Our data demonstrates that E + Q plays a protective role against the imbalance elicited by CsA between the production of free radicals and antioxidant defence systems, and suggests that a combination of these two antioxidants may find clinical application where cellular damage is a consequence of ROS.

Insulin resistance (IR) and infertility are two major complications of polycystic ovary syndrome (PCOS), which are the results of changes in certain parts of the reproductive and metabolic systems. We aimed to observe the effect of quercetin on dehydroepiandrosterone (DHEA)-induced PCOS and insulin resistance in rats. All animals were divided into five groups and DHEA was used to induce PCOS. Bodyweight and ovarian morphology of all groups were observed. Fasting blood glucose and insulin levels were analysed. The homeostasis model assessment of insulin resistance (HOMA-IR) method was used for IR level determination. The expression of oestrogen receptor α (ERα) and glucose transporter 4 (GLUT4) genes in the uterus was examined by real-time polymerase chain reaction. Liver hexokinase (HK) and glucokinase (GK) activity was determined using spectrophotometry. Quercetin significantly improved the IR state in PCOS rats. PCOS resulted in a decrease in liver GK and an increase in liver HK specific activity, whereas quercetin increased both liver HK and GK activity. Our data also showed a significant reduction in uterine ERα and GLUT4 expression in the PCOS group, which was increased by quercetin. A remarkable effect of quercetin was the intensive reduction of PCOS-IR and significant induction of uterine GLUT4 and ERα gene expression; it could thus be a possible effective treatment for PCOS and its complications, IR and infertility.

Nicotine is a natural component of tobacco plants and is responsible for the addictive properties of tobacco. Nicotine has been recognized to result in oxidative stress by inducing the generation of reactive oxygen species (ROS). The purpose of this work was to estimate the hepatotoxicity effect of nicotine on viability and on antioxidant defense system in cultures of HepG2 cell line and the other hand, ameliorative effect of quercetin (Q) as an antioxidant was analyzed. Nicotine induced concentration dependent loss in HepG2 cell line viability. The results indicated that nicotine decreased activity of superoxide dismutase (SOD) and glutathione reductase (GR) and increased activities of catalase (CAT) and glutathione peroxidase (GPx) and glutathione (GSH) content in the HepG2 cells. Q significantly increased activity of SOD, GR and GSH content and decreased activity of GPX in nicotine + Q groups. Our data demonstrate that Q plays a protective role against the imbalance elicited by nicotine between the production of free radicals and antioxidant defense systems, and suggest that administration of this antioxidant may find clinical application where cellular damage is a consequence of ROS.

1. The aim of the present study was to investigate the effects of vitamin E and/or quercetin (Q) on renal function, oxygen radical concentrations in the kidney and some anti-oxidant enzyme activities in rats treated with cyclosporine A (CsA). 2. Groups of rats (270 +/- 15 g), on standard rat chow and water, received all their treatments by gavage for either 4 or 8 weeks. Control groups received either olive oil (0.5 mL) or 25% ethanol (0.5 mL) + olive oil (0.5 mL) per day as vehicle. All experimental groups received 25 mg CsA/kg per day in 0.5 mL olive oil. The vitamin E group received 100 mg vitamin E/kg per day in olive oil in addition to CsA treatment. The quercetin group received 15 mg of Q/kg per day in 0.5 mL of 25% ethanol in addition to CsA treatment. The vitamin E + quercetin group received the two anti-oxidants at the concentrations given in addition to CsA treatment. 3. Quercetin, at a concentration less than one-quarter of vitamin E, was more efficient in lowering blood urea nitrogen, serum creatinine and kidney malondialdehyde in CsA-treated rats. However, neither of the two anti-oxidants was able to normalize these analytes to control values after either 4 or 8 weeks treatment. 4. Quercetin (50 micromol/kg per day) elevated all renal anti-oxidant enzyme activities to values observed in the negative controls. However, vitamin E (232 micromol/kg per day) only normalized glutathione peroxidase activity at the end of either 4 or 8 weeks treatment. Combination treatment with the two anti-oxidants abolished all the ill-effects of CsA. 5. Combination treatment with the two anti-oxidants of renal transplant patients receiving CsA may be beneficial in ameliorating the chronic nephrotoxic effects of the important immunosuppressive drug CsA.

Osteoporosis is the most prevalent metabolic bone disease and one of the most important postmenopausal consequences. The aim of this study was to investigate the effects of quercetin (Q) and vitamin E (vitE) on ovariectomy‐induced osteoporosis. Animals were ovariectomized and treated with Q (15 mg/kg/day), vitE (60 mg/kg/day), estradiol (10 µg/kg/day), and Q (7.5 mg/kg/day) + vitE (30 mg/kg/day) for 10 weeks by gavage, and osteoporosis markers and messenger RNA (mRNA) expression of autophagy and apoptosis‐related genes were analyzed in serum and tibia of rats. Data indicated that ovariectomy resulted in development of osteoporosis as demonstrated by reduction in serum calcium, bone weight, bone volume, trabeculae volume, and the total number of osteocytes and osteoblasts, and increase in the total number of osteoclasts and serum osteocalcin. Total mRNA expressions of LC3, beclin1, and caspase 3 were also increased and bcl2 expression was decreased in the tibia. By reversing these changes, treatment with Q and vitE markedly improved osteoporosis. In conclusion, Q, and to a lesser extent, vitE, prevented osteoporosis by regulating the total number of bone cells, maybe through regulating autophagy and apoptosis.