the anti-cytotoxic effect of CA was evaluated by apoptosis and necrosis quantification with fluorescent dyes. RESULTS: After 24 hours of ATS treatment, a reduction in cell viability was observed at 32 and 64 µg/mL, the latter being statistically significant (p < 0.05) in relation to the negative control. The concentration of 64 µg/mL was chosen for the subsequent experiments. ATS significantly induced both apoptosis and necrosis in Vero cells in relation to controls (p < 0.01). We also observed a statistically significant decrease in the number of apoptotic cells observed in the CA 16% + ATS co-treatment compared with ATS treatment (p < 0.01). Treatment with CA alone also had no influence on either type of cell death. CONCLUSION: Our results demonstrated that ATS is cytotoxic in the assessed conditions. However, such cytotoxicity was attenuated when the cells were treated simultaneously with ATS and CA.

Selective inhibitory effect of bufalin on growth of human tumor cells in vitro: association with the induction of apoptosis in leukemia HL-60 cells.

We found that bufalin, an active principle of the Chinese medicine chan'su, has selective inhibitory effects on the growth of various human cancer cells. In order to examine whether the growth-inhibitory effect of bufalin on human cancer cells is associated with apoptosis, human leukemia cells were treated with bufalin. HL-60, ML1, and U937 leukemia cells treated with bufalin at 10(-8) M and above had condensed and fragmented nuclei. Flow cytometric analysis of these cells treated with bufalin showed fragmented DNA smaller than that of the G1 phase. DNA of HL-60 cells treated with bufalin showed a ladder pattern characteristic of apoptosis, as analyzed by agarose gel electrophoretic analysis. DNA synthesis and topoisomerase II activity of HL-60 cells were markedly inhibited as the concentration of bufalin was increased. The concentration needed for inducing apoptosis of HL-60 cells was 10(-8) M, which is comparable to that of camptothecin, but lower than those of other antitumor drugs such as cisplatin, VP16 and all-trans retinoic acid. Apoptosis was not observed when human mononuclear and polymorphonuclear cells were treated with 10(-6) M bufalin for 24 h. These results indicate the association of the growth-inhibitory effect of bufalin with the induction of apoptosis, at least in HL-60 cells, and suggest the usefulness of bufalin for differentiation-apoptosis-inducing therapy for cancer.