CARBOHYDRATES IN DRUG RESEARCH
EUROCONFERENCE
Figure: carbohydrate signalling at cell surface
INTRODUCTION
The knowledge on the involvement of carbohydrates in most molecular recognition
phenomena is very recent and must be clarified in many of its aspects. The finding
that most pathological events involve glycoforms as adhesion molecules, has
recently stimulated the interest of Academy and pharmaceutical industries. Till now
the difficulties in structural characterization and synthesis of oligosaccharidic
structures has inhibited the finding of new carbohydrate-based drugs. Furthermore,
there is a need of “dialogue” between synthetic glyco-chemists and representatives
of pharmaceutical companies or glyco-biologists in order to “conjugate” the synthetic
expertise with a deep knowledge of the pharmacological and biological targets. This
is the aim of the EuroConference.
Report on the events
The First EuroConference on Carbohydrates in Drug Research (ECCDR1) has
been held in Sardinia, at Stintino, from September 16 to 19, 1999; the Second
EuroConference on Carbohydrates in Drug Research (ECCDR2) has been held in
Portugal, at Estoril from September 14 to 17, 2000.
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Organisational
The conferences have been organised around lectures (40 min each) and a poster
section on different aspects of the general topic of the synthesis of carbohydrate
and carbohydrate analogues and the study of their applications as drugs. The
speakers of the first event (17), and of the second event (16) coming from Italy,
Germany, Switzerland, France, England, Spain Denmark, Belgium, Austria,
Canada and USA (24 of which are citizen of the European Community) where
representative of universities or pharmaceutical companies.
In ECCDR1, the participation of 21 young researchers, EC citizens from 9 different
countries, 11 females and 10 males, has been supported (100% of
accommodation and travel expenses). In ECCDR2, on the light of the remaining
budget, the participation of 29 young researchers, EC citizens from 8 different
countries, 16 females and 13 males, has been supported (100% of
accommodation and travel expenses or, alternatively, inscription fee).
The participants were 100 in ECCDR1, and 73 in ECCDR2, coming from 19
different countries (Portugal, Germany, England, Norway, Italy, France, Denmark,
Spain, Switzerland, Sweden, Belgium, Holland, Austria, Iceland, Finland, Canada,
USA , Japan, New Zealand!). which indicates the great interest in the events.
Announcement
A web page devoted to the conference has been prepared for each event, the
announcements was published on the Journal of Carbohydrates Chemistry (1999,
18, 255-262and 200) and sent by e-mail to all the addresses of the European
carbohydrate community and to pharmaceutical companies. The web page and
the e-mail method resulted the most effective. The web page contained all the
instructions, including the abstract form, the inscription form and the applicant
request form.
Young researchers selection
ECCDR1: 24 applications from 21 different research groups were received. The
policy of selecting 1 applicant for each research group was adopted, and the other
3 applicants have been able to participate to the Conference being supported by
their research group. This selection allowed an equilibrate distribution between
females (11) and males (10), and among different European countries (citizens of
9 different EC countries).
ECCDR2: the Scientific and Organising Committee has been decided to support
all 29 applicants (from 8 different EC countries, 16 females and 13 males).
Scientific
The First EuroConference on Carbohydrates in Drug Research covered a
wide spectrum of carbohydrate-based therapeutic developments. The
presentations, based on an interdisciplinary effort, ranged from basic synthetic
chemistry to clinical trials. Excellent introductions on the biological role of
carbohydrates, their implications in pathologies, and the possibility to use
carbohydrate based drugs as antiviral, antibacterial, antitumor, immunostimulants
have been presented inter alia by Prof Giovanni Russo (University of Milano) and
Prof. Bryan Winchester (University College, London). In particular, Prof.
Winchester reviewed the role of glycosylation and shared clinical examples of
genetic defects, especially in children. He postulated that the modulation of the
activity of carbohydrate-recognising enzymes, by regulating the supply of the
precursors or by inhibiting carbohydrate processing, decreases the rate of
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glycolipids in lipid storage diseases, with enormous therapeutic potentiality. In
order to design new inhibitors of carbohydrate processing enzymes, the fine
mechanism of glycosidases and glycosyltransferases must be understood. Prof.
Andrea Vasella (ETH, Zurich) overviewed the new developments on the
mechanism of action of these enzymes. In particular he outlined the hypothesis for
classifying glycosidases into syn- and anti- protonating enzymes, on the basis of
different protonation trajectories. These finding clearly suggest the design and the
synthesis of new types of glycosidase inhibitors. In the field of glycosidase
inhibitors, particular attention has bed devoted to imino-sugars, the synthetic
methodologies for the synthesis of this class of compounds has been reviewed by
Prof. Arnold Stütz (Technical University of Graz). He also presented the new
analogues of 2,5-dideoxy-2,5-imino-D-mannitol as “second generation” analogues
with nitrogen in the sugar ring, which are potential agents for finding antibioticresistant pathogenic bacteria.
Synthetic methodologies to prepare new inhibitors of fucosidases and
fucosyltransferase, such as thiodisaccharides and analogues of GDP-fucose have
been presented by Prof. Zbigniew Witczak (University of Connecticut) and Prof.
Yves Chapleur (University of Nancy). Prof. Witczak in particular observed that
simple analogues, with a modified anomeric centre by chain elongation and
terminal amino function, proved the practical observation of increasing inhibitory
activity against fucosidases.
In the field of oligasaccharides and glycoconjugates as synthetic vaccines or
immunostimulators, Prof. Glenn Armstrong (University of Alberta) reported his
results based on the hypothesis that the level of circulating O-specific
polisaccharide-specific gig antibodies correlates with protection against the
homologues organisms. Dr. Oswald Lockhoff (Bayer AG) reported on glycolipid
analogues with immunomodulating properties. He presented Bay-P4581 and BayR1005, new glycosylamines both functionalized with a long aliphatic chain
attached to the nitrogen as well as to the keto function. The development,
production and analysis of glycoconjugate vaccines directed against bacterial
meningitis, which is currently in clinical trial, was summarised by Dr. Neil
Ravenscroft (Chiron Vaccines SpA). Dr. Moreau (Pasteur Merieux) illustrated the
production of vaccines for the prevention of Pneumococcal infections.
Interestingly, in order to cover 80 to 90% of Pneumococcal infections in newborns
and young children, the vaccine should include 7 to 11 serotypes and therefore up
to 11 conjugate molecules. Studies on the multivalent presentation of
oligosaccharides, in order to elicit an higher immuno-response were presented by
Dr. Gebard Thoma (Novartis). He described new developments in polylysinecarbohydrate conjugates. These new studies were designed as effective tools to
determine the specific role in the ELISA assay as coating reagents and multivalent
ligands. As a representative example, a homo-polymer containing a reactive
chloroacetamide group was conjugated with three various thiols (sLea-thiol, biotinthiol and thioglycerol) to form multivalent ligand binding assay, allowing the reliable
evaluation of a broad variety of antagonists. Dr. David Zopf (Noese Technologies
Inc) presented important aspects of developing Noese’s NE-1530, an experimental
drug in phase II trials. He not only presented enzymatic approaches to these types
of oligosaccharides, but also the formulation strategy. Interesting innovations in
the enzymatic synthesis of oligosaccharides have been reported by Prof. Joachim
Thiem (University of Hamburg). In particular, Prof. Thiem discussed application of
glycosyltransferases from both Leloir and non-Leloir pathway for preparative
glycosylation, and the application of glycohydrolases for preparation of complex
lower oligosaccharides, employing reverse hydrolysis and transglycosylation.
Interesting results in the field of antiviral agents were reported by Dr. Maria José
Camarasa (Institut of Medicinal Chemistry, Madrid). She reported an excellent
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methodology developed to synthesise 3’-spiro analogues of thymidine as highly
potential HIV-1RT inhibitors. Interestingly, these analogues are thus far the only
HIV-1RT inhibitors that interact at the interface between both HIV-1RT subunits
(p51 and p66) and do not require intracellular metabolism. The simultaneous
presence in the molecule of a 3’-spiro moiety, a ribo configuration, and a
terbutyldimethylsilyl group at both C-2’ and C-5’ position are prerequisite for
antiviral activity. Dr. Yogesh Sanghvi (ISIS Pharmaceuticals Inc) reported that
among a group of oligonucleosides undergoing human clinical trials, ISIS-2302,
which targets Crohn’s disease, is in an advanced stage IIb pivotal phase.
Dr. Choung Un Kim (Gilead Science Inc) presented the development of Gilead’s
project on oral drug design of influenza inhibitors. These molecules mime the
Sialic acid ring with carbocyclic templates and the novel carbocyclic derivative GS4071 (oseltamivir) is particularly promising. A number of prodrug analogues of the
carboxylate functionality of GS-4071 were investigated, in order to improve the
oral absorption. A simple ethyl ester was identified as the most promising clinical
candidate. Currently, Gileard Sciences has received FDA approval of this first
neuraminidase inhibitor in pill from the treatment of influenza.
Besides the lectures, 51 posters, ranging from new synthetic
methodologies to the use of genetically engineered
glycosyltransferases, and showing a variety of potential carbohydrate
based drugs, have been presented.
The Second EuroConference on Carbohydrates in Drug Research prosecuted
the successful approach of the first event, combining lectures on the modern
aspects on the synthetic carbohydrate chemistry with lectures on recent
progresses on glycobiology and on carbohydrate-based therapeutic
developments. Hydrolysis of glycosides is an extremely important topic not only
from a conceptual chemical point of view, but also in order to find new and more
active glycosidase inhiditors, which are potential antiviral and anticancer agents.
Prof Pierre Sinay (Ecole Normale Superieur, Paris) presented an excellent lecture
with a thorough examination on the structural requirements in glycosides
hydrolysis. Alteration of glycosylation delivers recognition signals in a wide array of
intracellular processes including infectious, inflammatory and tumoral diseases;
therefore there is a need of control of the glycosylation machinary. In this context,
Prof. Cartherine Ronin (University of Marsille) reported on new advances on
engineering cloned glycosyltransferases, and outlined the applications in
chemoenzymatic synthesis and drug targetting, and Prof. Richard R. Schmidt
(University of Konstanz) described new concepts and synthetic efforts on the
synthesis of new inhibitors of glycosyltransferases with particular attention to
sialyltransferases. Carbohydrate mimics in which the anomeric reactivity is lost are
either potential inhibitors of carbohydrate processing enzymes or stable analogues
of carbohydrate epitopes. Prof. Alessandro Dondoni (University of Ferrara) and
Prof. Pierre Vogel (University of Lausanne) reported different approaches for the
synthesis of C-glycosyl oligosaccharides exploiting a wide range of methodologies
which resulted of didactic relevance. Another classes of glycomimetics of
pharmaceutical interest are the iminosugars and the carbasugars, in which
respectively a nitrogen or a carbon atom substitute the ring oxygen of the natural
sugar. Both these class of compounds are able to inhibit glycosidases so
interfering in relevant processes such as the biosynthesis of N-linked
glycoproteins. The lecture of Prof. Inge Lundt (Technical University of Denmark,
Copenhagen) was devoted to both iminosugars and carbasugars; the synthesis
and the biological evaluation of an impressive variety of new compounds has been
reported.
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An extremely interesting and promising application of carbohydrates for targeting
of drugs as reported by Dr. Manfred Gerken (Aventis Pharma Deutschland GmdH,
Frankfurt). Conjugation through a proper spacer of the anticancer drug doxorubicin
with a glucuronic acid unit, resulted in the non-cytotoxic prodrug HMR 1826 which
is unable to penetrate the cell wall. At the tumor cell wall there is however an
higher expression of glucuronidased compared to normal cells, which results in the
hydrolysis of the prodrug and internalisation of the obtained parent drug into the
tumor cells. The results indicate a very high concentration of the drug inside the
tumor cells, a very low concentration into normal cells, and the inactivity of the
prodrug outside the cells, which is easily catabolised. Interestingly, Dr. Andrew
Stachulski (Ultrafine Chemicals, Manchester) described synthetic methodologies
for the preparation of biologically important glucuronides.
An alternative approach for targeted anticancer chemotherapy consists in the
conjugation of anticancer drugs with glycoforms for preferential receptor-mediated
uptake into tumor cells. Dr. Hans-George Lerchen has described this approach,
reporting interesting results obtained in a systematic investigation of the cellular
uptake of conjugates carrying various fucose or modified-fucose residues. The
selected lead compound, BAY 38-3441 is a camptothecin conjugate containing a
3_OH modified fucose residue and a thiourea modified dipeptide spacer.
Intravenuos administration once a day for three days effects tumor inhibition of
more than 95% in both the LXFL529 large cell lung cancer model and the MX-1
mammary cancer model.
Prof. George Fleet (Oxford University) described the potentiality of carbohydrate
aminoacids, in other words modified carbohydrates bearing an amino and a
carboxylic group. Interesting potentials of this artificial class of compounds are a)
provide structural diversity in generation of libraries of peptidomimetics, b) provide
template information for the generation of secondary structure relatively short
sequences, and c) generate novel polymers with adjustable physical properties.
The possibility to exploit carbohydrates as efficient and conformationally
constrained scaffolds for the production of libraries of compounds of
pharmaceutical interest, also applying the combinatorial approach, has been
differently described by Dr. Carlo Battistini (Pharmaia, Nerviano) and Dr. Hans
Peter Wessel (Hoffmann-La Roche, Basel).
Quite different antithrombotic carbohydrates have been described by Dr. Maurice
Petitou (Sanofi-Synthèlabo, Toulouse) and Dr. Veronique Barberousse
(Laboratoires Fournier, Dijon). Dr Petitou described new antithrombotic
carbohydrates related to heparin, whereas Dr. Barberousse reported interesting
results on the antithrombotic activity of 5-thio-ϒ-xylosides, suggesting that this
activity could be due to the fact that ϒ-xylosides initiate the biosynthesis of
glycosaminoglycans.
A quite particular topic, appreciated for the didactic content, was proposed by Dr.
Jaques Michaud (Cerestar, Vilvoorde). He opened the mind of the young
researchers on the drug formulation problems and how starch and modified
starches can be used in conventional dosage forms, as base materials for
microspheres and microcapsules and as bioadesive and drug carrier.
Finally Prof. Beat Ernst (University of Basel) described his attractive results on the
study of carbohydrate/selectin interaction. This didactic lecture started from the
elucidation of the structure-activity relationship for a lead structure (a Silayl LewisX analogue), then described the determination of the bioactive conformation of the
lead by NMR , and the docking mode of the lead to the protein. Then developed
the molecular modelling tools for the rational design of new antagonists, and finally
the chemical and chemo-enzymatic synthesis and biological evaluation of new
antagonists. In other words, the description of a complete medicinal chemistry
project has been described.
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Besides the lectures, 38 posters, ranging from new synthetic methodologies to
structural studied by NMR and/or computational ad initio calculations, and showing
a variety of potential carbohydrate based drugs, have been presented.
In conclusion, the presentations covered a great variety of interdisciplinary aspects
of synthetic chemistry, medicinal chemistry, chemoenzymatic approaches,
conformational studies by NMR and computing, docking studies, biochemistry and
pharmacology of potential and commercial carbohydrate drugs. New vaccines,
nucleoside and glycoconjugate drug candidates, promising prodrug strategies,
new drug delivery approaches, synthetic as well as analytical aspects of potential
carbohydrate therapeutics have been presented and will certainly open the mind of
the participants to new ideas and potential applications.
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Identification:
Scientist in charge:
Address:
Tel.:
Fax:
E-mail:
Contractor:
Contract n°:
LIFcarbhyd980327/EW/jb
Prof. Francesco Nicotra
Department of Biotechnology and Biosciences
University of Milano-Bicocca
Piazza della Scienza 2 -20126 Milano - Italy
+39.2.6448.3457
+39.2.3448.3565
[email protected]
University of Milano-Bicocca - Prof. Francesco
Nicotra
ERBFMMACT980327
Publications:
- special Journal Issue of the Journal of Carbohydrate Chemistry devoted to the EuroConference,
vol 12, n. 4 &5, 2000.
-report on the EuroConference appeared in “ID weekly highlights, Currend Drugs Ltd, October
1999, p.41
- books of abstracts of the EuroConferences
www site:
- for events:
- of contractor:
- other relevant:
www.btbs.unimib.it
www.btbs.unimib.it/ECCDR
www.btbs.unimib.it
PROGRAMME OF EVENTS
Event n°1:
Event n°2:
First EuroConference on
Carbohidrates in Drug Research
Second EuroConference on
Carbohydrates in Drug research
Dates: 16-19 September 1999
Dates: 14-17 September 2000
Place: Stintino, Sardinia, ITALY
Place: Sintra, Lisbon PORTUGAL
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