Catholic University of Louvain (UCL-Bruxelles)  School of Pharmacy and Department of Pharmaceutical Sciences Scientific Report 1996 (summary)  see links for details or additional data

Chemometrics in liquid chromatography

B. Tilquin (CHAM), J. Cumps (CMFA), B. Rollmann (CHAM), P. Vanbel (CHAM)

Supported by Région Wallonne grant n°3047 (1995-97)

Chemometrics is applied to High-Performance Liquid Chromatography (HPLC). Chemometrics has been defined as the chemical discipline that uses mathematical, statistical and other methods of formal logic : a) to design or select optimal measurement procedures and experiments ; and b) to provide maximum relevant chemical information by analysing chemical data. Our general goal is the fast development of good and robust HPLC methods. The ultimate objective is to develop flexible optimization strategies applicable in practical chromatographic separation problems. 

Ionizing irradiations of drugs

B. Tilquin (CHAM), N. Barbarin (CHAM), A.S. Crucq (CHAM), M. Gibella (CHAM), Th. Pronce (CHAM), B. Rollmann (CHAM)

Supported by the industry (Eli-Lilly) (1995-98)

 The use of ionizing radiations is one of the most promising method for the sterilization of solid pharmaceuticals. Indeed, the sterilization of thermo-sensitive drugs by gamma irradiation is a desirable alternative The choice of the sterilized radiation dose is based on the initial bioburden but the maximal admitted dose for the radiosterilization is 25 kGy. Major advantages are high penetrating power of gamma rays, isothermal character of the procedure, sterilization in the final package, ... This mode of sterilization is also cheaper than microfiltration, lyophylization and filling steps under aseptic conditions. Nevertheless, the irradiation of solid drugs produces characteristic chemical effects that are not detected by classical tests like melting point, ultra violet spectro-photometry... So, methods like ESR measurements, lumi-nescence, ... are to be developped. In the reverse order, radiolysis is the best way to study radical mechanisms in solid or liquid state; pulse radiolysis is suitable for the study of very fast radical kinetics.  

J. Quetin-Leclercq (CHAM), C. Djadjo Djipa (CHAM), A. Cachon Coello (CHAM), N. Delzenne (BCTC)

The aim of our work is to find new pharmacologically active substances from plants which could constitute new drugs for therapeutic use or be used as models by chemists to improve their properties. This implies pluridisciplinary researches which can be divided into several sections. Plants to be studied, selected on an ethnopharmacological or chemiotaxonomic basis are first extracted and their properties assessed by in vitro screenings. When an extract is found to possess an interesting effect, its constituents are fractionated and their active compounds isolated and purified by several chromatographic techniques. The chemical structures of these bioactive molecules are determined by the analysis of their spectroscopic data and methods for quantitative determinations are developed to standardise, when necessary, plants or crude extracts containing these substances. 

Molecular selectivity : transport, and receptor interactions.
Pharmacochemical studies on the amino-acids and the cannabinoid neutrotransmission

D. Lambert (CMFA), B. Gallez (CMFA), M. Kanyonyo (CMFA), J. Poupaert (CMFA), H. Ucar (CMFA),
R. Verbeeck (FATC), N. Delzenne (BCTC)

Supported by : UCL-FDS (1996-98) ; FNRS "Crédit aux Chercheurs" (1996-97)

The aim of these projects are devoted to the understanding of the properties affecting selectivity in drug transport and ligand-receptors interactions. We are focused on two principal axes :

J. Poupaert (CMFA), D. Lambert (CMFA), M. Kanyonyo (CMFA), A. Gozzo (CMFA), H. Ucar (CMFA), J.Bukuru (CMFA), K. Vander Poorten (CMFA), R. Verbeeck (FATC)

This project is based on the design, the synthesis and the evaluation of compounds aimed at targets located in the central nervous system (voltage-dependent sodium channels,, i.e. phenytoinergic compounds; G-protein coupled receptors, i.e. melatonin and sigma-1 receptors). The therapeutic objectives are the epilepsy and the neuroprotection. The main lead compounds used were phenytoin and melatonin.  

N. Delzenne (BCTC), N. Kok (BCTC), M. Roberfroid (BCTC), H. Taper (BCTC), R. Verbeeck (FATC), P. Buc Calderon (BCTC)

Supported by : the industry (Raffineries Tirlemontoises); CEE grant n° AIR2-CT94-1095 (1994-97); SSTC grant n° HH/10/031 (1991-95); ILSI Europe (1991-93)

Recent advance in nutrition research allows to classify nutrients and food components as functionnal, if beneficial for health, or as deleterious, if they are involved in toxic events or disease appearance. The major topic concerns the influence of carbohydrates on hepatic lipid metabolism. The induction of lipogenesis, through activation of key lipogenic enzymes gene expression, by digestible carbohydrates (saccharose, digestible starch) given after fasting leads to triglycerides accumulation in liver tissue, known as steatosis. On the contrary, other dietary carbohydrates like oligofructose (OFS), which escape digestion by gastro-intestinal enzymes but are fermented in the colon, decrease both hepatic synthesis and secretion of triglycerides. The objectives of the research are :

l to understand the biochemical events explaining the modulation of triglyceride (TG) synthesis by those nutrients;
l to assess the influence of digestible/non digestible carbohydrates on liver sensitivity to toxic treatments.

Development of radiopharmaceuticals and magnetopharmaceuticals as functional contrast agents. Oximetry probes. Liver and CNS-targeted ligands for receptor imaging.

B. Gallez (CMFA), J. Adline (CMFA), P. Buc-Calderon (BCTC), Ph. Levêque (CMFA),
R. Verbeeck (FATC)

Supported by FNRS (1995-1996)

The aim of these projects are devoted to the understanding of the biophysical and pharmacological properties of radiopharmaceuticals and magnetopharmaceuticals in order to increase their intrinsic diagnostic value. We are focused on two principal axes:

Molecular analysis of drug-membrane interactions

 M.P. Mingeot-Leclercq (FACM), F. Van Bambeke (FACM), J.P. Montenez (FACM), O. Antoine (FACM), P. M. Tulkens (FACM)

 Supported by : Communauté Française de Belgique (ARC) grant n°172/94-99 (1994-99) and FNRS grant n° 3.4589.96 (1996-99)

 
The molecular description of the interactions between drugs and membrane constituents is a powerful tool to understand their mechanism of activity or toxicity. By biophysical and biochemical approaches, we study the effects of drugs on critical membrane properties and characterize their mode of interaction with the lipidic constituents of membranes. This work allowed us to unravel the molecular mechanisms responsable for drug-induced phospholipid storage disorders and to develop strategies to reduce this toxicity.

Detailsand additional data

Cellular toxicity of antibiotics and other drugs

C. Gerbaux (FACM), M. El Mouedden (FACM), D. Tyteca (FACM), M.P. Mingeot-Leclercq (FACM), F. Van Bambeke (FACM), P. M. Tulkens (FACM).

Supported by : Communauté française de Belgique (ARC) grant n° 172/94-99 (1994-99) and FNRS grant n° 3.4516.94 (1994-97)

 
Lysosomes are the site of accumulation of many drugs, which may reach them by endocytosis or by proton trapping after diffusion through membranes. This accumulation often causes lysosomal disorders which we have undertaken to characterize by morphological and biochemical approaches. We have focused our attention on the lysosomal dysfunctions induced by aminoglycoside and macrolide antibiotics and by undigestible polyanionic peptides, with the aim to improve the knowledge of the toxicity of these compounds, as well as the physiopathology of the lysosomal apparatus.

Details and additional data

Chemotherapy of the intracellular infection

Y. Ouadrhiri (FACM), I. Paternotte (CMFA/FACM), Hujuan Fan (CMFA/FACM), E. Sonveaux (CMFA), P.M. Tulkens (FACM).

Supported by : Communauté française de Belgique (ARC) grant n° 172/94-99 (1994-99) and FNRS grant n° 3.4516.94 (1994-97)

 The efficacy of the chemotherapy of intracellular infection depends on an effective cooperation between host defenses and antibiotics. Host defenses are modulated by molecules such as cytokines. Antibiotic efficacy is governed by their intracellular penetration, accumulation, disposition, and bioavailability. In a cellular model of uninfected or infected macrophages, we study the intracellular pharmacokinetics of antibiotics, their efficacy against intracellular pathogens localized in different subcellular compartments, and the modulation of their activity by cytokines. This work establishes the rational basis for the treatment of intracellular infections.
 

Details and additional data

Cellular penetration of antisense oligodeoxyribonucleotides

C. Berens (CMFA), A. Kerkhofs (FACM), J. M. Tilquin (CMFA), E. Sonveaux (CMFA), M. P. Mingeot-Leclercq (FACM)

 Supported by : Agence Nationale de Recherche sur le Sida (ANRS, France) (1995-97); Commmunauté Française de Belgique grant n°172/94-99 (1994-99); FRSM grant n° 3.4589.96 (1996-99)

Antisense oligonucleotides will gain pharmacological interest only if their cellular penetration is enhanced. The aim of the research is to understand the intracellular traffic of oligonucleotides and to improve their cellular penetration by conjugation with fusogenic peptides.

Details

P. Buc-Calderon (BCTC), K.Evdokimova (BCTC), I. Latour (BCTC), S. Tinton (BCTC)

Supported by : FRSM grant n° 3.4528.91 (1991-94), n° 9.4551.91 (1991) .n° 3.4607.95 (1995); FNRS "Crédit aux Chercheurs" (1991-92); CEE grant n° BMH-92-0016-BE (1992-93); UCL-FDS (1994-95)

We are interested to study the loss of cellular homeostasis induced by physic or chemical agents. We focuse our study on the regulation of a major function of the hepatocyte, the protein synthesis. We have selected two classes of stress which are interconnected : an oxidative stress induced by an organic hydroperoxide and the transition hypoxia-reoxygenation. Indeed, in both conditions, free radicals and reactive oxygen species have been implicated. In addition, such conditions occured during liver transplantation procedures. 

Adaptive response to ionizing radiation.

A. Léonard (TEMU), C. Stecca (TEMU), E.D. Léonard (TEMU), C. Crutzen-Fayt (TEMU)

The study of the adaptive response, i.e. a reduced effect from a higher challenging dose of a stressor when a smaller inducing dose had been applied a few hours earlier, has opened many new vistas into the mechanisms by which cells can adapt to hazardous environments. Although the entire chain from the initial event, supposed by the presence of DNA damage, to the end effect, i.e. presumably an improved DNA repair, has not yet been fully elucidated, many individual links have been clarified mainly through in vitro studies on cell cultures. 

Biomonitoring of people exposed to chemicals.

 A. Léonard (TEMU), E.D. Léonard (TEMU), C. Crutzen-Fayt (TEMU).

The evaluation of mutagenic and carcinogenic potential of chemicals usually relies on experimental results of in vitro short-term tests or of in vivo studies on laboratory animals. For pharmaceutical drugs clinical studies provide, in addition, important and necessary informations on the effect of chronic or acute treatment in humans. Several reports published recently underlined the value of observations on self-poisoned patients as a model for the study of the mutagenicity of chemicals in Man. 

Investigations on the contamination of food by mutagenic compounds generated by moulds (Aflatoxin B1) or by the heat processes (polycyclic aromatic hydrocarbons or heterocyclic aromatic amines).

 C. de Meester (TEMU), B. Rollmann (CHAM)

Different food products were found to be contaminated by mutagens , which were detected after different extraction procedures by the Ames / Salmonella mutagenicity test .

On the other hand different natural compounds were tested in order to investigate how the mutagenicity of heterocyclic amines (Has) can be modulated ; vitamines , flavonoids , dietary fiber and b-carbolines can reduce and even supress the mutagenic activity of Has .

Beside the caracterization of the mutagenic properties of heterocyclic amines, the unit is involved in a European project which intend to improve the quantification methods in order to assess the human risk linked to the consumption of some cooked food. Sophisticated extraction and clean-up procedures have been devised, followed by HPLC analysis with UV, fluorescence and electrochemical detection. 

Biological dosimetry on people accidentally or professionally exposed to ionizing radiations.

A. Léonard (TEMU), E.D. Léonard (TEMU), C. Crutzen-Fayt (TEMU)

Observations of chromosome aberrations induced in peripheral blood lymphocytes is currently used to evaluate the dose of ionizing radiations received accidentally or professsionally. Using this method several studies are performed in collaboration with several belgian and foreign institutions :

l On patients treated for cancer disease by external or internal exposure ;
l On people receiving radiation from nuclear follout ;
l On cell culture irradiated in vitro.

Clinical evaluation of new therapeutic approaches

 S. Ibrahim (FACM), C. Bruno-Dusart (FACM) and P.M. Tulkens (FACM)

 Supported by the industry (Schering Plough Belgium and Bristol-Myers Squibb)

Clinical trials are the ultimate and most critical final step in the development of new drugs and are also essential to rationally improve their use. In this context, our efforts are directed towards the development of optimized therapeutic schemes for antibiotics, based on the knowledge of the pharmacodynamic and pharmacokinetic parameters governing their efficacy and/or toxicity.

Details and additional data

G. Lhoëst (FATC), M. Nickmilder (FATC), R. Verbeeck (FATC)

Metabolites of the recent immunosuppressive agents possessing a macrolide structure or a cylosporine like structure such as FK-506, rapamycin and SDZ-IMM-125 respectively, may retain or not the immunusuppressive activity were investigated and were found in the case of FK-506 to be related to some intra-molecular interactions of polar groups with the FK-506 binding region and are still under investigation for the other drugs. Also the influence of Phase II reaction on the immunosuppressive activity of the metabolites will be studied. 

Drug glucuronidation

 R. Verbeeck (FATC), F. Brunelle (FATC), C. Meunier (FATC), D. Lambert (CMFA)

Many drugs and/or their phase I metabolites undergo glucuronide conjugation leading in most cases to inactive conjugates. Some of these glucuronides may undergo ß-glucuronidase catalyzed hydrolysis. Such glucuronidation-deglucuronidation futile cycling will modulate the duration and intensity of the activity/toxicity of the aglycone. This phenomenon is investigated in rats in vitro and in vivo using diflunisal and ketoprofen as model compounds. In addition, the role of extrahepatic tissues to the overall glucuronidation of propofol is studied in rat and man.  

Plasma protein binding and pharmacokinetics microdialysis sampling

 R. Verbeeck (FATC), P. Evrard (FATC), N. Van Brandt (FATC),

Plasma protein binding of drugs is an important phenomenon affecting the distribution and elimination of many drugs. We are studying the interindividual variability in the plasma protein binding of midazolam and sufentanil in ICU patients and its effect on the pharmacokinetics and activity of these compounds. In addition, microdialysis techniques have been developed in our laboratory which permit the in vivo measurement of unbound concentrations of drugs in blood and other tissues (e.g. CNS) of small laboratory animals. Using this technique several projects are underway not only to study the in vivo plasma protein binding and pharmacokinetics of drugs, but also to investigate the transport of compounds across the blood brain barrier.  

J. Gillard (FARG), M.A. Benoit (FARG)

The main objective in the development of new forms in order to improve the biodisponibility of the drugs and more specially sustained release systems. The basic aspect consists in the understanding of the pharmaceutical profile of the drug in accordance with the therapeutic aim and the more appropriate administration route (gastrointestinal tract, in situ implantation. The practical goal may be sketched as follows : new forms for new drugs and current drugs in new forms. In view of the therapeutic treatment, sustained release systems are developped for different durations of activity :

V.Préat (FARG), A.Jadoul (FARG), V.Regnier (FARG), R. Vanbever (FARG)

Supported by : Pharmaceutical industry; FNRS "Crédit aux chercheur"; Région Wallone; UCL-FDS

 The objective of the research is to assess the potential of electrically enhanced transdermal drug delivery. For both iontophoresis (low density electric current application) and electroporation (high voltage pulse exposure), the following features were analyzed in vitro and/or in vivo :

l enhancement in drug delivery in vitro and in vivo
l mechanisms involved in drug transport
l parameters controlling drug permeation
l routes of passage in the skin
l skin structure and tolerance issues
l development of new therapeutic applications

Nanoparticles and microspheres as drugs and antigen delivery systems

V.Préat (FARG), D.Lemoine (FARG), C. Tasset (FARG)

 Suported by FRSM, WHO and Industry

The use of nanoparticles or colloid forms has been investigated for several applications :

l drug targeting of antileishmanial drug to the reticuloendothelial system by poly(alkyl cyanoacrylates) nanoparticles.
l nanoparticles of sustained release of calcitonin
l colloid carrier of amphotericin B
l improvement of mucosal immunization against influenza virus