Publications by authors named "Anna Eichinger"

15 Publications

  • Page 1 of 1

Upfront Enzyme Replacement via Erythrocyte Transfusions for PNP Deficiency.

J Clin Immunol 2021 Feb 27. Epub 2021 Feb 27.

Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany.

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http://dx.doi.org/10.1007/s10875-021-01003-9DOI Listing
February 2021

Venetoclax and decitabine for relapsed paediatric myelodysplastic syndrome-related acute myeloid leukaemia with complex aberrant karyotype after second stem cell transplantation.

Br J Haematol 2020 06 28;189(6):e251-e254. Epub 2020 Apr 28.

Pediatric Hematology and Oncology, Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, LMU Munich, Germany.

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http://dx.doi.org/10.1111/bjh.16682DOI Listing
June 2020

Comparison of antibiotic and acyclovir usage before and after the implementation of an on-site FilmArray meningitis/encephalitis panel in an academic tertiary pediatric hospital: a retrospective observational study.

BMC Pediatr 2020 02 5;20(1):56. Epub 2020 Feb 5.

Division of Pediatric Infectious Disease, Hauner Children's Hospital, University of Munich (LMU), Lindwurmstraße 4, 80337, Munich, Germany.

Background: Prompt initiation of empiric therapy is common practice in case of suspected meningitis or encephalitis. However, in children the most common pathogens are viruses that usually do not require and are not covered by the applied anti-infective treatment. Novel multiplex PCR (mPCR) panels provide rapid on-site diagnostic testing for a variety of pathogens. This study compared empiric antibiotic and acyclovir usage before and after the introduction of an on-site FilmArray Meningitis/Encephalitis Panel (FA ME Panel).

Methods: We retrospectively compared data for empiric antibiotic and acyclovir usage between pediatric patients with suspected central nervous system (CNS) infection receiving mPCR testing and a matched historical control group. Patients were matched by age and suspected CNS infection. We included all patients for whom empiric antibiotics and/or acyclovir were prescribed.

Results: Each study group consisted of 46 patients with 29 (63.0%) infants and 17 (37.0%) older children. A viral pathogen was diagnosed in 5/46 (10.9%) patients in the control group (all enteroviruses) and in 14/46 (30.4%) patients in the mPCR group (enterovirus n = 9; human herpesvirus 6 (HHV-6) n = 5), (p = 0.038)). Length of Therapy (LoT) and Days of Therapy (DoT) for antibiotics were significantly lower for infants (4.0 vs. 3.0, p = 0.038 and 8.0 vs. 6.0, p = 0.015, respectively). Acyclovir therapy was significantly shorter for both, infants and older children (3.0 vs. 1.0 day, p < 0.001 for both age groups).

Conclusion: The findings of our study suggest that the introduction of a FA ME Panel into clinical routine procedures is associated with a significantly reduced LoT and DoT of empiric anti-infective treatment in children with suspected meningoencephalitis. The largest effect was observed in infants.
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http://dx.doi.org/10.1186/s12887-020-1944-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001287PMC
February 2020

T Cell Impairment Is Predictive for a Severe Clinical Course in NEMO Deficiency.

J Clin Immunol 2020 04 21;40(3):421-434. Epub 2020 Jan 21.

Department of Pediatric Pulmonology, Immunology, and Intensive Care Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany.

Purpose: NEMO-deficient patients present with variable degrees of immunodeficiency. Accordingly, treatment ranges from antibiotic prophylaxis and/or IgG-substitution to allogenic hematopoietic stem cell transplantation (HSCT). The correct estimation of the immunodeficiency is essential to avoid over- as well as under-treatment. We compare the immunological phenotype of a NEMO-deficient patient with a newly-described splice site mutation that causes truncation of the NEMO zinc-finger (ZF) domain and a severe clinical course with the immunological phenotype of three NEMO-deficient patients with missense mutations and milder clinical courses and all previously published patients.

Methods: Lymphocyte subsets, proliferation, and intracellular NEMO-expression were assessed by FACS. NF-κB signal transduction was determined by measuring IκBα-degradation and the production of cytokines upon stimulation with TNF-α, IL-1β, and TLR-agonists in immortalized fibroblasts and whole blood, respectively.

Results: The patient with truncated ZF-domain of NEMO showed low levels of IgM and IgG, reduced class-switched memory B cells, almost complete skewing towards naïve CD45RA T cells, impaired T cell proliferation as well as cytokine production upon stimulation with TNF-α, IL-1β, and TLR-agonists. He suffered from severe infections (sepsis, pneumonia, osteomyelitis) during infancy. In contrast, three patients with missense mutations in IKBKG presented neither skewing of T cells towards naïvety nor impaired T cell proliferation. They are stable on prophylactic IgG-substitution or even off any prophylactic treatment.

Conclusion: The loss of the ZF-domain and the impaired T cell proliferation accompanied by almost complete persistence of naïve T cells despite severe infections are suggestive for a profound immunodeficiency. Allogenic HSCT should be considered early for these patients before chronic sequelae occur.
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http://dx.doi.org/10.1007/s10875-019-00728-yDOI Listing
April 2020

The German National Registry of Primary Immunodeficiencies (2012-2017).

Authors:
Sabine M El-Helou Anika-Kerstin Biegner Sebastian Bode Stephan R Ehl Maximilian Heeg Maria E Maccari Henrike Ritterbusch Carsten Speckmann Stephan Rusch Raphael Scheible Klaus Warnatz Faranaz Atschekzei Renata Beider Diana Ernst Stev Gerschmann Alexandra Jablonka Gudrun Mielke Reinhold E Schmidt Gesine Schürmann Georgios Sogkas Ulrich H Baumann Christian Klemann Dorothee Viemann Horst von Bernuth Renate Krüger Leif G Hanitsch Carmen M Scheibenbogen Kirsten Wittke Michael H Albert Anna Eichinger Fabian Hauck Christoph Klein Anita Rack-Hoch Franz M Sollinger Anne Avila Michael Borte Stephan Borte Maria Fasshauer Anja Hauenherm Nils Kellner Anna H Müller Anett Ülzen Peter Bader Shahrzad Bakhtiar Jae-Yun Lee Ursula Heß Ralf Schubert Sandra Wölke Stefan Zielen Sujal Ghosh Hans-Juergen Laws Jennifer Neubert Prasad T Oommen Manfred Hönig Ansgar Schulz Sandra Steinmann Klaus Schwarz Gregor Dückers Beate Lamers Vanessa Langemeyer Tim Niehues Sonu Shai Dagmar Graf Carmen Müglich Marc T Schmalzing Eva C Schwaneck Hans-Peter Tony Johannes Dirks Gabriele Haase Johannes G Liese Henner Morbach Dirk Foell Antje Hellige Helmut Wittkowski Katja Masjosthusmann Michael Mohr Linda Geberzahn Christian M Hedrich Christiane Müller Angela Rösen-Wolff Joachim Roesler Antje Zimmermann Uta Behrends Nikolaus Rieber Uwe Schauer Rupert Handgretinger Ursula Holzer Jörg Henes Lothar Kanz Christoph Boesecke Jürgen K Rockstroh Carolynne Schwarze-Zander Jan-Christian Wasmuth Dagmar Dilloo Brigitte Hülsmann Stefan Schönberger Stefan Schreiber Rainald Zeuner Tobias Ankermann Philipp von Bismarck Hans-Iko Huppertz Petra Kaiser-Labusch Johann Greil Donate Jakoby Andreas E Kulozik Markus Metzler Nora Naumann-Bartsch Bettina Sobik Norbert Graf Sabine Heine Robin Kobbe Kai Lehmberg Ingo Müller Friedrich Herrmann Gerd Horneff Ariane Klein Joachim Peitz Nadine Schmidt Stefan Bielack Ute Groß-Wieltsch Carl F Classen Jessica Klasen Peter Deutz Dirk Kamitz Lisa Lassay Klaus Tenbrock Norbert Wagner Benedikt Bernbeck Bastian Brummel Eusebia Lara-Villacanas Esther Münstermann Dominik T Schneider Nadine Tietsch Marco Westkemper Michael Weiß Christof Kramm Ingrid Kühnle Silke Kullmann Hermann Girschick Christof Specker Elisabeth Vinnemeier-Laubenthal Henriette Haenicke Claudia Schulz Lothar Schweigerer Thomas G Müller Martina Stiefel Bernd H Belohradsky Veronika Soetedjo Gerhard Kindle Bodo Grimbacher

Front Immunol 2019 19;10:1272. Epub 2019 Jul 19.

Institute for Immunodeficiency, Center for Chronic Immunodeficiency (CCI), Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1-25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36% of patients. Familial cases were observed in 21% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0-88 years). Presenting symptoms comprised infections (74%) and immune dysregulation (22%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE- syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49% of all patients received immunoglobulin G (IgG) substitution (70%-subcutaneous; 29%-intravenous; 1%-unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment.
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http://dx.doi.org/10.3389/fimmu.2019.01272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6659583PMC
October 2020

T-cell replete haploidentical bone marrow transplantation and post-transplant cyclophosphamide for patients with inborn errors.

Haematologica 2019 10 7;104(10):e478-e482. Epub 2019 Mar 7.

Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians Universität, Munich, Germany

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http://dx.doi.org/10.3324/haematol.2018.215285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6886426PMC
October 2019

Clinical benefits of introducing real-time multiplex PCR for cerebrospinal fluid as routine diagnostic at a tertiary care pediatric center.

Infection 2019 Feb 5;47(1):51-58. Epub 2018 Sep 5.

Division of Pediatric Infectious Disease, Dr. v. Hauner Children's Hospital, LMU Munich, University of Munich (LMU), Lindwurmstraße 4, 80337, Munich, Germany.

Background: Sepsis-like illness with suspected meningitis or encephalitis is a common reason for using empiric antimicrobial therapy in infants and children. However, in cases of viral meningitis not covered by these antimicrobials, this management is ineffective and due to side effects potentially harmful.

Methods: A retrospective analysis of cerebrospinal fluid (CSF) multiplex PCRs (Biofire FilmArray) in children with clinical suspicion of meningitis, encephalitis or sepsis-like illness was performed over the period of 1 year. Subsequently, a subgroup of children (age of 8-84 days of life) diagnosed with viral meningitis (enterovirus, HHV-6, human parechovirus) was compared to an age-matched control group.

Results: During the study period, the multiplex PCR panel was performed on 187 individual CSF samples that met the inclusion criteria. About half of the patients (92/187) were less than 1 year of age. In 27 cases (14.4%), the PCR yielded a positive result with the majority (12/27) being indicative of an enteroviral infection. In the age group of 8-84 days of life, 36.4% of the patients had a positive result. When the patients with a PCR positive for a viral agent were compared to an age-matched group of patients, no differences were observed regarding symptoms and laboratory parameters. However, the duration of antimicrobial therapy could be significantly reduced through the use of multiplex PCR.

Conclusion: The use of on-site diagnostic multiplex PCR was able to reduce the use of antimicrobials in selected cases. This test can guide clinical decisions earlier during the course of medical care compared to standard diagnostics.
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http://dx.doi.org/10.1007/s15010-018-1212-7DOI Listing
February 2019

Cyclosporine A responsive congenital nephrotic syndrome with single heterozygous variants in NPHS1, NPHS2, and PLCE1.

Pediatr Nephrol 2018 07 16;33(7):1269-1272. Epub 2018 Apr 16.

Dr. v. Hauner Children's Hospital, Division of Pediatric Nephrology, Ludwig-Maximilians University, Lindwurmstraße 4, 80337, Munich, Germany.

Background: Congenital nephrotic syndrome (CNS) is primarily a monogenetic disease, with the majority of cases due to changes in five different genes: the nephrin (NPHS1), podocin (NPHS2), Wilms tumor 1 (WT1), laminin ß2 (LAMB2), and phospholipase C epsilon 1 (PLCE1, NPHS3) gene. Usually CNS is not responsive to immunosuppressive therapy, but treatment with ACE inhibitors, AT1 receptor blockade and/or indomethacin can reduce proteinuria. If the disease progresses to end-stage renal disease, kidney transplantation is the therapy of choice.

Case-diagnosis: Here, we present the case of a 4-month-old girl with congenital nephrotic syndrome. Upon admission, the patient presented with life-threatening anasarca, hypoalbuminemia, proteinuria, and impaired growth. There was no evidence of an infectious or immunological etiology. The genetic evaluation revealed a heterozygous variant in NPHS1 (p.Arg207Trp), in NPHS2 (p.Ser95Phe) as well as in PLCE1 (p.Ala1045Ser) and did not explain CNS. In addition to daily parenteral albumin infusions plus furosemide, a pharmacological antiproteinuric therapy was started to reduce protein excretion. Based on the genetic results, immunosuppressive therapy with prednisolone was initiated, but without response. However, following cyclosporine A treatment, the patient achieved complete remission and now has good renal function, growth, and development.

Conclusions: A profound search for the cause of CNS is necessary but has its limitations. The therapeutic strategy should be adapted when the etiology remains unclear.
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http://dx.doi.org/10.1007/s00467-018-3961-zDOI Listing
July 2018

Secondary BH4 deficiency links protein homeostasis to regulation of phenylalanine metabolism.

Hum Mol Genet 2018 05;27(10):1732-1742

University Children's Research, Kinder-UKE.

Metabolic control of phenylalanine concentrations in body fluids is essential for cognitive development and executive function. The hepatic phenylalanine hydroxylating system is regulated by the ratio of l-phenylalanine, which is substrate of phenylalanine hydroxylase (PAH), to the PAH cofactor tetrahydrobiopterin (BH4). Physiologically, phenylalanine availability is governed by nutrient intake, whereas liver BH4 is kept at constant level. In phenylketonuria, PAH deficiency leads to elevated blood phenylalanine and is often caused by PAH protein misfolding with loss of function. Here, we report secondary hepatic BH4 deficiency in Pah-deficient mice. Alterations in de novo synthesis and turnover of BH4 were ruled out as molecular causes. We demonstrate that kinetically instable and aggregation-prone variant Pah proteins trap BH4, shifting the pool of free BH4 towards bound BH4. Interference of PAH protein misfolding with metabolite-based control of l-phenylalanine turnover suggests a mechanistic link between perturbation of protein homeostasis and disturbed regulation of metabolic pathways.
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http://dx.doi.org/10.1093/hmg/ddy079DOI Listing
May 2018

Acute Flaccid Myelitis in German Children in 2016-the Return of Polio?

Dtsch Arztebl Int 2017 Aug;114(33-34):551-557

Dr. von Hauner Children's Hospital, Ludwig-Maximilians University of Munich, Germany; Neuropediatric Department, Helios-Klinikum Hildesheim, Germany; Children's and Youth Hospital "Auf der Bult," Hannover, Germany; National Reference Center for Poliomyelitis and Enteroviruses, Robert Koch Institute, Berlin, Germany; German Center for Infection Research, Munich site, Germany.

Background: Although poliomyelitis has almost been eradicated worldwide, cases of a polio-like disease with asymmetrical flaccid paralysis of variable severity have been seen repeatedly in recent years.

Methods: Data were collected on children treated in hospitals in the German federal states of Bavaria and Lower Saxony in 2016. The frequency of disease across Germany was estimated on the basis of voluntary reporting to the Robert Koch Institute. 16 cases were registered there for the entire year 2016.

Results: 7 children with flaccid paralysis of acute onset were treated in the participating hospitals in the summer and fall of 2016. We describe two illustrative cases, one with a mild course and one with a severe course. Rapid diagnosis requires not only clinical neurological assessment but also neurophysiological studies, magnetic resonance imaging (MRI), and targeted microbiological testing. The characteristic features include damage to the anterior horn of the spinal cord that can be seen on MRI and/or electrophysiologically demonstrable abnormalities indicating motor neuron damage. A pathogen can hardly ever be identified in the cerebrospinal fluid, but the epidemiological context and the detection of viruses in the stool or respiratory secretions indicate that entero - viruses may be responsible.

Conclusion: The prognosis of this disease cannot be reliably assessed at first, and no specific treatment is currently available.
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http://dx.doi.org/10.3238/arztebl.2017.0551DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5596149PMC
August 2017

New insights into tetrahydrobiopterin pharmacodynamics from Pah enu1/2, a mouse model for compound heterozygous tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency.

Biochem Pharmacol 2010 Nov 10;80(10):1563-71. Epub 2010 Aug 10.

Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria.

Phenylketonuria (PKU), an autosomal recessive disease with phenylalanine hydroxylase (PAH) deficiency, was recently shown to be a protein misfolding disease with loss-of-function. It can be treated by oral application of the natural PAH cofactor tetrahydrobiopterin (BH(4)) that acts as a pharmacological chaperone and rescues enzyme function in vivo. Here we identified Pah(enu1/2) bearing a mild and a severe mutation (V106A/F363S) as a new mouse model for compound heterozygous mild PKU. Although BH(4) treatment has become established in clinical routine, there is substantial lack of knowledge with regard to BH(4) pharmacodynamics and the effect of the genotype on the response to treatment with the natural cofactor. To address these questions we applied an elaborate methodological setup analyzing: (i) blood phenylalanine elimination, (ii) blood phenylalanine/tyrosine ratios, and (iii) kinetics of in vivo phenylalanine oxidation using (13)C-phenylalanine breath tests. We compared pharmacodynamics in wild-type, Pah(enu1/1), and Pah(enu1/2) mice and observed crucial differences in terms of effect size as well as effect kinetics and dose response. Results from in vivo experiments were substantiated in vitro after overexpression of wild-type, V106A, and F263S in COS-7 cells. Pharmacokinetics did not differ between Pah(enu1/1) and Pah(enu1/2) indicating that the differences in pharmacodynamics were not induced by divergent pharmacokinetic behavior of BH(4). In conclusion, our findings show a significant impact of the genotype on the response to BH(4) in PAH deficient mice. This may lead to important consequences concerning the diagnostic and therapeutic management of patients with PAH deficiency underscoring the need for individualized procedures addressing pharmacodynamic aspects.
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http://dx.doi.org/10.1016/j.bcp.2010.07.042DOI Listing
November 2010

Pahenu1 is a mouse model for tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency and promotes analysis of the pharmacological chaperone mechanism in vivo.

Hum Mol Genet 2010 May 23;19(10):2039-49. Epub 2010 Feb 23.

Department of Molecular Pediatrics, Dr von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany.

The recent approval of sapropterin dihydrochloride, the synthetic form of 6[R]-l-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)), for the treatment of phenylketonuria (PKU) as the first pharmacological chaperone drug initiated a paradigm change in the treatment of monogenetic diseases. Symptomatic treatment is now replaced by a causal pharmacological therapy correcting misfolding of the defective phenylalanine hydroxylase (PAH) in numerous patients. Here, we disclose BH(4) responsiveness in Pah(enu1), a mouse model for PAH deficiency. Loss of function resulted from loss of PAH, a consequence of misfolding, aggregation, and accelerated degradation of the enzyme. BH(4) attenuated this triad by conformational stabilization augmenting the effective PAH concentration. This led to the rescue of the biochemical phenotype and enzyme function in vivo. Combined in vitro and in vivo analyses revealed a selective pharmaceutical action of BH(4) confined to the pathological metabolic state. Our data provide new molecular-level insights into the mechanisms underlying protein misfolding with loss of function and support a general model of pharmacological chaperone-induced stabilization of protein conformation to correct this intracellular phenotype. Pah(enu1) will be essential for pharmaceutical drug optimization and to design individually tailored therapies.
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http://dx.doi.org/10.1093/hmg/ddq085DOI Listing
May 2010

Tuning of redox properties for the design of ruthenium anticancer drugs: part 2. Syntheses, crystal structures, and electrochemistry of potentially antitumor [Ru III/II Cl6-n(Azole)n]z(n = 3, 4, 6) complexes.

Inorg Chem 2005 Sep;44(19):6704-16

Institute of Inorganic Chemistry-Bioinorganic, Environmental and Radiochemistry, University of Vienna, Währingerstrasse 42, A-1090 Vienna, Austria.

A series of mixed chloro-azole ruthenium complexes with potential antitumor activity, viz., mer-[RuIIICl3(azole)3] (B), trans-[RuIIICl2(azole)4]Cl (C), trans-[RuIICl2(azole)4] (D), and [RuII(azole)6](SO3CF3)2 (E), where azole = 1-butylimidazole (1), imidazole (2), benzimidazole (3), 1-methyl-1,2,4-triazole (4), 4-methylpyrazole (5), 1,2,4-triazole (6), pyrazole (7), and indazole (8), have been prepared as a further development of anticancer drugs with the general formula [RuCl4(azole)2]- (A). These compounds were characterized by elemental analysis, IR spectroscopy, electronic spectra, electrospray mass spectrometry, and X-ray crystallography. The electrochemical behavior has been studied in detail in DMF, DMSO, and aqueous media using cyclic voltammetry, square wave voltammetry, and controlled potential electrolysis. Compounds B and a number of C complexes exhibit one RuIII/RuII reduction, followed, at a sufficiently long time scale, by metal dechlorination on solvolysis. The redox potential values in organic media agree with those predicted by Lever's parametrization method, and the yet unknown EL parameters were estimated for 1 (EL = 0.06 V), 3 (EL = 0.10 V), 4 (EL = 0.17 V), and 5 (EL = 0.18 V). The EL values for the azole ligands 1-8 correlate linearly with their basicity (pK(a) value of the corresponding azolium acid H2L+). In addition, a logarithmic dependence between the homogeneous rate constants for the reductively induced stepwise replacement of chloro ligands by solvent molecules and the RuIII/RuII redox potentials was observed. Lower E(1/2) values (higher net electron donor character of the ligands) result in enhanced kinetic rate constants of solvolysis upon reduction. The effect of the net charge on the RuIII/RuII redox potentials in water is tentatively explained by the application of the Born equation. In addition, the pH-dependent electrochemical behavior of trans-[RuCl2(1,2,4-triazole)4]Cl is discussed.
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http://dx.doi.org/10.1021/ic0503737DOI Listing
September 2005

Redox-active antineoplastic ruthenium complexes with indazole: correlation of in vitro potency and reduction potential.

J Med Chem 2005 Apr;48(8):2831-7

Institute of Inorganic Chemistry, University of Vienna, Waehringer Strasse 42, A-1090 Vienna, Austria.

Antineoplastic ruthenium(III) complexes are generally regarded as prodrugs, being activated by reduction. Within a homologous series of ruthenium(III) complexes, cytotoxic potency is therefore expected to increase with increasing ease of reduction. Complexes of the general formula [Ru(III)Cl((6-n))(ind)n](3-n)- (n = 0-4; ind = indazole; counterions = Hind(+) or Cl(-)) and the compound trans-[Ru(II)Cl(2)(ind)(4)] have been prepared and characterized electrochemically. Lever's parametrization method predicts that a higher indazole-to-chloride ratio results in a higher reduction potential, which is confirmed by cyclic voltammetry. In vitro antitumor potencies of these complexes in colon cancer cells (SW480) and ovarian cancer cells (CH1) vary by more than 2 orders of magnitude and increase in the following rank order: [Ru(III)Cl(6)](3-) < [Ru(III)Cl(4)(ind)(2)](-) < [Ru(III)Cl(5)(ind)](2-) < [Ru(III)Cl(3)(ind)(3)] < [Ru(III)Cl(2)(ind)(4)](+) approximately [Ru(II)Cl(2)(ind)(4)]. Thus, the observed differences in potency correlate with reduction potentials largely, though not perfectly, pointing to the influence of additional factors. Differences in the cellular uptake (probably resulting from different lipophilicity) contribute to this correlation but cannot solely account for it.
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http://dx.doi.org/10.1021/jm0490742DOI Listing
April 2005

Tuning of redox potentials for the design of ruthenium anticancer drugs -- an electrochemical study of [trans-RuCl(4)L(DMSO)](-) and [trans-RuCl(4)L(2)](-) complexes, where L = imidazole, 1,2,4-triazole, indazole.

Inorg Chem 2004 Nov;43(22):7083-93

Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal.

The electrochemical behavior of [trans-RuCl(4)L(DMSO)](-) (A) and [trans-RuCl(4)L(2)](-) (B) [L = imidazole (Him), 1,2,4-triazole (Htrz), and indazole (Hind)] complexes has been studied in DMF, DMSO, and aqueous media by cyclic voltammetry and controlled potential electrolysis. They exhibit one single-electron Ru(III)/Ru(II) reduction involving, at a sufficiently long time scale, metal dechlorination on solvolysis, as well as, in organic media, one single-electron reversible Ru(III)/Ru(IV) oxidation. The redox potential values are interpreted on the basis of the Lever's parametrization method, and particular forms of this linear expression (that relates the redox potential with the ligand E(L) parameter) are proposed, for the first time, for negatively (1-) charged complexes with the Ru(III/II) redox couple center in aqueous phosphate buffer (pH 7) medium and for complexes with the Ru(III/IV) couple in organic media. The E(L) parameter was estimated for indazole showing that this ligand behaves as a weaker net electron donor than imidazole or triazole. The kinetics of the reductively induced stepwise replacement of chloride by DMF were studied by digital simulation of the cyclic voltammograms, and the obtained rate constants were shown to increase with the net electron donor character (decrease of E(L)) of the neutral ligands (DMSO < indazole < triazole < imidazole) and with the basicity of the ligated azole, factors that destabilize the Ru(II) relative to the Ru(III) form of the complexes. The synthesis and characterization of some novel complexes of the A and B series are also reported, including the X-ray structural analyses of (Ph(3)PCH(2)Ph)[trans-RuCl(4)(Htrz)(DMSO)], [(Ph(3)P)(2)N][trans-RuCl(4)(Htrz)(DMSO)], (H(2)ind)[trans-RuCl(4)(Hind)(DMSO)], and [(Hind)(2)H][trans-RuCl(4)(Hind)(2)].
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http://dx.doi.org/10.1021/ic049479cDOI Listing
November 2004