Glutathione conjugation of sesquimustard: in vitro investigation of potential biomarkers.

Sesquimustard (Q) is a powerful blistering agent that contains additional sulfur atoms. Sulfur mustard causes covalent bonding by alkylating nucleophilic groups of biologically important macromolecules such as lipids, proteins, DNA, or RNA. Most cells maintain relatively high amounts of a unique tripeptide called glutathione (GSH) (γ-glutamyl-cysteinyl glycine), which possesses a free thiol group, to prevent unwanted reactions caused by reactive chemical entities. Moreover, these thiol groups on cysteines (Cys) are the main target for alkylation. Although Q is the most potent vesicant among sulfur mustards, research studies identifying biomarkers of Q are very limited. Therefore, here in this study, we aimed to identify the GSH and Cys conjugates of Q using mass spectrometric methods and to observe the formation of these conjugates in HaCat cell culture following exposure to different doses. We identified four different conjugates of Q, which are bis-glutathionyl ethylthioethylthioethyl conjugate (GSH-ETETE-GSH), hydroxyethylthioethylthioethyl glutathione conjugate (HETETE-GSH), bis-cysteinyl ethylthioethylthioethyl conjugate (Cys-ETETE-Cys), and hydroxyethylthioethylthioethyl cysteine conjugate (HETETE-Cys). The identity of the conjugates was elucidated using liquid chromatography-high-resolution mass spectrometry (LC-HRMS). We also investigated changes in conjugate formation with exposure concentration and time elapsed after exposure in the cell culture. After exposure, GSH conjugates decreased until 1st hour, while Cys conjugates increased until 6th hour. We also observed that conjugate formation depended on the concentration of Q. This is the first study to elucidate the conjugates of Q dependent on GSH conjugation. As biomarkers are essential tools for evaluating exposure to Q, this study contributes to the limited number of studies identifying biomarkers for Q.

Synthesis and Tyrosinase Inhibitory Activity of Novel Benzimidazole/Thiazolidin-4-one Hybrid Derivatives.

In this study, novel 3-(phenylamino)thiazolidin-4-one 2 a-d and 3-(phenyl)thiazolidin-4-one 3 a-g derivatives which are having benzimidazole moiety were synthesized and their tyrosinase inhibitory activity were investigated. The structures of the target compounds were elucidated using 1 H/13 C-NMR, IR and MS. The structure of 2 b was also characterized using HSQC NMR technique. Among the target compounds, 3 b-g demonstrated stronger tyrosinase inhibitory activity (IC50 values for 3 b-g ranged from 80.93 to 119.20 µM), compared to the positive control kojic acid (IC50 : 125.08 µM). With IC50 value of 80.93 µM, 5-(2-(4-(1H-benzimidazol-1-yl)phenyl)-4-oxothiazolidin-3-yl)-2-methylbenzenesulfonamide 3 g was found to be the most active derivative of the series. Molecular docking studies were conducted to elucidate the binding interactions between compounds and tyrosinase. The MTT assay studies used to determine the cytotoxicity of 3 b-g showed that 3 c, 3 d, 3 f and 3 g were not cytotoxic in the range of 0-200 µM. Considering its tyrosinase inhibitory activity and cytotoxic effect, 3 g exhibits promising potential for further research and development as a novel tyrosinase inhibitor.

Design, Synthesis and Cytotoxic Evaluation of N-Acylhydrazone-Incorporated Isoxazolo[4,5-d]pyridazin-4(5H)-one Derivatives.

A series of isoxazolo[4,5-d]pyridazin-4(5H)-one hybrids with N-acylhydrazone structure was prepared and screened for their cytotoxic activities. The in vitro antiproliferative activity of the target molecules was evaluated against a panel of sixty cancer cell lines (NCI-60) by the National Cancer Institute. Seven of the target compounds showed prominent % inhibition against various cancer cell lines at the one-dose assay and were subsequently screened for five-dose assay. 4d, 4e and 4g (full panel mean graph midpoint GI50 =9.33, 5.25 and 7.94 µM) emerged as the most promising derivatives against multiple cancer cell lines in comparison with 5-fluorouracil and gefitinib (full panel mean graph midpoint GI50 =18.60 and 3.46 µM). They exhibited remarkable antiproliferative activity with GI50 values submicromolar concentrations against some of the cell lines. The compounds were also found to display mild toxicity to the healthy cells compared to the cancer cell lines indicating safety. Druglikeness and high oral bioavailability were predicted for most of the compounds. As a result, a current study unveiled isoxazolo[4,5-d]pyridazin-4(5H)-ones bearing N-acylhydrazone as promising anticancer agents with antiproliferative effects.

A Comprehensive Review on Oxysterols and Related Diseases.

The present review aims to provide a complete and comprehensive summary of current literature relevant to oxysterols and related diseases. Oxidation of cholesterol leads to the formation of a large number of oxidized products, generally known as oxysterols. They are intermediates in the biosynthesis of bile acids, steroid hormones, and 1,25- dihydroxyvitamin D3. Although oxysterols are considered as metabolic intermediates, there is a growing body of evidence that many of them are bioactive, and their absence or excess may be part of the cause of a disease phenotype. These compounds derive from either enzymatic or non-enzymatic oxidation of cholesterol. This study provides comprehensive information about the structures, formation, and types of oxysterols even when involved in certain disease states, focusing on their effects on metabolism and linkages with these diseases. The role of specific oxysterols as mediators in various disorders, such as degenerative (age-related) and cancer-related disorders, has now become clearer. Oxysterol levels may be employed as suitable markers for the diagnosis of specific diseases or in predicting the incidence rate of diseases, such as diabetes mellitus, Alzheimer's disease, multiple sclerosis, osteoporosis, lung cancer, breast cancer, and infertility. However, further investigations may be required to confirm these mentioned possibilities.

Drug response prediction by ensemble learning and drug-induced gene expression signatures.

Chemotherapeutic response of cancer cells to a given compound is one of the most fundamental information one requires to design anti-cancer drugs. Recently, considerable amount of drug-induced gene expression data has become publicly available, in addition to cytotoxicity databases. These large sets of data provided an opportunity to apply machine learning methods to predict drug activity. However, due to the complexity of cancer drug mechanisms, none of the existing methods is perfect. In this paper, we propose a novel ensemble learning method to predict drug response. In addition, we attempt to use the drug screen data together with two novel signatures produced from the drug-induced gene expression profiles of cancer cell lines. Finally, we evaluate predictions by in vitro experiments in addition to the tests on data sets. The predictions of the methods, the signatures and the software are available from http://mtan.etu.edu.tr/drug-response-prediction/.

A reappraisal on metformin.

This review investigates the different biological effect of Metformin (MET) in different conditions. MET is an oral antidiabetic drug used for the treatment of type 2 diabetes mellitus (T2DM) particularly in overweight people. The main mechanism of action of the MET is inhibition of hepatic glucose production and reduction of insulin resistance. In addition to its antidiabetic effects, MET is also found to be related with the risk for development of several human solid cancers types such as colorectal, breast and pancreas cancer in the diabetic patients. Nowadays according to some researches, MET is believed to decrease or prevent aging and mortality. Moreover, clinical and experimental evidence has shown that MET has beneficial effects in patient with obesity, polycystic ovarian syndrome and Alzheimer's disease. Recent studies have shown that activation of adenosine monophosphate-activated protein kinase (AMPK) by MET can explain its beneficial metabolic effects. In this manuscript, a reevaluation of mechanisms as well as pharmacokinetic properties, genetic variants of transporters, drug-drug interactions, side effects and potential clinical benefits of MET have been reviewed.

Phytochemical Content, Antioxidant and Cytotoxic Activities of Sedum spurium.

Sedum L. species are used for their hemostatic, antidiarrheal, antifungal, diuretic and wound healing properties, and there is growing interest in these species because of their usage in folk medicine. DPPH, SO, NO, and ABTS radical scavenging activities and protective effects against H(2)(02) induced cytotoxicity, as well as cytotoxic activities against the Hep-2 cell line of various extracts from Sedum spurium Bieb. were investigated. Besides, the total phenol, flavonoid, and flavonol contents of the extracts were determined to clarify their biological and phytochemical properties. Chromatographic studies on the most active extract led to the isolation of the major compound, identified as 2-methyl-erythritol by (1)H and (13)C NMR techniques. The EtOAc extract is found to be the most active extract in all tests. However, major compound of EtOAc extract did not possess tested activities. The EtOAC extract of S. spurium could be effective to improve antihemolytic defences of erythrocytes, and radical scavenging potential of the antioxidant mechanism. The extracts should be investigated in detail for their cytotoxic activities because of their possible pro-oxidant effects at high concentrations.

Cofactor metals and antioxidant enzymes in cisplatin-treated rats: effect of antioxidant intervention.

We explored the association between the activities of antioxidant enzymes and their metallic cofactors in rats treated with cisplatin. The antioxidant effects of aminoguanidine, and a combination of vitamins E and C were investigated. Plasma platin was significantly lower than liver and kidney. Cisplatin treatment caused significant increase in plasma Se-glutathione peroxidase activity. Activities of Se-glutathione peroxidase, glutathione S-transferase, catalase and Cu,Zn-superoxide dismutase have been found to be significantly decreased in liver and kidney compared to controls. Zn levels in these organs were diminished upon cisplatin treatment, while levels of Cu were unaffected. Interestingly, levels of iron, the cofactor of catalase, were found to be significantly increased in liver and kidney. Intervention with aminoguanidine or vitamins was generally prevented cisplatin-caused changes in the activity of enzymes and in the tissue levels of cofactor metals. These observations suggest that relation between activities of enzymes and levels of cofactor metals is multifactorial.

Antiapoptotic effect of aminoguanidine on doxorubicin-induced apoptosis.

Doxorubicin (DOX) is a broad-spectrum anthracycline that has cardiotoxicity as a major side effect. Reactive oxygen species (ROS) and reactive nitrogen species generations have been proposed to be an important mechanism of DOX-induced cardiotoxicity and cardiomyocyte apoptosis, which may be mediated by p53 protein. Aminoguanidine (AG) is an effective antioxidant due to its free radical scavenger activity. A549 lung cell line was incubated with various concentrations of AG (100-1,000 µM) wit/without 0.25 µM DOX for 24 h. The expression of p53 and its transcriptional target p21 were analyzed by Western blot. Apoptosis was analyzed with Annexin V assay. JC1 and H2AX immunofluorescence were used to assess mitochondrial and nuclear DNA damage, respectively. This study demonstrated that AG has a dose-dependent antiapoptotic effect on DOX-induced apoptosis. Thus, these data further identify AG as a potential chemopreventive agent to reduce ROS and nitric oxide synthase damage generated by DOX.

Nucleoside-catabolizing enzymes in mycoplasma-infected tumor cell cultures compromise the cytostatic activity of the anticancer drug gemcitabine.

The intracellular metabolism and cytostatic activity of the anticancer drug gemcitabine (2',2'-difluoro-2'-deoxycytidine; dFdC) was severely compromised in Mycoplasma hyorhinis-infected tumor cell cultures. Pronounced deamination of dFdC to its less cytostatic metabolite 2',2'-difluoro-2'-deoxyuridine was observed, both in cell extracts and spent culture medium (i.e. tumor cell-free but mycoplasma-containing) of mycoplasma-infected tumor cells. This indicates that the decreased antiproliferative activity of dFdC in such cells is attributed to a mycoplasma cytidine deaminase causing rapid drug catabolism. Indeed, the cytostatic activity of gemcitabine could be restored by the co-administration of tetrahydrouridine (a potent cytidine deaminase inhibitor). Additionally, mycoplasma-derived pyrimidine nucleoside phosphorylase (PyNP) activity indirectly potentiated deamination of dFdC: the natural pyrimidine nucleosides uridine, 2'-deoxyuridine and thymidine inhibited mycoplasma-associated dFdC deamination but were efficiently catabolized (removed) by mycoplasma PyNP. The markedly lower anabolism and related cytostatic activity of dFdC in mycoplasma-infected tumor cells was therefore also (partially) restored by a specific TP/PyNP inhibitor (TPI), or by exogenous thymidine. Consequently, no effect on the cytostatic activity of dFdC was observed in tumor cell cultures infected with a PyNP-deficient Mycoplasma pneumoniae strain. Because it has been reported that some commensal mycoplasma species (including M. hyorhinis) preferentially colonize tumor tissue in cancer patients, our findings suggest that the presence of mycoplasmas in the tumor microenvironment could be a limiting factor for the anticancer efficiency of dFdC-based chemotherapy. Accordingly, a significantly decreased antitumor effect of dFdC was observed in mice bearing M. hyorhinis-infected murine mammary FM3A tumors compared with uninfected tumors.

Evaluation of antihemolytic and antioxidant activities of Geranium tuberosum subsp. tuberosum with in vitro models.

CONTEXT: There are 33 Geranium species growing in Turkey characterized by the presence of polyphenolic compounds. Some Geranium (Geraniaceae) species are used as antidiabetics, hemostatics, antihemorrhoidals, antidiarrheics and for the treatment of pain, fevers, and gastrointestinal ailments, or are consumed as food. OBJECTIVE: The in vitro antioxidant activity and antihemolytic effect of ethyl acetate (EtOAc), n-butanol (BuOH), methanol (MeOH) and water extracts of Geranium tuberosum L. subsp. tuberosum (Geraniaceae), a medicinal food plant, have been evaluated. MATERIALS AND METHODS: The two antioxidant enzyme activities of human erythrocyte, namely superoxide dismutase (SOD) and catalase (CAT), after in vitro incubation with the extracts, were examined in order to see whether the observed effects are related to altered enzymatic efficiency. Reduced glutathione (GSH) levels were also measured as oxidative stress marker. Antihemolytic activity of extracts was shown by hemolysis assay in erythrocytes. Furthermore, total phenolic content of extracts was measured by Folin-Ciocalteu method. RESULTS: All extracts enhanced GSH levels, and the activity of SOD and CAT. The EtOAc extracts seems to be the most potent antioxidant at 100 µg/mL (SOD activity 173.736 ± 8.33, CAT activity 133.218 ± 3.31, GSH level 2.264 ± 2.21). However, apart from the MeOH extracts at 100 µg/mL (68.699 ± 3.93), they didn't increase the resistance of erythrocytes to H(2)O(2) induced cytotoxicity. Therefore, while a significant antioxidant effect was observed in these samples, antihemolytic effect was not determined. DISCUSSION AND CONCLUSION: The title plant has shown high antioxidant activity without cytotoxicity up to 100 µg/mL, thus could be a potent source as natural antioxidant.

Oxidative protein damage with carbonyl levels and nitrotyrosine expression after chemotherapy in bone marrow transplantation patients.

Protein oxidation is defined as the covalent modification ofa protein, induced either directly by reactive oxygen species/reactive nitrogen species or indirectly by reaction with secondary by-products of oxidative stress. Protein carbonyls are the most commonly measured products of protein oxidation. Additionally, nitrotyrosine is a product of tyrosine nitration mediated by reactive nitrogen species such as peroxynitrite anion and nitrogen dioxide. Samples were collected before the preparative regimen (10 days before transplantation; day ­10), on transplantation day (day 0), and after transplantation (days 7, 14, and 28) from 16 pediatric allogeneic hematopoietic stem cell transplantation (HSCT) patients.The erythrocyte 3-nitrotyrosine expression was shown to be significantly increased after chemotherapy. In accordance, the mean plasma carbonyl levels on days 14 and 28 were significantly higher than on the other days. High dose chemotherapy applied in the preparative regimen of HSCT may be responsible for this long-term oxidation of plasma proteins. These results show that high-dose chemotherapy resulted in protein oxidation both in plasma and in erythrocytes in HSCT patients.

Evaluation of antioxidative, protective effect against H2O2 induced cytotoxicity, and cytotoxic activities of three different Quercus species.

Quercus species are used as antidiarrheic, for the treatment of hemorrhoid, oral and anal mucosa inflammation. These tree species have been of interest to researchers because of their usage in folk medicine, consumption as food, beverage and especially usage of oak woods for construction in wine barrels. The DPPH, SO and NO radical scavenging activities, protective effect against H2O2 induced cytotoxicity as well as their cytotoxic activity against Hep-2 human larynx epidermoid carcinoma cell line of the MeOH and water extracts of the barks of Quercus cerris var. cerris, Quercusmacranthera subsp. syspirensis and Quercus aucheri were investigated for the first time. Total phenolic content of the extracts was also evaluated by Folin-Ciocalteu method. Results demonstrated that the extracts showed strong radical scavenging activity comparable to those of standard compounds. Extracts also showed good protective effect against H2O2 induced cytotoxicity on human erythrocytes comparing to ascorbic acid. On the other hand, while each extract showed dose dependent cytotoxic activity, MeOH extract of Q.macranthera subsp. syspirensis showed the strongest cytotoxicity against the tested cell line. Taken together, the results showed that Quercus species may be a promising alternative to synthetic substances as natural compound with high antioxidant and antiproliferative activities.

Determination of seasonal variations in serum ochratoxin A levels in healthy population living in some regions of Turkey by enzyme-linked immunosorbent assay.

This study has been undertaken to investigate the regional and seasonal variability in ochratoxin A (OTA) exposure of healthy population living in Black Sea and Mediterranean regions of Turkey by measuring serum OTA concentrations. The mean serum concentrations of OTA were determined to be 0.137 ng/mL (0.0306-0.887 ng/mL) and 0.312 ng/mL (0.028-1.496 ng/mL) in all samples for winter and summer, respectively by enzyme-linked immunosorbent assay (ELISA). The differences between mean values of OTA in all serum samples collected in summer and winter were statistically significant. The highest OTA concentration was determined in the children living in Black Sea Region in summer. The mean daily intake levels of OTA in all samples were estimated as 0.182 ng/kg b.w./day and 0.408 ng/kg b.w./day in winter and summer, respectively. The results showed that the mean serum concentrations of OTA in healthy population in both regions were found not to be exceeded 1 ng/mL in agreement with the distribution reported in most European countries and that the daily intake levels of OTA were calculated below the tolerable daily intake levels given by regulatory authorities. However, overall results suggest that Turkish population living in these regions is continuously exposed to OTA and that the exposure levels are also elevated in summer period compared to winter.