Publications by authors named "Alexis Perry"

22 Publications

  • Page 1 of 1

Experimental investigation of a combinational iron chelating protoporphyrin IX prodrug for fluorescence detection and photodynamic therapy.

Lasers Med Sci 2021 Jul 4. Epub 2021 Jul 4.

European Centre for Environment and Human Health, Environment and Sustainability Institute, University of Exeter Medical School, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, UK.

Photodynamic therapy (PDT) is an oxygen-dependent, light-activated, and locally destructive drug treatment of cancer. Protoporphyrin IX (PpIX)-induced PDT exploits cancer cells' own innate heme biosynthesis to hyper-accumulate the naturally fluorescent and photoactive precursor to heme, PpIX. This occurs as a result of administering heme precursors (e.g., aminolevulinic acid; ALA) because the final step of the pathway (the insertion of ferrous iron into PpIX by ferrochelatase to form heme) is relatively slow. Separate administration of an iron chelating agent has previously been demonstrated to significantly improve dermatological PpIX-PDT by further limiting heme production. A newly synthesized combinational iron chelating PpIX prodrug (AP2-18) has been assessed experimentally in cultured primary human cells of bladder and dermatological origin, as an alternative photosensitizing agent to ALA or its methyl or hexyl esters (MAL and HAL respectively) for photodetection/PDT. Findings indicated that the technique of iron chelation (either through the separate administration of the established hydroxypyridinone iron chelator CP94 or the just as effective combined AP2-18) did not enhance either PpIX fluorescence or PDT-induced (neutral red assessed) cell death in human primary normal and malignant bladder cells. However, 500 µM AP2-18 significantly increased PpIX accumulation and produced a trend of increased cell death within epithelial squamous carcinoma cells. PpIX accumulation destabilized the actin cytoskeleton in bladder cancer cells prior to PDT and resulted in caspase-3 cleavage/early apoptosis afterwards. AP2-18 iron chelation should continue to be investigated for the enhancement of dermatological PpIX-PDT applications but not bladder photodetection/PDT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10103-021-03367-1DOI Listing
July 2021

A combinatorial cis-regulatory logic restricts color-sensing Rhodopsins to specific photoreceptor subsets in Drosophila.

PLoS Genet 2021 Jun 23;17(6):e1009613. Epub 2021 Jun 23.

Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America.

Color vision in Drosophila melanogaster is based on the expression of five different color-sensing Rhodopsin proteins in distinct subtypes of photoreceptor neurons. Promoter regions of less than 300 base pairs are sufficient to reproduce the unique, photoreceptor subtype-specific rhodopsin expression patterns. The underlying cis-regulatory logic remains poorly understood, but it has been proposed that the rhodopsin promoters have a bipartite structure: the distal promoter region directs the highly restricted expression in a specific photoreceptor subtype, while the proximal core promoter region provides general activation in all photoreceptors. Here, we investigate whether the rhodopsin promoters exhibit a strict specialization of their distal (subtype specificity) and proximal (general activation) promoter regions, or if both promoter regions contribute to generating the photoreceptor subtype-specific expression pattern. To distinguish between these two models, we analyze the expression patterns of a set of hybrid promoters that combine the distal promoter region of one rhodopsin with the proximal core promoter region of another rhodopsin. We find that the function of the proximal core promoter regions extends beyond providing general activation: these regions play a previously underappreciated role in generating the non-overlapping expression patterns of the different rhodopsins. Therefore, cis-regulatory motifs in both the distal and the proximal core promoter regions recruit transcription factors that generate the unique rhodopsin patterns in a combinatorial manner. We compare this combinatorial regulatory logic to the regulatory logic of olfactory receptor genes and discuss potential implications for the evolution of rhodopsins.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pgen.1009613DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8259978PMC
June 2021

One-pot, three-component Fischer indolisation--alkylation for rapid synthesis of 1,2,3-trisubstituted indoles.

Org Biomol Chem 2021 01;19(3):627-634

Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.

A one-pot, three-component protocol for the synthesis of 1,2,3-trisubstituted indoles has been developed, based upon a Fischer indolisation-indole N-alkylation sequence. This procedure is very rapid (total reaction time under 30 minutes), operationally straightforward, generally high yielding and draws upon readily available building blocks (aryl hydrazines, ketones, alkyl halides) to generate densely substituted indole products. We have demonstrated the utility of this process in the synthesis of 23 indoles, benzoindoles and tetrahydrocarbazoles bearing varied and useful functionality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0ob02185gDOI Listing
January 2021

New mechanism, new chromophore: investigating the electrophilic behaviour of styrylindolium dyes.

Authors:
Alexis Perry

Org Biomol Chem 2019 05;17(19):4825-4834

Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.

To inform the design of future merocyanine-based sensors for nucleophilic analytes, a range of model styrylindolium salts were synthesised, and their behaviour towards cyanide, methanethiolate and sulfide was examined using spectroscopic techniques. In the majority of cases, standard 1,2- and 1,4-nucleophilic additions predominated; however, 4-nitrostyrylindolium salts underwent an unexpected dearomatising 1,8-addition with sulfur-centred nucleophiles. The enamine triene products thus produced display useful optical properties and provide a platform for novel sensor design, and the unusual 1,8-reaction pathway enables synthesis of novel molecular architecture.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c9ob00641aDOI Listing
May 2019

Improving in vitro photodynamic therapy through the development of a novel iron chelating aminolaevulinic acid prodrug.

Photodiagnosis Photodyn Ther 2019 Mar 13;25:157-165. Epub 2018 Dec 13.

Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, Devon, EX4 4QD, UK.

Background: Photodynamic therapy (PDT) is a light activated drug therapy that can be used to treat a number of cancers and precancers. It is particularly useful in its topical form in dermatology but improvement of efficacy is required to widen its application.

Methods: An ester between aminolaevulinic acid (ALA) and CP94 was synthesised (AP2-18) and experimentally evaluated to determine whether protoporphyrin IX (PpIX)-induced PDT effectiveness could be improved. A biological evaluation of AP2-18 was conducted in cultured human primary cells with both PpIX fluorescence and cell viability (as determined via the neutral red assay) being assessed in comparison to the PpIX prodrugs normally utilised in clinical practice (aminolaevulinic acid (ALA) or its methyl ester (MAL)) either administered alone or with the comparator iron chelator, CP94.

Results: No significant dark toxicity was observed in human lung fibroblasts but AP2-18 significantly increased PpIX accumulation above and beyond that achieved with ALA or MAL administration +/- CP94 in both human dermal fibroblasts and epithelial squamous carcinoma cells. On light exposure, the combined hydroxypyridinone iron chelating ALA prodrug AP2-18 generated significantly greater cytotoxicity than any of the other treatment parameters investigated when the lowest concentration (250 μM) was employed.

Conclusions: Newly synthesised AP2-18 is therefore concluded to be an efficacious prodrug for PpIX-induced PDT in these dermatologically relevant human cells, achieving enhanced effects at lower concentrations than currently possible with existing pharmaceuticals.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.pdpdt.2018.12.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6456724PMC
March 2019

Cardiovascular Effects and Molecular Mechanisms of Bisphenol A and Its Metabolite MBP in Zebrafish.

Environ Sci Technol 2019 01 20;53(1):463-474. Epub 2018 Dec 20.

Biosciences, College of Life and Environmental Sciences , University of Exeter , Geoffrey Pope, Stocker Road , Exeter , Devon EX4 4QD , U.K.

The plastic monomer bisphenol A (BPA) is one of the highest production volume chemicals in the world and is frequently detected in wildlife and humans, particularly children. BPA has been associated with numerous adverse health outcomes relating to its estrogenic and other hormonal properties, but direct causal links are unclear in humans and animal models. Here we simulated measured (1×) and predicted worst-case (10× ) maximum fetal exposures for BPA, or equivalent concentrations of its metabolite MBP, using fluorescent reporter embryo-larval zebrafish, capable of quantifying Estrogen Response Element (ERE) activation throughout the body. Heart valves were primary sites for ERE activation by BPA and MBP, and transcriptomic analysis of microdissected heart tissues showed that both chemicals targeted several molecular pathways constituting biomarkers for calcific aortic valve disease (CAVD), including extra-cellular matrix (ECM) alteration. ECM collagen deficiency and impact on heart valve structural integrity were confirmed by histopathology for high-level MBP exposure, and structural defects (abnormal curvature) of the atrio-ventricular valves corresponded with impaired cardiovascular function (reduced ventricular beat rate and blood flow). Our results are the first to demonstrate plausible mechanistic links between ERE activation in the heart valves by BPA's reactive metabolite MBP and the development of valvular-cardiovascular disease states.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.8b04281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6333396PMC
January 2019

Synthesis of stereochemically-biased spiropyrans by microwave-promoted, one-pot alkylation-condensation.

Org Biomol Chem 2018 10;16(39):7245-7254

Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.

A microwave-assisted, two-step, one-pot synthesis of spiropyrans has been developed. This process was used to synthesise a range of sterically-congested spiropyrans from readily available precursors, employing environmentally benign solvents. The unusual substituent pattern possessed by these structures has been shown to influence the stereoselectivity of spiropyran ring-closure.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c8ob01996gDOI Listing
October 2018

Estrogenic Mechanisms and Cardiac Responses Following Early Life Exposure to Bisphenol A (BPA) and Its Metabolite 4-Methyl-2,4-bis( p-hydroxyphenyl)pent-1-ene (MBP) in Zebrafish.

Environ Sci Technol 2018 06 17;52(11):6656-6665. Epub 2018 May 17.

Biosciences, College of Life and Environmental Sciences , University of Exeter , Stocker Road , Exeter EX4 4QD , United Kingdom.

Environmental exposure to Bisphenol A (BPA) has been associated with a range of adverse health effects, including on the cardiovascular system in humans. Lack of agreement on its mechanism(s) of action likely stem from comparisons between in vivo and in vitro test systems and potential multiple effects pathways. In rodents, in vivo, metabolic activation of BPA produces 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), which is reported to be up to 1000 times more potent as an estrogen than BPA. We investigated the estrogenic effects and estrogen receptor signaling pathway(s) of BPA and MBP following early life exposure using a transgenic, estrogen responsive (ERE-TG) zebrafish and a targeted morpholino approach to knockdown the three fish estrogen receptor (ER) subtypes. The functional consequences of BPA exposure on the cardiovascular system of zebrafish larvae were also examined. The heart atrioventricular valves and the bulbus arteriosus were primary target tissues for both BPA and MBP in the ERE-TG zebrafish, and MBP was approximately 1000-fold more potent than BPA as an estrogen in these tissues. Estrogen receptor knockdown with morpholinos indicated that the estrogenic responses in the heart for both BPA and MBP were mediated via an estrogen receptor 1 (esr1) dependent pathway. At the highest BPA concentration tested (2500 μg/L), alterations in the atrial:ventricular beat ratio indicated a functional impact on the heart of 5 days post fertilization (dpf) larvae, and there was also a significantly reduced heart rate in these larvae at 14 dpf. Our findings indicate that some of the reported adverse effects on heart function associated with BPA exposure (in mammals) may act through an estrogenic mechanism, but that fish are unlikely to be susceptible to adverse effects on heart development for environmentally relevant exposures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.8b01095DOI Listing
June 2018

An experimental investigation of a novel iron chelating protoporphyrin IX prodrug for the enhancement of photodynamic therapy.

Lasers Surg Med 2018 07 31;50(5):552-565. Epub 2018 Mar 31.

European Centre for Environment and Human Health, University of Exeter Medical School, University of Exeter, Environment and Sustainability Institute, Penryn Campus, Cornwall TR10 9FE, UK.

Objectives: Non-melanoma skin cancers are the most frequently occurring type of cancer worldwide. They can be effectively treated using topical dermatological photodynamic therapy (PDT) employing protoporphyrin IX (PpIX) as the active photosensitising agent as long as the disease remains superficial. Novel iron chelating agents are being investigated to enhance the effectiveness and extend the applications of this treatment modality, as limiting free iron increases the accumulation of PpIX available for light activation and thus cell kill.

Methods: Human lung fibroblasts (MRC-5) and epithelial squamous carcinoma (A431) cells were treated with PpIX precursors (aminolaevulinic acid [ALA] or methyl-aminolevulinate [MAL]) with or without the separate hydroxypyridinone iron chelating agent (CP94) or alternatively, the new combined iron chelator and PpIX producing agent, AP2-18. PpIX fluorescence was monitored hourly for 6 hours prior to irradiation. PDT effectiveness was then assessed the following day using the lactate dehydrogenase and neutral red assays.

Results: Generally, iron chelation achieved via CP94 or AP2-18 administration significantly increased PpIX fluorescence. ALA was more effective as a PpIX-prodrug than MAL in A431 cells, corresponding with the lower PpIX accumulation observed with the latter congener in this cell type. Addition of either iron chelating agent consistently increased PpIX accumulation but did not always convey an extra beneficial effect on PpIX-PDT cell kill when using the already highly effective higher dose of ALA. However, these adjuvants were highly beneficial in the skin cancer cells when compared with MAL administration alone. AP2-18 was also at least as effective as CP94 + ALA/MAL co-administration throughout and significantly better than CP94 supplementation at increasing PpIX fluorescence in MRC5 cells as well as at lower doses where PpIX accumulation was observed to be more limited.

Conclusions: PpIX fluorescence levels, as well as PDT cell kill effects on irradiation can be significantly increased by pyridinone iron chelation, either via the addition of CP94 to the administration of a PpIX precursor or alternatively via the newly synthesized combined PpIX prodrug and siderophore, AP2-18. The effect of the latter compound appears to be at least equivalent to, if not better than, the separate administration of its constituent parts, particularly when employing MAL to destroy skin cancer cells. AP2-18 therefore warrants further detailed analysis, as it may have the potential to improve dermatological PDT outcomes in applications currently requiring enhancement. Lasers Surg. Med. 50:552-565, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/lsm.22809DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6032951PMC
July 2018

Synthesis and metal binding properties of -alkylcarboxyspiropyrans.

Beilstein J Org Chem 2017 4;13:1542-1550. Epub 2017 Aug 4.

Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.

Spiropyrans bearing an -alkylcarboxylate tether are a common structure in dynamic, photoactive materials and serve as colourimetric/fluorimetric cation receptors. In this study, we describe an efficient synthesis of spiropyrans with 2-12 carbon atom alkylcarboxylate substituents, and a systematic analysis of their interactions with metal cations using H NMR and UV-visible spectroscopy. All -alkylcarboxyspiropyrans in this study displayed a strong preference for binding divalent metal cations and a modest increase in M binding affinity correlated with increased alkycarboxylate tether length.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3762/bjoc.13.154DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5550821PMC
August 2017

The novel mitochondria-targeted hydrogen sulfide (HS) donors AP123 and AP39 protect against hyperglycemic injury in microvascular endothelial cells in vitro.

Pharmacol Res 2016 11 23;113(Pt A):186-198. Epub 2016 Aug 23.

University of Exeter Medical School, Exeter, UK. Electronic address:

The development of diabetic vascular complications is initiated, at least in part, by mitochondrial reactive oxygen species (ROS) production in endothelial cells. Hyperglycemia induces superoxide production in the mitochondria and initiates changes in the mitochondrial membrane potential that leads to mitochondrial dysfunction. Hydrogen sulfide (HS) supplementation has been shown to reduce the mitochondrial oxidant production and shows efficacy against diabetic vascular damage in vivo. However, the half-life of HS is very short and it is not specific for the mitochondria. We have therefore evaluated two novel mitochondria-targeted anethole dithiolethione and hydroxythiobenzamide HS donors (AP39 and AP123 respectively) at preventing hyperglycemia-induced oxidative stress and metabolic changes in microvascular endothelial cells in vitro. Hyperglycemia (HG) induced significant increase in the activity of the citric acid cycle and led to elevated mitochondrial membrane potential. Mitochondrial oxidant production was increased and the mitochondrial electron transport decreased in hyperglycemic cells. AP39 and AP123 (30-300nM) decreased HG-induced hyperpolarisation of the mitochondrial membrane and inhibited the mitochondrial oxidant production. Both HS donors (30-300nM) increased the electron transport at respiratory complex III and improved the cellular metabolism. Targeting HS to mitochondria retained the cytoprotective effect of HS against glucose-induced damage in endothelial cells suggesting that the molecular target of HS action is within the mitochondria. Mitochondrial targeting of HS also induced >1000-fold increase in the potency of HS against hyperglycemia-induced injury. The high potency and long-lasting effect elicited by these HS donors strongly suggests that these compounds could be useful against diabetic vascular complications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.phrs.2016.08.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5113977PMC
November 2016

Phosphinodithioate and Phosphoramidodithioate Hydrogen Sulfide Donors.

Handb Exp Pharmacol 2015 ;230:337-63

University of Exeter Medical School, Exeter, UK,

Hydrogen sulfide is rapidly emerging as a key physiological mediator and potential therapeutic tool in numerous areas such as acute and chronic inflammation, neurodegenerative and cardiovascular disease, diabetes, obesity and cancer. However, the vast majority of the published studies have employed crude sulfide salts such as sodium hydrosulfide (NaSH) and sodium sulfide (Na2S) as H2S "donors" to generate H2S. Although these salts are cheap, readily available and easy to use, H2S generated from them occurs as an instantaneous and pH-dependent dissociation, whereas endogenous H2S synthesis from the enzymes cystathionine γ-lyase, cystathionine-β-synthase and 3-mercaptopyruvate sulfurtransferase is a slow and sustained process. Furthermore, sulfide salts are frequently used at concentrations (e.g. 100 μM to 10 mM) far in excess of the levels of H2S reported in vivo (nM to low μM). For the therapeutic potential of H2S is to be properly harnessed, pharmacological agents which generate H2S in a physiological manner and deliver physiologically relevant concentrations are needed. The phosphorodithioate GYY4137 has been proposed as "slow-release" H2S donors and has shown promising efficacy in cellular and animal model diseases such as hypertension, sepsis, atherosclerosis, neonatal lung injury and cancer. However, H2S generation from GYY4137 is inefficient necessitating its use at high concentrations/doses. However, structural modification of the phosphorodithioate core has led to compounds (e.g. AP67 and AP105) with accelerated rates of H2S generation and enhanced biological activity. In this review, the therapeutic potential and limitations of GYY4137 and related phosphorodithioate derivatives are discussed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/978-3-319-18144-8_17DOI Listing
November 2015

Effects of AP39, a novel triphenylphosphonium derivatised anethole dithiolethione hydrogen sulfide donor, on rat haemodynamic parameters and chloride and calcium Cav3 and RyR2 channels.

Nitric Oxide 2015 Apr 30;46:131-44. Epub 2014 Dec 30.

University of Exeter Medical School, Exeter, UK. Electronic address:

H2S donor molecules have the potential to be viable therapeutic agents. The aim of this current study was (i) to investigate the effects of a novel triphenylphosphonium derivatised dithiolethione (AP39), in the presence and absence of reduced nitric oxide bioavailability and (ii) to determine the effects of AP39 on myocardial membrane channels; CaV3, RyR2 and Cl(-). Normotensive, L-NAME- or phenylephrine-treated rats were administered Na2S, AP39 or control compounds (AP219 and ADT-OH) (0.25-1 µmol kg(-1)i.v.) and haemodynamic parameters measured. The involvement of membrane channels T-type Ca(2+) channels CaV3.1, CaV3.2 and CaV3.3 as well as Ca(2+) ryanodine (RyR2) and Cl(-) single channels derived from rat heart sarcoplasmic reticulum were also investigated. In anaesthetised Wistar rats, AP39 (0.25-1 µmol kg(-1) i.v) transiently decreased blood pressure, heart rate and pulse wave velocity, whereas AP219 and ADT-OH and Na2S had no significant effect. In L-NAME treated rats, AP39 significantly lowered systolic blood pressure for a prolonged period, decreased heart rate and arterial stiffness. In electrophysiological studies, AP39 significantly inhibited Ca(2+) current through all three CaV3 channels. AP39 decreased RyR2 channels activity and increased conductance and mean open time of Cl(-) channels. This study suggests that AP39 may offer a novel therapeutic opportunity in conditions whereby (•)NO and H2S bioavailability are deficient such as hypertension, and that CaV3, RyR2 and Cl(-) cardiac membrane channels might be involved in its biological actions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.niox.2014.12.012DOI Listing
April 2015

A direct C-H/Ar-H coupling approach to oxindoles, thio-oxindoles, 3,4-dihydro-1 H-quinolin-2-ones, and 1,2,3,4-tetrahydroquinolines.

Chemistry 2014 Oct 11;20(43):14063-73. Epub 2014 Sep 11.

Department of Chemistry, University of York, Heslington, York, YO10 5DD (UK), Fax: (+44) 1904324523.

A copper(II)-catalysed approach to oxindoles, thio-oxindoles, 3,4-dihydro-1H-quinolin-2-ones, and 1,2,3,4-tetrahydroquinolines via formal C-H, Ar-H coupling is described. In a new variant, copper(II) 2-ethylhexanoate has been identified as an inexpensive and efficient catalyst for this transformation, which utilises atmospheric oxygen as the re-oxidant.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.201403917DOI Listing
October 2014

AP39, a novel mitochondria-targeted hydrogen sulfide donor, stimulates cellular bioenergetics, exerts cytoprotective effects and protects against the loss of mitochondrial DNA integrity in oxidatively stressed endothelial cells in vitro.

Nitric Oxide 2014 Sep 19;41:120-30. Epub 2014 Apr 19.

Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA. Electronic address:

The purpose of the current study was to investigate the effect of the recently synthesized mitochondrially-targeted H2S donor, AP39 [(10-oxo-10-(4-(3-thioxo-3H-1,2-dithiol-5yl)phenoxy)decyl) triphenylphosphonium bromide], on bioenergetics, viability, and mitochondrial DNA integrity in bEnd.3 murine microvascular endothelial cells in vitro, under normal conditions, and during oxidative stress. Intracellular H2S was assessed by the fluorescent dye 7-azido-4-methylcoumarin. For the measurement of bioenergetic function, the XF24 Extracellular Flux Analyzer was used. Cell viability was estimated by the combination of the MTT and LDH methods. Oxidative protein modifications were measured by the Oxyblot method. Reactive oxygen species production was monitored by the MitoSOX method. Mitochondrial and nuclear DNA integrity were assayed by the Long Amplicon PCR method. Oxidative stress was induced by addition of glucose oxidase. Addition of AP39 (30-300 nM) to bEnd.3 cells increased intracellular H2S levels, with a preferential response in the mitochondrial regions. AP39 exerted a concentration-dependent effect on mitochondrial activity, which consisted of a stimulation of mitochondrial electron transport and cellular bioenergetic function at lower concentrations (30-100 nM) and an inhibitory effect at the higher concentration of 300 nM. Under oxidative stress conditions induced by glucose oxidase, an increase in oxidative protein modification and an enhancement in MitoSOX oxidation was noted, coupled with an inhibition of cellular bioenergetic function and a reduction in cell viability. AP39 pretreatment attenuated these responses. Glucose oxidase induced a preferential damage to the mitochondrial DNA; AP39 (100 nM) pretreatment protected against it. In conclusion, the current paper documents antioxidant and cytoprotective effects of AP39 under oxidative stress conditions, including a protection against oxidative mitochondrial DNA damage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.niox.2014.04.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4225488PMC
September 2014

Regulation of heart function by endogenous gaseous mediators-crosstalk between nitric oxide and hydrogen sulfide.

Antioxid Redox Signal 2011 Jun 17;14(11):2081-91. Epub 2011 Mar 17.

Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.

Both nitric oxide (NO) and hydrogen sulfide (H(2)S) are two important gaseous mediators regulating heart function. The present study examined the interaction between these two biological gases and its role in the heart. We found that l-arginine, a substrate of NO synthase, decreased the amplitudes of myocyte contraction and electrically induced calcium transients. Sodium hydrogen sulfide (an H(2)S donor), which alone had minor effect, reversed the negative inotropic effects of l-arginine. The effect of l-arginine + sodium hydrogen sulfide was abolished by three thiols (l-cysteine, N-acetyl-cysteine, and glutathione), suggesting that the effect of H(2)S + NO is thiol sensitive. The stimulatory effect on heart contractility was also induced by GYY4137, a slow-releasing H(2)S donor, when used together with sodium nitroprusside, an NO-releasing donor. More importantly, enzymatic generation of H(2)S from recombinant cystathionine-γ-lyase protein also interacted with endogenous NO generated from l-arginine to stimulate heart contraction. In summary, our data suggest that endogenous NO may interact with H(2)S to produce a new biological mediator that produces positive inotropic effect. The crosstalk between H(2)S and NO also suggests an intriguing potential for the endogenous formation of a thiol-sensitive molecule, which may be of physiological significance in the heart.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/ars.2010.3572DOI Listing
June 2011

First C-H activation route to oxindoles using copper catalysis.

Org Lett 2010 Aug;12(15):3446-9

Department of Chemistry, University of York, Heslington, York, YO10 5DD, United Kingdom.

The preparation of 3,3-disubstituted oxindoles by a formal C-H, Ar-H coupling of anilides is described. Highly efficient conditions have been identified using catalytic (5 mol %) Cu(OAc)(2).H(2)O with atmospheric oxygen as the reoxidant; no additional base is required, and the reaction can be run in toluene or mesitylene. Optimization studies are reported together with a scope and limitation investigation based on variation of the anilide precursors. The application of this methodology to prepare a key intermediate for the total synthesis of the anticancer, analgesic oxindole alkaloid Horsfiline is also described.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ol1012668DOI Listing
August 2010

Oxindole synthesis by direct C-H, Ar-H coupling.

Chem Commun (Camb) 2009 Jun 22(22):3249-51. Epub 2009 Apr 22.

Department of Chemistry, University of York, Heslington, York, UK YO10 5DD.

A novel copper(II)-mediated route for the conversion of anilides into 3,3-disubstituted-oxindoles is described which proceeds via a formal C-H, Ar-H coupling process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/b903516hDOI Listing
June 2009

Involvement of GSK-3 in regulation of murine embryonic stem cell self-renewal revealed by a series of bisindolylmaleimides.

Chem Biol 2009 Jan;16(1):15-27

Department of Pharmacy and Pharmacology, Centre for Regenerative Medicine, University of Bath, Bath, UK.

The ability to propagate embryonic stem cells (ESCs) while maintaining their pluripotency is critical if their potential use in regenerative medicine is to be realized. The mechanisms controlling ESC self-renewal are under intense investigation, and glycogen synthase kinase 3 (GSK-3) has been implicated in regulating both self-renewal and differentiation. To clarify its role in ESCs we have used chemical genetics. We synthesized a series of bisindolylmaleimides, a subset of which inhibit GSK-3 in murine ESCs and robustly enhance self-renewal in the presence of leukemia inhibitory factor (LIF) and serum, but not in the absence of LIF. Importantly, these molecules appear selective for GSK-3 and do not perturb other signaling pathways regulating self-renewal. Our study clarifies the functional importance of GSK-3 in regulation of ESC self-renewal and provides tools for investigating its role further.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chembiol.2008.11.003DOI Listing
January 2009

Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives.

Beilstein J Org Chem 2005 Aug 26;1(1). Epub 2005 Aug 26.

School of Chemistry, Chemical Development, GlaxoSmithKline, Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2NY, UK.

Background: Many polyhydroxylated piperidines are inhibitors of the oligosaccharide processing enzymes, glycosidases and glycosyltransferases. Aza-C-linked disaccharide mimetics are compounds in which saturated polyhydroxylated nitrogen and oxygen heterocycles are linked by an all-carbon tether. The saturated oxygen heterocycle has the potential to mimic the departing sugar in a glycosidase-catalysed reaction and aza-C-linked disaccharide mimetics may, therefore, be more potent inhibitors of these enzymes.

Results: The scope, limitations and diastereoselectivity of the dihydroxylation of stereoisomeric 2-butyl-1-(toluene-4-sulfonyl)-1,2,3,6-tetrahydro-pyridin-3-ols is discussed. In the absence of a 6-substituent on the piperidine ring, the Upjohn (cat. OsO4, NMO, acetone-water) and Donohoe (OsO4, TMEDA, CH2Cl2) conditions allow complementary diastereoselective functionalisation of the alkene of the (2R*,3R*) diastereoisomer. However, in the presence of a 6-substituent, the reaction is largely controlled by steric effects with both reagents. The most synthetically useful protocols were exploited in the two-directional synthesis of aza-C-linked disaccharide analogues. A two-directional oxidative ring expansion was used to prepare bis-enones such as (2R,6S,2'S)-6-methoxy-2-(6-methoxy-3-oxo-3,6-dihydro-2H-pyran-2-ylmethyl)-1-(toluene-4-sulfonyl)-1,6-dihydro-2H-pyridin-3-one from the corresponding difuran. Selective substitution of its N,O acetal was possible. The stereochemical outcome of a two-directional Luche reduction step was different in the two heterocyclic rings, and depended on the conformation of the ring. Finally, two-directional diastereoselective dihydroxylation yielded seven different aza-C-linked disaccharide analogues.

Conclusion: A two-directional approach may be exploited in the synthesis of aza-C-linked disaccharide mimetics. Unlike previous approaches to similar molecules, neither of the heterocyclic rings is directly derived from a sugar, allowing mimetics with unusual configurations to be prepared. The work demonstrates that highly unsymmetrical molecules may be prepared using a two directional approach. The deprotected compounds may have potential as inhibitors of oligosaccharide-processing enzymes and as tools in chemical genetic investigations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/1860-5397-1-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1399450PMC
August 2005

Quality of life.

Authors:
Alexis Perry

Rehab Manag 2005 Aug-Sep;18(7):18, 20-1

Spaulding Rehabilitation Hospital, Framingham, Mass, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
September 2005

A general, two-directional approach to aza-C-(1 --> 1)-linked disaccharide mimetics.

Chem Commun (Camb) 2005 Mar 2(12):1646-8. Epub 2005 Feb 2.

Synthetic Chemistry, Chemical Development, GlaxoSmithKline, Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2NY, UK.

The Upjohn and Donohoe dihydroxylations were exploited in divergent syntheses of aza-C-(1 --> 1)-linked disaccharides.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/b417899hDOI Listing
March 2005
-->