Genotoxic, cytostatic, antineoplastic and apoptotic effects of newly synthesized antitumour steroidal esters.

In this study, we have investigated the genotoxic, cytostatic, antineoplastic and apoptotic effects of three newly synthesized modified steroidal esters, having as alkylating agent p-N,N-bis(2-chloroethyl) aminophenyl butyrate (CHL) or p-N,N-bis(2-chloroethyl) aminophenyl acetate (PHE) esterified with the steroidal nucleus modified in the B- and D-ring. The genotoxic and cytotoxic effects of the compounds were investigated both in vitro, in lymphocyte cultures obtained from blood samples of healthy donors and in vivo, in ascites cells of P388 leukemia obtained from the peritoneal cavity of DBA/2 mice. Preparations were scored for sister-chromatid exchange (SCE) and proliferation-rate indices (PRI). The newly synthesized compounds were also studied for antineoplastic activity against lymphocytic P388 and lymphoid L1210 leukemias in mice, by calculating the mean of the median survival of the drug-treated animals (T) versus the untreated control (C) (T/C%). The activity of caspase-2 and caspase-3, indicators of apoptosis, was assessed biochemically in primary cultures of human lymphocytes. Our results show that the newly synthesized compounds caused severe genotoxic effects by significantly increasing the frequency of SCE and decreasing the PRI values in cultures of peripheral lymphocytes in vitro and in ascites cells of lymphocytic P388 leukemia in vivo. A significant correlation was also observed in both the in vitro and in vivo experiments: the higher the SCE frequency the lower the PRI value (r=-0.65, P<0.001 and r=-0.99, P<0.01, respectively). The measured antileukemic potency was statistically increased by all test compounds in both types of tumours, while the activity of caspase-2 and caspase-3 showed a statistically significant increase after two periods of exposure. The genotoxic (increase of SCE), cytostatic/cytotoxic (decrease of PRI) and antileukemic effects (increase of T/C%) in combination with the induction of apoptosis (activation of caspase-2 and caspase-3) caused by the newly synthesized compounds, lead us to propose them as agents with potentially antineoplastic properties.

Brosimacutins J-M, four new flavonoids from Brosimum acutifolium and their cytotoxic activity.

Four new flavonoids, brosimacutins J-M (1 - 4), were isolated from the bark of Brosimum acutifolium Huber together with a known flavan, brosimine A (5). The structures of compounds 1-4 were elucidated by spectroscopic means. 27 constituents of this plant including compounds 1-5 were evaluated for their cytotoxic activity against murine leukemia P388 cells. Although no compounds tested had any reversal effect on vincristine resistance, brocimacutins J-M (1-4) were cytotoxic to vincristine-resistant P388 cells (IC50 4.4 - 19 microg/mL).

New cytotoxic biflavonoids from Selaginella delicatula.

Five new biflavonoids, robustaflavone 7,4',4'''-trimethyl ether, robustaflavone 4',4'''-dimethyl ether, 2,3-dihydroamentoflavone 7,4',7''-trimethyl ether, 2,3-dihydroamentoflavone 7,4'-dimethyl ether, and 2'',3''-dihydroisocryptomerin 7-methyl ether, together with six known compounds have been isolated from the aerial parts of Selaginella delicatula. The structures of these new compounds were determined through spectral analyses. Among the isolates, robustaflavone 4',4'''-dimethyl ether, 2,3-dihydroamentoflavone 7,4'-dimethyl ether, and alpha-tocopheryl quinone exhibited cytotoxicities (ED50 values < 4 microg/mL) against P-388 and/or HT-29 cell lines in vitro.

Shiquandabutangjiaweibang inhibits tumor metastasis and angiogenesis via regulation of topoisomerase-1.

Shiquandabutangjiaweibang (SDJ) is a traditional medicine prescription used for increasing body resistance against cancer. In the present study, the effect of SDJ extract on tumor metastasis and angiogenesis was evaluated. SDJ showed cytotoxicity against P388 (leukemia cells) and B16-F10 (murine melanoma cells) to 60% of control at 1 mg. SDJ significantly inhibited lung metastasis and also restored the number of platelets in C57BL/6 mice with thrombocytopenia induced by intravenous injection of B16-F10 cells. SDJ significantly disrupted chick embryonic angiogenesis in the chorioallantoic membrane (CAM). Interestingly, SDJ suppressed DNA topoisomerase I in a concentration-dependent manner. These results suggest that SDJ can be a potent inhibitor of metastasis and angiogenesis, at least in part, via regulation of topoisomerase I.

Effect of testosterone on growth of P388 leukemia cell line in vivo and in vitro. Distribution of peripheral blood T lymphocytes and cell cycle progression.

In transplanted mice, the P388 tumor grew better in castrated than in non castrated (NC) mice. The proportion of CD8+ in the blood was more numerous in NC mice. The T cell subsets (CD4+ and CD8+) were also high in the mice with small tumor tissue (<10 mg). The correlation observed between the tumor weight and T cell subset in PBL and in the mice with small tumors could confirm the important intervention of CD4+ and CD8+ cells to inhibit growth of tumor. Depo-testosterone (DT) injection reduced strongly weight and tumor growth in mice and DT administration induced a significant increase in the percentage of blood CD8+ cells in grafted mice. The effect of DT was studied on the cell cycle progression, in the tumor tissue of P388 tumor bearing BDF1 mice and in the P388 murine leukemia cell line in culture. The cell cycle analysis showed that DT decreased both the cells in S phase and the proliferating leukemic cells, with accumulation of the cells in G0/G1 phase. The testosterone can inhibit the proliferation of leukemic cells with a pharmacological dose (10-7 M). This growth inhibition dose and time dependent was associated with cell cycle arrest; P388 cells accumulates in G0/G1 phase. We also observed a correlation between tumor weight and the percentage of cells in G0/G1 and the relative number of cells in proliferative state (S + G2/M). Our experiments showed that testosterone prevents the growth of tumor: indirectly by modulation of subsets T cells distribution and directly by alteration of the cell cycle.