DE4128183C1 - New technetium complexes and corresp. complexing agents - useful for measurement of cerebral perfusion, diagnosis of Alzheimer's disease or epilepsy and localisation of tumours - Google Patents

Abstract

Technetium complexes of formula (I) and (II) and intermediates of formula HY1(CH2)2N(R)CH2CHANH(CH2)2Y2H (III). In formulae, R = H or (CH2)2Y3H, A is alanine (i.e. CH2CHNH2COOH) or phenylalanine (i.e. C6H4CH2CH(NH2)COOH) residue, at least one of the coordinating atoms (Y1, Y2 and Y3) is S and the other(s) are NH. The molecule has 2 or 3 opt. different COOR gps. linked to alkylene (R = lower alkyl) and A may also be linked at another positions. (III) are prepd. by acylating opt. N-protected alanine or phenylalanine with N-phthaloylglycine chloride in the p-position using Friedel Crafts conditions, and reductively aminating the prod. with bis(2-mercaptoethyl) amine, and splitting the protecting gp. off with hydrazine hydrate. USE - For SPECT cerebral diagnosis. (I) and (II) cross the blood- brain barrier more rapidly.

Description

The invention relates to pharmacologically useful Technetium complexes and includes suitable complexing agents and their manufacture and provided with them Application kits.

Technetium, esp. ^99m TC, is known for radio diagnostic purposes. So z. B. from A. Yokoyana et al. (EP-A1-00 74 429) Technetium complexes with sugar or polyhydroxy ligands in the form of ^99m Tc-D-glucosone-bis- (thiosemicarbazone) (" ^99m Tc-GBT"), which are to be used for pharmacological studies. However, the radiotracer is quickly released again after the injection by the organs to be examined, especially the heart and brain.

Technetium-Podand complexes of the diaminodithiol type are also known. ^99m Tc-ECD - the most successful representative of this group so far - is currently in clinical testing and is probably suitable for brain perfusion diagnostics.

To keep the patient's radiation exposure as low as Keeping it possible is an even more effective and more selective enrichment in the target organ is desirable.

The aim of the invention is therefore new technetium complex compounds, the blood-brain barrier (BBB) faster can happen and stay in the brain for a sufficiently long time, to enable radio diagnostic measurements.

The inventive developed for this purpose Technetium complexes are characterized by the general Formulas

in which A is an alanine or phenylalanine residue

[-CH₂-CH (NH₂) -COOH or -C₆H₄-CH₂-CH (NH₂) -COOH]

is and at least one of the coordination atoms Y₁, Y₂, Y₃für -S- stands, while the remaining mean -NH-, where in Molecule up to three, possibly different, bound to alkylene -COOR' groups (with R '= lower alkyl) present can be and also the radical A bound to alkylene can take other positions.

The amino acid residue of these complexes may be in salt form available.

Such connections are for active transportation from technetium to the brain through the bras Carrier protein suitable, the neutral amino acids through the BHS and is able to do so  with a sterically relatively sophisticated rest To transport amino acids.

The technetium complexes according to the invention are for pharmacologically macological-diagnostic examinations sufficient  stable and relatively easy to manufacture and therefore for pharmacological-diagnostic examinations or Suitable applications, such as:

• - measurement of regional cerebral perfusion or Perfusion measurements of other organs due to the need for neutral amino acids Enrich Tc complexes in organ tissue;
• - Diagnosis of Alzheimer's disease or basic research For this;
• - the diagnosis of epilepsy and basic research Connections of this disease;
• - studies of metabolic processes;
• - for tumor localization, because tumor tissue is different Has metabolism as healthy tissue.

Of the new technetium complexes are as special useful to name the following (type 1-4):

R stands for COOR 'or H, the radicals R in one Molecule can be the same or different and both the amino acids as well as the residues R also others Can occupy positions of the alkylene chains.

These compounds are characterized by their high com plex stability and are due to their neutral Podandrests well suited for brain perfusion diagnostics.

The preparation of the complexing agents according to the invention  as well as the corresponding technetium complexes below using the example of the synthesis of the 2-amino 3- {4- [2-amino-1-bis (2-mercaptoethyl) amino ethyl] phenyl} propanoic acid technetium complex described:

A. Preparation of the bis (2-mercaptoethyl) amine (Pre-stage 1)

The synthesis is carried out as described by J. Harley-Mason in J. Chem. Soc. (1947), 320, is described in the following Steps:

Diethanolamine is used as the starting substance for the synthesis used which with the help of thionyl chloride in trichlorethylene at 50 ° C within 3 hours converted to the corresponding chloramine hydrochloride becomes. Using thiourea is used in boiling ethanol the S-alkyl within 2 hours thiouronium salt formed, which is then in aqueous Basic solution to bis (2-mercaptoethyl) amine is saponified.  

B. Presentation of the N-phthaloyl-glycine chloride (precursor 2)

The synthesis comprises the following steps and follows in the essential information in Houben-Weyl, Vol. XV / 1 (1974), pp. 46-305, and Vol. XI / 2 (1974), pp. 355-364.

In order to convert the amino acid glycine into its acid chloride, the amine function must first be protected. For this, e.g. B. the phthaloyl protecting group suitable. The amino acid is used to introduce the protective group 145-150 ° C dissolved in phthalic anhydride and approx. 30 Min. Stirred vigorously. After recrystallization with phosphorus (V) chloride in toluene at 60 ° C to the amino acid chloride implemented.  

B. Synthesis of 2-amino-3- {4- [2-amino-1-bis- (2-mer captoethyl) aminoethyl] phenyl} propanoic acid Technetium complex

The manufacture comprises the following steps and follows in essential information in Houben-Weyl, Vol. XI / 1 (1975), pp. 602-648, in particular 643, and pp. 648-664, in particular 661, and H.G. O. Becker et. al., "Organikum", 15. Edition, VEB Dt. Verl. D. Wiss. Berlin (1984), pp. 400- 405 and pp. 610-612.

To unwanted reactions to the amino acid function of phenylalanine may have to be prevented first an appropriate protection group will be introduced. This would be z. B. necessary if the α-amino function of Amino acid as an amine component in the Leukart-Wallach Reaction would act. When using the phthaloyl Protecting group could then do this in the course of the reaction together with the other phthaloyl protective group be split. The working procedure for the one The phthaloyl protective group has already been used for N-phthaloyl-glycine (see above).

The reaction now proceeds in such a way that initially Phenylalanine (or the protected derivative) in one Friedel-Crafts acylation using finely powdered Aluminum chloride under ice cooling with N-phthaloyl Glycine chloride implemented in 1,2-dichloroethane becomes. The product is then in a leukart Wallach reaction using 98% Formic acid as a reducing agent with bis- (2-mercapto implemented ethyl) amine. The cleavage of phthaloyl Protecting group happens through hydrazinolysis. For this is together with hydrazine hydrate in about 2 hours Methanol or ethanol heated to boiling and then slightly warmed in dilute hydrochloric acid. The now free 2-amino-3- {4- [2-amino-1-bis (2-mercaptoethyl) amino ethyl] -phenyl} -propanoic acid is now with ammonium per technetat and a suitable reducing agent (e.g. Sodium borohydride, sodium dithionite or tin (II) chloride) in basic to the corresponding technetium complex implemented.

The reaction is analogous to the representation of type 2 to be carried out, only in the p-position instead of the phenylalanine substituted by glycine an in 3-position alanine substituted by a glycyl residue be used in the reaction. For illustration of types 3 and 4 is 2-mercapto instead of glycine acetic acid chloride and instead of bis (2-mercapto ethyl) -amines an optionally amine-protected 5-amino-3-aza to use pentanethiol derivative in the reaction. The the key reaction is reductive ami nation to Leukart-Wallach if necessary.  

So-called application kits are suitable for the application, which contain the complexing agent, a reducing agent, and a corresponding buffer in suitable amounts. Complexing agents and reducing agents are preferably provided in dried form and practically neutral buffer solution in two separate ampoules. When used, the content of such kits is combined with pertechnetate solution from a ⁹⁹ ^m Tc generator and is then ready for injection.

With the help of such kits, all the ingredients for formation of the radiopharmaceutical may be inside the finished solution for injection is ready in no time be put. This is administered intravenously, whereby ensures quick transport to the target organ is.

More in detail one brings z. B. in an ampoule 1 both the chemically pure ligand and a ge suitable reducing agent (e.g. tin (II) chloride, Na triumborohydride or sodium dithionite) in freezer dried form. The ampoule 2 contains a 0.0187 molar phosphate buffer solution (pH = 7.5). For the production The contents of the ampoule become the finished solution for injection 1 mixed with physiological saline and then mixed with the contents of ampoule 2. To the combined solutions will eventually become the eluate of a Technetium-99-mGenerators added. After vigorous Shake the reaction solution for the purpose of complete complex formation left for about 15 minutes.

Claims (4)

1. Technetium complexes of the general formulas in which A is an alanine or phenylalanine residue [-CH₂-CH (NH₂) -COOH or -C₆H₄-CH₂-CH (NH₂) -COOH] and at least one of the coordination atoms Y₁, Y₂, Y₃ is -S-, while the other -NH- mean, where in the molecule up to three, if necessary. Different ge bound to alkylene -COOR 'groups (with R' = lower alkyl) may be present and the radical A bonded to alkylene can also assume other positions. 2. Complexing agents of the general formulas in which A is an alanine or phenylalanine residue [-CH₂-CH (NH₂) -COOH or -C₆H₄-CH₂-CH (NH₂) -COOH] and at least one of the coordination atoms Y₁, Y₂, Y₃ is -S-, while the other -NH- mean, where in the molecule up to three, if necessary. Different ge bound to alkylene -COOR 'groups (with R' = lower alkyl) may be present and the radical A bonded to alkylene can also assume other positions. 3. Process for the preparation of compounds of general Formulas (III) or (IV) according to claim 2, characterized, that if necessary. N-protected alanine or phenylalanine with N-phthaloyl-glycine chloride in the p-position below Friedel-Crafts conditions and the obtained Product with bis (2-mercaptoethyl) amine if necessary after Leukart gelding reductively aminated and finally the Cleaves phthaloyl protective group with hydrazine hydrate. 4. Application kits for SPECT cerebral diagnosis purposes, containing a podand or tripodand complexing agent according to claim 2 and a reducing agent.