Chemosensitivity of MCF-7 cells to eugenol: release of cytochrome-c and lactate dehydrogenase.

Phytochemicals have been extensively researched for their potential anticancer effects. In previous study, direct exposure of rat liver mitochondria to eugenol main ingredient of clove, uncoupled mitochondria and increased F0F1ATPase activity. In the present study, we further investigated the effects of eugenol on MCF-7 cells in culture. Eugenol demonstrated: a dose-dependent decrease in viability (MTT assay), and proliferation (real time cell analysis) of MCF-7 cells, (EC50: 0.9 mM); an increase in reactive oxygen species; a decrease in ATP level and mitochondrial membrane potential (MitoPT JC-1 assay); and a release of cytochrome-c and lactate dehydrogenase (Cytotoxicity Detection Kit PLUS) into culture media at eugenol concentration >EC50. Pretreatment with the antioxidants Trolox and N-acetyl cysteine partially restored cell viability and decreased ROS, with Trolox being more potent. Expression levels of both anti- and pro-apoptotic markers (Bcl-2 and Bax, respectively) decreased with increasing eugenol concentration, with no variation in their relative ratios. Eugenol-treated MCF-7 cells overexpressing Bcl-2 exhibited results similar to those of MCF-7. Our findings indicate that eugenol toxicity is non-apoptotic Bcl-2 independent, affecting mitochondrial function and plasma membrane integrity with no effect on migration or invasion. We report here the chemo-sensitivity of MCF-7 cells to eugenol, a phytochemical with anticancer potential.

Nigella sativa and thymoquinone suppress cyclooxygenase-2 and oxidative stress in pancreatic tissue of streptozotocin-induced diabetic rats.

OBJECTIVE: The aim of this study was to investigate the effect of Nigella sativa and thymoquinone (TQ) on oxidative stress, cyclooxygenase-2 (COX-2), and intracellular adhesion molecule-1 mRNA expression in the pancreas of streptozotocin (STZ)-induced diabetic rats as a model of type 1 diabetes. METHODS: Five experimental groups including control group, STZ-induced diabetic group, aqueous extract diabetic treated group, oil diabetic treated group, and TQ diabetic treated group were used to obtain the pancreatic tissue samples and serum for investigation. RESULTS: A significant increase in COX-2 mRNA expression was detected in STZ-induced diabetic group after 10 days of diabetes induction indicating an important role of the enzyme COX-2 in the inflammation accompanying STZ diabetes in contrast to that detected for intracellular adhesion molecule-1. Treatment of STZ diabetic rats with N. sativa aqueous extract and TQ significantly suppressed the expression of COX-2 enzyme in the pancreatic tissue. Nigella sativa and TQ treatment also suppressed pancreatic tissue lipid peroxidation malondialdehyde levels and increased the level of superoxide dismutase antioxidant enzyme correlated with the decrease in COX-2 mRNA expression. CONCLUSIONS: Results obtained in this study support a potential role for N. sativa and TQ in ameliorating inflammation during diabetes and preserving ß cells.

Effects of Nigella sativa and thymoquinone on biochemical and subcellular changes in pancreatic ß-cells of streptozotocin-induced diabetic rats.

BACKGROUND: The present study investigated the effects of Nigella sativa aqueous extract and oil, as well as thymoquinone, on serum insulin and glucose concentrations in streptozotocin (STZ) diabetic rats. METHODS: Rats were divided into five experimental groups (control, untreated STZ-diabetic, and aqueous extract-, oil-, or thymoquinone-treated diabetic rats). Treated rats received 2 mL/kg, i.p., 5%N. sativa extract, 0.2 mL/kg, i.p., N. sativa oil, or 3 mg/mL, i.p., thymoquinone 6 days/week for 30 days. Serum insulin and glucose concentrations, superoxide dismutase (SOD) levels, and pancreatic tissue malondialdehyde (MDA) were determined. Electron microscopy was used to identify any subcellular changes. RESULTS: Diabetes increased tissue MDA and serum glucose levels and decreased insulin and SOD levels. Treatment of rats with N. sativa extract and oil, as well as thymoquinone, significantly decreased the diabetes-induced increases in tissue MDA and serum glucose and significantly increased serum insulin and tissue SOD. Ultrastructurally, thymoquinone ameliorated most of the toxic effects of STZ, including segregated nucleoli, heterochromatin aggregates (indicating DNA damage), and mitochondrial vacuolization and fragmentation. The aqueous extract of N. sativa also reversed these effects of STZ, but to a lesser extent. The N. sativa oil restored normal insulin levels, but failed to decrease serum glucose concentrations to normal. CONCLUSIONS: The biochemical and ultrastructural findings suggest that N. sativa extract and thymoquinone have therapeutic and protect against STZ-diabetes by decreasing oxidative stress, thus preserving pancreatic ß-cell integrity. The hypoglycemic effect observed could be due to amelioration of ß-cell ultrastructure, thus leading to increased insulin levels. Consequently, N. sativa and thymoquinone may prove clinically useful in the treatment of diabetics and in the protection of ß-cells against oxidative stress.