JP2005120026A - Near infrared fluorescent contrast medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a near infrared fluorescent contrast medium radiating fluorescent light in a region in which the fluorescent light penetrates a biomedical tissue, and exhibiting excellent water-solubility and excreting properties. <P>SOLUTION: The near infrared fluorescent contrast medium contains a compound represented by general formula (I) (wherein, R1 and R2 are each an aliphatic group substituted with a water-soluble group; R3 and R4 are each a lower alkyl group or a nonmetallic atomic group forming a carbon ring by forming a bond between the R3 and the R4; L1 to L7 are each the same or different methine group; Z1 and Z2 are each a nonmetallic atomic group required for forming a 5- or 6-membered condensed ring; X is a charge required for neutralizing the charge of the molecule; p is the number required for neutralizing the charge of the whole molecule; m is an integer of 3-6; and n is 1 or 2). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fluorescent contrast agent.

  When treating a disease, it is required to detect a morphological change caused by the disease in a living body in an early stage of the disease with a precise and quick method. Especially when treating cancer, the determination of the location and size of the initial small lesion is essential for early treatment.

  Examples of methods already known for this purpose include diagnostic imaging, such as endoscopic biopsy, X-ray imaging, MRI and ultrasound imaging. Biopsy is effective in confirming the diagnosis because it can directly observe the lesion, but at the same time, the subject is forced to ache or pain. X-ray imaging and MRI expose the subject to radiation and magnetic fields that are harmful if excessive, and the exposure time increases in proportion to the tracking time when trying to track the time course. Equipment and devices are also large, and a great deal of labor and cost is required for their installation and maintenance.

  On the other hand, near-infrared fluorescence photography has recently attracted attention as a diagnosis that can be miniaturized, reduce driving effort, and simplify use. It is said that near-infrared light can be easily transmitted through living tissue because of no hemoglobin absorption in that region, and can be inspected and diagnosed up to 10 to 20 cm in thickness. Therefore, it has come to be developed as a diagnostic technique for near infrared CT while attracting attention in the field of clinical medicine. In this method, a compound that emits fluorescence when irradiated with excitation light having a near-infrared wavelength of 700 nm to 1000 nm as a contrast agent is irradiated into the living body and has a near-infrared wavelength from outside the body. Irradiation with excitation light, and detection of fluorescence emitted from a compound administered in the body, that is, a so-called fluorescent contrast agent, determines the lesion.

  As such a fluorescent contrast agent, for example, compounds such as porphyrin compounds and hematoporphyrin that accumulate in tumors are known. These compounds are excited by near-infrared light irradiation to generate triplet oxygen that can oxidize the living body of the lesion, killing cells of the lesion such as cancer, and treating them. Although possible, there is a risk of destroying tissues other than the lesion. On the other hand, contrast methods using known fluorescent dyes such as fluorescein and fluoresamine are known (US Pat. No. 4,945,239), but these fluorescent dyes have very low light transmission in the living body. It emits blue to green light and cannot detect lesions in the inner part of the body.

Cyanine dyes that emit fluorescence in the near infrared region are expected as fluorescent contrast agents, and various cyanine dye compounds have been studied. Since the reporting of fluorescent contrast agents of cyanine compounds, techniques using various peripheral cyanine compounds as contrast agents have been disclosed in order to change them into compounds with high hydrophilicity, molar extinction coefficient, and quantum yield (for example, patent documents) 1, 2, 3). However, no safe contrast agent has been found that combines the ability to distinguish normal tissue from diseased tissue (contrast power) and the complete discharge from the living body after contrast (non-accumulative).
JP-A 2000-95758, pages 1 to 20 JP-T 2002-526458, pages 1-33 JP-A-2003-160558, pages 1-6

  An object of the present invention is to provide a fluorescent contrast agent that emits fluorescence in a region that can be transmitted through a living tissue and exhibits excellent water solubility and excretion.

The above object of the present invention can be achieved by the following constitution.
(Claim 1)
A near-infrared fluorescent contrast agent comprising a compound represented by the following general formula (I):

(In the formula, R ₁ and R ₂ each represents an aliphatic group substituted with a water-soluble group, and R ₃ and R ₄ are each a lower alkyl group or a carbon bonded to R ₃ and R _4. Represents a group of non-metallic atoms that form a ring, and L _{1 to} L ₇ each represent the same or different methine group, and Z ₁ and Z ₂ each represent a non-ring necessary to form a 5-membered or 6-membered condensed ring. Represents a group of metal atoms, X represents a charge necessary to neutralize the charge of the molecule, p represents a number necessary to neutralize the charge of the whole molecule, m represents an integer of 3 to 6, and n Represents 1 or 2.)
(Claim 2)
The near-infrared fluorescent contrast agent according to claim 1, wherein the water-soluble group is a sulfonic acid group.
(Claim 3)
The near-infrared fluorescence imaging according to claim 1 or 2, wherein the general formula (I) is a compound represented by the following general formula (II) having at least two water-soluble groups in the molecule. Agent.

(In the formula, J ₁ and J ₂ each represent an alkylene group having 1 to 5 carbon atoms, and R ₃ , R ₄ , L _{1 to} L ₇ , m, n, p and X are each a general formula. (Same definition as in (I), R _{10 to} R ₁₇ each represent a hydrogen atom and a substituent having a π value smaller than 0.3.)
(Claim 4)
The near-infrared fluorescent contrast agent according to claim 2 or 3, wherein the number of the sulfonic acid groups is at least four.
(Claim 5)
The near-infrared fluorescent contrast agent according to claim 3 or 4, wherein the compound represented by the general formula (II) is represented by the following general formula (III).

(Wherein R ₅ and R ₆ each represent an alkyl group having 3 to 5 carbon atoms substituting the sulfonic acid group, and R ₃ , R ₄ , L _{1 to} L ₇ , m, n, p And X are respectively the same as defined in formula (I), and R _{10 to} R ₁₇ each represent a hydrogen atom and a substituent having a π value of less than 0.3.

  The near-infrared fluorescent contrast agent of the present invention emits fluorescence excellent in permeability of living tissue by excitation light, and is excellent in water solubility and dischargeability, and therefore can be used safely.

  Hereinafter, the present invention will be described in detail.

  The near-infrared fluorescent contrast agent of the present invention means a contrast agent that emits fluorescence in the near-infrared region.

Examples of the “aliphatic group” in the “aliphatic group substituting a water-soluble group” represented by R ₁ and R ₂ include an alkyl group, an alkenyl group, a cyclic alkyl group, and an alkynyl group. The alkyl group is preferably a linear or branched lower alkyl group having 1 to 5 carbon atoms, specifically, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl. Group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-methylpropyl group, 1,1-dimethylpropyl group, etc., and preferably an alkenyl group having 3 to 5 carbon atoms. Linear or branched lower alkenyl group, specifically, allyl group, 2-butenyl group, isobutenyl group and the like, and the cyclic alkyl group is preferably a lower alkyl group having 3 to 6 carbon atoms. Specific examples include a cyclopropyl group, a cyclobutyltyl group, a cyclopentyl group, a cyclohexyl group, etc., and preferred as an alkynyl group. Properly is a linear or branched lower alkynyl group having 3 to 5 carbon atoms, specifically 2-propynyl group, 2-butynyl group.

Examples of water-soluble groups include sulfonic acid groups, carboxyl groups, hydroxyl groups, and phosphate groups. Specific examples of the alkyl group substituted with a water-soluble group include 2-hydroxyethyl group, 2-hydroxy-3-sulfopropyl group, 3-hydr-hydroxypropyl group, carboxymethyl group, carboxyethyl group, carboxy Butyl group, 2-phosphonoethyl group, 3-phosphonopropyl group, sulfomethyl group, 2-sulfoethyl group, 3-sulfopropyl group, 4-sulfobutyl group, 3-sulfobutyl group, 2-hydroxy-3-sulfopropyl group Etc. More preferably, R ₁ and R ₂ are lower alkyl groups having 1 to 5 carbon atoms substituted with a sulfonic acid group (for example, 2-sulfoethyl group, 3-sulfopropyl group, 4-sulfobutyl group, 3-sulfobutyl group). , 2-hydroxy-3-sulfopropyl group, etc.).

The “lower alkyl group” represented by R ₃ and R ₄ is an alkyl group having 1 to 5 carbon atoms, and specifically includes a methyl group, an ethyl group, a propyl group, a butyl group, and an isobutyl group. Examples of the carbocycle formed by bonding between R ₃ and R ₄ include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring.

The 5-membered and 6-membered condensed ring formed by the nonmetallic atom group represented by Z ₁ and Z ₂ is, for example, a heterocyclic condensed ring, a benzo condensed ring or a naphtho condensed ring, and any arbitrary ring on the condensed ring. Any group can be substituted at the position. Specific examples of the substituent on these condensed rings include a sulfonic acid group, a carboxyl group, a hydroxyl group, a cyano group, and a substituted amino group (for example, dimethylamino group, diethylamino group, ethyl-4-sulfobutylamino group, di (3 -Sulfopropyl) amino group, etc.), or a substituted or unsubstituted alkyl group (as defined above) bonded to the ring directly or through a divalent linking group. As the divalent linking group, for example, —O—, —NHCO—, —NHSO ₂ —, —NHCOO—, —NHCONH—, —COO—, —CO—, —SO ₂ — and the like are preferable. Examples of the substituted or unsubstituted alkyl group bonded to the ring directly or through a divalent linking group include a methyl group, an ethyl group, a propyl group, and a butyl group, preferably a methyl group and an ethyl group. Preferred examples thereof include a sulfonic acid group, a carboxyl group, and a hydroxyl group, with a sulfonic acid group being particularly preferred. Among these condensed rings, a carbon condensed ring substituted with a water-soluble group and a nitrogen-containing condensed heterocyclic ring are preferable.

Examples of the substituent for the methine group represented by L _{1 to} L ₇ include a substituted or unsubstituted alkyl group (for example, substituted, non-substituted such as methyl, ethyl, propyl, butyl, benzyl, 2-phenoxyethyl, and 2-sulfoethyl). Substituted group), halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), substituted or unsubstituted aryl group (for example, phenyl group, sulfonic acid group-substituted phenyl group, methoxy group-substituted phenyl group, naphthyl group, etc. ), A heterocyclic group (for example, furyl group, thienyl group, pyrrolyl group, imidazolyl group, pyrrolidino group, morpholino group, etc.), lower alkoxy group (for example, methoxy group, ethoxy group, etc.), amino group (for example, dimethylamino group) , 2-sulfoethylamino group, etc.). Further, the substituents of the methine group represented by L _{1 to} L ₇ may be bonded to form a ring containing three methine groups, and this ring further forms a condensed ring with a ring containing another methine group. It may be formed. Preferred as a substituent for the methine group represented by L _{1 to} L ₇ are an alkyl group, an amino group, and a heterocyclic group. Specific examples of the ring containing three methine groups formed by combining substituents of the methine group represented by L _{1 to} L ₇ include a cyclopentene ring, a cyclohexene ring and a 4,4-dimethylcyclohexene ring. In the present invention, a cyclopentene ring is particularly preferable.

  The charge necessary for neutralizing the charge represented by X may be any as long as it forms a non-toxic salt with the compound represented by formula (I). As alkali metal ions such as sodium and potassium, alkaline earth metal ions such as magnesium and calcium, organic ammonium ions such as ammonium, triethylammonium, tributylammonium and pyridinium; ammonium ions of amino acids such as lysine salts and arginine salts Specific examples of the anion include halogen ions such as chlorine, bromine and iodine, organic carboxylic acid ions such as sulfate ion, acetic acid and citric acid, and toluenesulfonic acid. Particularly preferred are sodium ions and chloride ions that are less toxic to the living body.

In the general formula (II), examples of the alkylene group having 1 to 5 carbon atoms represented by J ₁ and J ₂ include a methylene group, an ethylene group, a propylene group, a butylene group, a pentene group, 2- A methylpropylene group etc. are mentioned, An ethylene group is preferable.

Next, the definition of π value used for the definition of the substituents R _{10 to} R ₁₇ in the general formula (II) will be described. The π value is a parameter indicating the influence of a substituent on the hydrophilicity / hydrophobicity of a compound molecule, and is defined by the following formula.

π = logP (PhX) −logP (PhH)
In the above formula, P means the partition coefficient of the compound with respect to octanol / water, and the difference between the log P value of the substituted benzene PhX and the log P value of the benzene is assigned as the π value of the substituent X. The logP value can be obtained by actual measurement by the method described in the following document (a), or can be obtained by calculation using the fragment method described in document (a) or the software package described in document (b). If the measured value does not match the calculated value, the measured π value is used in principle.

  (A) C.I. Hansch, A.M. J. et al. Leo, “Substituent Constants for Correlation Analysis in Chemistry and Biology”, John Wiley &amp; sold by Sons, New York, 1979, (b) Medichem software. .54 version).

  The π values for the respective substituents thus obtained are summarized as a list in the literature (a). The main ones with a π value of 0.3 or less are extracted as follows.

Substituent π value OH -0.67
CN -0.57
COCH ₃ -0.55
COOH -0.32
OCH ₃ −0.02
COOCH ₃ −0.01
H 0.00
F 0.14
N (CH _{3) 2} 0.18.

Preferred substituents having a π value represented by R _{10 to} R ₁₇ of less than 0.3 include phosphono groups, sulfonic acid groups, carboxyl groups, hydroxyl groups, cyano groups, substituted amino groups (for example, dimethylamino groups, ethylamino groups). A divalent linking group having a π value of less than 0.3 (for example, —O—, —NHCO—, —NHSO ₂ —, —NHCOO—, —NHCONH—, —COO—, —CO—, — A substituted or unsubstituted methyl group or ethyl group (for example, methoxy group, 2-sulfoethyl group, 2-hydroxyethyl group, methylamino) having a π value of 0.3 or less bonded to the ring via SO ₂ — etc. Carbonyl group, methoxycarbonyl group, acetyl group, acetamide group, poropionylamino group, ureido group, methanesulfonylamino group, ethanesulfonylamino group, ethylaminocarbonyl And the like, and the like. A particularly preferred group is a sulfonic acid group.

In the general formula (III), the water-soluble group in the sulfoalkyl group having 3 to 5 carbon atoms substituting the water-soluble group represented by R ₅ or R ₆ may be the above general formula (I In addition to the groups defined in (1), a hydrophilic nonionic group is exemplified, and examples thereof include a carbamoyl group, a sulfamoyl group, an acetamido group, a sulfonamido group, and a methanesulfonamido group. -3-sulfopropyl group, 2-carbamoylmethyl-4-sulfobutyl group, 2-acetamido-4-sulfobutyl group, 2-sulfamoyl-3-sulfopropyl group, 3-methanesulfonamido-5-sulfopentyl group, 3- Examples include groups such as methanesulfonyl-4-sulfobutyl group, 2-carboxy-4-sulfobutyl group, 3-phosphonooxy-5-sulfobutyl group, and the like. Especially 2-hydroxy-3-sulfopropyl group.

  In general formula (I), general formula (II), and general formula (III), n is preferably 1.

  When a fluorescent contrast agent is used in a living body, it is mentioned that it is water-soluble as a particularly necessary characteristic. In the near-infrared fluorescent contrast agent of the present invention, three or more sulfonic acid groups are contained in the compound. Introducing a remarkable improvement effect in water solubility. In water solubility, the number of sulfonic acid groups is preferably 4 or more.

The sulfonic acid group is any _one of R ₁ , R ₂ , Z ₁ and / or Z ₂ in the general formula (I), and R ₅ , R ₆ and R _{10 to} R ₁₇ in the general formula (III). It is preferably introduced at the position. Further, the sulfonic acid group is preferably introduced into L _{4 of the} conjugated methine chain via a divalent group such as an alkylene group. A lower alkyl group having 1 to 5 carbon atoms, which is represented by the general formula (III) and is substituted with a nonionic water-soluble group and a sulfonic acid group in R ₅ and R ₆ , and the sulfonic acid group in the molecule Sodium salts of compounds having 3 or more are particularly desirable.

  Specific examples of the compounds represented by the general formula (I) (including the compounds represented by the general formula (II) and the general formula (III)) used in the present invention are shown below. It is not limited.

  The compound included in the near-infrared fluorescent contrast agent of the present invention is a compound represented by the general formula (I) to the general formula (III), and has 3 or more, preferably 4 sulfonic acid groups in the molecule. It will not specifically limit if it has more than one.

  The compound is F.I. M.M. Hammer in The Cyanines Dies and Related Compounds, John Wiley and Sons, New York, 1964, Cytometry, 10 (1989) 3-10, Cytometry, 11 (1990) 418-430, Cy12 et al. Chem. 4 (1993) 105-111, Anal. Biochem. 217 (1994) 197-204, Tetrahedron 45 (1989) 4845-4866, European Patent Application Publication Nos. 591,820A1, 580,145A1, JP-A-4-147131, JP-A-2003-48891. Can be synthesized according to the known methods for producing cyanine compounds described in JP-A Nos. 2003-64063, 2003-261464, etc., and can be appropriately known from commercially available cyanine compounds. Can also be semi-synthesized. More specifically, it can be synthesized by a reaction between a dianyl compound and a heterocyclic quaternary salt.

  The compound represented by the general formula (I) of the present invention is synthesized, for example, by the following method, and other compounds can be synthesized in the same manner.

Compound No. Synthesis of 3 Heterocycl. Chem. To 4.2 g of heterocyclic quaternary salt compound Q-1 synthesized with reference to 39,2,2002,252 to 262, 20 ml of acetic acid, 3 g of triethylamine, 1.58 g of dianyl compound D-1 and 3 g of acetic anhydride And stirred at room temperature for 6 hours. Insoluble matter was removed by filtration, and 15 ml of a methanol solution containing 2 g of sodium acetate was added to the filtrate concentrated under reduced pressure at room temperature. After stirring for 1 hour at room temperature, the resulting crystals were collected by filtration and filtered with a small amount of methanol. Washed. 2.7 g of the obtained crude crystals were dissolved in 15 ml of water, 1 g of sodium acetate was added, 30 ml of methanol was added, and the mixture was stirred for 1 hour. The resulting crystals were collected by filtration, washed with a small amount of methanol, and dried to give 2.2 g of Compound No. 3 was obtained. Absorption maximum wavelength (MeOH): 771 nm, molar extinction coefficient (MeOH): 260,000.

  Salts that can be used in the compounds of the present invention may be those that form non-toxic salts with the compounds of general formula (I). Examples thereof include alkali metal salts such as sodium salts and potassium salts; alkaline earth metal salts such as magnesium salts and calcium salts, tryptophan, methionine, lysine, phenylalanine, leucine, isoleucine, valine, threonine and arginine. And amino acid salts such as salts thereof. Particularly preferred are sodium salts that have low toxicity in vivo.

  The near-infrared fluorescent contrast agent of the present invention is produced by means such as injection, spraying or application into blood vessels (veins, arteries), oral, intraperitoneal, subcutaneous, intradermal, intravesical, intratracheal (branch), etc. Can be administered into the body. The dose of the near-infrared fluorescent contrast agent of the present invention is not particularly limited as long as it is an amount that can finally detect the site to be diagnosed, and the type of compound that emits near-infrared fluorescence to be used, the age of the subject to be administered It can be appropriately increased or decreased depending on the size of the body, the target organ, etc., but is usually 0.1-100 mg / kg · body weight, preferably 0.5-20 mg / kg · body weight.

  The near-infrared fluorescent contrast agent of the present invention can also be suitably used as a contrast agent for animals, and its administration form, administration route, dosage, etc. are appropriately selected depending on the body weight and state of the target animal.

  The near-infrared contrast agent of the present invention has a property of accumulating in a tumor tissue at a certain concentration and being easily discharged outside the body when the concentration is less than a certain concentration. Can be used as a fluorescent contrast agent capable of performing contrast imaging. Further, the compound of the present invention is difficult to diffuse out of the blood vessel wall once injected into the blood vessel, has a high property of staying in the blood vessel, and can be used as an angiographic agent.

  The fluorescence contrast method according to the present invention is characterized by using the near-infrared fluorescent contrast agent of the present invention. The measurement method is performed using a method known to those skilled in the art. The conditions of the excitation wavelength, the fluorescence wavelength for detection, and the like are optimized so as to obtain the optimal and best detection state. It is determined appropriately according to the type, subject to be administered and the like. The time required to start measurement using the fluorescence imaging method according to the present invention after the near-infrared fluorescent contrast agent of the present invention is administered to the measurement object is also the type of the fluorescent contrast medium to be administered and the subject to be administered. For example, when administered for the purpose of tumor or cancer imaging, it is preferable to select an elapsed time of about 10 minutes to 6 hours after administration. If the elapsed time is too short, the fluorescence is unevenly distributed on the whole and it is difficult to distinguish between the target site and the other site, and if it is too long, the contrast agent is excreted outside the body. For the purpose of angiography, it is preferable to measure at an elapsed time of 1 hour after administration.

  After the near-infrared fluorescent contrast agent used in the present invention is administered to the measurement object, the excitation light is irradiated to the measurement object by the excitation light source, and the fluorescence from the fluorescent contrast agent generated by the excitation light is detected by the fluorescence detector. To do. The wavelength for excitation varies depending on the fluorescent contrast agent to be used, and is not particularly limited as long as the compound of the present invention emits fluorescence efficiently, but near infrared light excellent in biopermeability is preferably used. Usually, excitation is performed with excitation light having a wavelength of 600 to 1000 nm, preferably 700 to 850 nm, and fluorescence is detected with high sensitivity. In this case, as the fluorescence excitation light source, various laser light sources such as an ion laser, a dye laser, a semiconductor laser, or a normal excitation light source such as a halogen light source or a xenon light source may be used. Various optical filters can be used to obtain. Similarly, when detecting fluorescence, the fluorescence detection sensitivity can be increased by using various optical filters that select only fluorescence from the fluorescent contrast agent.

  Examples are given below to describe the present invention in more detail, but the present invention is not limited by these.

(Preparation of a breast cancer model mouse)
Production of Breast Cancer Carcinogenesis Model Mice Aging-promoting mice, SAMP6 / Ta mice, one of the so-called SAM strains, are administered with a carcinogen 7,12-dimethylbenz [a] anthracene (DMBA) to develop breast cancer. A carcinogenic model mouse was created. The method for carcinogenesis in mice was performed according to Japanese Patent Application Laid-Open No. 2003-33125.

  20 SAMP6 / Ta mice were administered to DMBA at a dose of 0.5 mg / mouse / week for a total of 6 times. As feed, high protein and high calorie CA-1 solid (manufactured by Claire Japan) was given. After the sixth administration of the carcinogen, the period from the first administration up to the 20th week was defined as a drug holiday. Breast cancer and lung metastases of breast cancer were examined histopathologically. DMBA was administered 6 times at weekly intervals, and the drug was withdrawn from the start of the subsequent administration until the 20th week, and mice with breast cancer (75% breast cancer incidence) were used.

(Fluorescence contrast test)
A tumor tissue fragment (2 mm × 2 mm square) of a breast cancer mouse was transplanted subcutaneously into the breast of the left breast of a BALB / c nude mouse (5 weeks old, Claire Japan). Ten days later, when the tumor grew to a diameter of about 5 mm, the mouse was subjected to the test. A titanium sapphire laser was used as the fluorescence excitation light source. The test mice were uniformly irradiated with laser light using a ring type light guide (Sumita Optical Glass Co., Ltd.) so that the dispersion of irradiation was within 2%. The irradiation output was adjusted to be about 36 μW / cm ² near the skin surface of the mouse. Fluorescence was excited at the maximum excitation wavelength of each compound, and fluorescence emission from the mouse was detected and imaged through a short wavelength cut filter using a CCD camera (C4880, Hamamatsu Photonics). The cut filter was selected to match the excitation wavelength (800-900 nm) of the compound. The irradiation time was adjusted according to the fluorescence intensity of each compound.

  Each test compound shown in Table 1 was dissolved in physiological saline to a concentration of 0.5 mg / ml and administered to the mouse via the tail vein. The dose was 1 mg / kg each. Twelve minutes after compound administration, the mice were anesthetized with diethyl ether, and a fluorescent image of the whole mouse was imaged. As a sensor, a photodiode (wavelength range: 220 to 730 nm) of a fluorometer (JASCO FP-750) was used.

  The relative fluorescence sensitivity was represented by the fluorescence intensity of the tumor part of each near-infrared contrast agent when the fluorescence intensity of the tumor part of the comparison (102) was 100. The remaining amount of the contrast agent in the blood is defined as the amount of the compound in the body (1 mg / kg) after administration of the contrast agent being 100, and the concentration in plasma after 1 hour, 24 hours, and 48 hours is calculated using the liquid chromatograph 2010A ( Obtained from Shimadzu Corporation). The results are shown in Table 1. As comparative contrast agents, indocyanine green (C-1) described in JP-A-2000-95758 and (C-2) and (C-3) described in JP-A-2003-261464 were used.

  In the water solubility test of the compound, 0.5 mg of the sample was dissolved to 1 ml with 0.9% physiological saline, and left standing in the dark at a storage temperature of 40 ° C. for 2 weeks to confirm precipitation and precipitation. did. A level at which no haze was applied was evaluated as し ま う, a level that disappeared by stirring was evaluated as ○, a level at which haze was applied but did not disappear by stirring was evaluated as △, and a level at which precipitation occurred was evaluated as ×. .

  From Table 1, it can be seen that the compound of the present invention emits fluorescence excellent in permeability of living tissue and is excellent in water solubility and excretion.

Claims (5)

A near-infrared fluorescent contrast agent comprising a compound represented by the following general formula (I):

(In the formula, R ₁ and R ₂ each represents an aliphatic group substituted with a water-soluble group, and R ₃ and R ₄ are each a lower alkyl group or a carbon bonded to R ₃ and R _4. Represents a group of non-metallic atoms that form a ring, and L _{1 to} L ₇ each represent the same or different methine group, and Z ₁ and Z ₂ each represent a non-ring necessary to form a 5-membered or 6-membered condensed ring. Represents a group of metal atoms, X represents a charge necessary to neutralize the charge of the molecule, p represents a number necessary to neutralize the charge of the whole molecule, m represents an integer of 3 to 6, and n Represents 1 or 2.) The near-infrared fluorescent contrast agent according to claim 1, wherein the water-soluble group is a sulfonic acid group. The near-infrared fluorescence imaging according to claim 1 or 2, wherein the general formula (I) is a compound represented by the following general formula (II) having at least two water-soluble groups in the molecule. Agent.

(In the formula, J ₁ and J ₂ each represent an alkylene group having 1 to 5 carbon atoms, and R ₃ , R ₄ , L _{1 to} L ₇ , m, n, p and X are each a general formula. (Same definition as in (I), R _{10 to} R ₁₇ each represent a hydrogen atom and a substituent having a π value smaller than 0.3.) The near-infrared fluorescent contrast agent according to claim 2 or 3, wherein the number of the sulfonic acid groups is at least four. The near-infrared fluorescent contrast agent according to claim 3 or 4, wherein the compound represented by the general formula (II) is represented by the following general formula (III).

(Wherein R ₅ and R ₆ each represent an alkyl group having 3 to 5 carbon atoms substituting the sulfonic acid group, and R ₃ , R ₄ , L _{1 to} L ₇ , m, n, p And X are respectively the same as defined in formula (I), and R _{10 to} R ₁₇ each represent a hydrogen atom and a substituent having a π value of less than 0.3.