Effect of Continuous and Intermittent Exercises on Oxidised HDL and LDL Lipids in Runners.

We studied the effects of different types of exercises on the concentrations of oxidised HDL (oxHDLlipids) and LDL lipids (oxLDLlipids), serum lipids, antioxidant potential, paraoxonase and malondialdehyde in endurance runners by performing both a 40-min continuous run (velocity corresponding to 80% VO2max) and a 40-min intermittent run (2-min run, velocity corresponding to 100% VO2max, and 2-min rest) using a treadmill. Blood samples were taken before exercise, after 20 and 40 min of exercise, and 15 and 90 min after the end of exercise. The concentrations of oxLDLlipids remained unchanged during the running tests, but after a 90-min recovery the concentrations decreased by 4% (P<0.05) for the intermittent run and by 16% (P<0.01) for the continuous run. The acute effect of the intermittent and continuous run increased the concentrations of oxHDLlipids by 26 and 25%, respectively (P<0.001 for both). Interestingly, oxHDLlipids did not increase after the first half of the run in middle-distance runners during the intermittent run, and a similar phenomenon was seen in marathon runners during the continuous run. These results may indicate that acute physical exercise increases the transport of lipid oxidation products by HDL, although a different training history or genetic background may alter these acute responses.

Weight gain and inflammation regulate aromatase expression in male adipose tissue, as evidenced by reporter gene activity.

Obesity and white adipose tissue (WAT) inflammation are associated with enhanced aromatization in women, but little is known about the regulation of aromatase (CYP19A1) gene expression in male WAT. We investigated the impact of weight gain and WAT inflammation on the regulation of CYP19A1 in males, by utilizing the hARO-Luc aromatase reporter mouse model containing a >100-kb 5'-region of the human CYP19A1 gene. We show that hARO-Luc reporter activity is enhanced in WAT of mice with increased adiposity and inflammation. Dexamethasone and TNFα, as well as forskolin and phorbol 12-myristate 13-acetate, upregulate hARO-Luc activity, suggesting the involvement of promoters I.4 and I.3/II. Furthermore, we show that diet enriched with antioxidative plant polyphenols attenuates WAT inflammation and hARO-Luc activity in obese males. In conclusion, our data suggest that obesity-associated WAT inflammation leads to increased peripheral CYP19A1 expression in males, and that polyphenol-enriched diet may have the potential to attenuate excessive aromatization in WAT of obese men.

The effects of equal caloric high fat and western diet on metabolic syndrome, oxidative stress and vascular endothelial function in mice.

AIM: Nutrition contributes to increased adiposity, but it remains to be determined whether high fat rather than Western diet exacerbates the development of obesity and other characteristics of metabolic syndrome and vascular function. METHODS: We studied the effects of high fat (45% kcal) diet (HFD) and equal caloric Western diet (WD) high in fat, sucrose and cholesterol for 8 weeks in male C57B1/6N mice. RESULTS: Mice fed with HFD and WD showed substantially higher body adiposity (body fat %) compared with control mice receiving low fat (10%) diet (LFD). However, total body weight was higher only in HFD mice compared with other groups. The amount of liver triglycerides, cholesterol and oxidative damage was higher in WD mice compared with mice on LFD. There were no significant differences in fasting blood glucose or serum insulin, serum or muscle triglycerides, glucose tolerance or systolic blood pressure between the groups, but serum free fatty acids were increased in HFD mice compared with LFD. Increased levels of tissue and serum diene conjugation as a marker of oxidative stress were evident especially in WD mice. The endothelium-dependent relaxations were significantly impaired in the small mesenteric arteries of HFD mice, but not in the aorta. Maximal relaxations correlated negatively with body adiposity in WD but not in HFD mice. CONCLUSIONS: The major finding in the present study is that without changing body weight, Western diet induces marked whole-body oxidative stress and elevates body adiposity, which associates with the endothelial function of resistance arteries.

High serum n6 fatty acid proportion is associated with lowered LDL oxidation and inflammation: the Cardiovascular Risk in Young Finns Study.

The intake of polyunsaturated fatty acids (PUFAs) is generally linked with a reduced cardiovascular disease (CVD) risk, but an elevated n6PUFA intake, without simultaneous n3PUFA supply, may elevate the risk. PUFAs are suspected as being easily oxidized and have a potential role in lipoprotein oxidation and inflammation. Saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) are resistant to oxidation. However, in a Western diet, their most important source is red meat, a food stuff rich in heme iron which can catalyze oxidative reactions. Therefore, different serum fatty acid (FA) proportions (free + esterified) were correlated with the status of low-density lipoprotein (LDL) oxidation in vivo (conjugated dienes = oxLDLlipids and antibody-based oxidized proteins = oxLDLprot) and inflammation (serum CRP) in 2196 Finnish subjects (age: 24-39 years) using CVD risk factor-adjusted linear regression models. High n6PUFA, PUFA/SFA and n6/n3 ratios, and low SFA and MUFA were all associated with reduced levels of oxLDLlipids, oxLDLprot, and CRP. These findings at the population level suggest that PUFAs are negatively and SFAs and MUFAs positively related with LDL oxidation and inflammation; these conclusions are in line with previous observations linking PUFAs, particularly n6PUFAs, with lower CVD risk, and SFAs with increased risk.

Decreased training volume and increased carbohydrate intake increases oxidized LDL levels.

We studied effects of probiotics and training volume on oxidized LDL lipids (ox-LDL), serum antioxidant potential (s-TRAP) and serum antioxidants (s-α-tocopherol, s-γ-tocopherol, s-retinol, s-ß-carotene and s-ubiquinone-10) in marathon runners during 3-months training period, 6-days preparation period and marathon run. Runners (n=127) were recruited for a randomized, double-blind intervention during which they received either Lactobacillus rhamnosus GG (LGG, probiotic group) or placebo drink (placebo group) during whole study. During the preparation period, subjects decreased training and increased carbohydrate intake. Blood samples were taken at baseline, before 6-days preparation, before and immediately after the marathon. Probiotics did not have any effect on ox-LDL, s-TRAP or serum antioxidants levels during the study. Interestingly, ox-LDL increased by 28% and 33% during the preparation period and decreased by 16% and 19% during the marathon run in the placebo and probiotic groups, respectively (in all, P<0.001). No changes were seen in s-TRAP before marathon, but during run s-TRAP raised by 16% in both groups (both, P<0.001). The increase of ox-LDL level during the preparative period after several months' training suggests that aerobic training may reduce the concentration of ox-LDL and that decrease of training together with increased energy intake, mainly carbohydrate, before marathon is capable of increasing the level of ox-LDL.

Both poor cardiorespiratory and weak muscle fitness are related to a high concentration of oxidized low-density lipoprotein lipids.

Good physical fitness is associated with favorable serum lipids. Oxidized low-density lipoprotein (ox-LDL) could be even more atherogenic than serum lipids. We studied the association of ox-LDL and serum lipids with physical fitness. Healthy young (mean age 25 years) men (n=846) underwent maximal oxygen uptake (VO(2max)) and muscle fitness index (MFI) tests and completed a leisure-time physical activity (LTPA) questionnaire. Age (ANCOVA1), age+waist circumference+systolic blood pressure+fasting blood glucose+smoking (ANCOVA3) were used as covariates. The groups with the lowest VO(2max), MFI and LTPA had 23%, 16% and 8% higher concentrations of ox-LDL than the groups with the highest VO(2max) (P<0.0001), MFI (P=0.022) and LTPA (P=0.039) groups, respectively. Subjects with poor fitness (low VO(2max) or low MFI) or low LTPA had elevated levels of ox-LDL/high-density lipoprotein (HDL)-cholesterol, total cholesterol, LDL-cholesterol, triglycerides and a low level of HDL-cholesterol (ANCOVA1, in all, P<0.05). Furthermore, low VO(2max) is associated with a high level of ox-LDL/HDL-cholesterol and triglycerides, and with a low level of HDL-cholesterol (ANCOVA3, in all, P<0.05). Also, subjects with low LTPA had a high ratio of ox-LDL/HDL-cholesterol (ANCOVA1, P=0.001). In conclusion, both poor fitness (both low VO(2max) and low MFI) and low LTPA are associated with a higher concentration of ox-LDL lipids and serum lipids, which may indicate a higher risk for atherosclerosis.

Different hormonal response to continuous and intermittent exercise in middle-distance and marathon runners.

In order to study the effects of different athletic backgrounds on exercise-induced hormonal responses, serum testosterone, luteinizing hormone, follicle-stimulating hormone and cortisol concentrations were measured before and after intensive continuous and intermittent running in well-trained middle-distance runners (MID) and marathon runners (MAR). They performed two 40-min exercises on a treadmill: a continuous run at an intensity of 80% [tempo run (TR)] and an intermittent run (IR) at an intensity of 100% of the velocity associated with VO(2max). The testosterone response to IR and the cortisol response to TR was higher (P<0.05) in MID compared with MAR. The testosterone response to IR correlated positively with the maximal blood lactate concentration achieved after the maximal running test (r=0.46, P<0.05, n=20), while the cortisol response to TR correlated negatively with the runner's VO(2max) (r=-0.62, P<0.05, n=20). In conclusion, a continuous running exercise resulted in a lower cortisol response in runners who are adapted for longer distances, and an intermittent running exercise resulted in a higher testosterone response in runners who are adapted to middle distances.

Carotid artery compliance in users of plant stanol ester margarine.

OBJECTIVE: To investigate the effects of stanol ester margarine use in healthy subjects on arterial compliance, endothelial function and intima-media thickness. DESIGN: Case-control study comparing regular stanol ester margarine users to non-users. SETTING: Occupational health service clinic. SUBJECTS: We recruited 50 cases and 50 controls (mean age 51+/-8, range 26-65 years). All subjects were non-smokers and the study groups were matched for age and sex. As cases, we invited subjects who had been using regularly (daily) plant stanol ester margarine for a period of 2 years or longer. Non-invasive ultrasound was used to measure carotid artery compliance, carotid intima-media thickness and brachial artery flow-mediated endothelial dependent vasodilatation. RESULTS: The carotid artery compliance was non-significantly higher in cases compared with controls, 1.84+/-1.02 vs 1.58+/-0.76 %/10 mm Hg (P=0.13). The difference in compliance became statistically significant (P=0.04) when the unbalance between the groups in family history of coronary artery disease and years of education were taken into account. There was also a significant dose-response relationship between stanol margarine use and carotid compliance, longer use being associated with higher compliance. Serum lipoproteins, blood pressure, flow-mediated dilation and intima-media thickness values did not differ between cases and controls. CONCLUSION: These data raise the possibility that regular stanol ester margarine use may be associated with beneficial changes in arterial compliance. Intervention studies are needed to test this hypothesis and to reveal possible mechanisms.

The expression of 8-hydroxydeoxyguanosine in oesophageal tissues and tumours.

PURPOSE: The most common marker of oxidative DNA damage is 8-hydroxydeoxyguanosine (8-OHdG), which is linked with several malignancies. In the present study we investigated whether DNA damage linked to oxidative stress (as 8-OHdG) is present in Barrett's mucosa with or without associated adenocarcinoma or high-grade dysplasia and in normal controls' squamous mucosa. EXPERIMENTAL DESIGN: We measured 8-OHdG in 51 patients (13 Barrett's metaplasia, six Barrett's oesophagus with high-grade dysplasia, 18 adenocarcinoma of the distal oesophagus/oesophagogastric junction and 14 normal controls). The amount of DNA damage was determined by high-performance liquid chromatography in oesophagus samples obtained either from endoscopy or as samples from surgery. The median 8-OHdG concentration was expressed as the ratio of 8-OHdG per 10(5) deoxyguanosine. RESULTS: Analysis revealed that 8-OHdG was present in both Barrett's metaplasia with and without dysplasia as well as in adenocarcinoma of the oesophagus/oesophagogastric junction. Although the study group was small the amount of 8-OHdG was significantly increased in the distal oesophagus both in Barrett's epithelium 1.26 (0.08-29.47) and in high-grade dysplasia 1.35 (1.04-1.65) as well as in adenocarcinoma of oesophagus/oesophagogastric junction 1.08 (0.59-1.94) compared to controls 0.06 (0-4.08) (p=0.002, p=0.012, p=0.001, respectively). Barrett's patients had no significant difference in 8-OHdG levels between their distal and proximal oesophageal samples. CONCLUSIONS: Our results show the presence of oxidative DNA damage in the distal oesophagus of patients with Barrett's oesophagus and adenocarcinoma of the oesophagus/oesophagogastric junction. This may have a connection to carcinogenesis in Barrett's oesophagus.

Successful weight maintenance preserves lower levels of oxidized LDL achieved by weight reduction in obese men.

OBJECTIVE: We studied the association between weight maintenance, oxidized low-density lipoprotein (ox-LDL) and other lipoproteins in obese men. METHODS: A 2-month weight reduction phase (WRP) with a very-low-energy diet was followed by a 6-month weight maintenance period and an unsupervised 2-year follow-up. Ninety men entered and 68 (76%) completed the study. Subjects were analyzed as one group and after division into two subgroups: 20 most successful men in maintaining the lost weight (subgroup 1) and the remaining (n=48) men (subgroup 2). Ox-LDL was measured by quantifying the amount of conjugated dienes in LDL particles. RESULTS: The mean (+/-s.d.) weight reduction at the end of the WRP (n=68) was 14% (confidence interval (CI) 12.9-14.7%, 14.5+/-4.2 kg, P<0.001). Ox-LDL decreased by 22% (CI 16.9-28.1, 12.3+/-15.4 micromol/l, P<0.001). At the end of the 2-year follow-up, the regain in weight from the end of the WRP was 11% (CI 9.0-12.4, 9.6+/-6.2 kg, P<0.001). The regain in ox-LDL was 30% (CI 18.7-41.2, 8.2+/-15.4 micromol/l, P<0.001). In subgroup 1 vs 2, the respective regains were 3% (CI 0.9-4.2, 2.2+/-3.0 kg, P=0.006) vs 14% (CI 12.7-15.6, 12.9+/-4.0 kg, P<0.001) regarding weight and 9% (2.0+/-6.9 micromol/l, P=NS) vs 39% (CI 23.7-53.9, 11.2+/-17.2 micromol/l, P

Acute prolonged exercise reduces moderately oxidized LDL in healthy men.

We studied the effects of a 2-day walk exercise (6 h+6 h) on the serum concentration of circulating moderately oxidized LDL (LDL baseline conjugated dienes), lipids (total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride), antioxidants (alpha-tocopherol, gamma-tocopherol, beta-carotene, and ubiquinol-10), and antioxidant potential in serum (S-TRAP) and LDL (LDL-TRAP) in healthy well-trained men. The exercise was performed twice with an interval of 14 days. While 6 h walking the subjects drank 6 cl . kg (-1) water which contained either carbohydrate (CHO trial) or placebo (PLA trial). During the 2-day exercise the level of oxidized LDL decreased by 25 % (p=0.001) in the PLA trial. At the same time serum gamma-tocopherol decreased by 20 % (p=0.049), while the other measured antioxidants remained unchanged and the serum antioxidant potential increased by 22 % (p=0.018). Serum total cholesterol decreased by 3 % (p=0.017), serum triglycerides by 22 % (p=0.001), and LDL-cholesterol by 14 % (p=0.045). HDL cholesterol increased by 9 % (p=0.001). The results in the carbohydrate trial were similar to the ones in the PLA trial. The findings suggest that exercise of long duration but of low, non-exhaustive intensity decreases the concentration of circulating oxidized LDL simultaneously with an increase in serum antioxidant potential in healthy trained men. Carbohydrate ingestion during the exercise does not have any further effect on these changes.

Decreased large artery distensibility in borderline hypertension is related to increased in vivo low-density lipoprotein oxidation.

The present study tested the hypothesis that reduced arterial elasticity seen in hypertension is related to increased oxidation of LDL. Fifteen men with borderline hypertension (BHT), with blood pressure values classified as high normal (systolic blood pressure 130-140 mmHg or diastolic blood pressure 85-89 mmHg) were included. The control group comprised 22 men with normal blood pressure values (<135/80 mmHg) matched for age, body size and LDL-cholesterol level. Distensibility of aorta was measured using magnetic resonance imaging, and distensibility of the common carotid artery using ultrasound. Baseline LDL diene conjugation was used as a marker for ox-LDL. Aortic and carotid distensibilities were lower in the BHT men than in controls (1.4 +/- 0.6 vs. 1.9 +/- 0.6%/10 mmHg, p<0.05 for aortic distensibility; 2.9 +/- 0.9 vs. 3.6 +/- 0.6%/10 mmHg, p<0.05 for carotid distensibility). Ox-LDL was significantly higher in the BHT men than in controls (44 +/-15 vs. 28 +/- 8 micromol/L, p<0.01). In univariate analysis, ox-LDL associated with aortic distensibility (r=-0.43, p<0.05). In multivariate analysis, the differences in distensibilities between the groups disappeared when the values were adjusted for ox-LDL. These data show decreased arterial elasticity and increased LDL oxidation in young men with borderline hypertension, and suggest that oxidative modification of LDL particles may play a pathophysiological role in the development of reduced arterial distensibility in hypertension.

Oxygen uptake response during maximal cycling in hyperoxia, normoxia and hypoxia.

BACKGROUND: Oxygen uptake (VO2) on-kinetics is decelerated in acute hypoxia and accelerated in hyperoxia in comparison with normoxia during submaximal exercise. However, the effects of fraction of oxygen in inspired air (FIO2) on VO2 kinetics during maximal exercise are unknown. HYPOTHESIS: The effects of FIO2 on VO2 on-kinetics during maximal exercise are similar to submaximal exercise. METHODS: There were 11 endurance athletes who were studied during maximal 7-min cycle ergometer exercise in hyperoxia (FIO2 0.325), hypoxia (FIO2 0.166) and normoxia (FIO2 0.209). The individual VO2 data were fit to a curve by using a three exponential model. RESULTS: In hypoxia, VO2 on-response amplitude during Phase 2 (approximately 20-100 s from the beginning of exercise) was lower (p < 0.05) when compared with hyperoxia; time constant of VO2 Phase 3 (beyond approximately 100 s after beginning of exercise) was shorter (p < 0.05) when compared with hyperoxia; and mean response time (MRT, O-63%) for VO2peak was shorter (p < 0.05) when compared with normoxia and hyperoxia. VO2peak was higher in hyperoxia (4.80 +/- 0.48 L x min(-1), p < 0.05) and lower in hypoxia (4.03 +/- 0.46 L x min(-1), p < 0.05) than in normoxia (4.36 +/- 0.44 L x min(-1)). CONCLUSIONS: Moderate hypoxia or hyperoxia do not affect VO2 time constants at the onset of maximal exercise. However, MRT for VO2peak is shortened in hypoxia. It is suggested that the differences in VO2peak and power output during the latter half of the test and the point that FIO2 was modified only moderately might explain most of the discrepancy with the previous studies.

No evidence for the in vivo activity of aromatase-inhibiting flavonoids.

Measurements of the aromatase-inhibiting and antioxidative capacities of flavonoids in vitro showed that slight changes in flavonoid structure may result in marked changes in biological activity. Several flavonoids such as 7-hydroxyflavone and chrysin (5,7-dihydroxyflavone) were shown to inhibit the formation of 3H-17beta-estradiol from 3H-androstenedione (IC(50)<1.0 microM) in human choriocarcinoma JEG-3 cells and in human embryonic kidney cells HEK 293 transfected with human aromatase gene (Arom+HEK 293). Flavone and quercetin (3,3',4',5,7-pentahydroxyflavone) showed no inhibition (IC(50)>100 microM). None of the requirements for optimal antioxidative capacity (2,3-double bond with 4'-hydroxy group, 3-hydroxyl group, 5,7-dihydroxy structure and the orthodihydroxy structure in the B-ring) is relevant for the maximum inhibition of aromatase by flavonoids. After oral administration to immature rats at a dose of 50 mg/kg body weight, which considerably exceeds amounts found in daily human diets, neither aromatase-inhibiting nonestrogenic flavonoids, such as chrysin, nor estrogenic flavonoids, such as naringenin and apigenin, induced uterine growth or reduced estrogen- or androgen-induced uterine growth. The inability of flavonoids to inhibit aromatase and, consequently, uterine growth in short-term tests may be due to their relatively poor absorption and/or bioavailability.

Reduced oxidized low-density lipoprotein after weight reduction in obese premenopausal women.

BACKGROUND: Several studies support the hypothesis that oxidation of low-density lipoprotein (LDL) promotes atherogenesis. Obesity is one of the risk factors of atherosclerosis, but it is not known whether obesity is related to LDL oxidation. OBJECTIVE AND DESIGN: We investigated the effect of weight reduction and subsequent weight maintenance program on LDL oxidation in 77 obese premenopausal women (BMI 29-46 kg/m(2)). Another group of seven obese women served as a control group. Oxidized LDL was measured as baseline concentration of conjugated dienes in LDL lipids (ox-LDL). The weight reduction was performed in 12 weeks, using a very-low-energy diet. RESULTS: The mean weight loss was 13 kg (92 vs 79 kg). During weight reduction, the concentration of LDL cholesterol decreased by 11%, the concentration of ox-LDL decreased by 40%, and the ratio of ox-LDL to LDL by 33%. The concentration of LDL antioxidant capacity (LDL-TRAP) decreased by 8%, but the decrease was caused by the decrease in LDL. The concentration of LDL, ox-LDL or LDL-TRAP did not change in the control group. The weight reduction correlated with the decrease of ox-LDL. During the subsequent 9 month weight maintenance programme, the concentrations of serum LDL (10%), ox-LDL (11%), LDL-TRAP (29%), and the ratio of LDL-TRAP to LDL (21%) decreased. CONCLUSION: This study strengthens the evidence that the risk of atherogenesis is influenced favourably by weight reduction in obese women. This risk reduction is associated with a reduced oxidation of LDL.

Reduced myocardial flow reserve relates to increased carotid intima-media thickness in healthy young men.

Increased carotid artery wall thickness and lipoprotein oxidation are key early events in atherosclerosis. To test the hypothesis that reduced myocardial flow reserve is a marker of subclinical atherosclerosis, we examined the relationships between flow reserve and carotid artery intima-media thickness (IMT) in young men free from coronary heart disease. Basal and dipyridamole stimulated coronary blood flow was measured using positron emission tomography (PET) in 55 healthy men aged 36+/-4 years. Myocardial flow reserve was calculated as the ratio of stimulated flow to basal flow. The mean carotid artery IMT was measured using high-resolution ultrasound. Oxidised LDL was measured as baseline LDL diene conjugation. Myocardial flow reserve decreased across the quartiles of increasing IMT (P=0.006), and was 5.2+/-1.9 in the lowest quartile for IMT and 3.7+/-1.2 in the highest (P=0.04, I vs. IV quartile). In univariate analysis, oxidised LDL correlated inversely with flow reserve (r=-0.35, P=0.01) and directly with IMT (r=0.51, P<0.001). The association between flow reserve and IMT remained significant (P< or =0.01) in multivariate regression model including age, blood pressure, left ventricular mass, ox-LDL, total cholesterol, HDL-cholesterol and triglycerides as covariates. These data support the concept that reduced myocardial flow reserve reflects subclinical atherosclerosis in asymptomatic subjects, and suggest that increased lipoprotein oxidation is directly related to early structural and functional atherosclerotic vascular changes.

Oxidized LDL and thickness of carotid intima-media are associated with coronary atherosclerosis in middle-aged men: lower levels of oxidized LDL with statin therapy.

We investigated the relation between serum lipids including oxidized LDL and the severity of coronary atherosclerosis. Serum lipids and oxidized LDL was measured in 62 men (33-66 years), who underwent diagnostic coronary angiography and sonography to measure the carotid intima-media thickness. LDL oxidation was found in chemical analyses to be due to conjugated fatty acids in cholesteryl esters and triglycerides. Regression analysis indicated that the carotid intima-media thickness and the ratio of LDL diene conjugation to LDL cholesterol (the ox-LDL:LDL ratio) were the only factors associated independently with the severity of coronary atherosclerosis. The patients with multi-vessel disease who did not use lipid lowering therapy had a 50% thicker carotid intima media (P = 0.030) and a 41% higher ox-LDL:LDL ratio (P = 0.020) than patients with normal vessels. Further, patients with multi-vessel disease on statin therapy had a 24% lower ox-LDL:LDL ratio than the subjects with multi-vessel disease who did not use lipid lowering drugs (P = 0.027), although the concentration of LDL cholesterol did not differ between the groups. This study supports the hypothesis that lipid oxidation plays a role in the development of atherosclerosis.

Total phenolics concentration and antioxidant potential of extracts of medicinal plants of Pakistan.

Thirty-seven plant organs, traditionally used as drugs, collected in Pakistan, were extracted with 70% acetone and analyzed for their total phenolics concentration and antioxidant potential. Seven extracts showed more than 85% inhibition of lipid peroxidation in vitro as compared with blank. Butylated hydroxytoluene (BHT) (IC50 = 233.6 microg/l +/- 28.3) was the strongest antioxidant in our test system. The IC50 results indicate that the extracts of Nymphaea lotus L. flowers, Acacia nilotica (Linn.) Delile beans, Terminalia belerica Roxb. fruits, and Terminalia chebula Retz. (fruits, brown) were stronger antioxidants than alpha-tocopherol, while Terminalia chebula Retz. (fruit coat), Terminalia chebula Retz. (fruits, black) and Ricinus communis L. leaves were weaker antioxidant extracts than alpha-tocopherol and BHT. Total phenolics concentration, expressed as gallic acid equivalents, showed close correlation with the antioxidant activity. High performance liquid chromatographic analysis with diode array detection at 280 nm, of the seven extracts indicated the presence of hydroxybenzoic acid derivatives, hydroxycinnamic acid derivatives, flavonol aglycones and their glycosides as main phenolics compounds. This information, based on quick screening methods, enables us to proceed towards more detailed chemical and pharmacological understanding of these plant materials.

Oxidative stress and AP-1 activity in tamoxifen-resistant breast tumors in vivo.

BACKGROUND: Most breast cancers, even those that are initially responsive to tamoxifen, ultimately become resistant. The molecular basis for this resistance, which in some patients is thought to involve stimulation of tumor growth by tamoxifen, is unclear. Tamoxifen induces cellular oxidative stress, and because changes in cell redox state can activate signaling pathways leading to the activation of activating protein-1 (AP-1), we investigated whether tamoxifen-resistant growth in vivo is associated with oxidative stress and/or activation of AP-1 in a xenograft model system where resistance is caused by tamoxifen-stimulated growth. METHODS: Control estrogen-treated, tamoxifen-sensitive, and tamoxifen-resistant MCF-7 xenograft tumors were assessed for oxidative stress by measuring levels of antioxidant enzyme (e.g., superoxide dismutase [SOD], glutathione S-transferase [GST], and hexose monophosphate shunt [HMS]) activity, glutathione, and lipid peroxidation. AP-1 protein levels, phosphorylated c-jun levels, and phosphorylated Jun NH(2)-terminal kinase (JNK) levels were examined by western blot analyses, and AP-1 DNA-binding and transcriptional activities were assessed by electrophoretic mobility shift assays and a reporter gene system. All statistical tests are two-sided. RESULTS: Compared with control estrogen-treated tumors, tamoxifen resistant tumors had statistically significantly increased SOD (more than threefold; P=.004) and GST (twofold; P=.004) activity and statistically significantly reduced glutathione levels (greater than twofold; P<.001) and HMS activity (10-fold; P<.001). Lipid peroxides were not significantly different between control and tamoxifen-resistant tumors. We observed no differences in AP-1 protein components or DNA-binding activity. However, AP-1-dependent transcription (P=.04) and phosphorylated c-Jun and JNK levels (P<.001) were statistically significantly increased in the tamoxifen-resistant tumors. CONCLUSION: Our results suggest that the conversion of breast tumors to a tamoxifen-resistant phenotype is associated with oxidative stress and the subsequent antioxidant response and with increased phosphorylated JNK and c-Jun levels and AP-1 activity, which together could contribute to tumor growth.