AU5954800A - Beta-amyloid peptide inhibitors - Google Patents

Description

WO 01/07442 PCT/AU0O/00886 BETA-AMYLOID PEPTIDE INHIBITORS The present invention relates to compounds which inhibit the binding of metal ions to the N-terminal region 5 of the -amyloid peptide. In addition, the present invention relates to pharmaceutical compositions including these compounds as the active agent, and to methods of treatment involving the administration of these compounds. The compounds of the invention are useful in the treatment 10 of Alzheimer's disease. BACKGROUND OF THE INVENTION Alzheimer's disease (AD) is characterised by the presence of distinctive lesions in the victim's brain. 15 These brain lesions include abnormal intracellular filaments called neurofibrillary tangles, and extracellular deposits of amyloid in senile, or amyloid, plaques. Amyloid deposits are also present in the walls of cerebral blood vessels of Alzheimer's patients. 20 The major constituent of amyloid plaques has been identified as a 4 kilodalton peptide (39-43 residues) called -amyloid peptide (AP) (Glenner and Wong, 1984). Diffuse deposits of AP peptides are frequently observed in normal adult brains, whereas Alzheimer's disease brain 25 tissue is characterised by more compacted, dense-core $-amyloid plaques. These observations suggest that A$ deposition precedes, and contributes to, the destruction of neurons that occurs in Alzheimer's disease. In further support of a direct pathogenic role for AD, $-amyloid has 30 been shown to be toxic to mature neurons both in culture and in vivo (Yanker et al., 1989). Natural A$ is derived from proteolysis from a much longer protein known as the amyloid precursor protein (APP) (Kang, J et al, 1987). The APP gene maps to chromosome 21, 35 thereby providing an explanation for the P-amyloid deposition seen at an early age in individuals with Down's syndrome, which is caused by trisomy of chromosome 21.

WO 01/07442 PCT/AUOO/00886 -2 AP peptides are cleaved from APP, and then undergo aggregation to produce the insoluble toxic S-sheet structures which are found in extracellular deposits in Alzheimer's disease and Down's syndrome. Recent data 5 suggest that the aggregated peptide has redox properties and can generate reactive oxygen species, which attack enzymes and possibly cell membranes, causing neurotoxicity (Markesbery, W.R. 1997). Antitioxidants are known to protect against AJ-induced toxicity. 10 AS has been shown to bind copper and iron in stoichiometric amounts, with the associated formation of reactive oxygen species such as peroxides and hydroxide radicals, which are possible sources of the neurotoxicity (Bush et al., 1998). While the formation of peroxide in 15 post-mortem samples of Alzheimer's disease brain has been observed, there was little peroxide formation in control tissue (Cherny et al., 1998). The peroxidase activity observed in the samples of Alzheimer's disease brain was abolished when treated with certain chelators (Cherny et 20 al., 1998). The formation of reactive oxygen species was accompanied by a reduction in the valence state of the metal, ie Cu(II) to Cu(I) and Fe(III) to Fe(II) (Atwood et al., 1998a). Reactive oxygen species can also lead to free radical formation on the AP peptide, which leads over time 25 to covalent cross-linking of the AS peptides (Bush et al., 1998). In addition, a number of metal ions, including Zn, Ni and Cu, have been shown to induce aggregation of AS (Atwood et al., 1998b). When brain tissue from both control and Alzheimer's disease-affected subjects was treated with 30 chelators which are specific for zinc and copper, there was greatly enhanced solubilisation of AS, with an increase of up to 700%, suggesting that zinc and copper play a role in the assembly of the AP deposits (Cherny et al., 1998). Histidine residues have been implicated in the 35 binding of metal ions to AP peptides. For instance rat Apl-40, in which Hisl3 is mutated to Arg, does not aggregate, nor does Apl-40 treated with diethyl WO 01/07442 PCT/AUOO/00886 -3 pyrocarbonate, which binds to the imidazole nitrogen of histidine (Atwood et al., 1998). Subsequently to the priority date of this application, it was reported that three histidine residues in the N-terminal hydrophilic 5 region of human AP provide primary metal binding sites, and that the solublity of the complex between matel and AS depends on the mode of metal binding. The authors proposed that Cu 2 1 would protect AP against Zn-induced aggregation by competing with zinc ions for binding sites on the 10 histidine residues (Miura et al., 2000). In contrast, we propose that inhibition of binding of zinc, copper and/or iron to the A$ peptide will have significant therapeutic value in the treatment of Alzheimer's disease. 15 It has been reported that certain tetrapyrroles, especially certain porphyrin and phthalocyanine compounds inhibit conversion of normal, protease-sensitive prion protein (PrPsen) to the protease-resistant form (PrPres) which is implicated in the pathogenesis of transmissible 20 spongiform encephalopathies (TSEs) such as Creutzfeldt Jacob disease (Caughey et al., 1998), and that three of these compounds inhibited TSE disease in vivo (Priola et al., 2000). However, both metal-free and metal-complexed tetrapyrroles were active, and the authors considered that 25 the mechanism of action involved direct interaction between the compound and the infectious agent. Although the authors speculated that the compounds might also be useful in the treatment of non-prion mediated amyloid-related conditions, such as Alzehimer's disease or Type II 30 diabetes, this was no more than speculation (Priola et al., 2000). Moreover, all of the compounds disclosed have multiple substitutions or the tetrapyrrole ring, whereas the tetrapyrrole compounds of the present invention are preferably substituted only on one of the rings. 35 It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of WO 01/07442 PCT/AUOO/00886 -4 these documents forms part of the common general knowledge in the art, in Australia or in any other country. SUMMARY OF THE INVENTION 5 The present inventors have now found that zinc and copper bind predominantly to a region in the N-terminal loop of AP which includes a cluster of histidine residues. This finding provides the basis for the rational design or selection of inhibitors of the binding of zinc, copper 10 and/or iron to Ap. Accordingly, in a first aspect the present invention provides a compound which interacts with the -amyloid peptide in such a way that the N-terminal loop of the peptide (amino acid residues 1-15) is blocked or 15 destabilised, thereby inhibiting the binding of one or more metal ions to at least one histidine residue within the N-terminal loop. Preferably the compound inhibits binding of Cu 2 +, Zn 2 and Fe3+ ions, but not Mg 2 * or Ca 2 + ions. 20 Preferably the compound has a conformation and polarity such that it binds to at least one, more preferably at least two, and more preferably three histidine residues in the N-terminal loop, selected from the group consisting of His6, Hisl3 and Hisl4. More 25 preferably the compound also binds to at least one additional amino acid in the N-terminal loop, selected from the group consisting of Asp7, TyrlO, and Glull. The compound may have acidic groups which interact with one or more of the His residues in the N-terminal 30 loop. For example, the compound may be represented as follows: WO 01/07442 PCT/AUOO/00886 -5 acid group 5 acid core acid group ................ __ _ _ __....u molecule group (optional) (optional) 10 wherein the core molecule has a conformation and polarity such that the acid group(s) interact with one of more of His6, His13 and His14. The acid may be any acid group, including, but not limited to, CO 2 H, P0 3

H

2 , SO 3 H, OS0 3

H

2 , OP0 3

H

2 and the like. 15 The compound may be a molecule with one to three carboxylic acid groups, the length of the molecule being such that it can be received within the N-terminal loop, and such that at least one carboxyl group is in proximity to at least one of the histidine residues. Without wishing 20 to be bound by theory, we believe that it is likely that such molecules will have a molecular mass in the region of 2000 Daltons. The compound may be an organic molecule, a peptide or a metal complex. In this aspect of the invention, however, 25 it is preferred that the compound is not a metal complex. Preferably the compound has overall hydrophobic character. More preferably the compound is able to penetrate the blood-brain barrier. In a particularly preferred embodiment of the 30 invention, the inhibitor compound comprises, or is conjugated to, a targeting moiety. The term "targeting moiety" as used herein refers to a functional group which will specifically interact with the J-amyloid peptide. That is, the inhibitor compound 35 includes or is covalently linked to a targeting moiety which will specifically bind to or associate with the $-amyloid peptide. Suitable targeting moieties include, WO 01/07442 PCT/AUOO/00886 -6 but are not limited to, polypeptides, nucleic acids, carbohydrates, lipids, -amyloid ligands, antibodies, dyes and the like. In a preferred embodiment the targeting moiety has a hydrophobic region which interacts with the 5 tail of the f-amyloid peptide. For example, the targeting moiety may include a fatty acid molecule. Preferably the targeting moiety targets the compound to the site defined by residues 15-21 of the P-amyloid peptide. The targeting moiety may be a peptide which 10 comprises a sequence which corresponds to that of residues 15-21 of the -amyloid peptide. More preferably the inhibitor-targeting moiety complex is able to penetrate the blood-brain barrier. In a second aspect, the invention provides a method 15 of selecting or designing a compound which inhibits the binding of metal ions to the N-terminal loop of the P-amyloid peptide, which method comprises the steps of (i) selecting or designing a compound which has a conformation and polarity such that it binds to at least 20 one, more preferably at least two and more preferably three amino acids in the N-terminal loop, selected from the group consisting of His6, His 13 and Hisl4; and (ii) testing the compound for the ability to inhibit binding of metal ions to the N-terminal loop of the 25 J-amyloid peptide. Preferably the compound inhibits binding of Cu 2 +, Zn 2 + and Fe 3 * ions, but not Mg 2 + or Ca2+ ions. Preferably the compound has a conformation or polarity such that it also binds to at least one amino acid 30 in the N-terminal loop, selected from the group consisting of Asp7, Tyr1O, and Glull. Preferably the compound also has overall hydrophobic character. More preferably the compound is able to penetrate the blood-brain barrier. In a third aspect, the invention provides a compound 35 which inhibits the binding of metal ions to the N-terminal loop of the S-amyloid peptide, wherein the compound is WO 01/07442 PCT/AUOO/00886 -7 obtained by a method according to the second aspect of the invention. In a fourth aspect, the invention provides a composition comprising a compound according to the first or 5 the third aspects of the present invention, together with a pharmaceutically acceptable carrier. Methods and pharmaceutical carriers for preparation of pharmaceutical compositions are well known in the art, as set out in textbooks such as Remington's Pharmaceutical Sciences, 19th 10 Edition, Mack Publishing Company, Easton, Pennsylvania, USA. The compounds of the present invention may be formulated into pharmaceutical compositions, and administered in therapeutically effective doses. The term 15 "therapeutically effective dose" means a dose which results in the inhibition of natural binding of metal ions to the N-terminal loop of the -amyloid peptide. The pharmaceutical compositions may be administered in a number of ways, including, but not limited to, orally, 20 subcutaneously, intravenously, intraperitoneally and intranasally. The most appropriate dose and route of administration will be dependent on the age and general state of health of the subject to be treated, and will be at the discretion of the attending physician. This dose can 25 be readily ascertained by one skilled in the art, using well-known techniques. In a fifth aspect, the invention provides a method of inhibiting the binding of one or more metal ions to the $-amyloid peptide, or inhibiting the aggregation of P 30 amyloid peptide, which method comprises the step of exposing the peptide to a compound which blocks or destabilises the N-terminal loop of the peptide, thereby inhibiting the binding of one or more metal ions to at least one histidine residue within the N-terminal loop. 35 Preferably the compound has a conformation and polarity such that it binds to at least one, more preferably at least two, and more preferably three WO 01/07442 PCT/AUOO/00886 -8 histidine residues in the N-terminal loop of the S-amyloid peptide, selected from the group consisting of His6, Hisl3 and His14. More preferably the compound also binds to at least one additional amino acid in the N-terminal loop, 5 selected from the group consisting of Asp7, Tyr1O, and Glull. In a particularly preferred embodiment, the compound is a metal complex which can exchange or bind functional moieties such as histidine, with the proviso that the 10 compound is not haemin or haematin. Preferably the metal complex is capable of binding between 1 and 3, preferably 2 or 3, histidine residues of the N-terminal loop of the $ amyloid peptide. The complex may bind to other residues in addition to the histidine residues. More preferably the 15 complex also binds to at least one additional amino acid in the N-terminal loop, selected from the group consisting of Asp7, Tyr1O, and Glull. Metal ions capable of binding to the imidazole nitrogen(s) of histidine include Mn, Fe, Co, Ni, Cu, Zn, 20 Ru, Pd, Ag, Cd, Pt, Au, Rh and Hg. Complexes of these metals are expected to be predominantly four coordinate tetrahedral (distorted tetrahedral)/square planar) complexes, five coordinate complexes with either a trigonal bipyramid or square pyramid configuration, or six 25 coordinate octahedral (or distorted octahedral) complexes. Even more preferably the inhibitor compound comprises, or is conjugated to, a targeting moiety. Preferably the targeting moiety targets the compound to the site defined by residues 15-21 on the j-amyloid peptide. 30 In a further preferred embodiment, the inhibition of binding of one or more metal ions to the -amyloid peptide occurs in vivo. In a sixth aspect, the invention provides a method of prevention, treatment or alleviation of Alzhemier's disease 35 which method comprises the step of administering a compound or a pharmaceutical composition according to the invention to a subject in need of such treatment.

WO 01/07442 PCT/AUOO/00886 -9 The patient is monitored for clinical improvement, which may commence within as little as one week, but more probably may be observed at six weeks, and may take as long as 12 months. The normal clinical indices which are used in 5 the monitoring of patients with the relevant condition are used. Where the treatment is prophylactic, the patient is monitored for signs of development of the condition. The attending clinician will be aware of the most suitable tests to use. 10 Where this method is to be used for prophylactic purposes, the subject is preferably one at increased risk of developing the condition. For example, the subject may have one or more family members with the condition, eg. familial Alzheimer's disease, or may have trisomy of 15 chromosome 21 (Down's syndrome). It will be clearly understood that, for the purposes of this aspect of the invention, the compound is not haemin. In a seventh aspect, the invention provides a method 20 of monitoring the efficacy of treatment according to the method of the invention, comprising the steps of obtaining a sample of a biological fluid for a patient undergoing treatment, and measuring the level of AS in the sample, in which increased AS levels compared to levels of AP in a 25 normal control sample are indicative of the efficacy of the treatment. For the purposes of this specification it will be clearly understood that the word "comprising" means "including but not limited to", and that the word 30 "comprises" has a corresponding meaning. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a representation of the S-amyloid peptide showing a structured turn in the region of amino acid 35 residues 15-21. Figure 2 shows a model of Zn bound to the three histidine residues of AP1-40.

WO 01/07442 PCT/AUOO/00886 - 10 Figure 3 is a NMR spectrum showing the effect of Zn2+ binding to AP1-28. Figure 4 is a NMR spectrum showing the effect of Cu 2 + binding to A11-28. 5 Figure 5 is a NMR spectrum showing the effect of addition of Cu2+ and cobalt complex to A11-28. Figure 6 is a NMR spectrum showing the binding of the cobalt complex to A1-28. Figure 7 is a Western blot showing results of brain 10 tissue assays testing the ability of a range of metal compounds to solublilize AP deposits. Figure 8 shows a model of the cobalt-corrin ring complex bound to AP1-40. Figure 9 shows NMR spectra demonstrating the binding 15 of the compound KJB001 to AP1-28. DETAILED DESCRIPTION OF THE INVENTION The present inventors have developed three dimensional structural information concerning the 20 N-terminal region of the S-amyloid peptide, and have identified a cluster of three histidine residues which constitute a binding site for metal ions. This information provides a rational basis for the development of compounds which inhibit the binding of metal ions to the N-terminal 25 loop of the P-amyloid peptide. Such inhibitors have the potential to inhibit aggregation of f-amyloid peptides and to reduce metal- induced neurotoxicity. Accordingly, these inhibitors are likely to have therapeutic value in the treatment of diseases such as Alzheimer's disease. 30 Using the structural information provided by the inventors, the general principles of drug design can be applied by persons skilled in the art to produce compounds which preferentially bind to at least one of the histidine residues in the N-terminal loop (ie His6, His13 or His14), 35 and inhibit the binding of metal ions to the N-terminal loop of the amyloid peptide.

WO 01/07442 PCT/AUOO/00886 - 11 Preferred inhibitors within the context of the present invention include metal complexes which can exchange or bind functional moieties such as histidine. Preferably the metal complex is capable of binding between 5 1 and 3, preferably 2 or 3, histidine residues of the N-terminal loop of the P-amyloid peptide. The complex may bind to other residues in addition to the histidine residues. Metal ions capable of binding to the imidazole nitrogen of histidine include Mn, Fe, Co, Ni, Cu, Zn, Ru, 10 Pd, Ag, Cd, Pt, Au, Rh and Hg . Complexes of these metals are expected to be predominantly four coordinate tetrahedral (distorted tetrahedral)/square planar complexes, or six coordinate octahedral (or distorted octahedral) complexes. In the case of the four coordinate 15 complexes they could react with the -amyloid peptide to replace ligands; alternatively, by binding to His residues as well as to their initial ligand(s) their coordination number is increased to 5 or 6. Five coordinate complexes with either a trigonal bipyramid or square pyramid 20 configuration may also be used. Examples of suitable complexes are shown below.

WO 01/07442 PCT/AUOO/00886 - 12 a C a c a y M M M b d b x b x x x x a c a C a y M M M b d b d b d e y c x x x a y a ya y M M M b z b c b w C z Z In these formulae: (i) a, b, c, d and e are non-leaving groups, 5 preferably chelating groups including Schiff bases, porphyrin rings, macrocycles, polyamino-carboxylates, heterocyclic aromatic groups such as 2,2'bipyridine and 1,10-phenanthrolene, peptides, nucleobases, or chelating ligands in which one of the donor atoms is a phosphine 10 phosphorus atom; (ii) M is a metal; and (iii) w, x, y and z are leaving groups (ie those groups which will be replaced by histidine and possibly other residues when the metal complex reacts with the 15 -amyloid peptide) , and include halogens, amines, ammonia, pyridyls, imidazoles, nucleobases, peptides,

H

2 0/OH,carboxylic acids, phosphates, sulfates, nitrate, triflate, or alkoxides.

WO 01/07442 PCT/AUOO/00886 - 13 The term " nucleobase" means a purine or a pyrimidine, or an analogue thereof. It will be appreciated that multidentate macrocyclic ligands may have a variety of donor atoms, and that it is possible that one or more of 5 the non-leaving groups could be a stable monodentate ligand such as cyanide, or an organic group such as a methyl group. Those skilled in the art will recognise that the appropriate combination of non-leaving and leaving groups 10 will be dependent on the identity of the metal. Metal complexes which have the potential to bind to histidine residues are described in WO 97/21431 and WO 96/18402, the entire contents of which are incorporated herein by this reference. Other examples of complexes which 15 may act as inhibitors are as follows: WO 01/07442 PCT/AUOO/00886 - 14 X R /~ R -N N R Co R 5 x o 0 R X R 10 R R R R R R R R R N N-- . P Co II 15 N Nl--,-R R 5 R R R 20 X N III Ru S \S 25 X In formulae I,II and III, the X and R groups may be any suitable leaving or targeting groups. For example, X and R may be the same or different, and include, without 30 being limited to, the group consisting of ammine; amine; peptide; halogen (chloride, fluoride or iodide); nucleobase; imidazole; H 2 0; hydrogen; saturated or unsaturated alkyl, alcohol, or carboxylate of 1 to 10 carbon atoms; aromatic; or heterocyle of up to four rings. 35 Other preferred compounds include cobalt(Il) phthalocyanine -form; (S,S)-(+)-N-N'-bis(3,5-di-tert butylsalicylidene)-1-2-cyclohexane diamino manganese (III) WO 01/07442 PCT/AUOO/00886 - 15 chloride; iron(II) phthalocyanine bis(pyridine) complex; iron(III) phthalocyanine chloride; manganese(II) phthalocyanine; 5,10,15,20-tetraphenyl-21H, 23H-porphine manganese (III) chloride; chloro(pyridine) bis 5 (dimethylglyoximato) cobalt (III); N-N' bis(salicylidene)dianilino-cobalt(II);cis-bis(2-2' bipyridine)dichloro-ruthenium (II) hydrate; and cobalt(acacen) (NH 3

)

2 ) Cl, in which (H 2 acacen represents bis(acetylacetone)-ethylenediamine). 10 Compounds which are designed or selected according to the methods of the invention may be tested for inhibitory activity by any suitable assay procedure. Assays to determine the binding of metal complexes to AP may be performed by NMR or UV-Visible spectroscopy, or by ESR in 15 the case of paramagnetic metals. Assays are available for measuring Cu/Fe reduction, hydrogen peroxide, hydroxyl radical generation, and carbonyl group, all of which assess the redox capacity of AP in the presence of Cu and Fe. Ex vivo assays using post mortem brain tissue may also be 20 performed. These include measuring the amount of AP which is solubilised and extracted in the presence of the compound, and determining the quantity of peroxide formed in post mortem brain tissue, as compared with control tissue which is solubilised and extracted in the absence of 25 the compound. Suitable methods are described for example in PCT/US99/05291 (W099/45907). The invention will now be described in detail by way of reference only to the following non-limiting examples and to the drawings. 30 WO 01/07442 PCT/AUOO/00886 - 16 Materials and Methods MUR spectroscopy Samples of Apl-40 and Afl-28 in aqueous solution were prepared by dissolving 0.5mgs and 1.0 mgs respectively in 5 0.55 ml of 10 % 2 H20/90%H 2 0, 100 mM KCl and 50 mM phosphate buffer. pH values were measured at room temperature, and were not corrected for isotope or solvent effects. The 1H chemical shifts were referenced to 2,2 dimethyl-2-silapentane-5-sulphonate at 0 ppm, via the 10 chemical shift of the H 2 0 resonance (Wishart et al., 1995a) or an impurity at 0.15 ppm. Spectra were recorded on a Bruker DRX-600 spectrometer. All spectra in aqueous solution were recorded at 271 K and pH 6.8, with probe temperatures calibrated 15 according to the method of van Geet (1970). All 2D spectra were recorded in phase-sensitive mode using time-proportional phase incrementation (Marion & Wuthrich, 1983). Water suppression was achieved using pulsed field gradients with the WATERGATE scheme and a 3-9-19 selective 20 pulse (Sklenar et al., 1993). 2D homonuclear NOESY spectra (Anil-Kumar et al., 1980; Macura et al., 1981) were recorded with mixing times of 50 and 250 ms. TOCSY spectra (Braunschweiler & Ernst, 1983) were recorded using the DIPSI-2 spin-lock sequence 25 (Rucker & Shaka, 1989) with spin-lock times of 70-80 ms. DQF- COSY (Rance et al., 1983) spectra were also recorded. Typically, spectra were acquired with 400-600 ti increments, 32-128 scans per increment, and 4096 data points. The 1H sweep width was 7575.6 Hz at 600 MHz. 30 Spectra were processed using UXNMR-941001.4 (Bruker) and analyzed using XEASY 1.3.7 (Bartels et al., 1995). Sine-squared window functions, phase shifted by 6 0

U-

9 0 0, were applied in both dimensions prior to Fourier transformation. 35 The 3JNHCaH coupling constants were measured from a DQF-COSY spectrum or by using the INFIT module of XEASY to analyze NOESY spectra.

WO 01/07442 PCT/AUOO/00886 - 17 For 3JNHCaXH coupling constants measured from a DQF-COSY the appropriate rows were extracted from the spectrum, inverse Fourier transformed, zero filled to 32 K data points, and multiplied by a Gaussian window function prior 5 to Fourier transformation. The dispersive peak shapes were simulated to take account of the effect of broad linewidths on small coupling constants, using an in-house program, COUPLING. 10 Metal Binding Studies Metal binding studies were performed by titrating concentrated metal solutions (30 mM CuCl 2 , ZnC1 2 in water) into the peptide solutions described above. The displacement of bound Cu 2 + from A1-28 by the Co(III) 15 Schiff-base was performed by adding two equivalents of Cu 2 + to AP1-28, followed by one equivalent of Co(III) Schiff-base. Brain Tissue Assays 20 Tissue selection Post-mortem tissues, stored at -80 0 C, were obtained from the NH&MRC-supported Brain Bank at the University of Melbourne, together with accompanying histopathological and clinical data. AD was assessed according to CERAD criteria 25 (Mirra et al, 1991). In order to examine the chemical architecture of the AP deposition observed in non-AD aged brain, Ap immunohistochemistry was used to select age-matched control (AC) cases which did not fulfil the CERAD criteria, and in which amyloid deposition, if 30 present, was detectable only in the form of diffuse plaques, but not neuritic plaques. Preparation of compounds Compounds were dissolved in DMSO and diluted in a PBS 35 mixture. Insoluble material was removed. Sample preparation: WO 01/07442 PCT/AUOO/00886 - 18 The cortical meninges were removed and gray matter (0.5 g) was homogenised using a DIAX 900 homogeniser (Heidolph & Co, Kelheim, Germany) for 3 x 30s periods at full speed, with a 30s rest between strokes, in 3 ml of 5 ice-cold phosphate-buffered saline (PBS), pH 7.4, containing a mixture of protease inhibitors (BioRad, Hercules, CA), but without ethylene diamine tetraacetic acid (EDTA), or in the presence of test compounds or metal ions prepared in PBS. The homogenate samples were 10 incubated for 24 h at room temperature. To obtain the PBS-extractable fraction, the homogenate was centrifuged at 100,000 x g for 30 min, the supernatant removed, and divided into 1 ml aliquots. Protein in a 1 ml supernatant sample was precipitated using 1:5 ice-cold 10% 15 trichloracetic acid (TCA), and pelleted by centrifugation at 10,000 x g for 20 mins. The pellet was prepared for PAGE by boiling for 10 min in Tris-tricine SDS-sample buffer containing 8% SDS, 10% mercaptoethanol and 8M urea. Total AP in the cortical samples was obtained by homogenizing in 20 1 ml PBS and boiling in sample buffer as described above. Polyacrylamide gel electrophoresis (PAGE) and Western blotting Tris-tricine PAGE was performed by loading samples on 25 to 10-20% gradient gels (Novex, San Diego, CA), followed by transfer on to 0.2 mm nitrocellulose membrane (BioRad, Hercules, CA). The AP was detected using the following monoclonal antibodies: W02, which detects Ap40 and A$42 at an epitope between residues 5 and 8; G210, which is 30 specific for AP species which terminate at carboxyl residue 40; or G211, which is specific for AP species which terminate at carboxyl residue 42 (Ida et al, 1996), in conjunction with horseradish peroxidase(HRP)-conjugated rabbit anti-mouse IgG (Dako, Denmark), and visualised using 35 chemiluminescence (ECL, Amersham Life Science, UK). Each gel included two or more lanes containing known quantities of synthetic AS (Keck Laboratory, Yale University New WO 01/07442 PCT/AUOO/00886 - 19 Haven, CT) as reference standards. Blot films were scanned using a Relisys scanner with transparency adapter (Tech Information Systems, Taiwan) and densitometry performed using Image 1.6 software (NIH, Bethesda, MA). All samples 5 were analysed at least twice, and gel loadings and dilutions adjusted to fit within the quantifiable region of the standard curve. The efficiency of the TCA precipitation procedure was validated by testing samples of whole human serum diluted 10 1:10 to which had been added 2mg of synthetic AP 1-40 or AP 1-42. AP recovery was assessed by extracting the precipitate into SDS sample buffer and performing Western blot analysis, using synthetic AP standards as described above. Protein in the TCA pellet was estimated by 15 resuspending the pellet in water and assaying the protein recovery using a BCA assay (Pierce, Rockford, IL). This indicated that the efficiency of protein and AP precipitation was approximately 90%. The efficiency of the 8M urea solubilization was found to be equivalent to that 20 of formic acid in a parallel, blinded assay conducted independently. All chemicals were obtained from Sigma (St. Louis, MO) unless otherwise indicated. Example 1 Characterisation of AP peptides in aqueous 25 solution In aqueous solution there is little chemical shift difference between the amide and CaH protons of Apl-28 compared with Apl-40, suggesting that both peptides are in a similar conformation. Comparisons of Al-28 and A0l-40 30 chemical shifts with random coil chemical shifts and the lack of NOE connectivities in the NOESY spectra indicate that both peptides are mostly in conformational exchange. However, there are some medium range NOE connectivities (1 < /ii-j/ < 5) observed in the region of residues 16-21 of 35 the peptide (KLVFFA), suggesting that this region of the peptide has a structured turn. This is illustrated in Figure 1.

WO 01/07442 PCT/AUOO/00886 - 20 This region of the peptide has previously been shown to be very important in defining the aggregation properties of AP (Hilbich et al. 1992), with the substitution of hydrophilic residues into this region resulting in altered 5 aggregation properties, including reduced 1-sheet content. In addition, several groups have described short peptides or slight variants thereof corresponding to this region which have the ability to bind to AP and to inhibit the formation of amyloid fibrils (Findeis et al. 1999; 10 Tjernberg et al. 1999). This evidence implies that this "structured" section of AP is important in the formation of amyloid fibrils. Example 2 Metal Binding Studies 15 To determine the metal-binding site of A1-40, Zn2 was titrated into a solution of Ap1-40 in SDS-micelles at pH 6.5. Peaks due to the C2H protons of the imidazole rings of His6, His13 and His14 broadened out such that they were no longer visible when a small amount of Zn solution (- 25% 20 of one mol. equivalents) was added. The addition of extra Zn (up to two mol. equivalents) did not change the spectrum, but when the pH of the solution was raised to 7.4 three broad overlapping peaks due to the C2H protons of the imidazole rings of His6, Hisl3 and His14 became visible. 25 These peaks did not sharpen significantly even upon the addition of a large excess of Zn (> 150 mol. equivalents). There appear to be no significant difference in the rest of the spectrum between the Zn-bound and free forms of AJ1-40, suggesting that there are no significant conformational 30 changes upon metal binding. These results indicate that all three histidine residues of Ap1-40 are involved in Zn binding. Figure 2 shows a model of Zn bound to the three histidine residues of Apl-40. To determine the metal-binding site of AP1-40 and 35 Afl-28 in aqueous solution, Zn and Cu2+ were titrated into solutions of Afl-40 and Ap1-28 at pH 6.9. All reactions were accompanied by significant precipitation. The NMR WO 01/07442 PCT/AUOO/00886 - 21 spectrum of the peptide-metal complex which remained in solution showed that peaks due to the C2H and C4H protons of His6, His13 and His14 broadened out such that they were no longer visible, indicating that these residues were 5 involved in metal binding. This is illustrated in Figures 3 and 4. The addition of more metal ion resulted in more precipitation, so that saturated binding was not possible. When the Co(III) Schiff-base complex was added to a solution containing Cu 2 +-bound AP1-28, a broad peak 10 appeared in the 1H spectrum at 6.55 ppm, as shown in Figure 5. The chemical shift of this peak is consistent with the chemical shift of a C4H proton of a histidine imidazole bound to a Co(III)Schiff-base complex, as shown in Figure 6. This indicates that the Co(III)Schiff-base complex can 15 compete with Cu 2 + for the histidine residues of AS. Example 3 Brain tissue assays Brain tissue assays were conducted in order to test the ability of the following compounds to reduce -amyloid 20 peptide aggregation: KJB001 Co(II) phthalocyanine f-form KJB002 (S,S)-(+)-N-N'-bis(3,5-di-tert butylsalicylidene)-1-2-cyclohexane diamino 25 manganese (III) chloride KJB003 Haemin KJB004 Iron(II) phthalocyanine bis(pyridine) complex KJB005 Iron(III) phthalocyanine chloride KJB006 Manganese(II) phthalocyanine 30 KJB007 5,10,15,20-tetraphenyl-21H,23H-porphine manganese(III) chloride KJB008 Chloro(pyridine) bis(dimethylglyoximato)cobalt (III) KJB009 N-N'-bis(salicylidene)dianilino-cobalt(II) 35 KJB010 cis-bis(2-2'-bipyridine)dichloro-ruthenium (II) hydrate.

WO 01/07442 PCT/AUOO/00886 - 22 BR16805 [Co(acacen) (NH3) 2 ]Cl (H 2 acacen represents bis(acetylacetone)ethylenediamine) Table 1 shows the approximate concentration of each 5 compound used in the extraction. Table 1 Compound Concentration (pmol/litre) KJB001 0.0105 KJB002 4.41 KJB003 60.87 KJB004 3.816 KJB005 3.08 KJB006 111.5 KJB007 0.64 KJB008 1289.9 KJB010 300.9 BR16805 1199.9 bathocuproine 2000 10 The results presented in Figure 7 clearly demonstrate that some of the metal complexes have the ability to solubilise AP deposited in the brains of Alzheimer's disease patients. In particular, compound KJB001 showed particularly strong solubilising activity, and compounds 15 KJB002, KJB005, KJB006, KJB007 and KJB010 also showed good activity. Example 4 Compounds designed to bind one or more of the three histidine residues in AP 20 BRI7080, BR17103 and BRI7104 are metal complexes of aza-macrocycles of the following structures.

WO 01/07442 PCT/AU00/00886 - 23 (a) BRI7080 H, H BR17080: M = Ni2 L = H 2 0 ~N L N") HK)H Ni(N0 3

)

2 .6H 2 0 (1.67 g, 5.75 mmol) was added in portions to a solution of 1,4,8,11-tetraazacyclotetradecane (1.0 g, 5.00 5 mmol) in ethanol (50 ml) at 50 0C. The mixture was heated at 50 0C for 2 h during which time the green coloured nickel salt dissolved to give a red solution. Upon cooling of the crude reaction mixture to room temperature, a purple solid had precipitated which was collected by filtration 10 and washed with several portions of 2-propanol. The product thus obtained was dried overnight in a vacuum oven. Spectral and analytical data acquired for this compound were in agreement with literature data. 15 (b) BR17103 BR17103: M = Mn 3 + L = CI .. N L N H ,H BR17103 was prepared following the method of P-K. Chan and C-K. Poon, J. C. S. Dalton Trans., 1976, 858-862. 20 (c) BR17104 This compound has similar structures to BR17080 and BR17103, but in this case M = Co3* and L = Cl.

WO 01/07442 PCT/AUOO/00886 - 24 BR17104 was prepared following the method of P-K. Chan and C-K. Poon, J. C. S. Dalton Trans., 1976, 858-862. Example 5 Histidine binding compounds conjugated with 5 an Ap-directing group. For the second class of molecules we chose derivatives of the pentapeptide leucine-valine phenylalanine-phenylalanine-alanine (LVFFA), designated herein as BR17082 and BRI7077, to direct histidine binding 10 compounds to AS. BR17106 is an example of a nicotine derivative conjugated to an AS-directing group. In this example the histidine-binding group is a small organic molecule rather than a metal complex, in contrast to most of the compounds 15 described above. BR17158 and BR17159 are examples of metal complexes conjugated to an A-directing group. (a) BR17082

TFA.H

2 HH N N N OCH 3 - N - N H H o 0 BR17082 20 BR17082 was prepared via standard HBTU-mediated peptide coupling methodology; see M. Bodanszky and A. Bodanszky, "The Practice of Peptide Synthesis", 2 nd Edition, Springer Verlag, 1994. Mass Spectrum (APCI) m/z 610 [ (MH-C 2

HO

2

F

3 )*, 100%]. 25 (b) BR17106 This compound was synthesised according to Reaction Scheme 1: WO 01/07442 PCT/AU00/00886 - 25 OH0 0 NHBoc OH HH HafAN N + H H yN 0 00 1 BR17077 N N 0 0 NHBoc

H

N N 0 0 0 BRI7106 Scheme 1 Compound 1 was prepared following the methods of P. Jacob III, J. Org. Chem., 1982, 47, 4165-4167 and N. D. P. Cosford et al., J. Org. Chem., 1998, 63, 1109-1118. 5 Mass Spectrum (APCI) m/z 217 [ (M+H)*, 100%] . BRI7077 was prepared via standard HBTU-mediated peptide coupling methodology; see M. Bodanszky and A. Bodanszky, "The Practice of Peptide Synthesis", 2 nd Edition, Springer-Verlag, 1994. 10 Mass Spectrum (APCI) m/z 696 [(M+H)+, 20%], 694 [(M-H), 95%]. BR17106 was prepared via standard DCC-mediated esterification methodology; see M. Bodanszky and A. Bodanszky, "The Practice of Peptide Synthesis", 2 nd 15 Edition, Springer-Verlag, 1994. Mass Spectrum (APCI) m/z 894 [(M+H)V, 10%], 892 [(M-H), 25%].

WO 01/07442 PCT/AUOO/00886 - 26 (c) Synthesis of BRT7158 This compound was synthesised according to Reaction Scheme 2: 2a H H N HN NH OR BRI7082 N N N H H ba:R =CH3 / \ N Ni2 N- - \N' NH O O N N H H 1 O - 0 BRI7158 Scheme 2 5 Porphyrin 2a was prepared following the methods of K. Nakanishi et al., Heterocycles, 1996, 42, 723-736 and D. A. James et al., Bioorg. Med. Chem. Lett., 1999, 9, 2379-2384.

WO 01/07442 PCT/AUOO/00886 - 27 NH N N HN 2a: R = CO 2 H N, N-Diisopropylethylamine (0.10 ml, 0.57 mmol) was added to a magnetically stirred mixture of porphyrin 2a (118 mg, 0.18 mmol), HBTU (68 mg, 0.18 mmol), and BR17082 5 (130 mg, 0.18 mmol) in dry DMF (4 ml) under an atmosphere of nitrogen. Stirring was continued at room temperature for 16 h, after which time, the crude reaction mixture was partitioned between ethyl acetate and brine. The separated organic layer was successively washed with 10% aqueous 10 citric acid solution, saturated aqueous NaHCO 3 solution and brine before being dried (MgSO 4 ), filtered and concentrated under reduced pressure to afford compound 3a as a deep purple, crystalline solid. N OR N H __H HJ HNN J OR N N Nl H H 0 o0 3a: R =CH 3 WO 01/07442 PCT/AUOO/00886 - 28 Mass Spectrum (APCI) m/z 1250 [(M+H)*, 45%]. A solution of compound 3a (23.3 mg, 0.019 mmol, THF (0.5 ml), methanol (50 drops) and 2M aqueous NaOH solution 5 (0.1 ml) was stirred at room temperature for 18 h. The crude reaction mixture was partitioned between ethyl acetate and water and the phases separated. The aqueous layer was acidified to pH 4 upon the addition of 10% aqueous citric acid solution and then extracted three times 10 with ethyl acetate. The combined organic layers were dried (MgSO 4 ), filtered and concentrated under reduced pressure to afford compound 3b as a purple solid. HH N O R4 NJ N N- N O HH 0 - 0 3b: R= H 15 Mass Spectrum (APCI) m/z 1236 [(M+H)*, 30%]. A magnetically stirred mixture of compound 3b (17 mg, 0.014 mmol), Ni(OAc) 2 .4H 2 0 (34.2 mg, 0.14 mmol), glacial acetic acid (0.73 ml) and dichloromethane (1.45 ml) was heated at reflux under an atmosphere of nitrogen for 18 h. 20 The now crimson red reaction mixture was cooled to room temperature and partitioned between ethyl acetate and 10% aqueous NaHCO 3 solution. The separated aqueous phase was extracted three times with ethyl acetate before being dried (Na 2

SO

4 ), filtered and concentrated under reduced pressure 25 to give a red solid. Subjection of this material to flash chromatography (silica, 10% methanol/dichloromethane WO 01/07442 PCT/AUOO/00886 - 29 elution) afforded, after concentration of the appropriate fractions (Rf 0.30), BR17158 as a red, crystalline solid. Mass Spectrum (ES) m/z 1291 [(M-H), <10%]. 5 (d) Synthesis of BR17105 and BR17159 These compounds were synthesised according to Reaction Scheme 3: 2b NH N- __ H0 NHBoc BR17077 N HHN N N \o 0 0 BRI7105 N, N ___ H0 NHBoc H2 H - -NINN N NN 00 0 BR7159 Scheme 3 WO 01/07442 PCT/AU00/00886 - 30 Porphyrin 2b was prepared following the method of W. J. Kruper, Jr. et al., J. Org. Chem., 1989, 54, 2753-2756. I NHN N HN 2b :R= NH 2 N, N-Diisopropylethylamine (0.21 ml, 1.18 mmol) was 5 added at room temperature to a magnetically stirred mixture of porphyrin 2b (151 mg, 0.24 mmol), HBTU (216 mg, 0.58 mmol), and BR17077 (200 mg, 0.29 mmol) in dry DMF (2 ml) under an atmosphere of nitrogen. Stirring was continued at 40'C for 40 h, after which time the crude reaction mixture 10 was partitioned between ethyl acetate and brine. The separated organic layer was successively washed with 10% aqueous citric acid solution, 5% aqueous NaHCO 3 solution and brine before being dried (MgSO 4 ), filtered and concentrated under reduced pressure to afford a deep purple 15 glass. Subjection of this material to flash chromatography (silica, 1% to 5% methanol/dichloromethane elution) gave, after concentration of the relevant fractions (Rf 0.35), BR17105 as a purple, crystalline solid. Mass Spectrum (APCI) m/z 1307 [(M+H)*, <5%]. 20 A magnetically stirred mixture of BR17105 (47 mg, 0.04 mmol), Ni(OAc) 2 .4H 2 0 (96 mg, 0.39 mmol), glacial acetic acid (2 ml) and dichloromethane (4 ml) was heated at reflux under an atmosphere of nitrogen for 18 h. The now crimson red reaction mixture was cooled to room temperature 25 and partitioned between ethyl acetate and 10% aqueous WO 01/07442 PCT/AUOO/00886 - 31 NaHCO 3 solution. The separated aqueous phase was extracted three times with ethyl acetate before being dried (Na 2

SO

4 ), filtered and concentrated under reduced pressure to give a red solid. Subjection of this material to flash 5 chromatography (silica, 10% methanol/dichloromethane elution) afforded, after concentration of the appropriate fractions (Rf 0.30), BRI7159 as a red, crystalline solid. Mass Spectrum (APCI) m/z 1385 [(M+Na), <5%]. 10 (e) Synthesis of BR17160 and BRI7161 The compounds were prepared according to Reaction Scheme 4: BocsN N Boc.N N C C~ NCLCO2R Boc/ Boc Boc/ Boc 4 5a:R=CH 3 1 5b: R H R,0 0 NI H H SO

OCH

3 NHN' N NO N N0 0 H H 0 0 BR17161 L = H 2 0 SCheme 4 WO 01/07442 PCT/AUOO/00886 - 32 Compound 4 was prepared following the method of R. Guilard et al., Bull. Soc. Chim. Fr., 1996, 133, 65-73. A magnetically stirred suspension of compound 4 (430 mg, 0.86 mmol), (4-bromomethyl) methyl benzoate (217 mg, 5 0.95 mmol), KHCO 3 (172 mg) and K 2

CO

3 (174 mg) in dry acetonitrile (17 ml) was heated at reflux for 18 h under an atmosphere of nitrogen. The reaction mixture was cooled to room temperature then concentrated under reduced pressure to yield a straw coloured oil which was purified by flash 10 chromatography (silica, 5% methanol/dichloromethane elution). Concentration of the appropriate fractions (Rf 0.38) afforded adduct 5a as a clear, colourless oil. Mass Spectrum (APCI) m/z 649 [(M+H)*, 100%]. A mixture of compound 5a (120 mg, 0.19 mmol), 1M 15 aqueous LiOH (5 ml) and THF (5 ml) was magnetically stirred at room temperature for 16 h. The crude reaction mixture was partitioned between ether and water and the separated aqueous layer was cooled to OC prior to acidification to pH 4 with 10% aqueous citric acid solution. Extraction of 20 the aqueous layer with ethyl acetate, followed by drying of the organic fraction with MgSO 4 afforded, after concentration under reduced pressure, compound 5b as a viscous, colourless oil. Mass Spectrum (APCI) m/z 633 [(M-H), 100%]. 25 N, N-Diisopropylethylamine (0.17 ml, 0.98 mmol) was added to a magnetically stirred mixture of compound 5b (167 mg, 0.26 mmol), HBTU (132 mg, 0.35 mmol), and BR17082 (209 mg, 0.29 mmol) in dry DMF (2 ml) under an atmosphere of nitrogen. Stirring was continued at room temperature for 30 16 h, after which time, the crude reaction mixture was partitioned between ethyl acetate and brine. The separated organic layer was successively washed with 10% aqueous citric acid solution, saturated aqueous NaHCO 3 solution and brine before being dried (MgSO 4 ), filtered and concentrated 35 under reduced pressure to afford compound 6 as a viscous oil.

WO 01/07442 PCT/AUOO/00886 - 33 Mass Spectrum (APCI) m/z 1226 [(M+H)*, 65%]. A solution of compound 6 (258 mg, 0.21 mmol) in dichloromethane (4 ml) was treated with trifluoroacetic acid (0.1 ml) under an atmosphere of nitrogen and stirring 5 was continued at room temperature for 20 h. The crude reaction mixture was concentrated under reduced pressure to afford a light tan oil which was purified by flash chromatography (silica, 6% methanol/dichloromethane elution). Concentration of the relevant fractions (Rf 10 0.30) afforded BR17160 as a pale yellow foam. Mass Spectrum (APCI) m/z 633 [(M-H), 100%]. A solution of BRI7160 (41 mg, 0.044 mmol) and Ni(OAc) 2 .4H 2 0 (103 mg, 0.41 mmol) in dry methanol (2 ml) was heated at reflux for 19 h under an atmosphere of 15 nitrogen. The cooled reaction mixture was concentrated under reduced pressure to afford a solid residue. This material was treated with chloroform (4 ml) and the resulting suspension was filtered. Concentration of the filtrate afforded BR17161 as a foam-like residue. 20 Mass Spectrum (APCI) m/z 1020 [(M+H)*, 30%]. Example 5 Testing of compound KJB030 for ability to inhibit amyloid 1-peptide neurotoxicity in vitro Compound KJB030 was dissolved in chelex 100-treated 25 double distilled H 2 0 (CH100-dH 2 O) at a concentration of 200 JJM. AZl-42 was dissolved in either 200 JM KJB030 solution or in CH100-dH 2 0. Both solutions contained 200 pM ASl-42. The A9l-42 solutions were incubated at ambient temperature (-20-24 0 C) for 3 days. The solutions were then brought to a 30 physiological state by adding lOx phosphate buffered saline (PBS), pH 7.4, thus bringing samples to 1x PBS. Samples were then incubated at 37 0 C for 24 hr to induce aggregation of AI1-42. Samples were subsequently dialysed in microdialysis cups (3500 Mr cut-off) placed in 5 L PBS for 35 24 hr, in order to remove some of the excess KJB030 without loss of A91-42.

WO 01/07442 PCT/AUOO/00886 - 34 Dialyzed samples were added to six day old cerebral cortical neuron cultures growing in Neurobasal medium with B27 supplements but without anti-oxidants (Gibco). Samples were diluted into the culture medium to a final 5 concentration of 20 4M AI-42. The concentration of the KJB030 was unknown, due to dialysis of the sample; however, the maximum concentration would be 20 pM if no dialysis had occurred. Six wells of each of the following were established: 1; Untreated control cells, 2; A91-42 (20 pM), 10 3; KJB030 (dialysed), 4; KJB030+ABl-42 (20 pIM, dialysed), 5; vehicle only (PBS). Cultures were treated for 5 days (37 0 C/5%CO 2 ,) and culture medium was removed for analysis of cell death. Determination of cell death was performed using the 15 lactate dehydrogenase (LDH) assay kit (Boehringer Mannheim). This is a measure of the release of LDH, a constitutively expressed, highly abundant enzyme, from dead (lysed) cells. Culture medium was mixed with the reagents from the LDH kit as per the manufacturer's instructions and 20 the level of LDH measured colourimetrically on a spectrophotometric 96 well plate reader at 490 nm. Using the equation supplied with the LDH assay kit, the percentage of LDH release and hence cell death compared to untreated control cultures was determined. The results are 25 shown in Table 1. Table 1 Results of LDH assay for cell death Treatment: % cell death Untreated control neurons: 0 Vehicle alone (PBS) -1.18 ± 1.4 KJB030 alone 8.1 ± 2.2 A9l-42 (20 VM) alone 22 ± 3.5 AS1-42 (20 pM) + KJB030 3.9 i 2.5* *Significantly different from AZ1-42 alone (p<0.01) WO 01/07442 PCT/AUOO/00886 - 35 Example 6 Demonstration of Reaction of Compound KJB001 with AP1-28 1.8 mgs of A01-28 was dissolved in 5 mls DMSO was 5 mixed with 0.33 mgs of compound KJB001 (~l equivalent) dissolved in 0.3 mls DMSO. The mixture was allowed to stand for 24 hrs before being freeze-dried. The resulting blue powder was dissolved in 550 11 of an aqueous solution containing 100 mM NaCl, 50 mM phosphate buffer, pH 6.9. A 10 solution of of 1.8 mgs Apl-28 dissolved in 550 pl of the same solution was used as a control. Figure 9(A) shows the 600 MHz 'H NMR spectrum of the aqueous solution of Afl-28 at 271 K. The resonances due to the C2H protons of His6, 13, 14 are marked with *. Figure 15 9(B) shows the H 600 MHz NMR spectrum of the solution of A01-28 plus KJB001, demonstrating that the peaks due to the histidine C2H protons had shifted, thus indicating that KJB001 had reacted with these residues. 20 DISCUSSION When copper and iron bind to A$, reactive oxygen species such as peroxide and superoxide are produced. When copper and zinc bind to AP, both induce aggregation, and copper binding is inhibited by zinc, suggesting that these 25 ions bind to similar binding sites, or share a single binding site. Zinc, and presumably copper, bind to the histidine residues of AP. Thus a molecule which prevents the binding of zinc and copper to these histidine residues has the potential to inhibit AP aggregation and to prevent 30 metal-induced neurotoxicity. Compounds of the kind described herein have the potential to bind to histidine residues and therefore to prevent zinc and copper binding, and so may have therapeutic value. A model of a cobalt-corrin ring complex 35 bound to A0l-40 is shown in Figure 8.

WO 01/07442 PCT/AUOO/00886 - 36 It will be apparent to the person skilled in the art that while the invention has been described in some detail for the purposes of clarity and understanding, various modifications and alterations to the embodiments and 5 methods described herein may be made without departing from the scope of the inventive concept disclosed in this specification. References cited herein are listed on the following pages, and are incorporated herein by this reference. 10 WO 01/07442 PCT/AUOO/00886 - 37 REFERENCES Atwood CS, Scarpa RC, Huang X, Moir RD, Multhaup G, Tanzi RE, Bush Al. 1998a. 5 Gain of Function of the Dutch-type mutant Ab protein: Altered copper binding and increased generation of SDS-Resistant AS polymers. Abstract, 6th International Conference on Alzheimer's Disease, Amsterdam, 18-23 July. 10 Atwood CS, Moir RD, Huang X, Scarpa RC, Bacarra NIVE, Romano DM, lo Hartshorn MA, Tanzi RE, Bush AI. 1998b J. Biol. Chem. 273: 12817-12826. 15 Anil-Kumar, Ernst RR, Wilthrich K. 1980. A two-dimensional nuclear Overhauser enhancement (2D NOE) experiment for the elucidation of complete proton-proton cross-relaxation networks in biological macromolecules. Biochem Biophys Res Commun 95: 1-6. 20 Bartels Q Xia T-H, Billeter M, G-intert P, Wuthrich K. 1995. The program XEASY for computer-supported NMR spectral analysis of biological macromolecules. J. Biomol NMR 5: 25 1-10. Braunschweiler L, Ernst RR. 1983. Coherence transfer by isotropic mixing: application to proton correlation spectroscopy. 30 J Magn Reson 53: 521-528. Bush AI, Huang X, Atwood CS, Cherny RA, Moir rd, Goldstein LE, O'Malley CM, Saunders AJ, Multhaup G, Beyreuther K, Master CL, Tanzi RE. 1998. 35 Interactions with ionic zinc, copper and iron govern AS redox activity and accumulation in Alzheimer's disease.

WO 01/07442 PCT/AUOO/00886 - 38 Abstract, 6th International Conference on Alzheimer's Disease, Amsterdam, 18-23 July. Cherny RA, Legg JT, Beyreuther K, Tanzi RE, Master CL, Bush 5 AI 1998. Differential effects of chelators upon the solubilization of cerebral A$ deposits in post-mortem Alzheimer and control brain tissue. Abstract, 6th International Conference on Alzheimer's 10 Disease, Amsterdam, 18-23 July. Findeis et al. 1999. Modified-Peptide Inhibitors of Amyloid $-Peptide Polymerisation. 15 Biochemistry 38: 6791-6800. Glenner, G.G, and Wong, CW 1984. Alzheimer's disease: initial report of the purification and characterization of a novel cerebovascular amyloid protein, 20 Biochem, Biophys, Res. Commun, 120: 885-890. Hilbich, G, Kisters-Woike, B., Reed, J., Masters, C.L., and Beyreuther K. (1992) J. Mol. Biol. 228: 460-473. 25 Ida, N., Hartmann, T., Pantel, J., Schroder, J., Zerfass, R., Forstl, H., Sandbrink, R., Masters, C.L. and Beyreuther, K. (1996) J. Biol Chem 271:22908-22914. 30 Kang, J. Et al, 1987. The precursor of Alzheimer's disease amyloid A4 protein resembles a cell-surface receptor. Nature 325: 733-736. 35 Macura S, Huang Y, Suter D, Ernst RR. 1981.

WO 01/07442 PCT/AUOO/00886 - 39 Two-dimensional chemical exchange and cross-relaxation spectroscopy of coupled nuclear spins. J. Magn Reson 43: 259-281. 5 Marion D, Wuthrich K. 1983. Application of phase sensitive two dimensional correlated spectroscopy (COSY) for measurements of 1HAH spin-spin coupling constants in proteins. Biochem Biophys Res Commun 113: 967-974. 10 Markesbery, WR 1997 Free radical Biology and Medicine, 23, 134-147. Mirra, S.S., Heyman, A., McKeel, D., Sumi, S.M., Crain, 15 B.j., Brownlee, L.M., Vogel, F.S., Hughes, J.P., van Belle, G. and Berg, L. (1991) Neurology 41:479486. Rance M, Sorenson OW, Bodenhausen G, Wagner G, Ernst RR, 20 Wuthrich K. 1983. Improved spectral resolution in COSY 'H NMR spectra of proteins via double quantum filtering. Biochem Biophys Res Commun 117: 479-485. 25 Rucker SP, Shaka Aj. 1989. Broadband homonuclear cross-polarisation in 2D NMR using DIPSI-2. Mol. Phys 68: 509-517. 30 Tjernberg et al. 1999. A Molecular Model of Alzheimer Amyloid f-Peptide Fibril Formation. J. Biol. Chem. 274: 12619-12625.

WO 01/07442 PCT/AUOO/00886 - 40 Van Geet AL. (1970) Calibration of methanol nuclear magnetic resonance thermometer at low temperature. Anal Chem 42: 679-680. 5 Wishart DS, Bigam CG, Yao J, Abildgaard F, Dyson J, Oldfield E, Markley JL, Sykes BD. 1995 a. 'H, "C and "N chemical shift referencing in biomolecular 10NMR. 10 J. Biomol NMR 6:135-140. Wishart DS, Sykes BD, Richards FM. 1992 The chemical shift index: a fast and simple method for the assignment of protein secondary structure through NIvM 15 spectroscopy. Biochemistry 31: 1647-165 1. 15 Yanker, B.A et al. 1989. Neurotoxicity of a fragment of the amyloid precursor 20 associated with Alzheimer's disease. Science 245: 417-420.

Claims (42)

1. A compound which interacts with the f-amyloid peptide in such a way that the N-terminal loop of the peptide 5 (amino acid residues 1-15) is blocked or destabilised, thereby inhibiting the binding of one or more metal ions to at least one histidine residue within the N-terminal loop.

2. A compound according to claim 1 which inhibits binding of Cu 2 *, Zn 2 * and Fe 3 ions, but not Mg2+ or Ca 2+ 10 ions.

3. A compound according to claim 1 or claim 2 which has a conformation and polarity such that it binds to at least one histidine residue in the N-terminal loop, selected from the group consisting of His6, His13 and 15 Hisl4.

4. A compound according to claim 3, which binds to at least two histidine residues in the N-terminal loop.

5. A compound according to claim 4, which binds to at least three histidine residues in the N-terminal loop. 20

6. A compound according to any one of claims 1 to 5, which also binds to at least one additional amino acid in the N-terminal loop, selected from the group consisting of Asp7, TyrlO, and Glull.

7. A compound according to any one of claims 1 to 5, 25 which has acidic groups which interact with one or more of the His residues in the N-terminal loop.

8. A compound according to claim 7, represented as follows: acid group 30 acid core acid group .................. molecule . group 35 (optional) (optional) WO 01/07442 PCT/AUOO/00886 - 42 wherein the core molecule has a conformation and polarity such that the acid group(s) interact with one of more of His6, His13 and His14.

9. A compound according to claim 9, in which the acid 5 group is selected from the group consisting of CO 2 H, P0 3 H 2 , SO 3 H, OS0 3 H 2 , and OP0 3 H 2

10. A compound according to claim 9, which is a molecule with one to three carboxylic acid groups, the length of the molecule being such that it can be received within the 10 N-terminal loop, and such that at least one carboxyl group is in proximity to at least one of the histidine residues.

11. A compound according to any one of claims 1 to 10, which is an organic molecule, a peptide or a metal complex.

12. A compound according to claim 9, which is not a metal 15 complex.

13. A compound according to claim 9, which has overall hydrophobic character.

14. A compound according to claim 10, which is able to penetrate the blood-brain barrier. 20

15. A compound according to any one of claims 1 to 14, which comprises, or is conjugated to, a targeting moiety.

16. A compound according to claim 15, in which the targeting moiety is selected from the group consisting of polypeptides, nucleic acids, carbohydrates, lipids, 25 $-amyloid ligands, antibodies, and dyes.

17. A compound according to claim 15, in which the targeting moiety has a hydrophobic region which interacts with the tail of the P-amyloid peptide.

18. A compound according to claim 17, in which the 30 targeting moiety comprises a fatty acid molecule.

19. A compound according to any one of claims 15 to 18, in which the targeting moiety targets the compound to the site defined by residues 15-21 of the P-amyloid peptide.

20. A compound according to claim 17, in which the 35 targeting moiety is a peptide which comprises a sequence which corresponds to that of residues 15-21 of the P-amyloid peptide. WO 01/07442 PCT/AUOO/00886 - 43

21. A compound according to any one of claims 15 to 20, in which the inhibitor-targeting moiety complex is able to penetrate the blood-brain barrier.

22. A method of selecting or designing a compound which 5 inhibits the binding of metal ions to the N-terminal loop of the 0-amyloid peptide, which method comprises the steps of (i) selecting or designing a compound which has a conformation and polarity such that it binds to at least 10 one, more preferably at least two and more preferably three amino acids in the N-terminal loop selected from the group consisting of His6, His 13 and His14; and (ii) testing the compound for the ability to inhibit binding of metal ions to the N-terminal loop of the 15 P-amyloid peptide.

23. A method according to claim 22, in which the compound binds to at least two histidine residues in the N-terminal loop.

24. A method according to claim 23, in which the compound 20 binds to at least three histidine residues in the N-terminal loop.

25. A method according to any one of claims 22 to 24, in which the compound also binds to at least one additional amino acid in the N-terminal loop, selected from 25 the group consisting of Asp7, TyrlO, and Glull. Preferably the compound inhibits binding of both Cu2+ and Zn 2 * ions, but not Mg2' or Ca2+ ions.

26. A method according to claim 26, in which the compound inhibits binding of Cu2+, Zn 2 and Fe ions, but not Mg2+ or 30 Ca2+ ions.

27. A method according to any one of claims 22 to 26, in which the compound has overall hydrophobic character.

28. A method according to claim 27, in which the compound is able to penetrate the blood-brain barrier. 35

29. A compound which inhibits the binding of metal ions to the N-terminal loop of the S-amyloid peptide, wherein WO 01/07442 PCT/AUOO/00886 - 44 the compound is obtained by a method according to any one of claims 22 to 28.

30. A composition comprising a compound according to any one of claims 1 to 21 or claim 29, together with a 5 pharmaceutically acceptable carrier.

31. A method of inhibiting the binding of one or more metal ions to the P-amyloid peptide, or of inhibiting the aggregation of $-amyloid peptide, which method comprises the step of exposing the peptide to a compound which blocks 10 or destabilises the N-terminal loop of the peptide, thereby inhibiting the binding of one or more metal ions to at least one histidine residue within the N-terminal loop.

32. A method according to claim 31, in which the compound has a conformation and polarity such that it binds to at 15 least one histidine residue in the N-terminal loop of the $-amyloid peptide, selected from the group consisting of His6, Hisl3 and His14.

33. A method according to claim 32, in which the compound binds to at least two histidine residues in the 20 N-terminal loop.

34. A method according to claim 33, in which the compound binds to at least three histidine residues in the N-terminal loop.

35. A method according to any one of claims 31 to 25 34, in which the compound also binds to at least one additional amino acid in the N-terminal loop, selected from the group consisting of Asp7, Tyr1O, and Glull.

36. A method according to any one of claims 31 to 35, in which the compound inhibits binding of Cu 2 +, Zn 2 + and Fe 3 30 ions, but not Mg2 or Ca ions.

37. A method according to any one of claims 31 to 36, in which the compound is a complex of Mn, Fe, Co, Ni, Cu, Zn, Ru, Pd, Ag, Cd, Pt, Au, Rh or Hg, with the proviso that the compound is not haemin or haematin. 35

38. A method according to any one of claims 31 to 37, in which the compound comprises, or is conjugated to, a targeting moiety. WO 01/07442 PCT/AUOO/00886 - 45

39. A method according to claim 38, in which the targeting moiety targets the compound to the site defined by residues 15-21 on the P-amyloid peptide.

40. A method according to any one of claims 31 to 39, in 5 which the inhibition of binding of one or more metal ions to the -amyloid peptide occurs in vivo.

41. A method of prevention, treatment or alleviation of Alzheimer's disease, which method comprises the step of administering a compound according to any one of claims 1 10 to 21 or a pharmaceutical composition according to claim 30 to a subject in need of such treatment.

42. A method of prevention, treatment or alleviation of Alzheimer's disease, which method comprises inhibiting the binding of one or more metal ions to the -amyloid peptide, 15 or inhibiting the aggregation of P-amyloid peptide, by the method of claim 40.