Synthesis of water-soluble cystine C_(60) derivative with catalyst and its active oxygen radical scavenging ability

A novel water-soluble cystine C60 derivative was synthesized in the presence of the catalyst, tetrabutylammonium hydroxide （TBAH）. The product was characterized by FT-IR, UV, ^1H NMR, ^13C NMR, MS and elemental analysis. Furthermore, the scavenging ability to superoxygen anion radical O2^·- and hydroxyl radical ^·OH was studied by chemiluminescence. It was found that cystine C60 derivative showed an excellent efficiency in eliminating superoxygen anion radical and hydroxyl radical. The 50% inhibition concentration （IC50） for superoxygen anion radical and hydroxyl radical were 0.167 and 0.008 mg/mL, respectively.

Synthesis of cystine C_(60) derivative and its protective effects on hydrogen peroxide-induced apoptosis in PC12 cells

Oxidative stress has been considered as a major cause of cellular injuries in a variety of clinical abnormalities, especially prominent in neural diseases. One of the usable ways to prevent the reactive oxygen species (ROS)-mediated cellular injury is dietary or pharmaceutical augmentation of some free radical scavenger. Water-soluble amino-fullerene is a novel compound that behaves as a free radical scavenger with excellent biology consistent. In the present study, we have synthesized and characterized a novel cystine C60 derivative for the first time, and investigated the effects on hydrogen peroxide-induced oxidative stress and apoptotic death in cultured rat pheochromocytoma (PC12) cells. PC12 cells treated with hydrogen peroxide underwent apoptotic death as determined by MTT, PI/Hoechst 33342 staining and flow cytometry analysis. These results suggested that cystine C60 derivative has the potential to prevent oxidative stress-induced cell death and has no evident toxicity.

Quantitative determination of D_(4)-cystine in mice using LC-MS/MS and its application to the assessment of pharmacokinetics and bioavailability

Cystine is the primary source material for the synthesis of glutathione.However,the pharmacokinetics and tissue distribution of cystine are largely unknown.A surrogate analyte D_(4)-cystine was employed to generate calibration curves for the determination of levels of D_(4)-cystine and endogenous cystine in mice by liquid chromatography-tandem mass spectrometry(LC-MS/MS).Validation assessments proved the sensitivity,specificity and reproducibility of the method with a lower limit of quantification(LLOQ)of 5 ng/mL over 5e5000 ng/mL in plasma.The pharmacokinetics of D_(4)-cystine were evaluated after administering injections and oral solutions,both of which minimally impacted endogenous cystine levels.The absolute bioavailability of cystine was 18.6%,15.1%and 25.6%at doses of 25,50 and 100 mg/kg,respectively.Intravenously injected D_(4)-cystine resulted in dramatically high plasma levels with reduced levels in the brain and liver.Intragastrically administered D_(4)-cystine resulted in high levels in the plasma and stomach with relatively low levels in the lung,kidney,heart and brain.

A Study on Adsorption of Electrogenerated Cystine Precipitate onto An Electrode using Electrochemical Quartz Crystal Impedance System

An electrochemical quartz crystal impedance system has been applied to monitorgeneration of precipitate and adsorption of the precipitate onto An electrode during electrochmicaloxidation and Fe(CN)_6,3-/Fe(CN),6 4- electrochemical catalytic oxidation of L-cysteine in phosphateaqueous buffer (pH 7.4). Significant decreases in the resonant frequency and increases in themotional resistance and the static capacitance were found during the precipitate adsorption, and thefrequency shift found in solution was ca. 2 times that in air. Similar responses of quartz crystalimpedance and a white precipitate were obtained during redox titration of L-cysteine solutionusing K_3Fe(CN)_6 solution. FT-IR analysis indicated that the white precipitate is cystine. Theelectrode collection efficiency of the electrogenerated cystine was estimated.

TREATMENT OF CYSTINE CALCULUS WITH EXTRACOR-POREAL SHOCK WAVE LITHOTRIPSY

Objective To evaluate the effectiveness of ESWL for treating patients with cystine calculus. Methods Of 31 patients, 20 were subjected to ESWL only, 6 were subjected to combination therapy of PCNL and ESWL, 2 Pneumatic Lithotriptor-ESWL, 3 Laser lithotripsy-ESWL. Results For 14 renal stones, the fragmentation after ESWL manotherapy was 85. 7% and 14.3% after twice ESWL sessions. For 17 ureter calculus, the fragmentation after ESWL manotherapy was 82.3% and 11.7% after twice ESWL sessions. One patient （ 5.8% ） failed and changed to open surgery. Conclusion ESWL is an effective and reliable method for treating patients with cystine calculus, however, better effects and shorter treatment time could be obtained by the combination of ESWL with other therapy options.

Cystine-assisted accumulation of gold nanoparticles on ZnO to construct a sensitive surface-enhanced Raman spectroscopy substrate

Recently,various semiconductor/metal composites have been developed to fabricate surfaceenhanced Raman spectroscopy substrates.However,low metal loading on semiconductors is still a challenge.In this study,cystine was introduced to increase the accumulation of gold nanoparticles on zinc oxide,owing to the biomineralization_property of_cystine.Morphological analysis revealed that the obtained ZnO/Au/cystine composite not only had a higher metal loading but also formed a porous structure,which is beneficial for Raman performance.Compared with ZnO/Au,the ZnO/Au/cystine substrate displayed a 40-fold enhancement in the Raman signal and a lower limit of detection(10^(-11) mol·L^(-1))in the detection of rhodamine 6G.Moreover,the substrate has favorable homogeneity and stability.Finally,ZnO/Au/cystine displayed excellent performance toward crystal violet and methylene blue in a test based on river water samples.This study provided a promising method to fabricate sensitive semiconductor/noblemetal-based surface-enhanced Ramans spectroscopy substrates for Raman detection.

Cystine transporter SLC7A11/xCT in cancer:ferroptosis,nutrient dependency,and cancer therapy

The cystine/glutamate antiporter SLC7A11(also commonly known as xCT)functions to import cystine for glutathione biosynthesis and antioxidant defense and is overexpressed in multiple human cancers.Recent studies revealed that SLC7A11 overexpression promotes tumor growth partly through suppressing ferroptosis,a form of regulated cell death induced by excessive lipid peroxidation.However,cancer cells with high expression of SLC7A11(SLC7A11^(high))also have to endure the significant cost associated with SLC7A11-mediated metabolic reprogramming,leading to glucose-and glutamine-dependency in SLC7A11^(high) cancer cells,which presents potential metabolic vulnerabilities for therapeutic targeting in SLC7A11^(high) cancer.In this review,we summarize diverse regulatory mechanisms of SLC7A11 in cancer,discuss ferroptosis-dependent and-independent functions of SLC7A11 in promoting tumor development,explore the mechanistic basis of SLC7A11-induced nutrient dependency in cancer cells,and conceptualize therapeutic strategies to target SLC7A11 in cancer treatment.This review will provide the foundation for further understanding SLC7A11 in ferroptosis,nutrient dependency,and tumor biology and for developing novel effective cancer therapies.

NADPH debt drives redox bankruptcy:SLC7A11/xCT-mediated cystine uptake as a double-edged sword in cellular redox regulation

Cystine/glutamate antiporter solute carrier family 7 member 11(SLC7A11;also known as xCT)plays a key role in antioxidant defense by mediating cystine uptake,promoting glutathione synthesis,and maintaining cell survival under oxidative stress conditions.Recent studies showed that,to prevent toxic buildup of highly insoluble cystine inside cells,cancer cells with high expression of SLC7A11(SLC7A11high)are forced to quickly reduce cystine to more soluble cysteine,which requires substantial NADPH supply from the glucose-pentose phosphate pathway(PPP)route,thereby inducing glucose-and PPP-dependency in SLC7A11high cancer cells.Limiting glucose supply to SLC7A11high cancer cells results in significant NADPH“debt”,redox“bankruptcy”,and subsequent cell death.This review summarizes our current understanding of NADPH-generating and-consuming pathways,discusses the opposing role of SLC7A11 in protecting cells from oxidative stresseinduced cell death such as ferroptosis but promoting glucose starvationeinduced cell death,and proposes the concept that SLC7A11-mediated cystine uptake acts as a double-edged sword in cellular redox regulation.A detailed understanding of SLC7A11 in redox biology may identify metabolic vulnerabilities in SLC7A11high cancer for therapeutic targeting.

Cystine proportion regulates fate of polypeptide nanogel as nanocarrier for chemotherapeutics

The physicochemical characteristics of nanoparticles are closely related to their drug delivery performances in vitro and in vivo.A well-designed nanocarrier can prolong the drug half-life in the blood circulation,upregulate the drug accumulation at the target site,and enhance the treatment efficacy.To elucidate the impact of physicochemical properties on the fate of nanogel as a nanocarrier of chemotherapeutics,three methoxy poly(ethylene glycol)-poly(L-phenylalanine-co-L-cystine)(mPEG-P(LP-coLC))nanogels with different L-cystine proportions were developed,namely mPEG-P(LP10-co-LC5)(NG10-5),mPEG-P(LP10-coLC10)(NG10-10),and mPEG-P(LP10-co-LC15)(NG10-15).The three nanogels shared similar surface charge and reductionresponsive behavior,but they had distinct diameters and different drug release profiles.Among them,NG10-5,which has the smallest diameter,was preferentially internalized by tumor cells in vitro and showed rapid migration to the tumor site in vivo.Using doxorubicin(DOX)as a model chemotherapeutic agent,NG10-5/DOX had the most prolonged blood circulation period and highest tumor accumulation after intravenous administration.NG10-5/DOX also had the most potent antitumor effect of all three drug-loaded nanogels.Accordingly,adjusting physicochemical characteristics by changing the amino acid composition might improve the therapeutic efficacies of nanogels and enhance their potential for clinical application.

Molecular cloning,tissue distribution and the expression of cystine/glutamate exchanger(xCT,SLC7A11) in different tissues during development in broiler chickens

The cystine/glutamate exchanger(xCT,SLC7 A11)is a component of the system X_c amino-acid antiporter that is able to export glutamate and import cysteine into cells.The xCT amino acid exchanger has received a lot of attention,due to the fact that cysteine is an essential substrate for the synthesis of glutathione(GSH),an endogenous antioxidant in cells.The objective of this research was to clone the full-length cDNA of chicken xCT,and to investigate the gene expression of xCT in different tissues,including intestinal segments of broiler chickens during development.The full-length cDNA of chicken xCT(2,703 bp)was obtained from the jejunum by reverse transcription-PCR and sequenced.Homology tests showed that chicken xCT had 80.4%,80.2%,and 71.2%homology at the nucleotide level with humans,cattle,and rats,respectively.Likewise,amino acid sequence analysis showed that chicken xCT protein is 86.4%,79.3%,and 75.6%homologous with humans,cattle,and rats,respectively.Additionally,phylogenetic analysis indicated that chicken xCT genes share a closer genetic relationship with humans and cattle,than with rats.The chicken xCT protein has 12 transmembrane helixes,6 extracellular loops,and 5 intracellular loops.The mRNA of xCT was detected in all tissues,including intestinal segments,in which the mRNA expression of xCT was significantly higher(P<0.05)within the colon,compared to the jejunum and ileum.During development,a linear pattern of changes regarding the levels of the xCT mRNA was found,indicating that there was an abundance of xCT within the duodenum(P<0.05).Furthermore,there were changes of the xCT mRNA abundance in the colon during development,which displayed linear and cubic patterns(P<0.05).These results indicated that xCT is widely expressed both in intestinal segments,as well as other organs that are not associated with nutrient absorption.Further investigation is needed to characterize the functional relevance of xCT activity in oxidative stress and inflammation in the small intestine of broiler chickens.

DL-3-n-butylphthalide alleviates motor disturbance by suppressing ferroptosis in a rat model of Parkinson’s disease

DL-3-n-butylphthalide(NBP)-a compound isolated from Apium graveolens seeds-is protective against brain ischemia via various mechanisms in humans and has been approved for treatment of acute ischemic stroke.NBP has shown recent potential as a treatment for Parkinson’s disease.However,the underlying mechanism of action of NBP remains poorly understood.In this study,we established a rat model of Parkinson’s disease by intraperitoneal injection of rotenone for 28 successive days,followed by intragastric injection of NBP for 14-28 days.We found that NBP greatly alleviated rotenone-induced motor disturbance in the rat model of Parkinson’s disease,inhibited loss of dopaminergic neurons and aggregation ofα-synuclein,and reduced iron deposition in the substantia nigra and iron content in serum.These changes were achieved by alterations in the expression of the iron metabolism-related proteins transferrin receptor,ferritin light chain,and transferrin 1.NBP also inhibited oxidative stress in the substantia nigra and protected mitochondria in the rat model of Parkinson’s disease.Our findings suggest that NBP alleviates motor disturbance by inhibition of iron deposition,oxidative stress,and ferroptosis in the substantia nigra.

Neuroprotective effect of deferoxamine on erastin-induced ferroptosis in primary cortical neurons

The iron chelator deferoxamine has been shown to inhibit ferroptosis in spinal cord injury.However,it is unclear whether deferoxamine directly protects neurons from ferroptotic cell death.By comparing the survival rate and morphology of primary neurons and SH-SY5Y cells exposed to erastin,it was found that these cell types respond differentially to the duration and concentration of erastin treatment.Therefore,we studied the mechanisms of ferroptosis using primary cortical neurons from E16 mouse embryos.After treatment with 50μM erastin for 48 hours,reactive oxygen species levels increased,and the expression of the cystine/glutamate antiporter system light chain and glutathione peroxidase 4 decreased.Pretreatment with deferoxamine for 12 hours inhibited these changes,reduced cell death,and ameliorated cellular morphology.Pretreatment with the apoptosis inhibitor Z-DEVD-FMK or the necroptosis inhibitor necrostain-1 for 12 hours did not protect against erastin-induced ferroptosis.Only deferoxamine protected the primary cortical neurons from ferroptosis induced by erastin,confirming the specificity of the in vitro ferroptosis model.This study was approved by the Animal Ethics Committee at the Institute of Radiation Medicine of the Chinese Academy of Medical Sciences,China(approval No.DWLL-20180913)on September 13,2018.

Biomolecule-assisted, cost-effective synthesis of a Zn_(0.9)Cd_(0.1)S solid solution for efficient photocatalytic hydrogen production under visible light

A series of alloyed Zn‐Cd‐S solid solutions with a cubic zinc blende structure were fabricated hydrothermally with the assistance of L‐cystine under mild conditions.The products were characterized by XRD,TEM,HRTEM,XPS,UV‐vis,and BET techniques,and the photocatalytic performance for the reduction of water to H2on the solid solutions was evaluated in the presence of S2?/SO32?as hole scavengers under visible light illumination.Among all the samples,the highest photocatalytic activity was achieved over Zn0.9Cd0.1S with a rate of4.4mmol h?1g?1,even without a co‐catalyst,which far exceeded that of CdS.Moreover,Zn0.9Cd0.1S displayed excellent anti‐photocorrosion properties during the photoreduction of water into H2.The enhancement in the photocatalytic performance was mainly attributed to the efficient charge transfer in the Zn0.9Cd0.1alloyed structure and the high surface area.This work provides a simple,cost‐effective and green technique,which can be generalized as a rational preparation route for the large‐scale fabrication of metal sulfide photocatalysts.

AN FTIR SPECTROSCOPIC STUDY OF LOW TEMPERATURE PLASMA TREATED WOOL FABRIC

FTIR-ATR technique with second-order derivative measurement was used for assessing the amount of oxidation products of cystine present on the plasma-treated wool fabric surface. In this paper, three non-polymerising gases namely oxygen, nitrogen and 25% hydrogen/75% nitrogen gas mixture were used for the plasma treatment of wool fabric. The oxidation products of cystine studied included S-sulphonate, cysteic acid, cystine monoxide and cystine dioxide. The variations of the amount of these products as a function of treatment time were studied. Experimental results showed that the oxygen plasma could produce a large amount of oxidation products of cystine on the wool fabric surface followed by nitrogen plasma and gas mixture plasma.

Clinical effects of Banxia Baizhu Tianma decoction in the treatment of hypertension

Objective:To observe the clinical effect of Banxia Atractylodes macrocephala Tianma decoction in the treatment of hypertension.Methods:A total of 100 patients with hypertension were selected from our hospital(April 2016 to July 2019)and divided into 2 groups by random digital method.The control group was given routine symptomatic treatment of western medicine,and the observation group was given Banxia Atractylodes Gastrodia decoction on the basis of the control group.the levels of syndrome score and adiponectin(apn),cysc(cysc),uric acid(ua),c-reactive protein(crp),superoxide dismutase(sod),malondialdehyde(mda),8-hydroxydeoxyguanylic acid(8-ohdg)were recorded before and after treatment in group 2,and the total effective rate of clinical treatment was counted in group 2.Results:After treatment,the total effective rate(92.00%)in the observation group was higher than that in the control group(74.00%),and the difference was statistically significant(P<0.05).The APN、SOD level of the observation group was higher than that of the control group after treatment,and the CysC、UA、CRP、MDA、8-OHdG level and TCM symptom score were lower than those of the control group(P<0.05).Conclusion:Rhizoma Pinelliae and Rhizoma Gastrodiae decoction for treating hypertension can relieve oxidative stress injury,adjust the expression level of APN,CysC,CRP and UA,and improve the symptoms and improve the curative effect.

A nanoagent for concurrent therapy of breast cancer bone metastasis and cancer-induced bone pain through SLC7A11 interruption and photodynamic therapy

Bone metastasis,a life-threatening complication of advanced breast cancer,is often accompanied by debilitating pain(cancer-induced bone pain,CIBP)that severely impairs life quality and survival.The concurrent treatment of bone metastases and CIBP remains a clinical challenge because the therapeutic options are limited.In this study,we construct a near-infrared light-activated nano-therapeutic system to meet this conundrum.In detail,sorafenib(SRF)and photosensitizer(chlorin e6,Ce6)are encapsulated into mesoporous hydroxyapatite nanoparticles(HANPs),which are further functionalized with hyaluronic acid(HA)to obtain HA-SRF/Ce6@HANPs system.The designed nanoplatform destroys tumor cells in vitro and in vivo via the synergism of SRF(interrupting the exchange of cystine/glutamate by inhibiting SLC7A11)and photodynamic therapy(PDT,inducing reactive oxygen species generation).The decrease in tumor burden and reduction of extracellular glutamate significantly attenuate CIBP in mice model with developing bone cancer.Moreover,the combination of HA-SRF/Ce6@HANPs and PDT inhibit osteoclasts activation,promote osteoblast differentiation and accelerate bone repair.Overall,the nanoagent with good biocompatibility may provide an effective therapy method for the concurrent treatment of breast cancer bone metastasis and CIBP.

Amino acid transporter SLC7A11/ xCT at the crossroads of regulating redox homeostasis and nutrient dependency of cancer

Cancer cells often upregulate nutrient transporters to fulfill their increased biosynthetic and bioenergetic needs,and to maintain redox homeostasis.One nutrient transporter frequently overexpressed in human cancers is the cystine/glutamate antiporter solute carrier family 7 member 11(SLC7A11;also known as xCT).SLC7A11 promotes cystine uptake and glutathione biosynthesis,resulting in protection from oxidative stress and ferroptotic cell death.Recent studies have unexpectedly revealed that SLC7A11 also plays critical roles in glutamine metabolism and regulates the glucose and glutamine dependency of cancer cells.This review discusses the roles of SLC7A11 in regulating the anti-oxidant response and nutrient dependency of cancer cells,explores our current understanding of SLC7A11 regulation in cancer metabolism,and highlights key open questions for future studies in this emerging research area.A deeper understanding of SLC7A11 in cancer metabolism may identify new therapeutic opportunities to target this important amino acid transporter for cancer treatment.