Syntheses and Reactions of Pyrroline, Piperidine Nitroxide Phosphonates.

Organophosphorus compounds occupy a significant position among the plethora of organic compounds, but a limited number of paramagnetic phosphorus compounds have been reported, including paramagnetic phosphonates. This paper describes the syntheses and further transformations of pyrroline and piperidine nitroxide phosphonates by well-established methods, such as the Pudovik, Arbuzov and Horner-Wadsworth-Emmons (HWE) reactions. The reaction of paramagnetic a-bromoketone produced a vinylphosphonate in the Perkow reaction. Paramagnetic a-hydroxyphosphonates could be subjected to oxidation, elimination and substitution reactions to produce various paramagnetic phosphonates. The synthesized paramagnetic phosphonates proved to be useful synthetic building blocks for carbon-carbon bond-forming reactions in the Horner-Wadsworth-Emmons olefination reactions. The unsaturated compounds achieved could be transformed into various substituted pyrroline nitroxides, proxyl nitroxides and paramagnetic polyaromatics. The Trolox® equivalent antioxidant capacity (TEAC) of new phosphonates was also screened, and tertiary a-hydroxyphosphonatate nitroxides exhibited remarkable antioxidant activity.

Synthesis of Spin-Labelled Bergamottin: A Potent CYP3A4 Inhibitor with Antiproliferative Activity.

Bergamottin (BM, 1), a component of grapefruit juice, acts as an inhibitor of some isoforms of the cytochrome P450 (CYP) enzyme, particularly CYP3A4. Herein, a new bergamottin containing a nitroxide moiety (SL-bergamottin, SL-BM, 10) was synthesized; chemically characterized, evaluated as a potential inhibitor of the CYP2C19, CYP3A4, and CYP2C9 enzymes; and compared to BM and known inhibitors such as ketoconazole (KET) (3A4), warfarin (WAR) (2C9), and ticlopidine (TIC) (2C19). The antitumor activity of the new SL-bergamottin was also investigated. Among the compounds studied, BM showed the strongest inhibition of the CYP2C9 and 2C19 enzymes. SL-BM is a more potent inhibitor of CYP3A4 than the parent compound; this finding was also supported by docking studies, suggesting that the binding positions of BM and SL-BM to the active site of CYP3A4 are very similar, but that SL-BM had a better ∆Gbind value than that of BM. The nitroxide moiety markedly increased the antitumor activity of BM toward HeLa cells and marginally increased its toxicity toward a normal cell line. In conclusion, modification of the geranyl sidechain of BM can result in new CYP3A4 enzyme inhibitors with strong antitumor effects.

Antiproliferative Effect of a Novel 4,4'-Disulfonyldiarylidenyl Piperidone in Human Colon Cancer Cells.

The synthesis and antiproliferative effect of a novel curcumin analog, 4,4'-disulfonyldiarylidenyl piperidone, are reported. The design of the molecule is based on the fusion of an antiproliferative segment, namely diarylidenyl piperidone (DAP), with N-hyroxypyrroline, which is known to metabolically convert to nitroxide and protect healthy cells. Cellular uptake, metabolic conversion, cytotoxicity and antiproliferative effect of the DAP derivative against HCT-116 human colon cancer cells have been determined. Based on cell viability and proliferation assays as well as western-blot analysis of major transcription factors and inhibitory proteins, it is determined that the DAP compound is cytotoxic by inhibiting cell survival and proliferation pathways. The findings may have important implications in the design and development of effective anticancer agents.

The curcumin analog HO-3867 selectively kills cancer cells by converting mutant p53 protein to transcriptionally active wildtype p53.

p53 is an important tumor-suppressor protein that is mutated in more than 50% of cancers. Strategies for restoring normal p53 function are complicated by the oncogenic properties of mutant p53 and have not met with clinical success. To counteract mutant p53 activity, a variety of drugs with the potential to reconvert mutant p53 to an active wildtype form have been developed. However, these drugs are associated with various negative effects such as cellular toxicity, nonspecific binding to other proteins, and inability to induce a wildtype p53 response in cancer tissue. Here, we report on the effects of a curcumin analog, HO-3867, on p53 activity in cancer cells from different origins. We found that HO-3867 covalently binds to mutant p53, initiates a wildtype p53-like anticancer genetic response, is exclusively cytotoxic toward cancer cells, and exhibits high anticancer efficacy in tumor models. In conclusion, HO-3867 is a p53 mutant-reactivating drug with high clinical anticancer potential.

Synthesis and Biological Evaluation of Curcumin-Nitroxide-Based Molecular Hybrids as Antioxidant and Anti-Proliferative Agents.

BACKGROUND: Natural products and their derivatives are widely used to treat cancer and other diseases associated with ROS- and RNS-induced damages. METHODS: A series of paramagnetic modified curcumin analogs and 3,5-diarylidene-piperidones (DAP) have been designed, synthesized, and characterized on their anti-proliferative and antioxidant activity. RESULTS: Biological characterization of the new compounds supported the earlier results that incorporation of a nitroxide moiety or its precursor into curcumin or diarylidenylpiperidone (DAP) scaffolds resulted in anti-proliferative effect toward cancerous cell-lines in case of aryl hydroxy and/or methoxy substituent containing derivatives, suggesting their potential for targeted therapeutic applications. In case of basic side chain derivatives, nitroxide incorporation gave unambiguous results, however in tendency the more accessible DAP derivatives had stronger anti-proliferative effect. In most cases, the nitroxide incorporation increased the TEAC value (proton and electron donation capability) of DAP derivatives. CONCLUSIONS: Among the compounds synthesized and investigated the spin-labeled curcumin and 3,5-bis(4-hydroxy-3-methoxybenzylidene)piperidin-4-one derivatives were the most effective antiproliferative and antioxidant derivatives.

Oligomerization Alters Binding Affinity Between Amyloid Beta and a Modulator of Peptide Aggregation.

The soluble oligomeric form of the amyloid beta (Aß) peptide is the major causative agent in the molecular pathogenesis of Alzheimer's disease (AD). We have previously developed a pyrroline-nitroxyl fluorene compound (SLF) that blocks the toxicity of Aß. Here we introduce the multi-parametric surface plasmon resonance (MP-SPR) approach to quantify SLF binding and effect on the self-association of the peptide via a label-free, real-time approach. Kinetic analysis of SLF binding to Aß and measurements of layer thickness alterations inform on the mechanism underlying the ability of SLF to inhibit Aß toxicity and its progression towards larger oligomeric assemblies. Depending on the oligomeric state of Aß, distinct binding affinities for SLF are revealed. The Aß monomer and dimer uniquely possess sub-nanomolar affinity for SLF via a non-specific mode of binding. SLF binding is weaker in oligomeric Aß, which displays an affinity for SLF on the order of 100 µM. To complement these experiments we carried out molecular docking and molecular dynamics simulations to explore how SLF interacts with the Aß peptide. The MP-SPR results together with in silico modeling provide affinity data for the SLF-Aß interaction and allow us to develop a new general method for examining protein aggregation.

A Metal-Free Method for Producing MRI Contrast at Amyloid-ß.

Alzheimer's disease (AD) is characterized by depositions of the amyloid-ß (Aß) peptide in the brain. The disease process develops over decades, with substantial neurological loss occurring before a clinical diagnosis of dementia can be rendered. It is therefore imperative to develop methods that permit early detection and monitoring of disease progression. In addition, the multifactorial pathogenesis of AD has identified several potential avenues for AD intervention. Thus, evaluation of therapeutic candidates over lengthy trial periods also demands a practical, noninvasive method for measuring Aß in the brain. Magnetic resonance imaging (MRI) is the obvious choice for such measurements, but contrast enhancement for Aß has only been achieved using Gd(III)-based agents. There is great interest in gadolinium-free methods to image the brain. In this study, we provide the first demonstration that a nitroxide-based small-molecule produces MRI contrast in brain specimens with elevated levels of Aß. The molecule is comprised of a  fluorene (a molecule with high affinity for Aß) and a nitroxide spin label (a paramagnetic MRI contrast species). Labeling of brain specimens with the spin-labeled fluorene produces negative contrast in samples from AD model mice whereas no negative contrast is seen in specimens harvested from wild-type mice. Injection of spin-labeled fluorene into live mice resulted in good brain penetration, with the compound able to generate contrast 24-h post injection. These results provide a proof of concept method that can be used for early, noninvasive, gadolinium-free detection of amyloid plaques by MRI.

Exploring Structure, Dynamics, and Topology of Nitroxide Spin-Labeled Proteins Using Continuous-Wave Electron Paramagnetic Resonance Spectroscopy.

Structural and dynamical characterization of proteins is of central importance in understanding the mechanisms underlying their biological functions. Site-directed spin labeling (SDSL) combined with continuous-wave electron paramagnetic resonance (CW EPR) spectroscopy has shown the capability of providing this information with site-specific resolution under physiological conditions for proteins of any degree of complexity, including those associated with membranes. This chapter introduces methods commonly employed for SDSL and describes selected CW EPR-based methods that can be applied to (1) map secondary and tertiary protein structure, (2) determine membrane protein topology, (3) measure protein backbone flexibility, and (4) reveal the existence of conformational exchange at equilibrium.

Protective spin-labeled fluorenes maintain amyloid beta peptide in small oligomers and limit transitions in secondary structure.

Alzheimer's disease is characterized by the presence of extracellular plaques comprised of amyloid beta (Aß) peptides. Soluble oligomers of the Aß peptide underlie a cascade of neuronal loss and dysfunction associated with Alzheimer's disease. Single particle analyses of Aß oligomers in solution by fluorescence correlation spectroscopy (FCS) were used to provide real-time descriptions of how spin-labeled fluorenes (SLFs; bi-functional small molecules that block the toxicity of Aß) prevent and disrupt oligomeric assemblies of Aß in solution. Furthermore, the circular dichroism (CD) spectrum of untreated Aß shows a continuous, progressive change over a 24-hour period, while the spectrum of Aß treated with SLF remains relatively constant following initial incubation. These findings suggest the conformation of Aß within the oligomer provides a complementary determinant of Aß toxicity in addition to oligomer growth and size. Although SLF does not produce a dominant state of secondary structure in Aß, it does induce a net reduction in beta secondary content compared to untreated samples of Aß. The FCS results, combined with electron paramagnetic resonance spectroscopy and CD spectroscopy, demonstrate SLFs can inhibit the growth of Aß oligomers and disrupt existing oligomers, while retaining Aß as a population of smaller, yet largely disordered oligomers.

A nucleotide-independent cyclic nitroxide label for monitoring segmental motions in nucleic acids.

BACKGROUND: Spin labels, which are chemically stable radicals attached at specific sites of a bio-molecule, enable investigations on structure and dynamics of proteins and nucleic acids using techniques such as site-directed spin labeling and paramagnetic NMR. Among spin labels developed, the class of rigid labels have limited or no independent motions between the radical bearing moiety and the target, and afford a number of advantages in measuring distances and monitoring local dynamics within the parent bio-molecule. However, a general method for attaching a rigid label to nucleic acids in a nucleotide-independent manner has not been reported. RESULTS: We developed an approach for installing a nearly rigid nitroxide spin label, designated as R5c, at a specific site of the nucleic acid backbone in a nucleotide-independent manner. The method uses a post-synthesis approach to covalently attach the nitroxide moiety in a cyclic fashion to phosphorothioate groups introduced at two consecutive nucleotides of the target strand. R5c-labeled nucleic acids are capable of pairing with their respective complementary strands, and the cyclic nature of R5c attachment significantly reduced independence motions of the label with respect to the parent duplex, although it may cause distortion of the local environment at the site of labeling. R5c yields enhanced sensitivity to the collective motions of the duplex, as demonstrated by its capability to reveal changes in collective motions of the substrate recognition duplex of the 120-kDa Tetrahymena group I ribozyme, which elude detection by a flexible label. CONCLUSIONS: The cyclic R5c nitroxide can be efficiently attached to a target nucleic acid site using a post-synthetic coupling approach conducted under mild biochemical conditions, and serves as a viable label for experimental investigation of segmental motions in nucleic acids, including large folded RNAs.

PARP-inhibitor treatment prevents hypertension induced cardiac remodeling by favorable modulation of heat shock proteins, Akt-1/GSK-3ß and several PKC isoforms.

Spontaneously hypertensive rat (SHR) is a suitable model for studies of the complications of hypertension. It is known that activation of poly(ADP-ribose) polymerase enzyme (PARP) plays an important role in the development of postinfarction as well as long-term hypertension induced heart failure. In this study, we examined whether PARP-inhibitor (L-2286) treatment could prevent the development of hypertensive cardiopathy in SHRs. 6-week-old SHR animals were treated with L-2286 (SHR-L group) or placebo (SHR-C group) for 24 weeks. Wistar-Kyoto rats were used as aged-matched, normotensive controls (WKY group). Echocardiography was performed, brain-derived natriuretic peptide (BNP) activity and blood pressure were determined at the end of the study. We detected the extent of fibrotic areas. The amount of heat-shock proteins (Hsps) and the phosphorylation state of Akt-1(Ser473), glycogen synthase kinase (GSK)-3ß(Ser9), forkhead transcription factor (FKHR)(Ser256), mitogen activated protein kinases (MAPKs), and protein kinase C (PKC) isoenzymes were monitored. The elevated blood pressure in SHRs was not influenced by PARP-inhibitor treatment. Systolic left ventricular function and BNP activity did not differ among the three groups. L-2286 treatment decreased the marked left ventricular (LV) hypertrophy which was developed in SHRs. Interstitial collagen deposition was also decreased by L-2286 treatment. The phosphorylation of extracellular signal-regulated kinase (ERK)1/2(Thr183-Tyr185), Akt-1(Ser473), GSK-3ß(Ser9), FKHR(Ser256), and PKC ε(Ser729) and the level of Hsp90 were increased, while the activity of PKC α/ßII(Thr638/641), ζ/λ(410/403) were mitigated by L-2286 administration. We could detect signs of LV hypertrophy without congestive heart failure in SHR groups. This alteration was prevented by PARP inhibition. Our results suggest that PARP-inhibitor treatment has protective effect already in the early stage of hypertensive myocardial remodeling.

PARP inhibitor attenuated colony formation can be restored by MAP kinase inhibitors in different irradiated cancer cell lines.

UNLABELLED: Abstract Purpose: Sensitizing cancer cells to irradiation is a major challenge in clinical oncology. We aimed to define the signal transduction pathways involved in poly(ADP-ribose) polymerase (PARP) inhibitor-induced radiosensitization in various mammalian cancer lines. MATERIALS AND METHODS: Clonogenic survival assays and Western blot examinations were performed following telecobalt irradiation of cancer cells in the presence or absence of various combinations of PARP- and selective mitogen-activated protein kinase (MAPK) inhibitors. RESULTS: HO3089 resulted in significant cytotoxicity when combined with irradiation. In human U251 glioblastoma and A549 lung cancer cell lines, Erk1/2 and JNK/SAPK were found to mediate this effect of HO3089 since inhibitors of these kinases ameliorated it. In murine 4T1 breast cancer cell line, p38 MAPK rather than Erk1/2 or JNK/SAPK was identified as the main mediator of HO3089's radiosensitizing effect. Besides the aforementioned changes in kinase signaling, we detected increased p53, unchanged Bax and decreased Bcl-2 expression in the A549 cell line. CONCLUSIONS: HO3089 sensitizes cancer cells to photon irradiation via proapoptotic processes where p53 plays a crucial role. Activation of MAPK pathways is regarded the consequence of irradiation-induced DNA damage, thus their inhibition can counteract the radiosenzitizing effect of the PARP inhibitor.

HO-3867, a safe STAT3 inhibitor, is selectively cytotoxic to ovarian cancer.

STAT3 is well corroborated preclinically as a cancer therapeutic target, but tractable translational strategies for its blockade by small molecule inhibitors have remained elusive. In this study, we report the development of a novel class of bifunctional STAT3 inhibitors, based on conjugation of a diarylidenyl-piperidone (DAP) backbone to an N-hydroxypyrroline (-NOH) group, which exhibits minimal toxicity against normal cells and good oral bioavailability. Molecular modeling studies of this class suggested direct interaction with the STAT3 DNA binding domain. In particular, the DAP compound HO-3867 selectively inhibited STAT3 phosphorylation, transcription, and DNA binding without affecting the expression of other active STATs. HO-3867 exhibited minimal toxicity toward noncancerous cells and tissues but induced apoptosis in ovarian cancer cells. Pharmacologic analysis revealed greater bioabsorption and bioavailability of the active (cytotoxic) metabolites in cancer cells compared with normal cells. The selective cytotoxicity of HO-3867 seemed to be multifaceted, eliciting differential activation of the Akt pathway in normal versus cancer cells. RNAi attenuation experiments confirmed the requirement of STAT3 for HO-3867-mediated apoptosis in ovarian cancer cells. In vivo testing showed that HO-3867 could block xenograft tumor growth without toxic side effects. Furthermore, in primary human ovarian cancer cells isolated from patient ascites, HO-3867 inhibited cell migration/invasion and survival. Our results offer preclinical proof-of-concept for HO-3867 as a selective STAT3 inhibitor to treat ovarian cancer and other solid tumors where STAT3 is widely upregulated.

Synthesis and functional survey of new Tacrine analogs modified with nitroxides or their precursors.

A series of new Tacrine analogs modified with nitroxides or pre-nitroxides on 9-amino group via methylene or piperazine spacers were synthesized; the nitroxide or its precursors were incorporated into the Tacrine scaffold. The new compounds were tested for their hydroxyl radical and peroxyl radical scavenging ability, acetylcholinesterase inhibitor activity and protection against Aß-induced cytotoxicity. Based on these assays, we conclude that Tacrine analogs connected to five and six-membered nitroxides via piperazine spacers (9b, 9b/HCl and 12) exhibited the best activity, providing direction for further development of additional candidates with dual functionality (anti Alzheimer's and antioxidant).

A quinazoline-derivative compound with PARP inhibitory effect suppresses hypertension-induced vascular alterations in spontaneously hypertensive rats.

AIMS: Oxidative stress and neurohumoral factors play important role in the development of hypertension-induced vascular remodeling, likely by disregulating kinase cascades and transcription factors. Oxidative stress activates poly(ADP-ribose)-polymerase (PARP-1), which promotes inflammation and cell death. We assumed that inhibition of PARP-1 reduces the hypertension-induced adverse vascular changes. This hypothesis was tested in spontaneously hypertensive rats (SHR). METHODS AND RESULTS: Ten-week-old male SHRs and wild-type rats received or not 5mg/kg/day L-2286 (a water-soluble PARP-inhibitor) for 32 weeks, then morphological and functional parameters were determined in their aortas. L-2286 did not affect the blood pressure in any of the animal groups measured with tail-cuff method. Arterial stiffness index increased in untreated SHRs compared to untreated Wistar rats, which was attenuated by L-2286 treatment. Electron and light microscopy of aortas showed prominent collagen deposition, elevation of oxidative stress markers and increased PARP activity in SHR, which were attenuated by PARP-inhibition. L-2286 treatment decreased also the hypertension-activated mitochondrial cell death pathway, characterized by the nuclear translocation of AIF. Hypertension activated all three branches of MAP-kinases. L-2286 attenuated these changes by inducing the expression of MAPK phosphatase-1 and by activating the cytoprotective PI-3-kinase/Akt pathway. Hypertension activated nuclear factor-kappaB, which was prevented by PARP-inhibition via activating its nuclear export. CONCLUSION: PARP-inhibition has significant vasoprotective effects against hypertension-induced vascular remodeling. Therefore, PARP-1 can be a novel therapeutic drug target for preventing hypertension-induced vascular remodeling in a group of patients, in whom lowering the blood pressure to optimal range is harmful or causes intolerable side effects.

A novel curcumin analog (H-4073) enhances the therapeutic efficacy of cisplatin treatment in head and neck cancer.

Chemotherapy constitutes the standard modality of treatment for localized head and neck squamous cell carcinomas (HNSCC). However, many patients fail to respond and relapse after this treatments due to the acquisition of chemo-resistance. Therefore, there is an urgent need to develop novel drugs that could reverse the resistant phenotype. Curcumin, the constituent of the spice turmeric has been shown to have anti-inflammatory, anti-oxidant and anti-proliferative properties in several tumor types. However, use of curcumin has been limited due to its poor bio-absorption. Recently, a novel class of curcumin analogs, based on diarylidenylpiperidones (DAP), has been developed by incorporating a piperidone link to the beta-diketone structure and fluoro substitutions on the phenyl groups. In this study, we evaluated the effectiveness of H-4073, a parafluorinated variant of DAP, using both in vitro and in vivo head and neck cancer models. Our results demonstrate that H-4073 is a potent anti-tumor agent and it significantly inhibited cell proliferation in all the HNSCC cell lines tested in a dose-dependent manner. In addition, pretreatment of cisplatin-resistant HNSCC cell lines with H-4073 significantly reversed the chemo-resistance as observed by cell viability assay (MTT), apoptosis assay (Annexin V binding) and cleaved caspase-3 (Western blot). H-4073 mediated its anti-tumor effects by inhibiting JAK/STAT3, FAK, Akt and VEGF signaling pathways that play important roles in cell proliferation, migration, survival and angiogenesis. In the SCID mouse xenograft model, H-4073 significantly enhanced the anti-tumor and anti-angiogenesis effects of cisplatin, with no added systemic toxicity. Interestingly, H-4073 inhibited tumor angiogenesis by blocking VEGF production by tumor cells as well as directly inhibiting endothelial cell function. Taken together, our results suggest that H-4073 is a potent anti-tumor agent and it can be used to overcome chemotherapy resistance in HNSCC.

Targeting constitutively-activated STAT3 in hypoxic ovarian cancer, using a novel STAT3 inhibitor.

Tumor hypoxia, a feature of many solid tumors including ovarian cancer, is associated with resistance to therapies. We previously demonstrated that hypoxic exposure results in increased expression of phosphorylated signal transducer and activator of transcription 3 (pSTAT3). We hypothesized the activation of STAT3 could lead to chemotherapeutic resistance in ovarian cancer cells in hypoxic conditions. In this study, we demonstrate the level of pSTAT3 Tyr705 is increased in the hypoxic regions of human epithelial ovarian cancer (EOC) specimens, as determined by HIF-1α and CD-31 staining. In vitro mutagenesis studies proved that pSTAT3 Tyr705 is necessary for cell survival and proliferation under hypoxic conditions. In addition, we show that S1PR1, a regulator of STAT3 transcription via the JAK/STAT pathway, is highly expressed in hypoxic ovarian cancer cells (HOCCs). Knock down of S1PR1 in HOCCs reduced pSTAT3 Tyr705 levels and was associated with decreased cell survival. Treatment of HOCCs with the STAT3 inhibitor HO-3867 resulted in a rapid and dramatic decrease in pSTAT3 Tyr705 levels as a result of ubiquitin proteasome degradation. STAT3-target proteins Bcl-xL, cyclin D2 and VEGF showed similar decreases in HO-3867 treated cells. Taken together, these findings suggest that activation of STAT3 Tyr705 promotes cell survival and proliferation in HOCCs, and that S1PR1 is involved in the initiation of STAT3 activation. Targeting hypoxia-mediated STAT3 activation represents a therapeutic option for ovarian cancer and other solid tumors.

Pulmonary hypertension secondary to left-heart failure involves peroxynitrite-induced downregulation of PTEN in the lung.

Pulmonary hypertension (PH) that occurs after left-heart failure (LHF), classified as Group 2 PH, involves progressive pulmonary vascular remodeling induced by smooth muscle cell (SMC) proliferation. However, mechanisms involved in the activation of SMCs remain unknown. The objective of this study was to determine the involvement of peroxynitrite and phosphatase-and-tensin homolog on chromosome 10 (PTEN) in vascular SMC proliferation and remodeling in the LHF-induced PH (LHF-PH). LHF was induced by permanent ligation of left anterior descending coronary artery in rats for 4 weeks. MRI, ultrasound, and hemodynamic measurements were performed to confirm LHF and PH. Histopathology, Western blot, and real-time polymerase chain reaction analyses were used to identify key molecular signatures. Therapeutic intervention was demonstrated using an antiproliferative compound, HO-3867. LHF-PH was confirmed by significant elevation of pulmonary artery pressure (mean pulmonary artery pressure/mm Hg: 35.9±1.8 versus 14.8±2.0, control; P<0.001) and vascular remodeling. HO-3867 treatment decreased mean pulmonary artery pressure to 22.6±0.8 mm Hg (P<0.001). Substantially higher levels of peroxynitrite and significant loss of PTEN expression were observed in the lungs of LHF rats when compared with control. In vitro studies using human pulmonary artery SMCs implicated peroxynitrite-mediated downregulation of PTEN expression as a key mechanism of SMC proliferation. The results further established that HO-3867 attenuated LHF-PH by decreasing oxidative stress and increasing PTEN expression in the lung. In conclusion, peroxynitrite and peroxynitrite-mediated PTEN inactivation seem to be key mediators of lung microvascular remodeling associated with PH secondary to LHF.

Synthesis and potential use of 1,8-naphthalimide type (1)O2 sensor molecules.

New double (fluorescent and spin) sensor molecules containing 4-amino substituted 1,8-naphthalimide as a fluorophore and a sterically hindered amine (pre-nitroxide) or pyrroline nitroxide as a quencher and radical capturing moiety were synthesized. All sensors were substituted with a diethylaminoethyl side-chain to increase the water solubility. Steady state fluorescence properties of these compounds and their responses to ROS in vitro are reported with perspectives of plant physiology use in vivo.