WO2010093128A2

WO2010093128A2 - Amphiphilic porphyrin derivatives and method for preparing the same

Info

Publication number: WO2010093128A2
Application number: PCT/KR2010/000326
Authority: WO
Inventors: Woo-Dong Jang; Kwang-Mo Choi
Original assignee: Industry-Academic Cooperation Foundation, Yonsei University
Priority date: 2009-02-11
Filing date: 2010-01-19
Publication date: 2010-08-19
Also published as: KR101010061B1; KR20100091696A; WO2010093128A3

Abstract

Amphiphilic porphyrin derivatives are provided. The amphiphilic porphyrin derivatives can contain various metals and are highly soluble in aqueous solutions. In addition, the amphiphilic porphyrin derivatives have the ability to form micelles having a uniform particle size of tens of nanometers in aqueous solutions. The amphiphilic porphyrin derivatives can be used as effective MRI contrast agents. Further provided are a method for preparing the porphyrin derivatives, micelles formed by self-assembly of the porphyrin derivatives, and MRI contrast agents comprising the porphyrin derivatives.

Description

[DESCRIPTION] [ Invention Title]

AMPHIPHILIC PORPHYRIN DERIVATIVES AND METHOD FOR PREPARING THE SAME

[ Technical Field]

The present invention relates to amphiphilic porphyrin derivatives. More specifically, the present invention relates to amphiphilic porphyrin derivatives that can contain various metals, are highly soluble in aqueous solutions, have the ability to form micelles having a uniform particle size of tens of nanometers in aqueous solutions, and can be used as effective MRI contrast agents. The present invention also relates to a method for preparing the porphyrin derivatives, micelles formed by self-assembly of the porphyrin derivatives, and MRI contrast agents comprising the porphyrin derivatives.

[Background Art]

Magnetic resonance imaging (MRI) is a way to obtain anatomical, physiological and biochemical data concerning the body as images based on the phenomenon that the spins of hydrogen atoms relax in the presence of a magnetic field. MRI is one of the most powerful imaging diagnostic techniques that enable real-time imaging of organs of living humans and animals in a noninvasive manner.

In attempts to precisely utilize MRI in various research fields, including bioscience and medical science, substances, called "contrast agents," are injected into the body to achieve enhanced image contrast in MRI. The contrast between tissues on an MR image is due to different spin relaxations in the respective tissues.

The spin relaxation refers to the phenomenon that the nuclear spins of water molecules in the tissues return to their equilibrium state. Contrast agents have an influence on the spin relaxations in tissues to increase the difference in the degree of relaxation between the tissues and to cause changes in MRI signals, making the contrast between the tissues more distinct. The degree of practical use and the degree of precision of contrast agents may vary according to the characteristics and functions of the contrast agents and subjects to which the contrast agents are to be injected. The use of contrast agents for the enhancement of contrast increases the image signals of specific organs and tissues and decreases the image signals of the surroundings (or vice versa) to more clearly visualize the images of the organs and tissues. A 'positive' contrast agent is a substance that enhances image signals of a particular body organ or tissue for MRI relative to its surroundings. A 'negative' contrast is a substance that weakens image signals of a body organ or tissue for MRI relative to its surroundings. The positive contrast agent is related to Tl relaxation, i.e. longitudinal relaxation. This longitudinal relaxation is a process in which the longitudinal magnetization components M_z of spins absorb RF energy applied from the X axis, are aligned in the Y axis on the X-Y plane, and return to the original values while releasing the absorbed energy to the outside. This phenomenon is referred to as "Tl relaxation." Tl relaxation time indicates the time required for M_z to reach 63% of the original value. The shorter the Tl relaxation, the stronger the MRI signals, implying shorter image acquisition time. The 'negative' contrast agent is related to T2 relaxation, i.e. transverse relaxation. This transverse relaxation is a process in which the transverse magnetization components M₂ of spins absorb RF energy applied from the X axis, are aligned in the Y axis on the X-Y plane, and return to the original values while losing the absorbed energy (decaying) or delivering the absorbed energy to the adjacent spins. At this time, the components M_y of the spins are evenly distributed on the X-Y plane and decay exponentially. This phenomenon is referred to as "T2 relaxation." T2 relaxation time indicates the time required for M_y to reach 37% of the original value. The signals of the components M_y are measured by a receiver coil installed in the Y axis as a function of time. The signals, which decrease with time, are called "free induction decay (FID) signals." A tissue having a short T2 relaxation time appears dark on the MR image.

Currently commercially available MRI contrast agents include paramagnetic compounds as positive contrast agents and superparamagnetic nanoparticles as negative contrast agents. The paramagnetic compounds are usually chelate compounds of gadolinium ions (Gd³⁺) or manganese ions (Mn²⁺). The use of the paramagnetic compounds accelerates the proton relaxation of water to obtain bright contrast images around the contrast agents. Gadolinium ion is used in the form of a compound that is bonded to a chelate compound or a polymeric material to remove , its high toxicity. Gd-DTPA is a most widely used gadolinium compound and its . major medical applications are diagnoses of damage to the blood-brain barrier -

(BBB), changes in the vascular system, blood circulation and infusion states. .-- However, contrast agents in the form of compounds are retained in blood for a short time of about 20 min because they activate the immune system in vivo or are decomposed in the liver. Manganese-enhanced MRI (MEMRI) using manganese ions (Mn²⁺) as Tl contrast agents is utilized in studying anatomical structures and cellular functions in various fields, including brain science (Lin YJ, Koretsky AP, Manganese ion enhances Tl -weighted MRI during brain activation: an approach to direct imaging of brain function, Magn. Reson. Med. 1997; 38: 378-388). MEMRI using manganese ions as Tl contrast agents provides excellent contrast characteristics, but it has disadvantages in that MnCl₂ permeates in a large amount (> 88-175 mg/kg) and manganese ions accumulated in tissues show toxicity. These disadvantages limit the application of MEMRI to the contrast of animal brains. MEMRI has practical limitations in applying to human brains owing to the toxicity and the possibility of in vivo accumulation of manganese ions. Mn-DPDP (teslascan), publicly known as a contrast agent using manganese ions, is used for contrasting the human liver. Mn-DPDP is converted to Zn-DPDP upon being administered to the body. The Zn-DPDP has a structure in which the Mn of the Mn-DPDP is replaced by Zn. The Zn-DPDP is secreted through the kidneys and the free Mn²⁺ circulates along with blood and is absorbed by the liver, kidneys, pancreas, etc., where it acts as a contrast agent. The toxicity of Mn²⁺ requires a slow infusion rate of about 2 to about 3 ml/hr. About 5 μmol of Mn²⁺ per kg of body weight (corresponding to 0.5 ml/kg of body weight) is a typical amount for use in a human. However, this amount is too small to contrast the brain and other organs (ref. Rofsky NM, Weinreb JC, Bernardino ME et al. Hepatocellular tumors: characterization with Mn-DPDP-enhanced MR imaging. Radiology 188:53, 1993).

Tl contrast using positive contrast agents does not cause distortion of images and is suitable for investigating the anatomical structures of tissues and the function of cells. In addition, Tl contrast is most widely used for MRI due to its high resolution. For these reasons, Tl contrast has been the subject of intense research and development. However, positive contrast agents developed hitherto have limitations in applying to the human body because they are based on toxic paramagnetic metal ions or complexes thereof. Further, the retention time of conventional positive contrast agents in blood is short and steric hindrance by ligands of complexes makes it difficult to attach target-directing substances to the positive contrast agents.

Many efforts have been made to solve the problems of the prior art. For example, U.S. Patent Publication No. 2003/0215392 Al discloses the research result that gadolinium ions are concentrated in polymeric nanostructures to maintain the shape of the nanoparticles while increasing the local concentration of the gadolinium ions. However, since the nanoparticles are large in size and the gadolinium ions are bound to the polymeric nanostructure in shape, the gadolinium ions can be easily separated from the surface of the particles. Another problem of the nanoparticles is low cell permeability.

Superparamagnetic nanoparticles, typified by superparamagnetic iron oxide (SPIO) nanoparticles, are currently used as negative contrast agent nanoparticles. U.S. Patent No. 4,951 ,675 describes the use of biocompatible superparamagnetic particles as T2 contrast agent particles for MRI, and U.S. Patent No. 6,274,121 discloses superparamagnetic particles consisting of superparamagnetic one-domain particles and aggregates of superparamagnetic one-domain particles to whose surfaces are bound inorganic and optionally organic substances optionally having further binding sites for coupling to tissue-specific binding substances, diagnostic or pharmacologically active substances.

SPIO nanoparticles are retained in living cells and tissues for several hours, which is much longer than the retention time of SPIO in the form of a compound, due to their sufficiently large size ranging from several to several hundreds of nanometers. In addition, numerous functional groups and target substances can be bound to the surface of SPIO nanoparticles. Due to these advantages, SPIO nanoparticles have drawn a great deal of attention and interest as target-directing contrast agent particles. However, the inherent magnetism of superparamagnetic nanoparticles results in a short T2 relaxation time and adversely generates a magnetic field during MRI, which may distort the images. Contrasted areas on a T2- enhanced image appear black. The black areas may be confused with already black- colored areas indicating the occurrence of internal hemorrhage, the presence of petrified tissues and deposited heavy metals in the body, etc.

Further, the inherent magnetism of SPIO nanoparticles may cause a blooming effect of a magnetic filed near the contrast agent particles. The blooming effect brings about loss of signals or distortion of background image, making it impossible to obtain images close to anatomical images.

Currently available injectable formulations for intracellular or extracellular delivery of poorly soluble drugs, contrast agents and oils include, for example, polymeric micelles prepared by self-assembly of amphiphilic block copolymers, biodegradable polymeric nanoparticles prepared by self-emulsifying diffusion, polymeric nanoparticles prepared by ionic bonding between ionic polymers, polymeric nanoparticles using dendrimers, liposomes, which are microspheres having a size of 100 to 800 nm and consisting of one or more phospholipid bilayers, and emulsions containing oily phase in aqueous phase (oil-in-water type) (R. Duncan, Nat. Rev. Drug Discovery 2 (2003) 347-360; A. Potineni, et al., J. Controlled

Release 86 (2003) 223-234; K. Kataoka, et al., Adv. Drug Deliv. Rev.. 47 (2001) 113131 ; H.S. Yoo, et al., J. Controlled Release 96 (2004) 273-283; A. Gabizon, et al., Cancer Res. 54 (1994) 987-992). Of these, polymeric micelles and liposomes are being widely investigated as formulations for extracellular delivery of physiologically active drugs, particularly, poorly soluble anticancer agents.

[ Disclosure] [ Technical Problem]

It is a first object of the present invention to provide amphiphilic porphyrin derivatives that can contain various metals, are highly soluble in aqueous solutions and can be imparted with various functionalities according to changes of hydrophobic and hydrophilic moieties.

It is a second object of the present invention to provide a method for preparing the amphiphilic porphyrin derivatives.

It is a third object of the present invention to provide micelles having a uniform size of tens of nanometers that are formed by self-assembly of the porphyrin derivatives in aqueous solutions.

It is a fourth object of the present invention to provide MRI contrast agents comprising the porphyrin derivatives that function as metal chelates and possess the characteristics of nanoassemblies.

[Technical Solution]

In order to accomplish the first object of the present invention, there is provided a porphyrin derivative represented by Formula 1 :

wherein M is H₂ or a metal atom, R₁, R₂, R₃ are each independently H or OR₅ (in which R₅ is a C₁-Ci₂ alkyl group), and R₄ is a dendron consisting of oligo(ethylene oxide) chains.

In a preferred embodiment, M in Formula 1 may be a metal selected from the group consisting of Mn, Cu, Co, Zn, Ni, Pd and Pt.

In a preferred embodiment, the porphyrin derivative of Formula 1 may be the compound represented by Formula 2 or 3 :

(2)

In order to accomplish the second object of the present invention, there is provided a method for preparing the porphyrin derivative of Formula 2 by reacting Mn(II)Cl₂(H₂O)₄ w

In an embodiment, the compound of Formula 4 may be prepared by reacting the compounds of Formulas 5 and 6:

(6) In an embodiment, the compound of Formula 5 may be prepared from the compound of Formula 7:

In an embodiment, the compound of Formula 7 may be prepared from the compound of Formula 8:

In an embodiment, the compound of Formula 8 may be prepared by the following reaction:

In an embodiment, the compound of Formula 6 may be prepared from the compound of Formula 9:

In an embodiment, the compound of Formula 9 may be prepared from the compound of Formula 10:

In an embodiment, the compound of Formula 10 may be prepared by the following reaction:

(10) In an embodiment, the compound of Formula 11 may be prepared from the compound of Formula 12:

In an embodiment, the compound of Formula 12 may be prepared by the following reaction:

(12)

In order to accomplish the third object of the present invention, micelles are provided that are formed by self-assembly of the porphyrin derivative in an aqueous solution. Preferably, the micelles have a size of 20 to 100 nm. In order to accomplish the fourth object of the present invention, there is provided an MRI contrast agent comprising the porphyrin derivative.

[Advantageous Effects]

As described above, the amphiphilic porphyrin derivatives of the present invention can contain various metals, are highly soluble in aqueous solutions, and have the ability to form micelles having a uniform particle size of tens of nanometers in aqueous solutions. In addition, the present invention provides new types of nanoparticles of the amphiphilic porphyrin derivatives. The nanoparticles function as metal chelates and possess the characteristics of nanoassemblies. Diagnosis of a variety of diseases in the early stage is gaining more importance in the medical field. In view of this situation, the nanoparticles of the present invention are expected to be highly marketable due to their applicability as contrast agents. [Description of Drawings]

FIG. 1 is a scanning electron microscopy (SEM) image of micelles formed by self-assembly of a porphyrin derivative according to the present invention in an aqueous solution.

[Best Mode]

Exemplary embodiments of the present invention will now be described in detail.

The present invention provides a porphyrin derivative represented by Formula 1 :

wherein M is H₂ or a metal atom, R₁, R₂, R₃ are each independently H or OR₅ (in which R₅ is a Ci-C₁₂ alkyl group), and R₄ is a dendron consisting of oligo(ethylene oxide) chains. M in Formula 1 may be a metal selected from the group consisting of Mn, Cu,

Co, Zn, Ni, Pd and Pt.

The porphyrin derivative of Formula 1 may be the compound represented by Formula 2 or 3 :

The present invention also provides micelles with uniform size that are formed by self-assembly of the porphyrin derivative in an aqueous solution.

Preferably, the micelles have a size of 20 to 100 nm. Within this range, the micelles exhibit enhanced permeation and retention (EPR) effect. In addition, the porphyrin derivative of the present invention is applicable as an MRI contrast agent, particularly, a Tl contrast agent.

[Mode for Invention] Hereinafter, the present invention will be explained in more detail with reference to the following examples. However, the scope of the invention is not limited by these examples in any manner.

EXAMPLES Example 1

Example 1 -1

5.3 g of methallyl dichloride and 11.9 g of tri(ethylene glycol)monomethyl ether) were put into a reactor, and then 60 mL of tetrahydrofuran was added thereto. To the mixture was added dropwise 3.84 g of sodium hydride. The reactor was kept at 65 ⁰C for 12 hr. 5 mL of water was added dropwise to the reactor. The reaction mixture was evaporated under vacuum to remove the tetrahydrofuran. The concentrate was extracted with 100 mL of diethyl ether and 100 mL of water. The organic layer was subjected to column chromatography using ethyl acetate/methanol (100/0-80/20), giving the compound of Formula 12 in a yield of 35%. ¹H NMR (250 MHz, CDCl₃): δ 5.18 (s, 2H; CH₂), 4.01 (s, 4H; CH₂(CH₂O)₂), 3.70-3.58 (m, 24H; OCH₂), 3.37 (s, 6H; OCH₃)

(12)

Example 1-2 3.8 g of the compound of Formula 12 and 5 mL of tetrahydrofuran were put into a -, reactor. The reactor was cooled in ice-water. To the mixture was added dropwise 4 mL of borane-tetrahydrofuran, followed by stirring for 2 hr. After 3 moles of sodium, hydroxide was added dropwise to the reactor, stirring was continued for 15 min. 4 , mL of a 30% aqueous solution of hydrogen peroxide was added dropwise to the _; reactor, followed by stirring for 30 min. The reaction mixture was extracted with

100 mL of a saturated solution of potassium carbonate and 100 mL of diethyl ether. The organic layer was subjected to column chromatography using ethyl acetate/methanol (100/0-80/20), giving the compound of Formula 11 in a yield of 68%. ¹H NMR (250 MHz, CDCl₃): δ 3.74 (d, 2H; CH₂OH), 3.65-3.60 (d, 4H; CH₂(CH₂O)₂), 3.65-3.60 (m, 24H; OCH₂), 3.38 (s, 6H; OCH₃), 2.13 (m, IH; CH)

(12) . (11) Example 1-3

1.7 g of methallyl dichloride and 8.9 g of the compound of Formula 11 were put into a reactor, and then 20 mL of tetrahydrofuran was added thereto. To the mixture was added dropwise 0.8 g of sodium hydride. The reactor was kept at 65 ⁰C for 24 hr. 2 mL of water was added dropwise to the reactor. The reaction mixture was evaporated under vacuum to remove the tetrahydrofuran. The concentrate was extracted with 100 mL of diethyl ether and 100 mL of water. The organic layer was subjected to column chromatography using ethyl acetate/methanol (100/0-80/20), giving the compound of Formula 10 in a yield of 28%. ¹H NMR (250 MHz, CDCl₃): δ 5.18 (s, 2H; CH₂), 4.02 (s, 8H; CH₂(CH₂O)₂), 3.62-3.41 (m, 64H; OCH₂), 3.37 (s,

12H; OCH₃), 2.22-2.04 (m, 4H; CH(OCH₂)₂)

(11) ^' (10)

Example 1 -4

9.3 g of the compound of Formula 10 and 6 mL of tetrahydrofuran were put into a reactor. The reactor was cooled in ice-water. To the mixture was added dropwise 4 mL of borane-tetrahydrofuran, followed by stirring for 2 hr. After 3 moles of sodium hydroxide was added dropwise to the reactor, stirring was continued for 15 min. 4 mL of a 30% aqueous solution of hydrogen peroxide was added dropwise to the reactor, followed by stirring for 30 min. The reaction mixture was extracted with 100 mL of a saturated solution of potassium carbonate and 100 mL of diethyl ether. The organic layer was subjected to column chromatography using ethyl acetate/methanol (100/0-80/20), giving the compound of Formula 9 in a yield of 74%. ¹H NMR (250 MHz, CDCl₃): δ 3.86 (d, 2H; CH₂OH), 2.95-3.59 (m, 64H; OCH₂), 3.38 (s, 12H; OCH₃), 2.01-2.14 (m, 3H; CH)

(10) (9)

Example 1 -5

5.5 g of the compound of Formula 9 and 3.8 g of para-toluenesulfonyl chloride were put into a reactor, and then 50 mL of dichloromethane and 3 mL of pyridine were added dropwise thereto. The mixture was stirred at room temperature for 5 hr. The reaction mixture was evaporated under vacuum to remove the dichloromethane. The concentrate was extracted with 100 mL of diethyl ether and. 100 mL of water. The organic layer was subjected to column chromatography using ethyl acetate/methanol (100/0-80/20), giving the compound of Formula 6 in a yield_* of 76%. ¹H NMR (400 MHz, CDCl₃): δ 7.76 (d, 2H; CH, phenyl), 3.30 (d, 2H; CH,, phenyl), 2.45 (s, 3H; CH₃), 4.10 (d, 2H; CH2), 3.29-4.06 (m, 64H; OCH₂), 3.37 (s,

12H; OC

(9) (6)

Example 2

Example 2-1 2.11 g of dipyrromethane, 1 g of 3,5-dihydroxybenzaldehyde and 1.19 g of terephthalaldehydic acid methyl ester were put into a reactor, simultaneously with 850 mL of dichloromethane. The mixture was stirred for 10 min. To the mixture was added 2 mL of boron trifluoride. The resulting mixture was stirred at room temperature for 24 hr. 1O g of chloranil was put into the reactor, followed by stirring for 12 hr. The reaction mixture was evaporated in a water bath to remove the dichloromethane. The concentrate was subjected to column chromatography using dichloromethane/methanol (100/0-95/5), giving the compound of Formula 8 in a yield of 10%. ¹H NMR (400 MHz, CDCl₃): δ 4.07 (s, 3H; OCH₃), 6.68 and 7.08 (s, 3H; C₆H₃), 8.37-8.44 (q, 4H;

8.91 -9.53 (m, 8H; pyrrole ring CH), 10.37 (s, 2H; meso-CH in Pzn)

(8)

Example 2-2 0.89 g of the compound of Formula 8, 2 g of potassium carbonate and 0.76 g of 18-crown-6 ether were put into a reactor, and then 140 mL of tetrahydrofuran was added dropwise thereto. To the mixture was added 5 mL of 1-bromooctane. The reactor was kept at 80 ⁰C for 25 hr. The reaction mixture was evaporated by heating under vacuum to remove the tetrahydrofuran. The concentrate was extracted with 100 mL of ethyl acetate and 100 mL of water. The organic layer was subjected to column chromatography using hexane/ethyl acetate (65/35), giving the compound of Formula 7 in a yield of 71%. ¹H NMR (400 MHz, CDCl₃): δ 0.87 (t, 6H; CH₃), 1.27 (m, 24H; C₁₂H₂₄), 4.15 (s, 3H; OCH₃), 5.35 (t, 4H; OCH₂), 6.90 (t, I H; p-C₆H₃), 7.42 (d, 2H; o-C₆H₃), 8.35 and 8.47 (d, 4H; C₆H₄), 9.08-9.47 (m, 8H; pyrrole ring CH), 10.35 (s, 2H; meso-CH in Pzn)

(8) (7)

Example 2-3 0.85 g of the compound of Formula 7 and 100 mL of tetrahydrofuran were put into a reactor. The reactor was cooled in an ice bath. To the mixture was added 57.6 mg of lithium aluminum hydride. The resulting mixture was stirred at room temperature for 1 hr. 5 mL of water was put into the reactor. The reaction mixture was evaporated by heating under vacuum to remove the tetrahydrofuran. The concentrate was extracted with 100 mL of ethyl acetate ether and 100 mL of water.

The organic layer was subjected to column chromatography using dichloromethane/methanol (100/0-95/5), giving the compound of Formula 5 in a yield of 91 %. ¹H NMR (400 MHz, CDCl₃): δ 0.84 (t, 6H; CH₃), 1.25-1.39 (m, 6OH; C₁₂H₂₄), 1.88 (m, 4H; CH₂ in alkyl chain), 4.13 (t, 4H; Ar-OCH₂), 5.02 (d, 2H; Ar- CH₂), 6.91 (t, IH; p-C₆H₃), 7.43 (d, 2H; 0-C₆H₃), 7.75 and 8.24 (d, 4H; C₆H₄), 9.12-

9.44 (m, 32 (s, 2H; meso-

(7) (5)

Example 2-4

70 mg of the compound of Formula 5 and 0.2 mL of the compound of Formula 6 were put into a reactor, and then 30 mL of tetrahydrofuran was added drop wise thereto. The reactor was cooled in an ice bath. To the mixture was added in one portion 20 mg of 60% sodium hydride. The resulting mixture was stirred at room temperature for 3 days. 2 mL of water was put into the reactor. The reaction mixture was evaporated by heating under vacuum to remove the tetrahydrofuran. The concentrate was extracted with 100 mL of ethyl acetate and 100 mL of water. The organic layer was subjected to column chromatography using ethyl acetate/methanol (100/0-80/20), giving the compound of Formula 4 in a yield of 21%. ¹H NMR (400 MHz, CDCl₃): δ 1.25-1.91 (m, 24H; CH₂ in alkyl chain), 0.86 (t, 6H; CH₃), 2.25- 2.40 (m, 3H; CH), 3.33 (s, 12H; OCH₃), 3.38-3.66 (m, 64H; OCH₂), 3.8 l (d, 2H; CH₂O), 4.14 (t, 6H; CH₂O), 4.88 (s, 2H; CH₂O), 6.95 (s, I H; C₆H₃), 7.42 (s, 2H; C₆H₃) 7.78 and 8.26 (d, 4H; C₆H₄), 9.09-9.41 (m, 8H; pyrrole ring CH), 10.31 (s, 2H; meso-CH in Pzn), -3.13 (s, 2H; NH)

(4)

Example 2-5

4 mg of the compound of Formula 4 and manganese (II) chloride tetrahydrate were put into a reactor, and then 20 mL of N,N-dimethylformamide was added dropwise thereto. The reactor was kept at 160 ⁰C for 12 hr. After the reactor was allowed to cool to room temperature, the reaction mixture was extracted with 100 mL of ethyl acetate and 100 mL of water. The organic layer was subjected to column chromatography using ethyl acetate/methanol (100/0-60/40), giving the compound of Formula 2 in a yield of 49%. UV- Vis (CH₂Cl₂): λ_max 369, 471 , 569, 601 ; (H₂O): λ_max 365, 461 , 560, 596

\

(2)

The porphyrin derivative of Formula 2 was self-assembled to form micelle structures. The relaxation time of water molecules was measured using the micelle structures at a concentration of 2.5 mM. As a result, the water molecules were found to have a relaxation time of 80.3 ms, which is much shorter than the normal relaxation time of water molecules. This result indicates that the micelle structures can be used as MRI contrast agents. In addition, the micelle structures can be expected to have enhanced permeation and retention (EPR) effect. Generally, neoplastic blood cells grow in tumor and inflammatory tissues. Relatively slow development of vascular endothelial cells in neoplastic vascular tissues is responsible for the presence of vascular defects above a specific size. Accordingly, substances above a specific size, like the micelle structures, tend to selectively accumulate in tumor and inflammatory tissues. Based on this principle, attempts are currently made to selectively deliver T2 contrast agents using nanoparticles to tumor tissues. In contrast, chelates of paramagnetic metal ions, most of which are low molecular weight compounds, are used as Tl contrast agents. The substances suggested in the present invention are applicable as Tl contrast agents while possessing the characteristics of nanoparticles.

Claims

[CLAIMS]

[Claim 1]

A porphyrin derivative represented by Formula 1 :

wherein M is H₂ or a metal atom, Ri, R₂, R₃ are each independently H or OR₅

(in which R₅ is a C₁-Cj₂ alkyl group), and R₄ is a dendron consisting of oligo(ethylene oxide) chains.

[Claim 2] The porphyrin derivative of claim 1, wherein M is selected from the group consisting of Mn, Cu, Co, Zn, Ni, Pd and Pt.

[Claim 3]

The porphyrin derivative of claim 1, wherein the porphyrin derivative is the compound represented by Formula 2 or 3:

[Claim 4] A method for preparing the porphyrin derivative of Formula 2:

by reacting a 4:

[ Claim 5 ]

The method of claim 4, wherein the compound of Formula 4 is prepared by reacting the compounds of Formulas 5 and 6:

(6)

[ Claim 6 ]

The method of claim 5, wherein the compound of Formula 5 is prepared from the compound of Formula 7:

[ Claim 7]

The method of claim 6, wherein the compound of Formula 7 is prepared from the compound of Formula 8:

[ Claim 8 ]

The method of claim 7, wherein the compound of Formula 8 is prepared by the following reaction:

[ Claim 9 ]

The method of claim 8, wherein the compound of Formula 6 is prepared from the compound of Formula 9:

[ Claim 10]

The method of claim 9, wherein the compound of Formula 9 is prepared from the compound of Formula 10:

[Claim 11]

The method of claim 10, wherein the compound of Formula 10 is prepared by the following reaction:

(10)

[Claim 12]

The method of claim 11, wherein the compound of Formula 11 is prepared from the compound of Formula 12:

[Claim 13]

The method of claim 12, wherein the compound of Formula 12 is prepared by the following reaction:

(12)

[ Claim 14]

A micelle formed by self-assembly of the porphyrin derivative of any of claims 1 to 3 in an aqueous solution.

[ Claim 15 ]

The micelle of claim 14, wherein the micelle has a size of 20 to 100 nm.

[ Claim 16]

An MRI contrast agent comprising the porphyrin derivative of any of claims 1 to 3.