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To improve the antioxidant activity, sulfhydryl groups (-SH) were introduced into chitosan. Acylated chitosan derivatives, chitosan cationic salt derivatives, hydroxypropyl trimethylammonium chloride chitosan quaternary ammonium salt (HACC) derivatives and N,N,N-trimethyl chitosan iodine (TMC) derivatives were obtained. The chitosan derivatives were characterized by FTIR and 1H NMR to confirm the successful synthesis. Ellman's reagent was used to determine that the compound contained free sulfhydryl groups. The water solubility and thermal stability of chitosan and derivatives were evaluated. The antioxidant activities of the derivatives were verified, including DPPH radical scavenging activity, superoxide anion radical scavenging activity and reducing power activity. The novel chitosan derivatives showed excellent antioxidant activities. Toxicity assay used L929 cells proved that the derivatives had no significant toxic. The results showed that the chitosan derivatives bearing sulfhydryl groups described in this paper has a certain antioxidant effect, which provides a practical approach for further study of chitosan.

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Angiotensin-converting enzyme inhibitors (ACEIs) reduce arterial stiffness beyond their antihypertensive effect. Studies showed that sulfhydryl ACEIs have the antioxidative potential to improve endothelial function, which might have a clinical effect on arterial distensibility. However, there are no studies that directly compare the effects of sulfhydryl (zofenopril) and non-sulfhydryl ACEIs (enalapril) on arterial stiffness. Therefore, this prospective study aims to compare the effects of enalapril and zofenopril on arterial stiffness and oxidative stress in both short- and long-term treatment of arterial hypertension (AH). Baseline and post-treatment peripheral and central arterial pressure indices, augmentation index (Aix), aortic pulse wave velocity (ao-PWV), serum levels of oxidized low-density cholesterol lipoprotein, LDL and uric acid (UA) were measured. The results showed that acute treatment with zofenopril, in contrast to enalapril, significantly decreased peripheral and central Aix (p < 0.001). Chronic treatment with zofenopril showed a superior effect over enalapril on the reduction of the peripheral systolic arterial pressure with reduction of ao-PWV (p = 0.004), as well as a reduction in peripheral Aix (p = 0.021) and central Aix (p = 0.021). Therefore, this study indicates that zofenopril has beneficial effects on the reduction of arterial stiffness compared to enalapril. It has potent clinical efficacy in AH treatment and further studies should compare its safety and long-term efficacy to other AH drugs that would aid clinicians in treating AH and other various cardiovascular diseases that have arterial stiffness as a common denominator.

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According to the Food and Agriculture Organization (FAO), protein demand is expected to increase globally by around 40% by 2030 as a response to the world's population growth. Due to their clean label, vegan or vegetarian based applications, nutritional value, and cost-efficient properties, plant-based proteins have been widely studied. However, most of the alternatives currently found in the market have some challenges because of their poor solubility, emulsifying, gelling, and foaming attributes. Hemp seed protein has gained increasing attention due to its unique amino acids and fatty acids profiles. In this study, commercial HPC mixtures were adjusted to pH 2, 4, 6, 8, 10, and 12 followed by ultrasonication (US) for 5 min (5 s on: 5 s off) and incubated for an hour before neutralizing to pH 7. Following the treatments, the samples were analyzed for their hydrodynamic diameter, conductivity, zeta potential, polydispersity index, surface hydrophobicity, solubility, electrophoresis (SDS-PAGE), free sulfhydryl group, and optical characteristics. The samples treated with ultrasound at pH 8 and 10 significantly (p < 0.05) enhanced the solubility of the hemp seed protein by 12.12% and 19.05%, respectively. Similarly, the samples treated with ultrasonication and pH shifting at pH 6, 8, and 10 also significantly increased the amount of free sulfhydryl content (p < 0.05) to 41.6, 58.72, and 46.54 mmol/g from 32.8 mmol/g, respectively. This study shows that the application of ultrasonication and pH shifting is a promising alternative method to modify the functional properties of HPC and widen their applications in the food, cosmetics, and pharmaceutical industries.

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OBJECTIVE: Insulin autoimmune syndrome (IAS) is the third most common cause of spontaneous hypoglycaemia in Japan but very rare in the rest of the world. We aimed to identify factors, which are associated with the occurrence of IAS and which may differ between East Asian and non-East Asian patients. DESIGN: A PubMed search using the search terms 'insulin autoimmune syndrome' and 'Hirata disease' revealed a total of 287 reports of IAS cases, including one previously unpublished own case. RESULTS: Mean age (±standard deviation) was 52 ± 19 years in East Asian and 54 ± 21 years in non-East Asian patients (p > .05). In both groups, there were more females. Mean body mass index was lower in East Asian than in non-East Asian patients (23.0 ± 4.3 vs. 27.1 ± 5.6 kg/m2 , p < .0001). Postprandial hypoglycaemia was more common in non-East Asian patients (p < .05). East Asian patients took more frequently antithyroid medications and non-East Asian patients angiotensin-converting enzyme (ACE) inhibitors (both p < .0001). Graves' disease and other autoimmune diseases were more frequently observed in East Asian patients (both p < .01). Parameters of glucose metabolism were comparable in both groups, independent of diabetes diagnosis (p > .05), except for insulin that was higher in East Asian compared to non-East Asian metabolically healthy patients (p < .01). Human leukocyte antigen (HLA)-DRB1*0406 was the most frequent HLA-type in East Asian patients (p < .0001), whereas DRB1*0403 and *0404 were more frequent in non-East Asian patients (both p < .05). Non-East Asian patients received more secondary treatments, including plasmapheresis and rituximab, whereas medication discontinuation was more common in East Asian patients (all p < .05). Outcome was similar in both groups (p > .05). CONCLUSIONS: Factors associated with IAS markedly differ between East Asian and non-East Asian patients, with autoimmune disorders, particularly Graves' disease, antithyroid medications, and HLA-DRB1*0406 more prevalent in East Asian patients and cardiovascular and plasma cell diseases, ACE inhibitors and HLA-DRB1*0403 more prevalent in non-East Asian patients.

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Understanding aggregation in food protein systems is essential to control processes ranging from the stabilization of colloidal dispersions to the formation of macroscopic gels. Patatin rich potato protein isolates (PPI) have promising techno-functionality as alternatives to established proteins from egg white or milk. In this work, the influence of pH and temperature on the kinetics of PPI denaturation and aggregation was investigated as an option for targeted functionalization. At a slightly acidic pH, rates of denaturation and aggregation of the globular patatin in PPI were fast. These aggregates were shown to possess a low amount of disulfide bonds and a high amount of exposed hydrophobic amino acids (S0). Gradually increasing the pH slowed down the rate of denaturation and aggregation and alkaline pH levels led to an increased formation of disulfide bonds within these aggregates, whereas S0 was reduced. Aggregation below denaturation temperature (Td) favored aggregation driven by disulfide bridge formation. Aggregation above Td led to fast unfolding, and initial aggregation was less determined by disulfide bridge formation. Inter-molecular disulfide formation occurred during extended heating times. Blocking different protein interactions revealed that the formation of disulfide bond linked aggregation is preceded by the formation of non-covalent bonds. Overall, the results help to control the kinetics, morphology, and interactions of potato protein aggregation for potential applications in food systems.

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The extensive use of angiotensin-converting enzyme inhibitors (ACEIs) as antihypertensive agents and the huge amount of data collected in clinical trials and post-marketing studies has allowed the extending of the indication of ACEIs beyond blood pressure control. Current guidelines recommend ACEIs in symptomatic patients with heart failure with reduced ejection fraction to decrease the risk of heart failure hospitalization, and also in patients after acute myocardial infarction (AMI) with ST-elevation with or without post-AMI ventricular dysfunction. Analyzing the association between the choice of an ACEI after AMI with the risk of mortality and re-infarction, a class effect, rather than the superiority of some agents, has been described. The focus of this review is centered on the role of ACEIs in addition to and beyond blood pressure control. It summarizes clinical evidence on the use of these agents in cardiovascular diseases, with a specific interest in the experience with zofenopril, which presents a peculiar pharmacological profile that may contribute to additional clinical benefits in some identifiable populations of patients. Indeed, the presence of a sulfhydryl group in its structure confers on zofenopril high anti-oxidant and anti-ischemic properties involving the activation of the H2S system, resulting in a cardioprotective effect. The efficacy and safety of zofenopril have been extensively evaluated and proved in the Survival of Myocardial Infarction Long-Term Evaluation (SMILE) program in numerous clinical settings. The pharmacological features and ancillary characteristics of zofenopril with potent cardioprotective effects seem to differentiate it from other ACEIs and to confer further benefits to patients.

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To further understand the gluten-starch interactions in dough, this study investigated the effects of exogenous starch on the structural-thermal properties of gluten via reconstituting Xinong 836 starch with gluten from near-isogenic lines HMW-D1a (Dy12) and HMW-D1p (Dx2 + Dy12) according to the following proportions (gluten/starch): 9/91 (G09), 12/88 (G12), 15/85 (G15), and two controls, where G00 and G01 represent the original and self-reconstituted flours, respectively. Adding exogenous starch significantly improved the dough strength for the reconstituted flours containing gluten from HMW-D1a and HMW-D1p, especially those with HMW-D1a. When the ratios of gluten to starch were 15/85 and 12/88 in the HMW-D1a and HMW-D1p reconstituted flours, respectively, the concentrations of free sulfhydryl groups were minimized in the flour, and thus more glutenin polymers were formed. Changes in the secondary structure, such as the proportion of ß-sheets and the α-helices differed among the gluten types after adding starch. Compared with G00, the microstructures of dough obtained from G15 with HMW-D1a and G12 with HMW-D1p were more compact and denser, respectively; the thermal stability was also improved significantly for G15 with HMW-D1a and G12 with HMW-D1p. The effects of adding starch on the gluten characteristics were greater in HMW-D1a than HMW-D1p, attributing to differences in gluten-starch interactions. These findings indicate that adding exogenous starch was more readily to modify the structural properties of HMW-D1a gluten with inferior subunits, which helps to improve the quality of dough prepared with inferior gluten.

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Diallyl trisulfide (DATS) is a secondary metabolite of allicin, a volatile organosulfur flavoring compound generated by the crushing of garlic. These compounds have various medicinal effects such as antiplatelet activity. In this study, we demonstrated for the first time the cellular mechanism involved in the inhibition of platelet aggregation by DATS and dipropyl trisulfide (DPTS), which is a saturated analogue of DATS. Washed murine platelets were incubated with these sulfides, and platelet aggregation was evaluated by light transmission aggregometry. The amount of reaction products produced by DATS, DPTS, and glutathione (GSH) was measured using liquid chromatography-mass spectrometry. Compared with DPTS, DATS potently inhibited platelet aggregation induced by thrombin, U46619, and collagen. N-Ethylmaleimide (NEM), which is commonly used to modify sulfhydryl groups, also suppressed platelet aggregation. The reactivity of DATS with GSH was higher than that of DPTS. These data suggested that DATS inhibited platelet aggregation through the reaction of sulfhydryl groups.

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ETHNOPHARMACOLOGICAL RELEVANCE: Zanthoxylum nitidum (Roxb.) DC. is a traditional Chinese medicine characterised by anti-inflammatory and anti-Helicobacter pylori, which is widely used to treat H. pylori-induced gastric disease in China. However, the underlying mechanism related to its anti-H. pylori activity remains unclear. Urease plays a crucial role in the colonisation and survival of H. pylori. AIM OF THE STUDY: The root aqueous extract of Z. nitidum against H. pylori urease (HPU) and jack bean urease (JBU) was investigated to illuminate the inhibitory potency, kinetics and potential mechanism. MATERIALS AND METHODS: Z. nitidum components were determined by UPLC. The enzyme inhibitory effects of Z. nitidum were examined using modified spectrophotometric Berthelot (phenol-hypochlorite) method. Urease inhibition kinetics were determined by Lineweaver-Burk plots. Sulfhydryl group reagents and Ni2+-binding inhibitors were used in the mechanism study. Moreover, the molecular docking technique was used to investigate the binding conformations of the main compounds of Z. nitidum on Urease. RESULTS: According to UPLC results, the major components of Z. nitidum were magnoflorine, sanguinarine, nitidine chloride, chelerythrine, skimmianine and L-Sesamin. Z. nitidum has higher enzyme inhibitory activity on HPU (IC50 = 1.29 ± 0.10 mg/mL) than on JBU (IC50 = 2.04 ± 0.27 mg/mL). Enzyme inhibitory kinetic analysis revealed that the type of Z. nitidum inhibition against HPU was a slow-binding and mixed-type, whereas a slow-binding and non-competitive type inhibited JBU. Further mechanism study indicated that the active site of sulfhydryl group might be the target of inhibition by Z. nitidum. The molecular docking study indicated that the above six main components of Z. nitidum exhibited stronger affinity to HPU than to JBU through interacting with the key amino acid residues located on the mobile flap or interacting with the active site Ni2+. Results indicated that these components are potential active ingredients directed against urease. CONCLUSIONS: Z. nitidum inactivated urease in a concentration-dependent manner through slow-binding inhibition and binding to the urease active site sulfhydryl group. Our investigation might provide experimental evidence for the traditional application of Z. nitidum in the treatment of H. pylori-associated gastric disorders.

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Many proteins contain free sulfhydryl groups which can be involved in a variety of biochemical reactions. Reactive thiol groups can either reside within the active center of oxidoreductases or represent a part of a thiol-based redox switch in proteins. Therefore, the exact position of a free sulfhydryl within a protein is mostly very important.This chapter describes a mass spectrometry-based method to determine the location of protein sulfhydryl groups exemplary shown for a synthetic decapeptide and the plasma glycoprotein von Willebrand factor (VWF). We outline (1) labeling of free sulfhydryl groups, (2) enrichment of labeled peptides, and (3) detection and identification of labeled peptides by mass spectrometry.

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PURPOSE: Insulin autoimmune syndrome (IAS) is a relatively rare cause of hypoglycemia characterized by endogenous hyperinsulinism and autoantibodies against endogenous insulin despite no prior exposure to exogenous insulin. We present a series of IAS cases and describe the clinical characteristics of these cases. METHODS: The medical records of inpatients with the final diagnosis of IAS were collected from August 2007 to August 2017 in Peking Union Medical College Hospital. Clinical characteristics and laboratory test results were summarized. The results of serum glucose, insulin, true insulin, and C-peptide testing during 5-h oral glucose tolerance tests were also summarized. Circulating immune complexes were assessed qualitatively by precipitation with polyethylene glycol (PEG) in some patients. FINDINGS: Sixteen patients were included in this study. Insulin autoimmune antibody test results were found positive in 12 patients and weakly positive in 1 patient. Nine patients had an insulin to C-peptide molar ratio >1, whereas 6 patients had an insulin to C-peptide molar ratio <1. Circulating immune complexes were verified in all 4 patients who had been assessed with PEG. During 5-h oral glucose tolerance tests, the C-peptide level responded earlier to the glucose tolerance and had a shorter peak value period compared with insulin, although C-peptide's fluctuation still lagged behind the glucose fluctuation. Three patients presented with self-limited disease courses or limited disease course after discontinuing use of the sulfhydryl group drugs. Some patients' symptoms were relieved after small frequent meals, and some were relieved after taking acarbose. Only 3 patients took glucocorticoids as the anti-immune therapy. IMPLICATIONS: The insulin to C-peptide molar ratios were not consistently >1 in patients with confirmed diagnoses of IAS in our study, which suggested the low sensitivity of insulin to C-peptide molar ratio to detect IAS. The therapy in our study also revealed the self-limited disease course of IAS, and despite the effectiveness of anti-immunity therapy, convenient therapy, such as frequent small meals and adding acarbose, performed well in many patients.

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The effects of five phosphate salts (PS) on the pasting properties of flour, mixing properties of dough and qualities of cooked noodles were investigated. Rapid Visco Analysis showed that all types of PS increased the peak and final viscosities of wheat flour. Trisodium phosphate (TSP) significantly increased pasting temperature with increasing concentration. The Farinograph characteristics indicated that TSP markedly increased stability time and progressively decreased the degree of softening of the dough. The cooking yield of the TSP, sodium pyrophosphate (TSPP) and disodium phosphate (DSP) groups clearly increased, and the cooking loss was reduced by adding 0.3% sodium tripolyphosphate (STPP), 0.1% TSPP or 0.1% TSP. Texture profile analysis revealed that the hardness of cooked noodles from STPP and TSP groups slightly decreased, while that of TSPP and DSP groups decreased significantly. Overall, PS improved the qualities of noodles mainly by promoting starch gelatinization and strengthening the gluten network.

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BACKGROUND: Skin hydration is generally assessed using the parameters of skin surface water content (SWC) and trans-epidermal water loss (TEWL). To date, few studies have characterized skin conditions using correlations between skin hydration parameters and corneocyte parameters. AIMS: The parameters SWC and TEWL allow the classification of skin conditions into four distinct Groups. The purpose of this study was to assess the characteristics of skin conditions classified by SWC and TEWL for correlations with parameters from corneocytes. METHODS: A human volunteer test was conducted that measured SWC and TEWL. As corneocyte-derived parameters, the size and thick abrasion ratios, the ratio of sulfhydryl groups and disulfide bonds (SH/SS) and CP levels were analyzed. RESULTS: Volunteers were classified by their median SWC and TEWL values into 4 Groups: Group I (high SWC/low TEWL), Group II (high SWC/high TEWL), Group III (low SWC/low TEWL), and Group IV (low SWC/high TEWL). Group IV showed a significantly smaller size of corneocytes. Groups III and IV had significantly higher thick abrasion ratios and CP levels. Group I had a significantly lower SH/SS value. The SWC/TEWL value showed a decline in order from Group I to Group IV. CONCLUSION: Groups classified by their SWC and TEWL values showed characteristic skin conditions. We propose that the SWC and TEWL ratio is a comprehensive parameter to assess skin conditions.

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2,3-Dimethoxy-5-methyl-p-benzoquinone is a common chemical structure of coenzyme Q (CoQ) that conjugates different lengths of an isoprenoid side chain at the 6-position of the p-benzoquinone ring. In a series of studies to explore the cytotoxic mechanism of CoQ homologues with a short isoprenoid side chain, we found that a CoQ analogue without an isoprenoid side chain, CoQ0, showed marked toxicity against HeLa cells in comparison with cytotoxic homologues. Therefore, we examined the cytotoxic mechanism of CoQ0. Different from the cytotoxic CoQ homologues that induced apoptosis, 100 µM CoQ0 induced necrosis of HeLa cells. The CoQ0-induced cell death was accompanied by a decrease in endogenous non-protein and protein-associated sulfhydryl (SH)-groups, but this improved with the concomitant addition of compounds with SH-groups but not antioxidants without SH-groups. In addition, UV-spectrum analysis suggested that CoQ0 could rapidly form S-conjugated adducts with compounds with SH-groups by Michael addition. On the other hand, enzyme activities of both glyceraldehyde-3-phosphate dehydrogenase, which has a Cys residue in the active site, and α-ketoglutarate dehydrogenase complex, which requires cofactors with SH-groups, CoA and protein-bound α-lipoic acid, and CoA and ATP contents in the cells were significantly decreased by the addition of CoQ0 but not CoQ1. Furthermore, the decrease of an endogenous antioxidant, glutathione (GSH), by CoQ0 treatment was much greater than the predicted increase of endogenous GSH disulfide. These results suggest that CoQ0 rapidly forms S-conjugate adducts with these endogenous non-protein and protein-associated SH-groups of HeLa cells, which disrupts carbohydrate metabolism followed by intracellular ATP depletion and necrotic cell death.

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In this study, we examined the anti-Helicobactor pylori effects of the main protoberberine-type alkaloids in Rhizoma Coptidis. Coptisine exerted varying antibacterial and bactericidal effects against three standard H. pylori strains and eleven clinical isolates, including four drug-resistant strains, with minimum inhibitory concentrations ranging from 25 to 50 µg/mL and minimal bactericidal concentrations ranging from 37.5 to 125 µg/mL. Coptisine's anti-H. pylori effects derived from specific inhibition of urease in vivo. In vitro, coptisine inactivated urease in a concentration-dependent manner through slow-binding inhibition and involved binding to the urease active site sulfhydryl group. Coptisine inhibition of H. pylori urease (HPU) was mixed type, while inhibition of jack bean urease was non-competitive. Importantly, coptisine also inhibited HPU by binding to its nickel metallocentre. Besides, coptisine interfered with urease maturation by inhibiting activity of prototypical urease accessory protein UreG and formation of UreG dimers and by promoting dissociation of nickel from UreG dimers. These findings demonstrate that coptisine inhibits urease activity by targeting its active site and inhibiting its maturation, thereby effectively inhibiting H. pylori. Coptisine may thus be an effective anti-H. pylori agent.

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Cellular thiols such as cysteine spontaneously and readily react with the respiratory intermediate fumarate, resulting in the formation of stable S-(2-succino)-adducts. Fumarate-mediated succination of thiols increases in certain tumors and in response to glucotoxicity associated with diabetes. Therefore, S-(2-succino)-adducts such as S-(2-succino)cysteine (2SC) are considered oncometabolites and biomarkers for human disease. No disposal routes for S-(2-succino)-compounds have been reported prior to this study. Here, we show that Bacillus subtilis metabolizes 2SC to cysteine using a pathway encoded by the yxe operon. The first step is N-acetylation of 2SC followed by an oxygenation that we propose results in the release of oxaloacetate and N-acetylcysteine, which is deacetylated to give cysteine. Knockouts of the genes predicted to mediate each step in the pathway lose the ability to grow on 2SC as the sulfur source and accumulate the expected upstream metabolite(s). We further show that N-acetylation of 2SC relieves toxicity. This is the first demonstration of a metabolic disposal route for any S-(2-succino)-compound, paving the way toward the identification of corresponding pathways in other species.

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RS-4-(4-hydroxyphenyl)-2-butanol (rhododendrol (RD))-a skin-whitening ingredient-was reported to induce leukoderma in some consumers. We have examined the biochemical basis of the RD-induced leukoderma by elucidating the metabolic fate of RD in the course of tyrosinase-catalyzed oxidation. We found that the oxidation of racemic RD by mushroom tyrosinase rapidly produces RD-quinone, which gives rise to secondary quinone products. Subsequently, we confirmed that human tyrosinase is able to oxidize both enantiomers of RD. We then showed that B16 cells exposed to RD produce high levels of RD-pheomelanin and protein-SH adducts of RD-quinone. Our recent studies showed that RD-eumelanin-an oxidation product of RD-exhibits a potent pro-oxidant activity that is enhanced by ultraviolet-A radiation. In this review, we summarize our biochemical findings on the tyrosinase-dependent metabolism of RD and related studies by other research groups. The results suggest two major mechanisms of cytotoxicity to melanocytes. One is the cytotoxicity of RD-quinone through binding with sulfhydryl proteins that leads to the inactivation of sulfhydryl enzymes and protein denaturation that leads to endoplasmic reticulum stress. The other mechanism is the pro-oxidant activity of RD-derived melanins that leads to oxidative stress resulting from the depletion of antioxidants and the generation of reactive oxygen radicals.

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In our previous study, Rhizoma Coptidis extract was found to exert more potent inhibitory effect than its major component berberine towards urease from Helicobacter pylori (HPU) and jack bean (JBU). In continuation of our work, the present study was designed to further comparatively investigate the urease inhibitory activities of five major protoberberine alkaloids in Rhizoma Coptidis, namely berberine, palmatine, coptisine, epiberberine, jateorhizine to identify the bioactive constituent, and illuminate the potential mechanism of action. Results indicated that the five protoberberine alkaloids acted as concentration-dependent inactivators of urease with IC50 values ranging between 3.0 and 5087µM for HPU and 2.3->10,000µM for JBU, respectively. Notably, epiberberine (EB) was found to be the most potent inhibitor against both ureases with IC50 values of 3.0±0.01µM for HPU and 2.3±0.01µM for JBU, which was more effective than the standard urease inhibitor, acetohydroxamic acid (83±0.01µM for HPU and 22±0.01µM for JBU, respectively). Further kinetic analysis revealed that the type of EB inhibition against HPU was slow-binding and uncompetitive, with Ki of 10.6±0.01µM, while slow-binding and competitive against JBU with Ki of 4.6±0.01µM. Addition of thiol reagents, such as l-cysteine, glutathione and dithiothreitol, significantly abolished the inhibition, while Ni2+ competitive inhibitors, boric acid and sodium fluoride, synergetically inhibited urease with EB, indicating the obligatory role of the active site sulfhydryl group for the inhibition. In addition, binding of EB with the urease proved to be reversible, as about 65% and 90% enzymatic activity of HPU and JBU, respectively, could be restored by dithiothreitol application. These findings highlighted the potential role of Rhizoma Coptidis protoberberine alkaloids, especially EB, as a lead urease inhibitor in the treatment of diseases associated with ureolytic bacteria. Thus, EB had good potential for further development into a promising therapeutic approach for the treatment of urease-related diseases.

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BACKGROUND: Obesity's impact on micro-environmental oxidative stress and follicular fluid (FF) viscosity and whether or not it has any effect on in vitro fertilization (IVF) success is a matter of debate. AIMS: In this study, our aim was to evaluate the levels of oxidative stress markers and the FF viscosity in obese and non-obese patients. METHODS: Eighty norm-responder patients undergoing IVF were prospectively grouped according to their body mass indexes (BMI). Group 1 (n = 40) and group 2 (n = 40) had BMI values of ≤24.9 and ≥25.0, respectively. Total sulfhydryl (RSH) levels (nmol/m) and the formation of thiobarbituric acid-reactive substances (malondialdehyde, or MDA) (µmol/ml) in FFs were quantified. For the first time in our study, FF viscosity with changing BMI values was also determined. RESULTS: The mean levels of MDA (µmol/ml) and RSH (nmol/ml) were not significantly different between groups (1.37 ± 0.51; 1.51 ± 0.51; p > 0.05 for MDA and 0.42 ± 0.30; 0.41 ± 0.20; p > 0.05 for RSH, respectively). Similarly, the FF viscosity (centipoise) was not different between groups (1.28 ± 0.28; 1.30 ± 0.19; p < 0.05, respectively). Independent of BMI, no correlation was found between FF levels of oxidative markers and the number of oocytes retrieved or the fertilization rates. CONCLUSIONS: In our study, we found no difference in the levels of follicular oxidative and anti-oxidative markers or the follicular fluid viscosity with changing BMI values. We also demonstrated that the levels of oxidative stress markers and the viscosity of follicular fluid did not affect clinical outcomes.

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Hyperhomocysteinemia, which is characterized by elevated blood levels of the non-protein amino acid homocysteine (Hcy), is an independent risk factor for many diseases, including cardiovascular diseases, neurodegenerative diseases and birth defects. The incorporation of homocysteine into proteins, known as protein N-homocysteinylation, has been considered a major mechanism that contributes to hyperhomocysteinemia. However, the process of dehomocysteinylation, the N-homocysteinylation substrates and the regulatory enzyme(s) remain largely unknown. In this study, we observed that the dehomocysteinylation reaction is a spontaneous process that can be inhibited by blocking -SH groups, which have been demonstrated to be critical for non-enzymatic dehomocysteinylation reactions. We also report that CobB, a known Sir2-like bacterial lysine deacetylase, catalyzes lysine dehomocysteinylation reactions both in vitro and in vivo. Our work provides insight into how this non-enzymatic modification might be removed from affected proteins, supplies potential targets for developing identification methods for N-homocysteine proteins, and identifies CobB as the first prokaryotic dehomocysteinylation enzyme.

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