The cytotoxicity of nine naphthoquinones (NQ) was assayed against HL-60 (leukaemia), MDA-MB-435 (... more The cytotoxicity of nine naphthoquinones (NQ) was assayed against HL-60 (leukaemia), MDA-MB-435 (melanoma), SF-295 (brain) and , all human cancer cell lines, and peripheral blood mononuclear cells (PBMC), as representatives of normal cells, after 72 h of incubation. 5-Methoxy-1,4naphthoquinone was the most active compound, showing IC 50 values in the range of 0.31 (1.7 M) in HL-60 to 0.88 g/mL (4.7 M) in SF-295 and IC 50 of 0.69 g/mL (3.7 M) against PBMC. With the introduction of a bromo-substituent in position 2 or 3 of juglone, the IC 50 significantly decreased, regardless of the position on the NQ moiety. However, compared with juglone methyl ether, the halogen substitution decreased the activity. To further understand the mechanism underlying the cytotoxicity of 5-methoxy-1,4-naphthoquinone, studies involving DNA fragmentation, cell cycle analysis, phosphatidyl serine externalization, mitochondrial depolarization and activation of caspases 8 and 3/7 were performed in HL-60 cell line, using doxorubicin as a positive control. The results indicate that the cytotoxic 5methoxy-1,4-naphthoquinone activates caspases 8 and 3/7 and thus induces apoptosis independent of mitochondria. * Data are presented as IC50 values and 95% of confidence interval for leukaemia (HL-60), melanoma (MDAMB-435), nervous system (SF-295), colon (HCT-8) cancer cells and peripheral blood mononuclear cells (PBMC). Doxorubicin (Dox) was used as a positive control. Experiments were performed in triplicate. nd -not determined.
Withaphysalins are C 28 -steroidal lactones structurally based on the ergostane skeleton that pos... more Withaphysalins are C 28 -steroidal lactones structurally based on the ergostane skeleton that possess antiproliferative activity against tumor cell lines. In the present study, the antileukemic actvity of withaphysalin O (1), M (2), and N (3) isolated from Acnistus arborescens, against two leukemic cell lines, HL-60 and K562, was evaluated, and the cytotoxicity compared with the effects on peripheral blood mononuclear cells (PBMC). All tested compounds reduced the number of viable cells of the tumor cell lines after 24 h of exposure, except for compound 2 against the K562 cell line. The reduction was time-and concentration-dependent, and the IC 50 values ranged from 0.7 to 3.5 μM after 72 h of incubation. In addition to the growth inhibitory properties, the drugs decreased DNA synthesis after 24 h of drug exposure evaluated by the 5-bromo-2´deoxyuridine incorporation method. None of the tested compounds reduced the number of PBMC (IC 50 > 20 μM) after 72 h of incubation, in contrast to doxorubicin that decreased viable cells and increased non-viable cells even after 24 h of incubation. Morphological analysis of treated cells using hematoxylin/eosin staining indicated the presence of necrotic cells for all tested compounds in HL-60, confirmed by the use of acridine orange/ethidium bromide staining. In addition to necrotic cells, K562 cells showed morphological alterations consistent with apoptosis.
Many compounds used in the treatment of cancer possess tubulin-interacting properties that lead t... more Many compounds used in the treatment of cancer possess tubulin-interacting properties that lead to mitotic arrest. Withaphysalins are potent cytotoxic compounds that are commonly found in plants belonging to the Solanaceae family, such as Acnistus arborescens; however, the cytotoxic mechanisms or molecular targets of these compounds remain unknown. Thus, the aim of this study was to evaluate the effects of whitaphysalins on cancer cell cycle progression and tubulin interaction. In this report, we show the antiproliferative activity of withaphysalin F and its effect in arresting cells in the G2/M phase of the cell cycle. These two effects are the result of the interference of withaphysalin F in the polymerization of microtubules. Withaphysalin F also induced DNA fragmentation, which can be related to an increase in mitochondrial membrane depolarization. These results suggest that interference of withaphysalin F in microtubule polymerization may induce cell cycle arrest in the G2/M phase and therefore contribute to growth inhibition of tumor cells in vitro. Taken together, these studies indicate that withaphysalin F could potentially be used as an anticancer drug.
The antiproliferative effects of twenty-eight tetrasubstituted olefins bearing a ferrocenyl group... more The antiproliferative effects of twenty-eight tetrasubstituted olefins bearing a ferrocenyl group, including six never-reported compounds, were evaluated against SF-295 (human glioblastoma), HCT-8 (human colon cancer), MDA-MB-435 (human melanoma) and HL-60 (human promyelocytic leukemia) using the MTT test. IC 50 values were determined for twenty-three active compounds and of these, ten compounds had IC 50 values lower than 2 mM on one or more cell lines. Of all the compounds, only two produced significant amounts of ROS on HL-60 cells, and ROS production and growth inhibition could not be correlated. The ten most antiproliferative compounds were tested for their hemolytic activity on mouse erythrocytes. Five compounds showing high antiproliferative activity and low hemolytic activity were thus identified for further study.
The cytotoxicity of nine naphthoquinones (NQ) was assayed against HL-60 (leukaemia), MDA-MB-435 (... more The cytotoxicity of nine naphthoquinones (NQ) was assayed against HL-60 (leukaemia), MDA-MB-435 (melanoma), SF-295 (brain) and , all human cancer cell lines, and peripheral blood mononuclear cells (PBMC), as representatives of normal cells, after 72 h of incubation. 5-Methoxy-1,4naphthoquinone was the most active compound, showing IC 50 values in the range of 0.31 (1.7 M) in HL-60 to 0.88 g/mL (4.7 M) in SF-295 and IC 50 of 0.69 g/mL (3.7 M) against PBMC. With the introduction of a bromo-substituent in position 2 or 3 of juglone, the IC 50 significantly decreased, regardless of the position on the NQ moiety. However, compared with juglone methyl ether, the halogen substitution decreased the activity. To further understand the mechanism underlying the cytotoxicity of 5-methoxy-1,4-naphthoquinone, studies involving DNA fragmentation, cell cycle analysis, phosphatidyl serine externalization, mitochondrial depolarization and activation of caspases 8 and 3/7 were performed in HL-60 cell line, using doxorubicin as a positive control. The results indicate that the cytotoxic 5methoxy-1,4-naphthoquinone activates caspases 8 and 3/7 and thus induces apoptosis independent of mitochondria. * Data are presented as IC50 values and 95% of confidence interval for leukaemia (HL-60), melanoma (MDAMB-435), nervous system (SF-295), colon (HCT-8) cancer cells and peripheral blood mononuclear cells (PBMC). Doxorubicin (Dox) was used as a positive control. Experiments were performed in triplicate. nd -not determined.
Withaphysalins are C 28 -steroidal lactones structurally based on the ergostane skeleton that pos... more Withaphysalins are C 28 -steroidal lactones structurally based on the ergostane skeleton that possess antiproliferative activity against tumor cell lines. In the present study, the antileukemic actvity of withaphysalin O (1), M (2), and N (3) isolated from Acnistus arborescens, against two leukemic cell lines, HL-60 and K562, was evaluated, and the cytotoxicity compared with the effects on peripheral blood mononuclear cells (PBMC). All tested compounds reduced the number of viable cells of the tumor cell lines after 24 h of exposure, except for compound 2 against the K562 cell line. The reduction was time-and concentration-dependent, and the IC 50 values ranged from 0.7 to 3.5 μM after 72 h of incubation. In addition to the growth inhibitory properties, the drugs decreased DNA synthesis after 24 h of drug exposure evaluated by the 5-bromo-2´deoxyuridine incorporation method. None of the tested compounds reduced the number of PBMC (IC 50 > 20 μM) after 72 h of incubation, in contrast to doxorubicin that decreased viable cells and increased non-viable cells even after 24 h of incubation. Morphological analysis of treated cells using hematoxylin/eosin staining indicated the presence of necrotic cells for all tested compounds in HL-60, confirmed by the use of acridine orange/ethidium bromide staining. In addition to necrotic cells, K562 cells showed morphological alterations consistent with apoptosis.
Many compounds used in the treatment of cancer possess tubulin-interacting properties that lead t... more Many compounds used in the treatment of cancer possess tubulin-interacting properties that lead to mitotic arrest. Withaphysalins are potent cytotoxic compounds that are commonly found in plants belonging to the Solanaceae family, such as Acnistus arborescens; however, the cytotoxic mechanisms or molecular targets of these compounds remain unknown. Thus, the aim of this study was to evaluate the effects of whitaphysalins on cancer cell cycle progression and tubulin interaction. In this report, we show the antiproliferative activity of withaphysalin F and its effect in arresting cells in the G2/M phase of the cell cycle. These two effects are the result of the interference of withaphysalin F in the polymerization of microtubules. Withaphysalin F also induced DNA fragmentation, which can be related to an increase in mitochondrial membrane depolarization. These results suggest that interference of withaphysalin F in microtubule polymerization may induce cell cycle arrest in the G2/M phase and therefore contribute to growth inhibition of tumor cells in vitro. Taken together, these studies indicate that withaphysalin F could potentially be used as an anticancer drug.
The antiproliferative effects of twenty-eight tetrasubstituted olefins bearing a ferrocenyl group... more The antiproliferative effects of twenty-eight tetrasubstituted olefins bearing a ferrocenyl group, including six never-reported compounds, were evaluated against SF-295 (human glioblastoma), HCT-8 (human colon cancer), MDA-MB-435 (human melanoma) and HL-60 (human promyelocytic leukemia) using the MTT test. IC 50 values were determined for twenty-three active compounds and of these, ten compounds had IC 50 values lower than 2 mM on one or more cell lines. Of all the compounds, only two produced significant amounts of ROS on HL-60 cells, and ROS production and growth inhibition could not be correlated. The ten most antiproliferative compounds were tested for their hemolytic activity on mouse erythrocytes. Five compounds showing high antiproliferative activity and low hemolytic activity were thus identified for further study.
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