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Researcher in Laboratory © HIPS

Prof Dr Alexander Titz

About

Alexander Titz studied chemistry at the Technical University Darmstadt and the University of Bordeaux I. For his diploma thesis, he moved to the Protein Structure Unit at Novartis Pharma in Basel. After receiving his doctorate from the University of Basel in 2008, covering the medicinal chemistry of carbohydrate-protein interactions, he conducted post-doctoral research at the Institute of Microbiology and Immunology at ETH Zürich (Swiss Federal Institute of Technology). In 2010, he was awarded the Klaus-Grohe Prize for medicinal chemistry of the GDCh.

After establishing a research group at the Zukunftskolleg of the University of Constance focusing on carbohydrate chemistry and inhibitors of bacterial biofilm formation, Alexander Titz has been head of the research group ‘Chemical Biology of Carbohydrates’ at the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), an outpost of the Helmholtz Centre for Infection Research, since 2013. His group is furthermore part of the German Centre for Infection Research (DZIF), a national association of the German Centres for Health Research. Alexander Titz is teaching at Saarland University since 2014 and has been appointed Juniorprofessor for Chemical Biology in 2018.
Since 2017, the research in the Titz lab is funded by an ERC starting grant of the European Research Council. In 2018, Alexander Titz was awarded the Innovation Award in Medical/Pharmaceutical Chemistry by the German Chemical Society and the German Pharmaceutical Society as well as the Prize for a Young Medicinal Chemist in Academia of the European Federation of Medicinal Chemistry (EFMC). In 2019, Alexander obtained a call for the professorship for Organic Chemistry at the University of Osnabrück. Since 2020, Alexander Titz holds a professorship for Organic and Pharmaceutical Chemistry at Saarland University.


2024

Dual inhibitors of Pseudomonas aeruginosa virulence factors LecA and LasB

Metelkina O, Konstantinovic J, Klein A, Shafiei R, Fares M, Alhayek A, Yahiaoui S, Elgaher W, Haupenthal J, Titz* A, Hirsch* A (2024)

Chem. Sci. 15DOI: 10.1039/D4SC02703E

2023

The resuscitation-promoting factor (Rpf) from Micrococcus luteus and its putative reaction product 1,6-anhydro-MurNAc increase culturability of environmental bacteria

Guzman J, Raval D, Hauck D, Titz A, Poehlein A, Degenkolb T, Daniel R, Vilcinskas A (2023)

Access microbiology 5 (9)DOI: 10.1099/acmi.0.000647.v4

Switch-on luminescent sensing of unlabelled bacterial lectin by terbium(III) glycoconjugate systems

Wojtczak K, Zahorska E, Murphy I, Koppel F, Cooke G, Titz A, Byrne J (2023)

Chem. Commun. (Cambridge, U. K.) 59 (54): 8384-8387DOI: 10.1039/D3CC02300A

Pseudomonas aeruginosa LecB suppresses immune responses by inhibiting transendothelial migration

Sponsel J, Guo Y, Hamzam L, Lavanant A, Pérez-Riverón A, Partiot E, Muller Q, Rottura J, Gaudin R, Hauck D, …, Römer W, Mueller C (2023)

EMBO reports 24 (4)DOI: 10.15252/embr.202255971

Tackling the outer membrane: facilitating compound entry into Gram-negative bacterial pathogens

Saxena D, Maitra R, Bormon R, Czekanska M, Meiers J, Titz A, Verma S, Chopra S (2023)

npj Antimicrob Resist 1 (1)DOI: 10.1038/s44259-023-00016-1

Glycomimetics for the inhibition and modulation of lectins

Leusmann S, Ménová P, Shanin E, Titz A, Rademacher C (2023)

Chem. Soc. Rev. 52 (11): 3663-3740DOI: 10.1039/d2cs00954d

Neutralizing the Impact of the Virulence Factor LecA from Pseudomonas aeruginosa on Human Cells with New Glycomimetic Inhibitors

Zahorska E, Rosato F, Stober K, Kuhaudomlarp S, Meiers J, Hauck D, Reith D, Gillon E, Rox K, Imberty A, Römer W, Titz A (2023)

Angewandte Chemie (International ed. in English) 62 (7)DOI: 10.1002/anie.202215535

2022

Targeting undruggable carbohydrate recognition sites through focused fragment library design

Shanina E, Kuhaudomlarp S, Siebs E, Fuchsberger F, Denis M, da Silva Figueiredo Celestino Gomes P, Clausen M, Seeberger P, Rognan D, Titz A, Imberty A, Rademacher C (2022)

Commun Chem 5 (1): 1-11DOI: 10.1038/s42004-022-00679-3

NamZ1 and NamZ2 from the Oral Pathogen Tannerella forsythia Are Peptidoglycan Processing Exo-β-N-Acetylmuramidases with Distinct Substrate Specificities

Borisova M, Balbuchta K, Lovering A, Titz A, Mayer C (2022)

J. Bacteriol. 204 (3)DOI: 10.1128/jb.00597-21

Targeting the Central Pocket of the Pseudomonas aeruginosa Lectin LecA

Siebs E, Shanina E, Kuhaudomlarp S, da Silva Figueiredo Celestino Gomes P, Fortin C, Seeberger P, Rognan D, Rademacher C, Imberty A, Titz A (2022)

Chembiochem : a European journal of chemical biology 23 (3)DOI: 10.1002/cbic.202100563

β-Boronic Acid-Substituted Bodipy Dyes for Fluorescence Anisotropy Analysis of Carbohydrate Binding

Hoffmann C, Jourdain M, Grandjean A, Titz A, Jung G (2022)

Analytical chemistry 94 (16): 6112-6119DOI: 10.1021/acs.analchem.1c04654

Pineapple Lectin AcmJRL binds SARS-CoV-2 Spike Protein in a carbohydrate-dependent fashion

Meiers J, Dastbaz J, Adam S, Rasheed S, Kirsch S, Meiser P, Gross P, Müller R, Titz A (2022)

Chembiochem : a European journal of chemical biologyDOI: 10.1002/cbic.202200463

The Glycan-Specificity of the Pineapple Lectin AcmJRL and its Carbohydrate-Dependent Binding of the SARS-CoV-2 Spike Protein

Meiers J, Dastbaz J, Adam S, Rasheed S, Kirsch S, Meiser P, Gross P, Müller R, Titz A (2022)

BookDOI: 10.1101/2022.05.27.493400

Lectin-Targeted Prodrugs Activated by Pseudomonas aeruginosa for Self-Destructive Antibiotic Release

Meiers J, Rox K, Titz A (2022)

Journal of medicinal chemistry 65 (20): 13988-14014DOI: 10.1021/acs.jmedchem.2c01214

Discovery of N-β-l-Fucosyl Amides as High-Affinity Ligands for the Pseudomonas aeruginosa Lectin LecB

Mala P, Siebs E, Meiers J, Rox K, Varrot A, Imberty A, Titz A (2022)

Journal of medicinal chemistry 65 (20): 14180-14200DOI: 10.1021/acs.jmedchem.2c01373

Targeting extracellular lectins of Pseudomonas aeruginosa with glycomimetic liposomes

Metelkina O, Huck B, O'Connor J, Koch M, Manz A, Lehr C, Titz A (2022)

Journal of Materials Chemistry B 10 (4): 537-548DOI: 10.1039/d1tb02086b

Nano-in-Microparticles for Aerosol Delivery of Antibiotic-Loaded, Fucose-Derivatized, and Macrophage-Targeted Liposomes to Combat Mycobacterial Infections: In Vitro Deposition, Pulmonary Barrier Interactions, and Targeted Delivery

Huck B, Thiyagarajan D, Bali A, Boese A, Besecke K, Hozsa C, Gieseler R, Furch M, Carvalho-Wodarz C, Waldow F, …, Loretz B, Lehr C (2022)

Advanced healthcare materials 11 (11)DOI: 10.1002/adhm.202102117

2021

Short Peptides and Their Mimetics as Potent Antibacterial Agents and Antibiotic Adjuvants

Panjla A, Kaul G, Chopra S, Titz A, Verma S (2021)

ACS chemical biology 16 (12): 2731-2745DOI: 10.1021/acschembio.1c00626

A Remote Secondary Binding Pocket Promotes Heteromultivalent Targeting of DC-SIGN

Wawrzinek R, Wamhoff E, Lefebre J, Rentzsch M, Bachem G, Domeniconi G, Schulze J, Fuchsberger F, Zhang H, Modenutti C, …, Ernst B, Rademacher C (2021)

J. Am. Chem. Soc. 143 (45): 18977-18988DOI: 10.1021/jacs.1c07235

Towards the sustainable discovery and development of new antibiotics

Miethke M, Pieroni M, Weber T, Brönstrup M, Hammann P, Halby L, Arimondo P, Glaser P, Aigle B, Bode H, …, Moser H, Müller R (2021)

Nature reviews. Chemistry 5 (10): 726-749DOI: 10.1038/s41570-021-00313-1

Non-Carbohydrate Glycomimetics as Inhibitors of Calcium(II)-Binding Lectins

Kuhaudomlarp S, Siebs E, Shanina E, Topin J, Joachim I, da Silva Figueiredo Celestino Gomes P, Varrot A, Rognan D, Rademacher C, Imberty A, Titz A (2021)

Angew. Chem. Int. Ed. 60 (15): 8104-8114DOI: 10.1002/anie.202013217

The exo-β-N-acetylmuramidase NamZ from Bacillus subtilis is the founding member of a family of exo-lytic peptidoglycan hexosaminidases

Müller M, Calvert M, Hottmann I, Kluj R, Teufel T, Balbuchta K, Engelbrecht A, Selim K, Xu Q, Borisova M, Titz A, Mayer C (2021)

The Journal of biological chemistry 296DOI: 10.1016/j.jbc.2021.100519

2020

Protein-observed 19F NMR of LecA from Pseudomonas aeruginosa

Shanina E, Siebs E, Zhang H, Silva D, Joachim I, Titz A, Rademacher C (2020)

GlycobiologyDOI: 10.1093/glycob/cwaa057

Directing Drugs to Bugs: Antibiotic-Carbohydrate Conjugates Targeting Biofilm-Associated Lectins of Pseudomonas aeruginosa

Meiers J, Zahorska E, Röhrig T, Hauck D, Wagner S, Titz A (2020)

Journal of medicinal chemistry 63 (20): 11707-11724DOI: 10.1021/acs.jmedchem.0c00856

A rapid synthesis of low-nanomolar divalent LecA inhibitors in four linear steps from d -galactose pentaacetate

Zahorska E, Kuhaudomlarp S, Minervini S, Yousaf S, Lepsik M, Kinsinger T, Hirsch A, Imberty A, Titz A (2020)

Chem. Commun. 56 (62): 8822-8825DOI: 10.1039/d0cc03490h

Expression, Purification, and Functional Characterization of Tectonin 2 from Laccaria bicolor: A Six-Bladed Beta-Propeller Lectin Specific for O-Methylated Glycans

Wohlschlager T, Titz A, Künzler M, Varrot A (2020)

Methods Mol Biol 2132: 669-682DOI: 10.1007/978-1-0716-0430-4_58

2019

Lectin antagonists in infection, immunity, and inflammation

Meiers J, Siebs E, Zahorska E, Titz A (2019)

Current opinion in chemical biology 53: 51-67DOI: 10.1016/j.cbpa.2019.07.005

Anti-biofilm Agents against Pseudomonas aeruginosa: A Structure-Activity Relationship Study of C-Glycosidic LecB Inhibitors

Sommer R, Rox K, Wagner S, Hauck D, Henrikus S, Newsad S, Arnold T, Ryckmans T, Brönstrup M, Imberty A, …, Hartmann R, Titz A (2019)

Journal of medicinal chemistry 62 (20): 9201-9216DOI: 10.1021/acs.jmedchem.9b01120

Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis

Siebert D, Sommer R, Pogorevc D, Hoffmann M, Wenzel S, Müller R, Titz A (2019)

Beilstein journal of organic chemistry 15: 2922-2929DOI: 10.3762/bjoc.15.286

Induction of rare conformation of oligosaccharide by binding to calcium-dependent bacterial lectin: X-ray crystallography and modelling study

Lepsik M, Sommer R, Kuhaudomlarp S, Lelimousin M, Paci E, Varrot A, Titz A, Imberty A (2019)

European journal of medicinal chemistry 177: 212-220DOI: 10.1016/j.ejmech.2019.05.049

2018

Bivalent LecA inhibitors targeting Pseudomonas aeruginosa LecA

Zahorska E, Minervini S, Kuhaudomlarp S, Imberty A, Titz A (2018)

Patent (EP19306432.6)

N-Acetylmuramic Acid (MurNAc) Auxotrophy of the Oral Pathogen Tannerella forsythia: Characterization of a MurNAc Kinase and Analysis of Its Role in Cell Wall Metabolism

Hottmann I, Mayer V, Tomek M, Friedrich V, Calvert M, Titz A, Schäffer C, Mayer C (2018)

Frontiers in microbiology 9DOI: 10.3389/fmicb.2018.00019

Crystal Structures of Fungal Tectonin in Complex with O-Methylated Glycans Suggest Key Role in Innate Immune Defense

Sommer R, Makshakova O, Wohlschlager T, Hutin S, Marsh M, Titz A, Künzler M, Varrot A (2018)

Structure (London, England : 1993) 26 (3): 391-402DOI: 10.1016/j.str.2018.01.003

Glycomimetic, Orally Bioavailable LecB Inhibitors Block Biofilm Formation of Pseudomonas aeruginosa

Sommer R, Wagner S, Rox K, Varrot A, Hauck D, Wamhoff E, Schreiber J, Ryckmans T, Brunner T, Rademacher C, …, Imberty A, Titz A (2018)

Journal of the American Chemical Society 140 (7): 2537-2545DOI: 10.1021/jacs.7b11133

Virtual Screening Against Carbohydrate-Binding Proteins: Evaluation and Application to Bacterial Burkholderia ambifaria Lectin

Dingjan T, Gillon É, Imberty A, Pérez S, Titz A, Ramsland P, Yuriev E (2018)

Journal of chemical information and modeling 58 (9): 1976-1989DOI: 10.1021/acs.jcim.8b00185

Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections

Calvert M, Jumde V, Titz A (2018)

Beilstein journal of organic chemistry 14: 2607-2617DOI: 10.3762/bjoc.14.239

2017

An efficient synthesis of 1,6-anhydro-N-acetylmuramic acid from N-acetylglucosamine

Calvert M, Mayer C, Titz A (2017)

Beilstein journal of organic chemistry 13: 2631-2636DOI: 10.3762/bjoc.13.261

Covalent Lectin Inhibition and Application in Bacterial Biofilm Imaging

Wagner S, Hauck D, Hoffmann M, Sommer R, Joachim I, Müller R, Imberty A, Varrot A, Titz A (2017)

Angewandte Chemie (International ed. in English) 56 (52): 16559-16564DOI: 10.1002/anie.201709368

Photorhabdus luminescens lectin A (PllA): A new probe for detecting α-galactoside-terminating glycoconjugates

Beshr G, Sikandar A, Jemiller E, Klymiuk N, Hauck D, Wagner S, Wolf E, Koehnke J, Titz A (2017)

J Biol Chem 292 (48): 19935-19951DOI: 10.1074/jbc.M117.812792

Ciprofloxacin-loaded lipid-core nanocapsules as mucus penetrating drug delivery system intended for the treatment of bacterial infections in cystic fibrosis

Torge A, Wagner S, Chaves P, Oliveira E, Guterres S, Pohlmann A, Titz A, Schneider M, Beck R (2017)

Int J Pharm 527 (1-2): 92-102DOI: 10.1016/j.ijpharm.2017.05.013

Efficient Two Step β-Glycoside Synthesis from N-Acetyl d-Glucosamine: Scope and Limitations of Copper(II) Triflate-Catalyzed Glycosylation

Sommer R, Hauck D, Titz A (2017)

ChemistrySelect 2 (15)DOI: 10.1002/slct.201700161

Photoswitchable Janus glycodendrimer micelles as multivalent inhibitors of LecA and LecB from Pseudomonas aeruginosa

Hu Y, Beshr G, Garvey C, Tabor R, Titz A, Wilkinson B (2017)

Colloids and surfaces. B, Biointerfaces 159: 605-612DOI: 10.1016/j.colsurfb.2017.08.016

2016

Novel Strategies for the Treatment of Pseudomonas aeruginosa Infections

Wagner S, Sommer R, Hinsberger S, Lu C, Hartmann R, Empting M, Titz A (2016)

Journal of medicinal chemistry 59 (13): 5929-69DOI: 10.1021/acs.jmedchem.5b01698

Inhibitors of Pseudomonas aeruginosa LecB

Sommer R, Titz A (2016)

Patent (WO2016/151066 A1)

The virulence factor LecB varies in clinical isolates: consequences for ligand binding and drug discovery

Sommer R, Wagner S, Varrot A, Nycholat C, Khaledi A, Häussler S, Paulson J, Imberty A, Titz A (2016)

Chem Sci 7 (8): 4990-5001DOI: 10.1039/c6sc00696e

O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside

Sommer R, Hauck D, Varrot A, Imberty A, Künzler M, Titz A (2016)

Beilstein journal of organic chemistry 12: 2828-2833DOI: 10.3762/bjoc.12.282

Development of a competitive binding assay for the Burkholderia cenocepacia lectin BC2L-A and structure activity relationship of natural and synthetic inhibitors

Beshr G, Sommer R, Hauck D, Siebert D, Hofmann A, Imberty A, Titz A (2016)

Med Chem Commun 7 (3): 519-530DOI: 10.1039/C5MD00557D

Development and optimization of a competitive binding assay for the galactophilic low affinity lectin LecA from Pseudomonas aeruginosa

Joachim I, Rikker S, Hauck D, Ponader D, Boden S, Sommer R, Hartmann L, Titz A (2016)

Org. Biomol. Chem. 14 (33): 7933-48DOI: 10.1039/c6ob01313a

2015

Cinnamide Derivatives of d-Mannose as Inhibitors of the Bacterial Virulence Factor LecB from Pseudomonas aeruginosa

Sommer R, Hauck D, Varrot A, Wagner S, Audfray A, Prestel A, Möller H, Imberty A, Titz A (2015)

ChemistryOpen 4 (6): 756-67DOI: 10.1002/open.201500162

Parasite Glycobiology: A Bittersweet Symphony

Rodrigues J, Acosta-Serrano A, Aebi M, Ferguson M, Routier F, Schiller I, Soares S, Spencer D, Titz A, Wilson I, Izquierdo L (2015)

PLoS Pathog. 11 (11)DOI: 10.1371/journal.ppat.1005169

Synthesis of mannoheptose derivatives and their evaluation as inhibitors of the lectin LecB from the opportunistic pathogen Pseudomonas aeruginosa

Hofmann A, Sommer R, Hauck D, Stifel J, Göttker-Schnetmann I, Titz A (2015)

Carbohydrate research 412: 34-42DOI: 10.1016/j.carres.2015.04.010

Bisecting Galactose as a Feature of N-Glycans of Wild-type and Mutant Caenorhabditis elegans

Yan S, Brecker L, Jin C, Titz A, Dragosits M, Karlsson N, Jantsch V, Wilson I, Paschinger K (2015)

Mol Cell Proteomics 14 (8): 2111-25DOI: 10.1074/mcp.M115.049817

2014

Methylated glycans as conserved targets of animal and fungal innate defense

Wohlschlager T, Butschi A, Grassi P, Sutov G, Gauss R, Hauck D, Schmieder S, Knobel M, Titz A, Dell A, …, Aebi M, Künzler M (2014)

Proceedings of the National Academy of Sciences of the United States of America 111 (27): 2787-96DOI: 10.1073/pnas.1401176111

A biophysical study with carbohydrate derivatives explains the molecular basis of monosaccharide selectivity of the Pseudomonas aeruginosa lectin LecB

Sommer R, Exner T, Titz A (2014)

PLoS ONE 9 (11)DOI: 10.1371/journal.pone.0112822

Amphiphilic cationic β(3R3)-peptides: membrane active peptidomimetics and their potential as antimicrobial agents

Mosca S, Keller J, Azzouz N, Wagner S, Titz A, Seeberger P, Brezesinski G, Hartmann L (2014)

Biomacromolecules 15 (5): 1687-95DOI: 10.1021/bm500101w

2013

Glycomimetics as Pseudomonas aeruginosa lectin inhibitors

Titz A (2013)

Patent (WO2013152848A1)

Biofilme Neue Forschungsansätze zur Therapie bakterieller Infektionskrankheiten

Titz A (2013)

GIT Labor-Fachzeitschrift (2): 120-121

Discovery of two classes of potent glycomimetic inhibitors of Pseudomonas aeruginosa LecB with distinct binding modes

Hauck D, Joachim I, Frommeyer B, Varrot A, Philipp B, Möller H, Imberty A, Exner T, Titz A (2013)

ACS chemical biology 8 (8): 1775-84DOI: 10.1021/cb400371r

New approaches to control infections: anti-biofilm strategies against gram-negative bacteria

Sommer R, Joachim I, Wagner S, Titz A (2013)

Chimia (Aarau) 67 (4): 286-90DOI: 10.2533/chimia.2013.286

2012

Conformational Constraints: Nature Does It Best with Sialyl Lewis x

Titz A, Marra A, Cutting B, Smieško M, Papandreou G, Dondoni A, Ernst B (2012)

Eur. J. Org. Chem. 2012 (28)DOI: 10.1002/ejoc.201200744

2010

Core beta-galactosyltransferase and uses thereof

Titz A, Butschi A, Aebi M, Wilson I, Hengartner M, Künzler M (2010)

Patent (WO2010/136209A1)

Caenorhabditis elegans N-glycan core beta-galactoside confers sensitivity towards nematotoxic fungal galectin CGL2

Butschi A, Titz A, Wälti M, Olieric V, Paschinger K, Nöbauer K, Guo X, Seeberger P, Wilson I, Aebi M, Hengartner M, Künzler M (2010)

PLoS Pathog. 6 (1)DOI: 10.1371/journal.ppat.1000717

Probing the carbohydrate recognition domain of E-selectin: the importance of the acid orientation in sLex mimetics

Titz A, Patton J, Smiesko M, Radic Z, Schwardt O, Magnani J, Ernst B (2010)

Bioorg Med Chem 18 (1): 19-27DOI: 10.1016/j.bmc.2009.11.024

2009

Molecular basis for galactosylation of core fucose residues in invertebrates: identification of caenorhabditis elegans N-glycan core alpha1,6-fucoside beta1,4-galactosyltransferase GALT-1 as a member of a novel glycosyltransferase family

Titz A, Butschi A, Henrissat B, Fan Y, Hennet T, Razzazi-Fazeli E, Hengartner M, Wilson I, Künzler M, Aebi M (2009)

J Biol Chem 284 (52): 36223-33DOI: 10.1074/jbc.M109.058354

2008

Is adamantane a suitable substituent to pre-organize the acid orientation in E-selectin antagonists?

Titz A, Patton J, Alker A, Porro M, Schwardt O, Hennig M, Francotte E, Magnani J, Ernst B (2008)

Bioorg Med Chem 16 (2): 1046-56DOI: 10.1016/j.bmc.2007.07.025

2007

Mimetics of Sialyl Lewis<sup>x</sup>: The Pre-Organization of the Carboxylic Acid is Essential for Binding to Selectins

Titz A, Ernst B (2007)

CHIMIA 61 (4): 194-197DOI: 10.2533/chimia.2007.194

2006

A safe and convenient method for the preparation of triflyl azide, and its use in diazo transfer reactions to primary amines

Titz A, Radic Z, Schwardt O, Ernst B (2006)

Tetrahedron Lett. 47 (14)DOI: 10.1016/j.tetlet.2006.01.157

Complexation of copper(II)-Chelidamate: A multifrequency-pulsed electron paramagnetic resonance and electron nuclear double resonance analysis

Ramic E, Eichel R, Dinse K, Titz A, Schmidt B (2006)

J. Phys. Chem. B 110 (41): 20655-63DOI: 10.1021/jp061940u

2004

Electrochemical synthesis of dimerizing and nondimerizing orthoquinone monoketals

Deffieux D, Fabre I, Titz A, Léger J, Quideau S (2004)

The Journal of organic chemistry 69 (25): 8731-8DOI: 10.1021/jo048677i

Copper dipicolinates as peptidomimetic ligands for the Src SH2 domain

Schmidt B, Jiricek J, Titz A, Ye G, Parang K (2004)

Bioorg Med Chem Lett 14 (16): 4203-6DOI: 10.1016/j.bmcl.2004.06.018