Unravelling copper effect on the production of varietal thiols during Colombard and Gros Manseng grape juices fermentation by Saccharomyces cerevisiae

Nowadays the rapidly increasing organic vineyard management with the utilization of copper as sole fungal control pesticide against downy mildew raises once again the question of copper impact on varietal thiols in wine. For this purpose, Colombard and Gros Manseng grape juices were fermented under different copper levels (from 0.2 to 3.88  mg/l) to mimic the consequences in must of organic practices. The consumption of thiol precursors and the release of varietal thiols (both free and oxidized forms of 3-sulfanylhexanol and 3-sulfanylhexyl acetate) were monitored by LC-MS/MS. It was found that the highest copper level (3.6 and 3.88  mg/l for Colombard and Gros Manseng respectively) significantly increased yeast consumption of precursors (by 9.0 and 7.6% for Colombard and Gros Manseng respectively). For both grape varieties, free thiol content in wine significantly decreased (by 84 and 47% for Colombard and Gros Manseng respectively) with the increase of copper in the starting must as already described in the literature. However, the total thiol content produced throughout fermentation was constant regardless of copper conditions for the Colombard must, meaning that the effect of copper was only oxidative for this variety. Meanwhile, in Gros Manseng fermentation, the total thiol content increased along with copper content, resulting in an increase up to 90%; this suggests that copper may modify the regulation of the production pathways of varietal thiols, also underlining the key role of oxidation. These results complement our knowledge on copper effect during thiol-oriented fermentation and the importance of considering the total thiol production (reduced+oxidized) to better understand the effect of studied parameters and differenciate chemical from biological effects.

Evaluation of serum thiol-disulphide homeostasis parameters as oxidative stress markers in epilepsy patients

The present study focuses on the investigation of the dynamic thiol-disulphide homeostasis in patients with epilepsy and understanding the effects of antiepileptic drugs on thiol levels. A total of 148 participants, 75 of whom had epilepsy and 73 were healthy volunteers, were included in the study. Total thiol and native thiol levels of all epilepsy patients and healthy volunteers were measured. Disulphide level, disulphide/native thiol, disulphide/total thiol and native/total thiol ratios were calculated from these values. The results were compared between epilepsy patients and healthy volunteers. A statistically significant difference was found between native thiol level, total thiol level, disulphide level, disulfide/total thiol, disulphide/native thiol and native/total thiol ratios between patients with epilepsy and healthy volunteers (p = 0.002, p = 0.035, p < 0.001, p < 0.001, p < 0.001, p < 0.001, respectively). The drugs used had a significant effect on disulphide, disulphide/total thiol, native/total thiol levels (p values 0.004, 0.009, 0.009, respectively). Decreased levels of serum native, total thiol and increased disulfide levels as parameters of oxidative stress may be considered as parameters to explain the pathogenesis or consequences of epilepsy.

High concentration of MSG alters antioxidant defence system in lobster cockroach Nauphoeta cinerea (Blattodea: Blaberidae)

Objective

Monosodium glutamate (MSG) is a food additive that has been shown to be toxic to rodents at high concentrations. The available studies in Drosophila melanogaster suggest that MSG toxicity depends on concentration and gender, thus the safety of MSG as a food enhancer still requires further investigation. We have documented impaired locomotor activity and altered oxidative stress markers in cockroaches co-exposed to methylmercury and monosodium glutamate (MSG). We herein examined the susceptibility of Nauphoeta cinerea to high and low concentrations (4% and 1%) of MSG, while monitoring the activities of acetylcholinesterase (AChE), as well as markers of oxidative stress and antioxidant activity over 30 days.

Results

There was no significant alteration in the parameters assessed at 1% MSG while 4% MSG caused an increase in the activity of reactive oxygen and nitrogen species, with a corresponding reduction in the activities of acetylcholinesterase, glutathione-S-transferase and catalase, suggesting the capacity of MSG to alter redox homeostasis in Nauphoeta cinerea.

Dynamic thiol-disulphide homeostasis in low-grade gliomas: Preliminary results in serum

OBJECTIVE

Maintaining of precise balance between oxidation and anti-oxidation is important in both physiological and pathological states. Knowledge about this balance may give an idea about the process of the disease. The aim of this study was to investigate dynamic thiol-disulfide homeostasis in patients with low-grade gliomas.

PATIENTS AND METHODS

Serial serum samples were collected in 13 patients operated on low-grade gliomas before and after surgery. Control serum samples were obtained from venous cord blood from 13 healthy women during cesarean section. Total thiol, native thiol, and disulfide bond formation were measured and compared with the controls.

RESULTS

Total thiols, native thiols, and disulfide bond formation were significantly elevated in patients before the surgery compared to the controls (p<0.05). Even after the surgery, these three parameters were still high in patients, and the differences were significant (p<0.05). Although no significant difference was found between patients and controls regarding the ratios of disulfide/total thiol, disulfide/native thiol, and native thiol/total thiol (p>0.05), the balance seemed to shift to oxidative side.

CONCLUSIONS

Thiol-disulfide homeostasis was disrupted in patients with low-grade gliomas, and oxidation may play a role in the process of this disease. Supplementation with antioxidants before and after surgery may be taken into consideration.

A novel marker in acute central serous chorioretinopathy: thiol/disulfide homeostasis

PURPOSE

The aim of this study was to compare dynamic thiol/disulfide homeostatic status in acute central serous chorioretinopathy (CSCR) patients by using a novel and automated assay determining dynamic thiol/disulfide homeostasis.

METHODS

Fifty-one patients with acute CSCR (study group) and 65 healthy individuals (control group) were enrolled in this study. Diagnosis of acute CSCR was made clinically and using spectral-domain RTVue OCT (optical coherence tomography) (Optovue, Fremont, CA). Fluorescein angiography confirmed the diagnosis of acute CSCR in all subjects. Total thiol, native thiol, disulfide amount, and native thiol/disulfide ratio (TDR) were calculated in the blood samples.

RESULTS

Mean total thiol, native thiol, and native TDR values were lower in patients with acute CSCR (364.2 ± 14.1, 326.4 ± 13.2, 17.14 ± 1.9, respectively) than in healthy eyes (441.2 ± 16.3, 398.5 ± 16.4, 22.70 ± 2.15, respectively; mean total thiol, p = 0.017; native thiol, p = 0.011; native TDR, p = 0.031).

CONCLUSIONS

Total thiol, native thiol, and native TDR were significantly lower statistically in patients with acute CSCR when compared with healthy controls.

Evaluation of oxidative stress markers and intra-extracellular antioxidant activities in patients with endometriosis

OBJECTIVE

The aim of the study is to evaluate alterations in intracellular and extracellular antioxidant enzymes activities and serum oxidative stress markers in patients with endometriosis.

STUDY DESIGN

The current prospective study consisted of 31 female patients with endometriosis and 27 healthy controls. Serum total thiol, native thiol, disulphide, catalase, myeloperoxidase, and ceruloplasmin concentrations were measured. Laboratory and clinical data of all participants were recorded to compare the differences between the study and the control groups.

RESULTS

Serum native thiol and total thiol levels in the study group were significantly lower than those in the control group [(p=0.009, p=0.03, respectively)]. Serum catalase levels are significantly higher in patients with endometriosis comparing to the control group (p=0.009).

CONCLUSIONS

The finding that significant differences in serum total thiol, native thiol, and catalase levels observed in endometriotic patients supports that oxidative stress carries weigh in the pathophysiological aspects of endometriosis. Also significantly low levels of extracellular antioxidants and significantly high levels of intracellular antioxidants in endometriotic patients may arise from differences of free radicals in endometriosis and the activity levels of endometriosis. These non-invasive serum markers might give us an opportunity to monitor the disease's progress during the treatment.

A bioactive probe for glutathione-dependent antioxidant capacity in breast cancer patients: implications in measuring biological effects of arsenic compounds

INTRODUCTION

Glutathione, a major cellular non-protein thiol (NPSH), serves a central role in repairing damage induced by cancer drugs, pollutants and radiation and in the detoxification of several cancer chemotherapeutic drugs and toxins. Current methods measure glutathione levels only, which require cellular extraction, rather than the glutathione recycling dependent antioxidant activity in intact cells. Here, we present a novel method using a bioactive probe of the oxidative pentose phosphate cycle, termed the OxPhos™ test, to quantify glutathione recycling dependent antioxidant activity in whole blood and intact human and rodent cells without the need for the isolation and cytoplasm extraction of cells.

METHODS

OxPhos™ test kit (Rockland Immunochemicals, USA), which uses hydroxyethyldisulfide (HEDS) as a probe for the oxidative pentose phosphate cycle, was used in these studies. The results with OxPhos™ test kit in human blood and intact cells were compared with total thiol and high pressure liquid chromatography/electrochemical detection of HEDS metabolism.

RESULTS

The OxPhos™ test measured glutathione-dependent antioxidant activity both in intact human and rodent cells and breast cancer patient's blood with a better correlation coefficient and biological variability than the thiol assay. Additionally, human blood and mammalian cells treated with various arsenicals showed a concentration-dependent decrease in activity.

DISCUSSION

The results demonstrate the application of this test for measuring the antioxidant capacity of blood and the effects of environmental pollutants/toxins. It opens up new avenues for an easy and reliable assessment of glutathione-dependent antioxidant capacity in various diseases such as stroke, blood borne diseases, infection, cardiovascular disease and other oxidative stress related diseases and as a prognostic indicator of chemotherapy response and toxicity. The use of this approach in pharmacology/toxicology including screening drugs that improve the glutathione-dependent antioxidant capacity and not just the glutathione level is clinically relevant since mammalian cells require glutathione dependent pathways for antioxidant activity.

Protein and lipid oxidative damage in healthy students during and after exam stress

Oxidative damage at cellular level is thought to be one of the mechanisms in the pathogenesis of psychological stress (anxiety). The aim of this study was to investigate lipid and protein oxidative damage in exam anxiety conditions. Blood samples were collected in two stages (during the exam period and post vacation) from 51 healthy female students after responding to Beck Anxiety Inventory (BAI) and test anxiety questionnaire. Protein carbonyl, total thiol and malondialdehyde (MDA) levels were determined in serum. Participants reported significantly higher levels of subjective anxiety during the exam period than post vacation. Also the level of total thiol was significantly lower during the exam period compared with post vacation (p<0.001). Meanwhile, protein carbonyl and MDA levels during the exams were significantly higher than those in post-exam period (p<0.01). During the exam period, there was a negative correlation between serum total thiol levels and the severity of anxiety (r=-0.45, p<0.01). A significant positive correlation between the changes in serum protein carbonyl and MDA levels, also between those markers and anxiety score was found during the exam period. The high level of protein carbonyl and MDA, also low level of total thiol during the exam period demonstrated an oxidative damage to proteins and lipids in stress conditions. Our results suggest that oxidative damage to cellular compounds may be one of the mechanisms involved in the pathogenesis of anxiety.