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Human Immunodeficiency Virus (HIV) is the causative agent of Acquired Immune Deficiency Syndrome (AIDS). The C₂-symmetric HIV-1 protease is one of the prime targets for chemotherapy in the treatment of the HIV infection. Inhibition of HIV-1 protease leads to immature and non-infectious viral particles. Design and synthesis of a number of C₂-symmetrical C-terminal duplicated HIV-1 protease inhibitors and subsequent biological evaluation is presented in this thesis.

A versatile three step synthetic route has been developed using a carbohydrate as an inexpensive chiral starting material thus allowing inhibitors with the desired stereochemistry to be obtained. By this efficient method a series of tailor-made P2/P2' modified inhibitors were synthesized, and these were evaluated on purified HIV-1 protease and in HIV-1 infected cell assays. Highly active HIV-1 protease inhibitors were identified among the tested compounds. Analyses of the X-ray crystal structures of two of the most active compounds, as complexes with the protease, guided the further design of P1/P1' elongated inhibitors. Substitutions in the para-position of the P1/P1' benzyl groups were promoted efficiently by microwave-irradiated of palladium-catalyzed reactions. Particular modifications in the P1/P1' region of the inhibitors resulted in a 40-fold increase of the anti-viral activity on HIV-1 infected cells. Furthermore, a fast, efficient, and general one-pot microwave enhanced synthesis protocol for transformations of organo-bromides to tetrazoles was developed and applied on the inhibitor scaffold. Attachment of linker molecules to the P1/P1' benzyl groups of one inhibitor was used to develop of sensitivity enhancer tools in surface plasmon resonance biosensor assays. These new assays enable the evaluation of low-molecular weight compounds as HIV-1 protease inhibitors.

Capillary electrophoresis as a powerful separation technique was employed for resolution of racemic drugs. Taurodeoxycholate (TDC), different cyclodextrins and α₁- acid glycoprotein (AGP) were dissolved in the background electrolyte at low pH (3.0 to 4.0 ) as chiral selectors.

Enantioresolutions were based on the principle of micellar electrokinetic chromatography, inclusion complexation and affinity interactions between the enantiomers and TDC, cyclodextrins and AGP, respectively.

The influence of chiral selector concentration and type, temperature and addition of organic modifiers on enantioselectivity were studied. The temperature was found to be an important factor for regulation of the enantioresolution.

In order to avoid UV-absorbance interferences between AGP as a UV-absorbing chiral selector as well as to reduce consumption of chiral selector solution, the partial filling technique (PFT) was employed. The technique was developed and equations describing the feature of the technique as an efficient separation mode in CE was presented. Parameters such as applied plug length (PL_app) and effective plug length (PL_eff) were determined. Equations expressing the relation between the PL_eff and selectivity and resolution factors were developed.

The PFT was used for determination of association constants between AGP as chiral selector and the enantiomers of disopyramide and remoxipride. The association was strongly temperature dependent, and a maximum in binding was observed at 25°C. The PFT was found to be a very convenient approach for measurement of association constants.

To verity the above mentioned technique for evaluation of binding constants, the association constants between methyl-β-cyclodextrin and the enantiomers of orciprenaline at different chiral selector concentrations were measured and compared with the data obtained by the conventional technique. The results illustrate the reliability of the system based on the PFT.

The susceptibility of ethoxylated non-ionic surfactants to oxidation on exposure to air was investigated. Surfactants have a complex chemical composition and are widely used in a variety of applications for to their amphiphilic properties. Ethoxylated non-ionic surfactants are regarded by the producers to be stable at normal handling. However, ethoxylated surfactants are polyethers and as such susceptible to oxidation on exposure to air, which is theoretically discussed in literature. Hand eczema is a common occupational disease of which mom than half of the cases is considered to be caused by work with surfactants and water. Surfactants are known to cause skin irritation, but cases of allergic contact dermatitis have also been reported.

Some ethoxylated surfactants were handled at room temperature in a manner that imitated ordinary handling at work. All samples autoxidized and the structures of some of the components formed were identified with liquid chromatography (HPLC) and gas chromatography (GC). Structural analogues were synthesized and could be identified in the complex oxidation mixture using nuclear magnetic resonance, infrared and mass spectroscopy (NMR, FT-IR, MS). The allergenic potential of the identified oxidationproducts was studied in experimental sensitization studies in guinea pigs. The physicochemical behavior of individual oxidation products in pure water solutions was investigated.

A well-known contact allergen, i.e. formaldehyde, and previously undescribed allergenic compounds were identified after air exposure of the ethoxylated surfactants. At oxidation, the content of free formaldehyde increased above the level for warning labelling within the European Union. The allergenic potential of one of the main compounds identified, an ethoxylated aldehyde, was of similar magnitude as that of formaldehyde. The oxidation led to a gradual change in the physicochemical properties.

The observed autoxidation of commonly used ethoxylated surfactants and formation of a complex degradation mixture indicate a potential health risk that has not been considered before. Previously unknown breakdown/oxidation products were identified, some of which had allergenic properties. This oxidation can also affect the technical performance of the surfactants. The observed allergenic properties of the formed oxidation products may be of importance in occupational exposure to polyoxyethylene surfactants.

The complete series of Boc-protected C-4 mono- and difluoroallyl Phe-Gly dipeptidomimetics and their corresponding saturated derivatives has been synthesized. A mechanism that rationalizes the formation of the two isomeric allylic mono-fluorides from an allylic alcohol with diethylaminosulfur trifluoride (DAST) has been investigated. Most likely, the reaction proceeds via an aziridine intermediate. An allylic ketone isostere wasused as starting material for all the fluorination transformations. Two synthetic approaches to this ketone were developed.

A series of vicinal diamines was synthesized by reactions of allylic cis- and transaziridines with nucleophilic amines. The nucleophiles reacted either via ring opening or 1,4-addition reactions with the α,β-unsaturated aziridines. The 1,4-addition reaction was found to be favoured in most cases. To improve the yield of ring opening products, various reaction conditions were examined. The Lewis acids Yb(OTf)₃ and Zn(OTf)₂ were chosen as the reaction catalysts since they are believed to coordinate differently to acylaziridines. It was observed that addition of these Lewis acids did not influence the outcome of the reaction.

Five Boc-protected Phe-Gly and Phe-Phe vinyl isosteres were synthesized using a Julia olefination reaction. The epoxidation of the vinyl isosteres were performed with three different peracids and VO(acac)₂/TBHP. The stereoselectivities observed in the peracid epoxidation may emanate from a cooperative coordination of the incoming peracid by the allylic carbamate group and more weakly coordinating allylic methyl ester, alcohol,and acetate functions. The vanadium catalyzed reactions demonstrated that the face selectivity in the epoxidation of the double bond of the Phe-Gly and Phe-Phe vinyl isosteres is only dependent of the steric interference.

Spray drying is a method with a high potential in the preparation of protein particles suitable for pulmonary delivery. However, surface induced denaturation of bio-molecules during atomization and subsequent drying can be substantial and it is therefore important to develop new formulation concept for concurrent encapsulation and stabilization of proteins during spray drying. Hence, with an overall objective to increase the knowledge of the formation of particulate systems for systemic administration of proteins by spray drying, the first part of this thesis, systematically investigated the particle formation by droplet size and particle size measurements. It was described how specific properties, such as the solubility and the crystallization propensity of the solute, can affect the product, e.g. the particle size, internal structures, and possibly particle density. A new method using atomic force microscopy (AFM) for the assessment of the effective particle density of individual spray-dried particles was demonstrated. In the second part, two different formulation concepts for encapsulation of protein during spray drying were developed. Both systems used non-ionic polymers for competitive adsorption and displacement of protein from the air/water interface during spray drying. The aqueous two-phase system (ATPS) of polyvinyl alcohol (PVA) and dextran, and the surface-active polymers, hydroxypropyl methylcellulose (HPMC) and triblock co-polymer (poloxamer 188) used for in situ coating, proved efficient in encapsulation of a model protein, bovine serum albumin (BSA). Inclusion of polymeric materials in a carbohydrate matrix also influenced several particle properties, such as the particle shape and the surface morphology, and was caused by changes in the chemical composition of the particle surface and possibly the surface rheology. In addition, powder performance of pharmaceutical relevance, such as dissolution and flowability, were affected.

Pharmaceutical formulations often contain polymers used as binders, swelling agents, etc., to give the formulation mechanical stability or specific drug release features. Many drug substances, as well as polymers, are amphiphilic which will give an associative polymer-drug interaction, affecting the dissolution rate and drug release. This thesis focuses on the molecular dynamics of model nonionic polymer-anionic drug complexesformed in aqueous solution. Two low molecular weight amphiphiles with different surface activities are used; the surfactant sodium dodecyl sulfate (SDS) and the sodium salt of ibuprofen. The polymers studied are a set of cellulose ethers of different hydrophobicity, with special emphasis on ethyl(hydroxyethyl)cellulose (EHEC).

Fluorescence probe techniques and nuclear magnetic resonance (NMR) are the main methods used. The molecular dynamics of the EHEC/SDS system is strongly composition dependent. Mixed EHEC/SDS micelles with low SDS aggregation numbers and a high relative content of EHEC is more than three times as rigid as mixed micelles with a high relative content of SDS, as monitored by the fluorescent probe 1,3-di(1-pyrenyl)propane(P3P) and ¹H NMR transverse relaxation.

The microviscosities as monitored by P3P of a set of ten cellulose ethers with different hydrophobicity, interacting with SDS, are compared. A correlation between the microviscosity and the polymer-SDS interaction energy, as qualitatively estimated from the SDS concentration at onset of polymer-SDS association, is found. This correlation is further described by principal component analysis for a subset of six EHEC samples. The microviscosity of mixed polymer-SDS micelles as monitored by P3P is found to be a valuable parameter for the characterization of polymer samples, and can be used to predict the surface tension of the polymer.

The interaction between EHEC and the sodium salt of ibuprofen resembles the normally accepted model for polymer-surfactant interaction, but is more complex. Fluorescence probe- and pulsed gradient spin echo self diffusion NMR- (PGSE-NMR) measurements indicate that premicellar aggregates of ibuprofen adsorb onto EHEC below the onset of cooperative adsorption with respect to the ibuprofen concentration. The thesis shows theimportance of detailed knowledge of the molecular dynamics for design of controlled release preparations.

The protein cellobiohydrolase I (CBH I) immobilized on silica particles has been used as a chiral selector in liquid chromatography (LC) and the free enzyme has served as a chiral complexing agent in the background electrolyte in capillary electrophoresis (CE) using the partial tilling technique.

The CE systems were much more efficient and more solutes could be enantioseparated than in the LC systems. Due to the high enantioselectivity, a few substances could be completely enantioresolved in an injected CBH I zone that was shorter than the sample zone. The affinity for the amino alcohol propranolol was very high at neutral pH and in order to displace this solute for detection, a plug of the disaccharide cellobiose was injected after the sample zone. The high affinity of propranolol combined with the displacing ability of cellobiose made it possible to preconcentrate the solute prior to enantioseparation by compression of long dilute sample zones.

The mechanisms of retention and enantioselectivity in LC have been studied using charged and uncharged additives in the mobile phase. Site-specific mutation and covalent modification of the protein were also used to elucidate retention mechanisms. The enantioselective sites of amino alcohols and the acid warfarin overlap in the vicinity of the catalytically active site of CBH I. The main binding mechanism for both amines and acids was electrostatic attraction. Interestingly, both the retention and the enantioselectivity increased upon changing from potassium to sodium as mobile phase cation.

The thermodynamics of the system was studied by microcalorimetry and LC. Both enantiomers of the amino alcohol alprenolol bind to CBH I with an endothermic enthalpy change. Hence, the complexation is entropy driven.

Molecular mechanics calculations were carried out on the complex between propranolol and CBH I. The bound conformation of (S)-piopranolol differs both in geometry and energy compared to the preferred conformation in water solution. The ability of different parameter setups to reproduce the experimental structure of the (S)-propranolol - CBH I complex was investigated. One setup was chosen to suggest possible conformations of the (R)-enantiomer. The water structure in the bindning site seems to be an important factor in the complexation mechanism.

Cellobiohydrolase 58 (EC 3.2.1.91, pc. Cel 7D) from Phanerochaete chrysosporium was immobilized on silica and the resulting material, CBH 58-silica, was then used as a chiral stationary phase (CSP) in liquid chromatographic separations of enantiomers. The enantioselectivities obtained on CBH 58-silica were compared with those on CBH I-silica (a phase based on a corresponding cellulase from Trichoderma reesei). CBH 58-silica displayed higher selectivity than CBH I-silica for the more hydrophilic compounds, such as atenolol and metoprolol, although great similarities in chiral separation of beta -adrenergic antagonists were found between the two phases. None of the acidic compounds tested could be resolved on the CBH 58 phase. Moreover, the solutes were retained more on the CBH 58 phase in general, indicating an improved application potential in bioanalysis. Addition of cellobiose or lactose, both of which are inhibitors of cellulases, To the mobile phase impaired the enantioselectivity, indicating an overlap of the enantioselective and catalytic sites. The chiral analytes also functioned as competitive inhibitors and their inhibition constants were determined.

The central theme is how the structural characteristics of sulphated polyelectrolytes and theirinteraction with counter- and coions determine the degree of polyelectrolyte self-association (gelformation), interaction with oppositely charged polyelectrolyte and polyelectrolyte-amphiphilic druginteraction in protolytic solvent medium. Such knowledge is essential for understanding and regulatingthe interaction between polyelectrolytes as well as between polyelectrolytes and a drug substance in apharmaceutical formulation and for its fate in the human organism.

The gel formation of the sulphated polyelectrolyte ê-carrageenan was found to be dependent on theextent of inter-chain helical association and thus the nature of the polyelectrolyte counterions. This wasshown from the relationship between the gel-sol melting temperature of the hydrophobic microdomains(T₀), the fraction of polymer in helical conformation at T₀, and the storage modulus of the samples inthe gel-state. Interaction between the oppositely charged polyelectrolytes carrageenan and chitosanresulted in the formation of polyelectrolyte complexes with a charge ratio of unity. However, in casesof inter helical association of carrageenan chitosan acted as a bridging element producing complexeswith a charge ratio below unity. This mechanism may be used to control the charge ratio ofpolyelectrolyte complexes.

The solvation characteristics of the polyelectrolyte counterions also affected the polyelectrolyte-amphiphilic drug interaction (amitriptyline). The binding isotherm was shifted to a higher concentrationof free amphiphile according to the counterion sequence Li⁺ < Na⁺ < K⁺ < Rb⁺ ≈Cs⁺. The change inGibbs free energy per monomer amphiphile originating from exchanging the counterions (Li⁺ for Cs⁺),was of the order of kT. This is of the same order of magnitude as that obtained by significantlychanging the hydrophobicity of the amphiphilic drug molecule. Increasing the polyelectrolyte chargedensity decreased the critical aggregation concentration, increased the degree of cooperativity andincreased the magnitude of ion specific effects. Furthermore, the dependence of the. critical aggregationconcentration on ionic strength was linear and the polymer flexibility affected the efficiency of thepolycounterion properties of the polyelectrolyte. The binding isotherms, micropolarity, microviscosityand surface tension indicated the amitriptyline-polyelectrolyte interaction to be qualitatively andquantitatively similar to that observed for "typical" cationic surfactants.

Human Immunodeficiency Virus (HIV) is the causative agent of Acquired Immune Deficiency Syndrome (AIDS). Inhibition of HIV-1 protease leads to immature and non-infectious viral particles. The synthesis of a number of cyclic HIV-1 protease inhibitors and the subsequent evaluation in an enzyme assay is presented in this thesis. A centrally positioned water molecule (W301), unique to retroviral proteases, guided the design ofthe inhibitors.

A synthetic procedure utilising carbohydrates as chiral starting materials has been used to gain control of the stereochemistry of the target compounds. Synthesis of four C₂-symmetric cyclic urea inhibitors revealed the importance of correct stereochemistry in rigid cyclic structures for activity. According to the X-ray crystal structures of the cyclic inhibitors, in complex with the protease, a displacement of the water molecule W301 by aurea carbonyl, or alternatively by a sulfamide group was accomplished.

Changing the water-mimicking group from urea to sulfamide resulted in an unexpected non-symmetric binding mode as deduced from comparison of the X-ray crystal structure of a urea and a sulfamide inhibitor in complex with the protease. A small X-ray structure of a sulfamide inhibitor in absence of the protease established that thenon-symmetric conformation of the inhibitor was an inherent feature of the sulfamide scaffold and not induced by the protease.

In an attempt to establish the structure activity relationship (SAR) of the sulfamide class of inhibitors, symmetric and non-symmetrically substituted sulfamide inhibitors were prepared. A comparative molecular field analysis (CoMFA) was performed to rationalise the SAR and give a model of predictive value. The cyclic inhibitors wereevaluated against a series of mutant forms of the protease and found to have a considerably lower affinity towards I84V and V82A than towards the wild type enzyme.

Neutral and anionic chiral mobile phase additives have been employed to separate enantiomers of drugs and related compounds using aqueous buffer solution and hydro-organic solvent mixtures as mobile phases.

Ester derivatives of tartaric acid, e. g. (2R,3R)-dicyclohexyl tartrate, was adsorbed on an achiral solid phase of porous graphitic carbon (PGC) and acted as a chiral stationary phase for the enantiomer separation of neutral, acidic and basic compounds (e.g. atropine, mandelic acid, ephedrine) The antipode, (2S,3S)-dicyclohexyl tartrate was applied for the determination of the enantiomeric impurity of a pharmaceutical preparation of (S)-atropine.

(2R,3R)-(-)-Dibenzoyl-tartaric acid mono (dimethylamide), a tartaric acid amide derivative having a free carboxylic group was also adsorbed on PGC and simultaneously acted as a chiral counter ion to several racemic drugs. Complete chiral resolution was obtained for several β-blocking agents (e.g. alprenolol, metoprolol and propranolol) and antiulcer agents (e.g. omeprazole and lansoprazole)

In contrast to the tartaric acid derivatives, N-protected di-and tripeptides, e.g. N-benzyloxycarbonyl-glycyl-L-proline (L-ZGP), had low affinity to PGC when dissolved in mobile phase of methanol. Nevertheless they gave high enantiomeric resolution for several racemic drugs of pharmacological interest (e.g. terbutalin, alprenolol, trimipramine and promethazine) by acting as a counter ion to the solute enantiomers. This chiral counter ion enabled the determination of the enantiomeric composition of mefloquine at micro-molar levels in biological fluids.

When charged selectors were used, solute retention conformed with ion-pair retention mechanism. Counter ion concentration and pH were the main parameters utilized to control both retention and enantioselectivity. Other achiral additives e.g. organic modifiers, co-ions etc might also influence the enantioselective retetion. Thus many factors could be used to regulate the chiral separation by ion-pair chromatography. The chemometric approach, using experimental design and multivariate data analysis, was shown to be an effective tool for optimization of the separation of mefloquine. (1S,3S,4S)-(+)-3-bromocamphor-10-sulfonic acid was used as a counter ion.

HIV-1 reverse transcriptase (RT) is a target for anti-HIV chemotherapy. A series of PETT PhenylEthylThiazoleThiourea) non-nucleoside HIV-1 RT inhibitors were synthesised. All compounds were tested in an HIV-1 RT enzyme assay, and in cell culture using MT-4 cells and wild-type virus. Many compounds were also tested in HIV-1 RT enzyme assays with three constructed mutants, Ile100, Cys181 and Asn103, and in cell culture using virus containing a mutation in residue 100, 181 or 103.

The lead PETT compound, N-(2-phenethyl)-N'-(2-thiazolyl)thiourea, has an IC₅₀ of 0.9 µM in an HIV-1 RT enzyme assay and an ED₅₀ of 1.3 µM in an HIV-1 cell culture assay. The optimisation of this compound resulted in a clinical candidate, trovirdine, N-[2-(2-pyridylethyl)]-N'-[2-(5-bromopyridyl)]thiourea, which inhibits HIV-1 RT with an IC₅₀ of 15 nM and has an ED₅₀ of 20 nM in cell culture. Further optimisation produced more potent thiourea compounds comprising 2, 3, 6-trisubstituted phenethyl 5-chloro, 5-bromo or 5-cyano-2-pyridyl thiourea analogs. The IC₅₀ and ED₅₀ values of the most active of these analogs were 1 to 5 nM. Bioisosteric substitution of the thiourea moiety of PETT compounds with cyanoguanidine, guanidine and sulfonyldiamide is studied. Finally, the synthesis and structure activity relationship studies of highly potent, conformationally restricted, racemic and enantiomeric cyclopropyl urea analogs are described with enhanced antiviral activities even on mutant form of HIV-1 virus in the nanomolar range.

The three-dimensional structures of complexes between HIV-1 RT and an enantiomeric pair of cyclopropyl compounds have been determined. The structures show similar binding in the NNI binding pocket. The cyclopropyl moiety of both enantiomers has close-packing interactions with leucine residue 100, valine residue 179 and tyrosine residue 181, but in addition to these interactions the cyclopropyl moiety of the (+)-enantiomer has extensive hydrophobic close-packing interactions with glutamine residue 1138.

Iontophoresis is a modern method of drug delivery by which charged bioactive molecules (drugs) are transferred from an electrolytic reservoir into and through a tissue, normally skin, by means of a weak electric current. The drug is placed in a conductive medium, usually an aqueous solution or a hydrogel, between the "active" electrode and the skin. The circuit is completed by a second "passive" electrode and the skin. Although iontophoresis is a well-known method for transdermal delivery of drugs, basic physicochemical knowledge of this phenomenon is still lacking.

This thesis aimed to obtain a wide understanding of electrolyte structures and ionization conditions in iontophoresis, and a firm physicochemical basis for improvement of iontophoretic drug formulation of local anesthetics. The precision conductometric technique was used mainly. Lidocaine hydrochloride (LidHCl) was selected as a model local anesthetic substance. The conductance theory of Fuoss, Hsia and Fernandez-Prini was used to interpret the experimental data, with respect to ionization and mobility of LidHCl in different solvent media. LidHCl was studied in the following solvents:, water, propylene glycol (a transdermal enhancer),aqueous propylene glycol (20 weight-% PG) and 1-octanol. To compare the ionization properties of prilocaine hydrochloride (PrilHCl) with those of LidHCl, PrilHCl was studied in the same pharmaceutical aqueous-enhancer medium. Furthermore, the molecular diffusive transport properties of the local anesthetics lidocaine-, prilocaine-,bupivacaine-, etidocaine-, mepivacaine- and ropivacaine hydrochloride in an agarose hydrogel (1 weight-% agarose) were studied.

The results indicate that, for the solvents studied, LidHCl has the highest ionic mobility in aqueous propylene glycol; u(LidH⁺) = 1.35 mm² V^-1 min^-1. No measurable difference in ionization properties and ionic mobility between LidHCl and PrilHCl in aqueous propylene glycol was observed. Within the concentration range investigated in this solvent, more than 98% of both LidHCl and PrilHCl are in ionized form (LidH⁺ and PrilH⁺). Of the six local anesthetics studied by diffusion measurements in agarose hydrogel (1 weight-% agarose) as medium, LidHCl and PrilHCl have the highest diffusion coefficients; D_(lido) = 7.79 · 10-6 and D_(prilo) = 7.76  · 10-6 cm²/s.

From a pharmaceutical point of view, it might be interesting to study the possibility of combining lidocaine- and prilocaine hydrochloride in an aqueous-enhancer medium as an iontophoretic drug formulation of local anesthetics.

This study addresses the issue of how to convert peptides into drug-like non-peptides while retaining the biological activity at peptide receptors. Angiotensin II (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe, Ang II) was used as a model peptide.

Small bioactive peptides are in most cases conformationally flexible molecules. Rigidified peptide analogues or peptidomimetic scaffolds can be introduced into the peptide, to enforce a particular backbone conformation, and thereby locate the side-chains at defined positions in space. The conformationally constrained analogues are of considerable value in determining biologically active conformation(s) of the studied peptide. The strategy applied in this thesis includes identification of non-pharmacophoric amino acid residues, rigidification, conformational analysis and incorporation of turn mimicking scaffolds in

Ang II. Several side-chain cyclized (disulfide and methylendithioether) Ang II analogues have been synthesized. The binding studies of the rigidified analogues demonstrated that the compounds designed for the AT₁-receptor had affinity for both receptor subtypes, while the compounds designed for the AT₂-receptor displayed high selectivity only for this receptor subtype. Conformational evaluation revealed that several of the cyclized Ang II analogues most probably adopt a γ-turn like conformation around Tyr-4 while interacting with the

Ang II receptor. Based on this hypothesis, three different γ-turn mimetics replacing amino acid residues 3-5 were designed, synthesized and incorporated into Ang II. One of the synthesized pseudopeptides, incorporating an azepine-containing γ-turn mimetic, exerted high binding affinity and agonistic activity. These results strongly support the theory that Ang II adopts a γ-turn like conformation when activating the AT₁ receptor. The other Ang II analogues, incorporating bicyclic and aromatic γ-turn mimetics, did not display any binding to the AT₁ receptor.

Novel series of well-characterized and stereochemically pure 11-substituted (R)-aporphine derivatives have been prepared and their interaction with serotonin 5-HT₇ and 5-HT_1A receptors and dopamine D_2A and D₁ receptors have been studied. Efficient palladium catalyzed reactions were utilized for the diastereoselective synthesis of atropisomers as well as for the synthesis of several of the other (R)-aporphine derivatives. A number of 11-arylated (R)-aporphines displayed high affinity for 5-HT₇ and 5-HT_1A receptors and derivatives with selectivity for either 5-HT₇ or 5-HT_1A receptors were obtained by chosing the proper substituents on the 11-phenyl ring. Simultaneous substitution of the 2' and 6' positions of (R)-11-phenylaporphine afforded derivatives, including some atropisomers, with increased 5-HT₇ selectivity and several of these analogues were characterized as selective 5-HT₇ receptor antagonists. Introduction of substituents in the other positions of the 11-phenyl group resulted in derivatives with selectivity for 5-HT_1A receptors.

In addition, new series of novel pentacyclic (R)-aporphines were synthesized either by the introduction of a methylene group between carbon atoms C1 and C11 in the (R)-aporphine skeleton or by ring expansion reactions of (R)-1,11-carbonylaporphine. These series of derivatives afforded the possibility to introduce substituents/functional groups below, above and in the plane of the ring system thereby allowing for structural extensions into previously unexplored areas of receptor binding sites. Compounds with various affinities for the serotonin and dopamine receptors were obtained and novel 5-HT₇ receptor antagonists were identified.

The identification of selective serotonin 5-HT₇ receptor antagonists is of particular interest since only a few putatively selective 5-HT₇ receptor antagonistic ligands have been reported.

The palladium-catalysed Heck-reaction has been utilised in organic synthesis, where the introduction of aryl groups at the internal, β-carbon of different allylic substrates has been achieved with high regioselectivity.

The β-stabilising effect of silicon enhances the regiocontrol in the internal arylation of allyltrimethylsilane, while a coordination between palladium and nitrogen induces very high regioselectivities in the arylation of N,N-dialkylallylamines and the Boc-protected allylamine, producing β-arylated arylethylamines, which are of interest for applications in medicinal chemistry. Phthalimido-protected allylamines are arylated with poor to moderate regioselectivity.

Single-mode microwave heating can reduce the reaction times of Heck-, Stille- and radical mediated reactions drastically from approximately 20 hours to a few minutes with, in the majority of cases, retained, high regioselectivity.

The use of heavily fluorinated tin reagents, which proved to be unreactive under thermal heating, is shown to be applicable with microwave-heating and the high fluorous content of the products is utilised with the aim of improving and simplifying the work-up procedure.

Polymers are important in a variety of pharmaceutical applications. Many of them are derived from cellulose but there are several biological sources of importance for their production. Polymers display a very wide diversity of properties which makes a detailed characterization necessary. The investigated polymers are more or less surface active due to the presence of hydrophilic and hydrophobic parts. They show surface activity at very low concentrations which makes them useful as stabilizers in suspensions and emulsions. The surface tension measurements were performed by the pendant drop method.

The surface activity and the cloud point (CP) are related to each other. These parameters depend on the hydrophilic/hydrophobic balance of the polymer. The time dependence of surface tension is mainly related to the concentration in the dynamic region (2-10 ppm). The half-life of the surface tension (t_1/2) at these concentrations was found to be inversely correlated to the diffusion coefficient and to the square of the bulk concentration, which is expected for a diffusion process. Furthermore, t_1/2 was related to the intrinsic viscosity of the polymers.

The in situ colonic effective permeability of fluvastatin in the rat was found to be inversely proportional to the surface tension of fluvastatin.

The interaction between charged amphiphiles and oppositely charged polymers was investigated by surface tension measurements since surface activity is an important property of pharmaceutical formulation. The adsorption of charged amphiphiles to oppositely charged polyelectrolytes involve charge to charge interaction at low amphiphile concentration. An increase in amphiphile concentration is followed by a cooperative increase in adsorption at a certain concentration due to hydrophobic interaction between already adsorbed amphiphiles. The strength of the interaction is related to the hydrophobicity of the amphiphile. Also the charge density isimportant since the distance between the charges influence the concentration where the hydrophobic interaction starts.

Drug formulations come in many forms, some intended for direct and immediate action and others aiming at a controlled manner of drug delivery. Viewed in a more general way drug transport often involves charged units, it takes place in a medium which in many respects must be considered complex - to some degree even reactive. Drug transport may also be competitive because of thermo- and hydrodynamic interactions, These three aspects of drug transport in general is discussed and exemplified in specific studies: 1) A conductivity study as a fundamental investigation for iontophoretic drug delivery; 2) a methodological development and diffusivity investigation of a steroidal hormone transport in silica containing silicone; 3) an investigation of competitive diffusion transport of small amphiphilic molecules in a polyelectrolyte containing semi-solid system.

Iontophoresis - drug administration by electric current - normally requires charged drug molecules, hence their mobility and state of dissociation are essential parameters. The medium in which the drug is situated regulates the electrolytic drug content (e.g. dissociation equilibrium) and thus the iontophoretic efficiency. The conductivity of the local anesthetic, IidocaineHCl was investigated by high precision conductometry in aqueous and octanol solutions. From conductivity data and applied advanced electrolyte theory drug mobility parameters as well as, dissociation and association constants were obtained. The drug ion mobility was found, to be a factor 50 lower in octanol. The equilibrium constants obtained show that increasing drug concentration favors ion formation in water while favoring ion pair association in octanol. Hence, such a drug behaves very differently in different media, with obvious clinical implications.

The dynamic diffusion in the complex system silicone/silica/estradiol was studied by means of a new equipment design which has considerably improved the possibility to perform precise quantitative dynamic diffusion measurements in such systems, The method avoids all disturbing interfaces between different media and allows for a precise spatial resolution of concentration of the diffusing drug. Data showed the method to be dependable and accurate. The effect on estradiol diffusivity due to varied silica content in the silicone is found to be paramount, increasing [SiO₂] from 17 to 30% decreased the diffusivity by 68%. Some mechanisms are discussed.

The diffusion of amphiphiles within and the release from agarose hydrogels containing the polyelectrolyte carrageenan was investigated. All drugs exhibit same apparent diffusivity in pure agarose gel. The diffusivity decreased when carrageenan was introduced in the gel. The order of the decrease follows the order of increased hydrophobic character of the drug. Competing diffusion was studied for amitriptyline and chlorpromazine, the former released significantly faster than chlorpromazine when simultaneously released from a hydrogel slab. Data indicate the possibility to adjust the simultaneous release rates individually for the two drugs by means of polyion charge density.

Cellobiohydrolase Cel7A (previously called CBH 1), the major cellulase produced by the mould fungus Trichoderma reesei, has been successfully exploited as a chiral selector for separation of stereo-isomers of some important pharmaceutical compounds, e.g. adrenergic beta -blockers. Previous investigations, including experiments with catalytically deficient mutants of Cel7A, point unanimously to the active site as being responsible for discrimination of enantiomers.

In this work the structural basis for enantioselectivity of basic drugs by Cel7A has been studied by X-ray crystallography. The catalytic domain of Cel7A was co-crystallised with the (S)-enantiomer of a common beta -blocker, propranolol, at pH 7, and the structure of the complex was determined and refined at 1.9 Angstrom resolution. Indeed, (S)-propranolol binds at the active site, in glucosyl-binding subsites -1/ + 1. The catalytic residues Glu212 and Glu217 make tight salt links with the secondary amino group of (S)-propranolol. The oxygen atom attached to the chiral centre of (S)-propranolol forms hydrogen bonds to the nucleophile Glu212 O-epsilon1 and to Gln175 N-epsilon2, whereas the aromatic naphthyl moiety stacks with the indole ring of Trp376 in site +1. The bidentate charge interaction with the catalytic glutamate residues is apparently crucial, since no enantioselectivity has been obtained with the catalytically deficient mutants E212Q and E217Q.

Activity inhibition experiments with wild-type Cel7A were performed in conditions close to those used for crystallisation. Competitive inhibition constants for (R)- and (S)-propranolol were determined at 220 muM and 44 muM, respectively, corresponding to binding free energies of 20 kJ/ mol and 24 kJ/mol, respectively. The K-i value for (R)-propranolol was 57-fold lower than the highest concentration, 12.5 mM, used in co-crystallisation experiments. Still several attempts to obtain a complex with the (R)-enantiomer have failed.

By using cellobiose as a selective competing ligand, the retention of the enantiomers of propranolol on the chiral stationary phase (CSP) based on Cel7A mutant D214N were resolved into enantioselective and non-selective binding. The enantioselective binding was weaker for both enantiomers on D214N-CSP than on wild-type-CSP