Radioactively labeled compound

Abstract

The present invention relates to radiolabeled compounds, precursor compounds and reference compounds as described herein, and pharmaceutical compositions comprising the radiolabeled compounds, which are used in diagnostic methods carried out on a human or animal body using positron emission tomography (PET).

Description

Technical Field

[0001] The present invention relates to radiolabeled compounds, precursor compounds and reference compounds, and pharmaceutical compositions comprising said radiolabeled compounds. Aspects of the present invention also relate to radiolabeled compounds for use in diagnostic methods performed on a human or animal body using positron emission tomography (PET). Further aspects of the present invention relate to methods for radiolabeling precursor compounds to form radiolabeled compounds, and methods for preparing precursor compounds or reference compounds. Background Art

[0002] Reactive oxygen species (ROS) are produced as by-products of the electron transport chain in living cells. At low levels, and in the presence of endogenous antioxidants, ROS play an integral role in regulating cell growth, neurotransmission and immune responses. However, at elevated levels, they cause oxidation of DNA, proteins and lipids and underlie the pathogenesis of many cardiovascular and neurodegenerative diseases as well as cancer and inflammatory disorders.

[0003] In the cardiovascular system, increased ROS are responsible for tissue damage during ischemia / reperfusion and are associated with the progression from cardiac hypertrophy to heart failure, the evolution of atherosclerotic plaques and diabetes-related cardiac and microvascular dysfunction. ROS production is also associated with the cardiotoxicity of cancer chemotherapeutic agents, which severely limits their dosimetry and effectiveness. Most notably, the cardiotoxicity induced by the widely used cancer chemotherapeutic agent doxorubicin is associated with ROS production.

[0004] For both diagnostic and prognostic purposes, as well as in the development and evaluation of emerging targeted antioxidant therapies, a clinically translatable means for non-invasively identifying and quantifying increased ROS production in vivo would be highly desirable.

[0005] Positron emission tomography (PET) is a non-invasive nuclear imaging technique that uses radiolabeled molecules to detect the expression of targets or monitor metabolic processes in the body. Some radiolabeled small molecules have been reported to indirectly report oxidative stress levels, and hydroethydium-based radiotracers have been tested in vivo in rodent models of cardiotoxicity and inflammation. However, there are currently no radiotracers for directly detecting ROS using PET imaging in clinical practice.

[0006] There is still a need for improved PET imaging tools for detecting ROS. Summary of the Invention

[0007] One aspect of the present invention provides a radiolabeled compound of formula (I):

[0008]

[0009] Wherein:

[0010] X is selected from -O-, -S- or -NR 20 -;

[0011] Z is a double bond or a triple bond;

[0012] R 1 is -H or -D;

[0013] R 2 and R 3 are linked to form part of an optionally substituted 5- or 6-membered aromatic ring;

[0014] R 4 is selected from -H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl and optionally substituted aryl;

[0015] R 5 is selected from optionally substituted alkylene, optionally substituted alkenylene, optionally substituted alkynylene and optionally substituted arylene;

[0016] R 20 is selected from -H, alkyl, alkenyl, alkynyl, acyl and aryl;

[0017] n is an integer from 0 to 18;

[0018] m is an integer from 0 to 18; and

[0019] p is an integer from 0 to 18;

[0020] or a pharmaceutically acceptable salt thereof.

[0021] Another aspect of the present invention provides a reference compound of formula (II):

[0022]

[0023] Wherein X, Z, R 1 、R 2 、R 3 、R 4 、R 5 、R 20 、n, m and p are as defined above for the radiolabeled compound of formula (I);

[0024] or a pharmaceutically acceptable salt thereof.

[0025] Another aspect of the present invention provides a precursor compound of formula (III):

[0026]

[0027] wherein

[0028] X, Z, R 1 , R 2 , R 3 , R 4 , R 5 , R 20 , n, m and p are as defined above for the radiolabeled compound of formula (I); and

[0029] L is a leaving group;

[0030] or a pharmaceutically acceptable salt thereof.

[0031] Another aspect of the present invention provides a pharmaceutical composition comprising a radiolabeled compound of formula (I) and a pharmaceutically acceptable carrier.

[0032] Another aspect of the present invention provides a method for forming a radiolabeled compound of formula (I) from a radiolabeled precursor compound.

[0033] Yet another aspect of the present invention provides a method for preparing a precursor compound or a reference compound, the method comprising the following steps:

[0034] (i) reacting a compound of formula (A) with a compound of formula (E) via a cyclization reaction to form a compound of formula (B); and

[0035] (ii) reacting the compound of formula (B) with a compound of formula (F) via a nucleophilic addition reaction to form a compound of formula (C); and

[0036] (iii) reducing the compound of formula (C) to form a compound of formula (D);

[0037] According to the following reaction scheme:

[0038]

[0039] wherein X, Z, R 1 , R 2 , R 3 , R 4 , R 5 , R 20 , n, m and p are as defined above for the radiolabeled compound of formula (I);

[0040] L' is -F or a leaving group L as defined above for the precursor compound of formula (III); and

[0041] L" is a leaving group.

[0042] Yet another aspect of the present invention provides a radiolabeled compound of formula (I) for use in a diagnostic method performed on a human or animal body using positron emission tomography (PET).

[0043] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of these words, such as "comprising" and "comprises", mean "including but not limited to" and do not exclude other components, integers or steps. Further, unless the context otherwise requires, the singular encompasses the plural, and in particular, in the case of using an indefinite article, unless the context otherwise requires, the specification should be understood to contemplate both the plural and the singular.

[0044] Preferred features of each aspect of the present invention may be combined with any one of the other aspects as described. Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set forth in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular, their individual features, may be adopted independently or in any combination. That is, all embodiments and / or features of any embodiment may be combined in any manner and / or combination, unless such features are incompatible. Description of the Drawings

[0045] One or more embodiments of the present invention will now be described by way of example only with reference to the drawings, in which:

[0046] Figure 1 The proposed mechanism for the direct detection of intracellular oxidative stress by the PET radiotracer 18 18F-FM074 is shown.

[0047] Figure 2 shows (A) 18 the HPLC chromatogram of the 18F-FM074 preparation; (B) 18 the co-elution of 18F-FM074 with its non-radioactive reference compound; (C) 18 the HPLC chromatogram of the 18F-FM108 preparation; (D) 18 the co-elution of 18F-FM108 with its non-radioactive reference compound.

[0048] Figure 3 shows (A) the 18 stability of 18F-FM074 in rat serum at 37 °C within 1 hour as determined by radio-HPLC; (B) the 18 stability of 18F-FM108 in rat serum at 37 °C within 30 minutes (more than 30 minutes and less than 5 minutes) as determined by radio-HPLC.

[0049] Figure 4 shows (A) 18 F]FM074 and (B) 18 F]FM108's chemoselectivity.

[0050] Figure 5 shows 18 PET / CT imaging of F-FM074 in mice: a) PET / CT scans of representative mice at 1, 5, 20, and 60 min after injection; b) radioactive uptake in the heart; c) radioactive uptake in the brain; d) radioactive uptake in the kidney; e) radioactive uptake in the liver. Data are represented as SUV mean ± SD, n = 3.

[0051] Figure 6 shows at 1, 5, and 30 min after intravenous injection (A) 18 F-FM074 and (B) 18 F-FM074-Ox's biodistribution in healthy rats.

[0052] Figure 7 shows the ejection fractions of control and treated animals before and after treatment in a rat model of doxorubicin-induced cardiotoxicity.

[0053] Figure 8 shows representative sagittal, coronal, and axial images of co-registered PET / CT imaging from 18 F-FM074 in Wistar rats after 7 days of exposure to saline (n = 4, top) or doxorubicin (n = 6, bottom). Legend: M - micropump; LV - left ventricle.

[0054] Figure 9 shows the SUVRLV / blood at 3, 10, and 30 min after injection of 18 F-FM074.

[0055] Figure 10 shows the time-activity curves (standard uptake value relative to time) of 18 F-FM074 uptake in the left ventricle (LV) and intramyocardial blood pool in a rat model of doxorubicin-induced cardiotoxicity. Detailed Description

[0056] Aspects of the present invention provide or utilize radiolabeled compounds.

[0057] Suitably, the radiolabeled compound is a compound of formula (I):

[0058]

[0059] Wherein:

[0060] X is selected from -O-, -S- or -NR 20 -;

[0061] Z is a double bond or a triple bond;

[0062] R 1 is -H or -D;

[0063] R 2 and R 3 are linked to form part of an optionally substituted 5- or 6-membered aromatic ring;

[0064] R 4 is selected from -H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl and optionally substituted aryl;

[0065] R 5 is selected from optionally substituted alkylene, optionally substituted alkenylene, optionally substituted alkynylene and optionally substituted arylene;

[0066] R 20 is selected from -H, alkyl, alkenyl, alkynyl, acyl and aryl;

[0067] n is an integer from 0 to 18;

[0068] m is an integer from 0 to 18; and

[0069] p is an integer from 0 to 18;

[0070] or a pharmaceutically acceptable salt thereof.

[0071] In some embodiments, the radiolabeled compound of formula (I) can be used as a radiotracer in positron emission tomography (PET). As shown in the examples, the compound can have physicochemical properties that are favorable for unassisted cell membrane permeability and blood-brain barrier penetration. The radiolabeled compound of formula (I) can be oxidized intracellularly:

[0072]

[0073] After oxidation by intracellular ROS, the compound can become cationic and more hydrophilic, which can alter its pharmacokinetics and thus increase its intracellular retention (see Figure 1 ).

[0074] X is selected from -O-, -S- or -NR 20 -. Preferably, X is -O- or -S-. More preferably, X is -S-.

[0075] Z is a double bond or a triple bond. In one embodiment, Z is a double bond. In another embodiment, Z is a triple bond. When p is zero, Z does not exist.

[0076] R 1 is -H or -D. In one embodiment, R 1 is -H. In another embodiment, R 1 is -D. Deuterium can increase the oxidation potential of the compound.

[0077] R 2 and R 3 are linked to form part of an optionally substituted 5- or 6-membered aromatic ring. R 2 and / or R 3 can be a heteroatom, such as nitrogen, oxygen or sulfur.

[0078] In one embodiment, the aromatic ring in the optionally substituted 5- or 6-membered aromatic ring is an optionally substituted 5-membered aromatic ring. Alternatively, the aromatic ring in the optionally substituted 5- or 6-membered aromatic ring is an optionally substituted 6-membered aromatic ring.

[0079] In the definition of the optionally substituted 5- or 6-membered aromatic ring, in addition to the substituents listed in the definition of the following optionally substituted groups, the substituent can also be linked to the 5- or 6-membered aromatic ring to form a fused ring.

[0080] In one embodiment, the aromatic ring in the optionally substituted 5- or 6-membered aromatic ring can be a fully carbon aromatic ring, such as benzene; or a heteroaromatic ring, such as pyridine, pyrimidine, pyrazine, pyrrole, imidazole, pyrazole, furan, thiophene, oxazole, isoxazole or thiazole.

[0081] Preferably, the aromatic ring in the optionally substituted 5- or 6-membered aromatic ring is selected from benzene, pyridine, pyrimidine, pyrazine, pyridazine, furan, thiophene and pyrrole.

[0082] Preferably, R 2 and R 3 are linked to form part of a 5- or 6-membered aromatic ring selected from the following:

[0083]

[0084] wherein

[0085] Y 1 is selected from -O-, -S- and -NR 20 -;

[0086] R 6 、R 7 、R 8 and R 9 are independently selected from -H, alkyl, alkenyl, alkynyl, aryl, -CF 3 、halogen, -B(OR 20 ) 2 、-OR 20 、-NR 202 、 -SR 20 、 -SiR 20 3 、 -SO 3 、 -SO 3 R 20 、 -SO 2 NR 20 2 、 -S(O)R 20 、 -C(O)R 20 、 -C(O)NR 20 2 、 -CO 2 R 20 、 -NO 2 and -CN;

[0087] R 10 and R 11 are independently selected from -H, alkyl, alkenyl, alkynyl, acyl and aryl; and

[0088] R 20 is as defined above.

[0089] Preferably, R 6 、 R 7 、 R 8 and R 9 are independently selected from -H and alkyl. More preferably, each of R 6 、 R 7 、 R 8 and R 9 is -H.

[0090] Preferably, R 2 and R 3 are linked to form

[0091] More preferably, R 2 and R 3 are linked to form part of a benzene ring.

[0092] R 4 is selected from -H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl and optionally substituted aryl.

[0093] In one embodiment, R 4 is -H.

[0094] Suitably, R 4 can be optionally substituted alkyl. The alkyl in the optionally substituted alkyl can be C 1-20 alkyl, or C 1-12 alkyl, such as C 1-8 alkyl, for example C 1-6 alkyl, or C1-4 An alkyl group, such as a methyl or ethyl group.

[0095] R 4 may be an optionally substituted alkenyl group. The alkenyl group in the optionally substituted alkenyl group may be C 2-20 alkenyl, or C 2-12 alkenyl, such as C 2-8 alkenyl, for example C 2-6 alkenyl, or C 2-4 alkenyl, for example vinyl (-CH=CH 2 ).

[0096] R 4 may be an optionally substituted alkynyl group. The alkynyl group in the optionally substituted alkynyl group may be C 2-20 alkynyl, or C 2-12 alkynyl, such as C 2-8 alkynyl, for example C 2-6 alkynyl, or C 2-4 alkynyl, for example ethynyl (-C≡CH).

[0097] Preferably, R 4 may be an optionally substituted aryl group. The aryl group in the optionally substituted aryl group may be a fully carbon aromatic moiety, such as phenyl (derived from benzene) or naphthyl (derived from naphthalene); or a heteroaryl moiety, such as pyridinyl (or pyridyl, derived from pyridine), pyrimidinyl (derived from pyrimidine), pyrazinyl (derived from pyrazine), pyrrolyl (derived from pyrrole), imidazolyl (derived from imidazole), pyrazolyl (derived from pyrazole), furyl (derived from furan), thienyl (derived from thiophene), oxazolyl (derived from oxazole), isoxazolyl (derived from isoxazole) or thiazolyl (derived from thiazole).

[0098] When R 4 is an optionally substituted aryl group, the aryl group in the optionally substituted aryl group may suitably be a 5- or 6-membered aromatic moiety, such as phenyl, pyridinyl, pyrimidinyl, pyrazinyl, pyrrolyl, imidazolyl, pyrazolyl, furyl, thienyl, oxazolyl, isoxazolyl or thiazolyl. Preferably, the optionally substituted aryl group is an optionally substituted phenyl, an optionally substituted pyridinyl, an optionally substituted pyrrolyl, an optionally substituted furyl, thienyl or an optionally substituted thienyl. More preferably, R 4 is an optionally substituted phenyl.

[0099] In a preferred embodiment, R 4 is a 5- or 6-membered aromatic moiety selected from the following:

[0100]

[0101] wherein

[0102] Y 2 Selected from -O-, -S- and -NR 20 -;

[0103] R 12 , R 13 , R 14 , R 15 and R 16 are independently selected from -H, alkyl, alkenyl, alkynyl, aryl, -CF 3 , halogen, -B(OR 20 ) 2 、-OR 20 、-NR 20 2 、-SR 20 、-SiR 20 3 、-SO 3 、-SO 3 R 20 、-SO 2 NR 20 2 、-S(O)R 20 、-C(O)R 20 、-C(O)NR 20 2 , -CO 2 R 20 、-NO 2 and -CN; and

[0104] R 20 As defined above.

[0105] Preferably, R 12 , R 13 , R 14 , R 15 and R 16 is independently selected from -H and alkyl. More preferably, R 12 , R 13 , R 14 , R 15 and R 16 Each of -H.

[0106] Preferably, R 4 yes

[0107] More preferably, R 4 It is phenyl.

[0108] R 5 is selected from optionally substituted alkylene, optionally substituted alkenylene, optionally substituted alkynylene and optionally substituted arylene.

[0109] In one embodiment, R 5 is an optionally substituted alkylene group. Preferably, R 5 is -(CH 2 ) q -, where q is an integer from 1 to 20. In one embodiment, q is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20. R 5 can be, for example, methylene, ethylene, propylene or butylene.

[0110] In a preferred embodiment, n and m are both zero, and R 5 is -(CH 2 ) q -, where q is an integer from 1 to 20, such as from 1 to 6. In one embodiment, q is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20. Preferably, q is 0, 1, 2, 3, 4, 5 or 6. More preferably, n and m are both zero, and R 5 is propylene (q is 3).

[0111] In another embodiment, R 5 is an optionally substituted arylene group. The arylene group in the optionally substituted aryl group can suitably be a 5- or 6-membered aromatic moiety, such as phenylene, pyridylene, pyrimidinylene, pyrazinylene, pyrrolylene, imidazolylene, pyrazolylene, furanylene, thienylene, oxazolylene, isoxazolylene or thiazolylene. Preferably, the optionally substituted arylene group is an optionally substituted phenylene group.

[0112] Throughout the specification, R 20 is selected from -H, alkyl, alkenyl, alkynyl, aryl and acyl; for example, -H, C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, C 3-20 aryl and acyl. Preferably, R 20 is -H or C 1-20 alkyl, such as C 1-6 alkyl.

[0113] n is an integer from 0 to 18.

[0114] In one embodiment, n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18. Preferably, n is 0, 1, 2, 3, 4, 5 or 6. More preferably, n is 0 or 1. Most preferably, n is 0.

[0115] m is an integer from 0 to 18.

[0116] In one embodiment, m is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18. Preferably, m is 0, 1, 2, 3, 4, 5 or 6. More preferably, m is 0 or 1. Most preferably, m is 0.

[0117] p is an integer from 0 to 18.

[0118] In one embodiment, p is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18. In one embodiment, p is 0 or 1. Preferably, p is 0.

[0119] In one embodiment, the compound of formula (I) is phenylbenzothiazole.

[0120] In one embodiment, the compound of formula (I) is a compound of the following formula:

[0121]

[0122] This compound is 18 F]3-(3-fluoropropyl)-2-phenyl-2,3-dihydrobenzothiazole. Throughout the specification, it is phenylbenzothiazole and may be interchangeably referred to as 18 F-FM074,

[0123] 18 F]FM074 or 18 F-ROS-PROBE.

[0124] The compound of formula (I) may exist in the form of a pharmaceutically acceptable salt.

[0125] Another aspect of the present invention provides a reference compound of formula (II):

[0126]

[0127] wherein X, Z, R 1 、R 2 、R 3 、R 4 、R 5 、R 20 、n, m and p are as defined above for the radiolabeled compound of formula (I);

[0128] or a pharmaceutically acceptable salt thereof.

[0129] ​The reference compound of formula (II) can be used as a reference compound for the radiolabeled compound of formula (I), said reference compound having a 18 F atom that replaces the

[0130] Another aspect of the present invention provides a precursor compound of formula (III):

[0131]

[0132] wherein

[0133] X, Z, R 1 、R 2 、R 3 、R 4 、R 5 、R 20 、n, m and p are as defined above for the radiolabeled compound of formula (I); and

[0134] L is a leaving group;

[0135] or a pharmaceutically acceptable salt thereof.

[0136] The precursor compound of formula (III) can be used as a precursor compound for the radiolabeled compound of formula (I), said precursor compound having a 18 leaving group that replaces the

[0137] F atom in formula (I).

[0138] Preferably, L is selected from -I, -Br, -Cl and sulfonate groups such as trifluoromethanesulfonate group (-OTf), methanesulfonate group (-OMs) and tosylate group (-OTs). More preferably, L is selected from -I, -Br, -OTf, -OMs and -OTs. Most preferably, L is -I.

[0139] Another aspect of the present invention provides a method for radiolabeling a precursor compound to form a radiolabeled compound of formula (I).

[0140] The radiolabeled compound of formula (I) contains 18 F radioisotope. 18 F-fluoride is a commonly used PET radioisotope due to the mainstream use of 18 F-FDG (2-deoxy-2-[fluoro-18]fluoro-D-glucose) scans. 18 F has a relatively short half-life (t 1 / 2= 109 min). The radiolabeling method of the present invention can provide a "late-stage" 18 18F-labeling strategy, in which the radioisotope is added only in the last process step before use. Furthermore, as can be seen from the examples, the radiolabeling step of the present invention achieves very high radiochemical yields and molar activities. Compared to other known PET radiotracers with lower (much lower) radiolabeling yields, this means that a smaller amount of 18 18F is required to obtain the same amount of radiotracer, resulting in less exposure for radiotechnicians preparing radiotracers for PET imaging. Additionally, this means that the radiolabeling step can be easily automated on a large scale using existing radiosynthesis methods.

[0141] Preferably, the precursor compound in the radiolabeling method can be the precursor compound of formula (III) as defined above.

[0142] Suitably, the method comprises the step of reacting a precursor compound of formula (III) with nucleophilic fluoride-18 to form a radiolabeled compound of formula (I) according to the following reaction scheme:

[0143]

[0144] wherein X, Z, R 1 , R 2 , R 3 , R 4 , R 5 , R 20 , n, m and p are as defined above; and L is as defined above.

[0145] Suitably, the nucleophilic fluoride-18 can be provided, for example, in the form of a compound selected from K 18 18F, Cs 18 18F, tBu 4 18N 18 18F and Et 4 18N 18 18F.

[0146] Yet another aspect of the present invention provides a method for preparing a precursor compound or a reference compound, the method comprising the following steps:

[0147] (i) reacting a compound of formula (A) with a compound of formula (E) via a cyclization reaction to form a compound of formula (B); and

[0148] (ii) reacting the compound of formula (B) with a compound of formula (F) via a nucleophilic addition reaction to form a compound of formula (C); and

[0149] (iii) Reduce the compound of formula (C) to form a compound of formula (D);

[0150] According to the following reaction scheme:

[0151]

[0152] wherein X, Z, R 1 , R 2 , R 3 , R 4 , R 5 , R 20 are as defined above for the radiolabeled compound of formula (I);

[0153] L' is -F or the leaving group L as defined above for the precursor compound of formula (III); and

[0154] L" is a leaving group.

[0155] The method can be a method for preparing a precursor compound or a reference compound of the radiolabeled compound of formula (I).

[0156] In one embodiment, the method is a method for preparing the reference compound of formula (II) as defined above. In this embodiment, the compound of formula (D) is the reference compound of formula (II), and L' is -F.

[0157] In another embodiment, the method is a method for preparing the precursor compound of formula (III) as defined above. In this embodiment, the compound of formula (D) is the precursor compound of formula (III), and L' is the leaving group L as defined above. Preferably, the leaving group L can be selected from -I and -Br.

[0158] Suitably, L" can be a better leaving group than L'. For example, L" can be a more reactive leaving group than L'.

[0159] Preferably, the leaving group L" is a sulfonate group. The sulfonate group can be selected, for example, from trifluoromethanesulfonate group (-OTf), methanesulfonate group (-OMs) and tosylate group (-OTs); more preferably trifluoromethanesulfonate group (-OTf).

[0160] The precursor compound for radiolabeling provided by the present invention can be easily prepared in only a few synthetic steps. Therefore, the production of the precursor compound for clinical use is easy and economical.

[0161] In one embodiment of the method for preparing a precursor compound or a reference compound, the method further comprises the step of converting a compound of formula (G) into a compound of formula (F) according to the following reaction scheme:

[0162]

[0163] wherein R 5 n, m, L' and L" are as defined above.

[0164] Yet another aspect of the present invention provides a radiolabeled compound of formula (I) as defined above, which is used in a diagnostic method implemented on a human or animal body using positron emission tomography (PET).

[0165] Preferably, the diagnostic method is a method for detecting reactive oxygen species in a human or animal body.

[0166] Suitably, the diagnostic method may be a method for diagnosing a disease caused and / or aggravated by an increase in ROS production.

[0167] Diseases caused and / or aggravated by an increase in ROS production may be, for example, neurodegenerative diseases such as Alzheimer's disease or Parkinson's disease. Alternatively, diseases caused and / or aggravated by an increase in ROS production may be, for example, atherosclerotic plaques. Detection of vulnerable atherosclerotic plaques can prevent plaque rupture leading to myocardial infarction.

[0168] Suitably, the diagnostic method may be a method for monitoring the therapeutic efficacy of a therapy such as cancer chemotherapy or radiotherapy, or antioxidant therapy.

[0169] Definition

[0170] It should be understood that the wavy line (such as shown below) in any chemical structure or moiety shown herein indicates the attachment point of the structure or moiety.

[0171]

[0172] As used herein, the term "hydrogen" or "hydrogen atom" refers to the -H moiety.

[0173] As used herein, the terms "halo", "halogen" or "halogen atom" refer to the -F, -Cl, -Br or -I moiety.

[0174] As used herein, the term "hydroxy" or "hydroxyl" refers to the -OH moiety.

[0175] The prefix "C x " "C x-y” represents the number or range of carbon atoms present in the group. Thus, the term “C 1-12 alkyl” refers to an alkyl group having 1 to 12 carbon atoms.

[0176] The term “alkyl” refers to a monovalent moiety obtained by removing a hydrogen atom from a carbon atom of, for example, a saturated hydrocarbon compound having 1 to 20 carbon atoms, which may be straight-chain, branched-chain or cyclic. Thus, the term “alkyl” includes the following cycloalkyl subclasses. Examples of alkyl include, but are not limited to, methyl (C 1 ), ethyl (C 2 ), propyl (C 3 ), butyl (C 4 ), pentyl (C 5 ), hexyl (C 6 ), heptyl (C 7 ), octyl (C 8 ), nonyl (C 9 ) and decyl (C 10 ). Examples of straight-chain alkyl include, but are not limited to, methyl (C 1 ), ethyl (C 2 ), n-propyl (C 3 ), n-butyl (C 4 ), n-pentyl (pentyl) (C 5 ), n-hexyl (C 6 ) and n-heptyl (C 7 ). Examples of branched-chain alkyl include, but are not limited to, isopropyl (C 3 ), isobutyl (C 4 ), sec-butyl (C 4 ), tert-butyl (C 4 ), isopentyl (C 5 ) and neopentyl (C 5 ).

[0177] The term “cycloalkyl” refers to a monovalent moiety obtained by removing a hydrogen atom from a carbon atom of, for example, a cyclic saturated hydrocarbon compound having 3 to 20 carbon atoms. “Cycloalkyl” includes monocyclic and polycyclic, including bicyclic. Examples of monocyclic cycloalkyl include, but are not limited to, cyclopropyl (C 3 ), cyclobutyl (C 4 ), cyclopentyl (C 5 ), cyclohexyl (C 6 ), cycloheptyl (C 7 ) and methylcyclopropyl (C 4)。The cycloalkyl group includes bicyclic molecules in which one, two, three or more atoms are shared between the two rings. The term "fused cycloalkyl" refers to a bicyclic cycloalkyl in which each ring shares two adjacent atoms with the other ring. The second ring of the bicyclic cycloalkyl can be selected from saturated, unsaturated and aromatic rings. Examples of saturated polycyclic hydrocarbon compounds include, but are not limited to, thujane (C 10 ), carane (C 10 ), pinane (C 10 ), camphane (C 10 ), norcarane (C 7 ), norpinane (C 7 ), norbornane (C 7 ), adamantane (C 10 ) and decalin (C 10 ).

[0178] The term "alkenyl" refers to a monovalent hydrocarbon moiety obtained by removing a hydrogen atom from a carbon atom of a (partially) unsaturated hydrocarbon compound having one or more carbon-carbon double bonds and having, for example, 2 to 20 carbon atoms, which may be straight-chain, branched-chain or cyclic. Thus, the term "alkenyl" includes the following cycloalkenyl subclasses. Examples of alkenyl include, but are not limited to, ethenyl (vinyl, -CH=CH 2 ), 1-propenyl (-CH=CH-CH 3 ) and 2-propenyl (allyl, -CH-CH=CH 2 ).

[0179] The term "cycloalkenyl" refers to a monovalent cyclic hydrocarbon moiety obtained by removing a hydrogen atom from a carbon atom of a cyclic (partially) unsaturated hydrocarbon compound having one or more carbon-carbon double bonds and having, for example, 3 to 20 carbon atoms. "Cycloalkenyl" includes monocyclic and polycyclic, including bicyclic. Examples of unsaturated monocyclic hydrocarbon compounds include, but are not limited to, cyclopropene (C 3 ), cyclobutene (C 4 ), cyclopentene (C 5 ), cyclohexene (C 6 ), methylcyclopropene (C 4 ) and dimethylcyclopropene (C 5 ). Examples of unsaturated polycyclic hydrocarbon compounds include, but are not limited to, camphene (C 10 ), limonene (C 10 ) and pinene (C 10 ).

[0180] The term "alkynyl" refers to a monovalent hydrocarbon moiety obtained by removing a hydrogen atom from a carbon atom of a (partially) unsaturated hydrocarbon compound having one or more carbon-carbon triple bonds and having, for example, 2 to 20 carbon atoms, which may be straight-chain, branched-chain or cyclic. Thus, the term "alkynyl" includes the following cycloalkynyl subclasses. Examples of alkynyl include, but are not limited to, ethynyl (ethinyl, -C≡CH) and 2-propynyl (propargyl, -CH 2 -C≡CH).

[0181] The term "cycloalkynyl" refers to a monovalent cyclic hydrocarbon moiety obtained by removing a hydrogen atom from a carbon atom of a cyclic (partially) unsaturated hydrocarbon compound having one or more carbon-carbon triple bonds and having, for example, 2 to 20 carbon atoms. "Cycloalkynyl" includes monocyclic and polycyclic, including bicyclic.

[0182] The term "aryl" refers to a monovalent moiety obtained by removing a hydrogen atom from a ring atom of an aromatic compound, which moiety may be, for example, a monocyclic or bicyclic group. The aromatic compound as the source of the aryl may contain a fully carbon ring structure, or may be a heteroaromatic compound containing one or more heteroatoms in the ring structure. Thus, the term "aryl" includes the following heteroaryl subclasses. An aryl having a fully carbon ring structure may have, for example, 3 to 20 carbon atoms. Examples of aryl include, but are not limited to, phenyl (derived from benzene) and naphthyl (derived from naphthalene).

[0183] The term "heteroaryl" refers to a monovalent moiety obtained by removing a hydrogen atom from a ring atom of a heteroaromatic compound, which moiety may be, for example, a monocyclic or bicyclic group. The heteroaryl moiety may contain, for example, one or more N, O, S or P atoms, and may contain, for example, 1 to 20 carbon atoms. Examples of heteroaryl include, but are not limited to, pyridinyl (or pyridyl, derived from pyridine), pyrimidinyl (derived from pyrimidine), pyrazinyl (derived from pyrazine), pyrrolyl (derived from pyrrole), imidazolyl (derived from imidazole), pyrazolyl (derived from pyrazole), furyl (derived from furan), thienyl (derived from thiophene), oxazolyl (derived from oxazole), isoxazolyl (derived from isoxazole) and thiazolyl (derived from thiazole).

[0184] The term "heterocyclic group" refers to a monovalent moiety obtained by removing a hydrogen atom from a ring atom of a heterocyclic compound, which moiety may be, for example, a monocyclic or bicyclic group. The heterocyclic group may contain, for example, one or more N, O, S or P atoms, and may contain, for example, 1 to 20 carbon atoms.

[0185] The term "alkoxy" or "alkoxyl" refers to an alkyl-oxy group, where the alkyl is as defined above. Examples of alkoxy groups include, but are not limited to, -OMe (methoxy), -OEt (ethoxy), -O( n Pr) (n-propoxy), -O( i Pr) (isopropoxy), -O( n Bu) (n-butoxy), -O( s Bu) (sec-butoxy), -O( i Bu) (isobutoxy), and -O( t Bu) (tert-butoxy).

[0186] The term "acyl" refers to a group represented by the general formula -C(O)-hydrocarbyl, such as -C(O)-alkyl.

[0187] The term "alkylene" refers to a divalent hydrocarbon moiety obtained by removing two hydrogen atoms from the same carbon atom of a saturated hydrocarbon compound having, for example, from 1 to 20 carbon atoms, or by removing one hydrogen atom from each of two different carbon atoms of the saturated hydrocarbon compound, and the moiety may be straight-chain, branched-chain, or cyclic. Thus, the term "alkylene" includes the following subclasses of cycloalkylene. Examples of straight-chain alkylene groups include, but are not limited to, -CH 2 - (methylene), -CH 2 CH 2 - (ethylene), -CH 2 CH 2 CH 2 - (propylene), and -CH 2 CH 2 CH 2 CH 2 - (butylene). Examples of branched-chain alkylene groups include, but are not limited to, -CH(CH 3 )-, -CH(CH 3 )CH 2 -, and -CH(CH 3 )CH 2 CH 2 -.

[0188] The term "cycloalkylene" refers to a divalent moiety obtained by removing two hydrogen atoms from the same carbon atom of a cyclic saturated hydrocarbon compound having, for example, from 3 to 20 carbon atoms, or by removing one hydrogen atom from each of two different carbon atoms of the cyclic saturated hydrocarbon compound. "Cycloalkylene" includes monocyclic and polycyclic, including bicyclic. Examples of cyclic alkylene groups include, but are not limited to, cyclopentylene (e.g., cyclopent-1,3-ylidene) and cyclohexylene (e.g., cyclohex-1,4-ylidene).

[0189] The term "alkenylene" refers to a divalent hydrocarbon moiety obtained by removing two hydrogen atoms from the same carbon atom of a (partially) unsaturated hydrocarbon compound having one or more carbon-carbon double bonds and, for example, having 2 to 20 carbon atoms, or by removing one hydrogen atom from each of two different carbon atoms of the (partially) unsaturated hydrocarbon compound, and the moiety may be straight-chain, branched-chain or cyclic. Thus, the term "alkenylene" includes the following subclasses of cycloalkenylene. Examples of straight-chain alkenylene include, but are not limited to, -CH=CH- (vinylidene), -CH=CHCH 2 -, -CH 2 -CH=CH 2 - and -CH=CHCH 2 CH 2 -. Examples of branched-chain alkenylene include, but are not limited to, -C(CH 3 )=CH-, -C(CH 3 )=CHCH 2 - and -CH=CHCH(CH 3 ).

[0190] The term "cycloalkenylene" refers to a divalent moiety obtained by removing two hydrogen atoms from the same carbon atom of a cyclic (partially) unsaturated hydrocarbon compound having one or more carbon-carbon double bonds and, for example, having 3 to 20 carbon atoms, or by removing one hydrogen atom from each of two different carbon atoms of the cyclic (partially) unsaturated hydrocarbon compound. "Cycloalkenylene" includes monocyclic and polycyclic, including bicyclic. Examples of cycloalkenylene include, but are not limited to, cyclopentenylene (e.g., 4-cyclopentene-1,3-ylidene) and cyclohexenylene (e.g., 2-cyclohexene-1,4-ylidene; 3-cyclohexene-1,2-ylidene; 2,5-cyclohexadiene-1,4-ylidene).

[0191] The term "alkynylene" refers to a divalent moiety obtained by removing two hydrogen atoms from the same carbon atom of a (partially) unsaturated hydrocarbon compound having one or more carbon-carbon triple bonds and, for example, having 2 to 20 carbon atoms, or by removing one hydrogen atom from each of two different carbon atoms of the (partially) unsaturated hydrocarbon compound, and the moiety may be straight-chain, branched-chain or cyclic. Thus, the term "alkenylene" includes the following subclasses of cycloalkenylene.

[0192] The term "cycloalkynylene" refers to a divalent moiety obtained by removing two hydrogen atoms from the same carbon atom of a cyclic (partially) unsaturated hydrocarbon compound containing one or more carbon-carbon triple bonds and, for example, having 3 to 20 carbon atoms, or by removing one hydrogen atom from each of two different carbon atoms of the cyclic (partially) unsaturated hydrocarbon compound. "Cycloalkynylene" includes monocyclic and polycyclic, including bicyclic.

[0193] The term "arylene" refers to a divalent moiety obtained by removing two hydrogen atoms from the same carbon atom of an aromatic compound, or by removing one hydrogen atom from each of two different carbon atoms of the aromatic compound, and the moiety can be, for example, a monocyclic or bicyclic group. The aromatic compound as the source of the arylene can contain a fully carbonaceous ring structure, or can be a heteroaromatic compound containing heteroatoms in the ring structure. Thus, the term "arylene" includes the following heteroarylene subclasses. The arylene having a fully carbonaceous ring structure can have, for example, 3 to 20 carbon atoms.

[0194] The term "heteroarylene" refers to a divalent moiety obtained by removing two hydrogen atoms from the same carbon atom of a heteroaromatic compound, or by removing one hydrogen atom from each of two different carbon atoms of the heteroaromatic compound, and the moiety can be, for example, a monocyclic or bicyclic group. The heteroarylene moiety can contain, for example, one or more N, O, S or P atoms, and can contain, for example, 1 to 20 carbon atoms.

[0195] The term "substituent" refers to a chemical moiety that is covalently attached to a parent group or, if appropriate, fused to the parent group.

[0196] The phrase "optionally substituted" means that the parent group can be unsubstituted or can be substituted by one or more, for example one or two substituents. The substituents on an "optionally substituted" group can be selected, for example, from alkyl, alkenyl, alkynyl, aryl, heteroaryl and heterocyclic groups; carboxylic acids and carboxylate ions; carboxylic acid ester groups; carbamate groups; alkoxy groups; ketone and aldehyde groups; amine and amide groups; -OH; -CN; -NO 2 ; and halogens.

[0197] As used herein, the term "protecting group" refers to a group capable of protecting a functional group (such as a heteroatom, such as an oxygen atom), and after the reaction using the protection, the protecting group can be removed without disturbing the rest of the molecule. Protecting groups are well known and are listed in standard texts such as Kocienski P.J., Protecting Groups, 3rd Edition, Georg Thieme Verlag, New York, 2005; and Greene T.W., Wuts P.G.M., Protective Groups In Organic Synthesis, 3rd Edition, John Wiley & Sons, New York, 1998.

[0198] Certain compounds can exist in one or more specific geometric, enantiomeric, diastereomeric, tautomeric or conformational forms. Unless otherwise indicated, mention of a particular compound includes all such isomeric forms, including its (fully or partially) racemic forms and other mixtures. Methods for the preparation and separation of such isomeric forms are known in the art.

[0199] Pharmaceutically acceptable salt forms include pharmaceutically acceptable acidic / anionic or basic / cationic salts.

[0200] Examples of pharmaceutically acceptable acidic / anionic salts include acetate, besylate, benzoate, bicarbonate, bitartrate, bromide, calcium edetate, camphorsulfonate, carbonate, chloride, citrate, dihydrochloride, edetate, edisylate, ethohexylate, esylate, fumarate, glucoheptonate, gluconate, glutamate, glycollylarsanilate, hexylresorcinate, hydrobromide, hydrochloride, hydroxynaphthoate, iodide, isethionate, lactate, lactobionate, malate, maleate, malonate, mandelate, mesylate, methylsulfate, mucate, napsylate, nitrate, nizatidine, pantothenate, phosphate / diphosphate, pectinate, salicylate, stearate, subacetate, succinate, sulfate, bisulfate, tannate, tartrate, teoclate, tosylate and triethiodide.

[0201] Examples of pharmaceutically acceptable basic / cationic salts include sodium, potassium, calcium, magnesium, diethanolamine, N-methyl-D-glucamine, L-lysine, L-arginine, ammonium, ethanolamine, piperazine and triethanolamine salts.

[0202] If the compound is anionic, or has a functional group that can be anionic, it can form salts with suitable cations. Examples of suitable inorganic cations include alkali metal ions such as Na + and K + , alkaline earth metal cations such as Ca 2+ and Mg 2+ , and other cations such as Al 3+ . Examples of suitable organic cations include ammonium ions (i.e., NH 4 + ) and substituted ammonium ions (e.g., NH 3 R + , NH 2 R 2+ , NHR 3+ , NR 4+ , where R is an alkyl group).

[0203] If the compound is cationic or has a functional group that can be cationic, it can form salts with suitable anions. Examples of suitable inorganic anions include those derived from the following inorganic acids: hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, phosphoric acid, and phosphorous acid. Examples of suitable organic anions include those derived from the following organic acids: 2-acetoxybenzoic acid, acetic acid, ascorbic acid, aspartic acid, benzoic acid, camphorsulfonic acid, cinnamic acid, citric acid, edetic acid, ethanedisulfonic acid, ethanesulfonic acid, fumaric acid, glucoheptonic acid, gluconic acid, glutamic acid, glycolic acid, hydroxymaleic acid, hydroxynaphthalenecarboxylic acid, isethionic acid, lactic acid, lactobionic acid, lauric acid, maleic acid, malic acid, methanesulfonic acid, mucic acid, oleic acid, oxalic acid, palmitic acid, pamoic acid, pantothenic acid, phenylacetic acid, benzenesulfonic acid, propionic acid, pyruvic acid, salicylic acid, stearic acid, succinic acid, sulfanilic acid, tartaric acid, toluenesulfonic acid, and valeric acid.

[0204] If the compound has both a cationic functional group or a functional group that can become cationic and an anionic functional group or a functional group that can become anionic, the compound can exist as a zwitterion.

[0205] The following non-limiting examples are provided for illustration only.

[0206] Examples

[0207] Abbreviation

[0208] ROS represents reactive oxygen species.

[0209] K222 represents kryptofix 222.

[0210] 18 F-FM074 or 18 F]FM074 represents 18 F]3-(3-fluoropropyl)-2-phenyl-2,3-dihydrobenzo[d]thiazole. This compound is also known as 18 F-ROS-PROBE.

[0211] As may be required by the context, 18 F-FM074-Ox or 18 F]FM074-Ox represents 18 F]3-(3-fluoropropyl)-2-phenylbenzo[d]thiazol-3-ium chloride or its cation. This compound is also known as 18 F-ROS-PROBE-Ox.

[0212] 18 F-FM108 or 18 F]FM108 represents 18F]3-(3-Fluoropropyl)-2-(4-methoxyphenyl)-2,3-dihydrobenzothiazole.

[0213] If context requires, 18 F-FM108-Ox or 18 F]FM108-Ox represents 18 F]3-(3-Fluoropropyl)-2-(4-methoxyphenyl)-2,3-dihydrobenzothiazol-3-ium chloride or its cation.

[0214] 1. Synthetic Chemistry

[0215] We have synthesized a library of benzothiazoline-based 18 F-labeled molecular probes for in vivo visualization of ROS by PET as shown in Scheme 1 below. The compound with the general formula structure 1 is converted to structure 2 upon oxidation.

[0216]

[0217] Scheme 1

[0218] General Synthetic Methods

[0219] (a) Synthesis of 2-Arylbenzothiazoles

[0220] A mixture of aryl carboxylic acid (12.3 mmol, 1.4 equiv), 2-aminobenzenethiol (9.5 mmol, 1.0 equiv) and polyphosphoric acid (3x acid weight) was heated overnight at 150 °C with stirring. After cooling, the resulting mixture was neutralized with 7% NH 4 OH (25 mL) and stirred for 2 h. The green solid was filtered off and washed thoroughly with 7% NH 4 OH solution. The precipitate was recrystallized from a mixture of ether and hexane to give the desired compound.

[0221] (b) Synthesis of 3-Halopropyl Trifluoromethanesulfonate

[0222] At 0 °C under nitrogen, a solution of trifluoromethanesulfonic anhydride (30 mmol) in anhydrous DCM (15 mL) was added dropwise to a solution of 3-iodo-1-propanol or 3-fluoro-1-propanol (30 mmol) and anhydrous pyridine (30 mmol) in anhydrous DCM (20 mL). A white precipitate of pyridinium salt formed upon addition. The reaction mixture was stirred at 0 °C for 30 min before quenching with deionized water (20 mL). The organic layer was separated and washed with deionized water (50 mL x 2), brine (50 mL), dried over MgSO 4Dry, filter, and concentrate in vacuo to afford a light brown liquid (43%-63% yield). Complete conversion was observed by the appearance of a new single spot on a TLC plate (EtOAc / hexanes 1:1), and the resulting compound was used in the next reaction without any further purification.

[0223] (c) N-Alkylation of 2-Arylbenzothiazoles

[0224] Add 3-halopropyl trifluoromethanesulfonate (2.5 mmol, 5.0 equiv) to a suspension of NaHCO 3 (2.5 mmol, 5.0 equiv) and 2-arylbenzothione (0.5 mmol, 1.0 equiv) in nitrobenzene (10 mL). Stir the reaction mixture at room temperature for 24 h. Remove nitrobenzene by a short flash column on silica. Load the reaction mixture directly onto the column and elute with DCM until all of the nitrobenzene is removed. Then elute the crude product on the column with DCM / MeOH (9:1). Remove the solvent in vacuo. The quaternary ammonium triflate salt undergoes reduction without any further purification.

[0225] (d) Reduction of Quaternary Ammonium Trifluoromethanesulfonate

[0226] In a round-bottom flask covered with aluminum foil, dissolve the quaternary ammonium salt (0.22 mmol) synthesized in method (c) in THF (5 mL) and MeOH (10 mL). Add NaBH 4 (0.22 mmol) in methanol (1 mL) dropwise to the above brown solution. Stir the resulting solution for 20 min, during which time the solution turns colorless. Remove the solvent in vacuo. Redissolve the resulting solid in DCM (20 mL) and wash with water (10 mL). Extract the aqueous layer with additional DCM (2 x 10 mL). Wash the combined organic phases with brine and dry over anhydrous MgSO 4 Dry. Remove the solvent under reduced pressure, and purify the crude material by flash column chromatography using a gradient of 0-30% ethyl acetate in hexanes.

[0227] HPLC Analysis Method

[0228] Perform HPLC analysis using an Agilent column (Eclipse XDB-C18, 4.6 X 150 mm, 5 μm), with AcCN (0.1% TFA) and water (0.1% TFA) as the mobile phase at a flow rate of 1 mL / min. Use the following gradient: 5% AcCN for 3 min, 5% to 95% AcCN for 10 min, 95% AcCN for 7 min.

[0229] Synthesis of Precursors and Reference Compounds

[0230]

[0231] Solution 2

[0232] Scheme 2 above shows the preparation of 18 Non-radioactive reference compounds (i.e., containing no radioisotope) for F-labeled radiotracers and for radiofluorination 18 Iodinated precursor of a F-labeled radiotracer.

[0233] 2-Phenylbenzo[d]thiazole (FM055)

[0234]

[0235] The title compound was synthesized using method (a) above and isolated in 67% yield.

[0236] 1 HNMR (400 MHz, DMSO-d 6 )δ:8.19-8.05(4H,m,Ar-H),7.63-7.53(4H,m,Ar-H),7.48(1H,ddd,J=8.3,7.2,1.2Hz,Ar-H).

[0237] 13 C NMR (101 MHz, DMSO-d 6 )δ:167.25(qC),153.50(qC),134.40(qC),132.79(qC),131.41(CH),129.39(CH),127.16(CH),126.65(CH),125.53(CH),122.86(CH),122.36(CH).

[0238] 3-(3-Iodopropyl)-2-phenylbenzo[d]thiazol-3-ium trifluoromethanesulfonate (FM068)

[0239]

[0240] The title compound was synthesized using method (c) above and isolated in 32% yield (crude).

[0241] 1 HNMR (400 MHz, DMSO-d 6) δ 8.58 (1H, dd, J = 8.2, 1.2 Hz, Ar-H), 8.51 (1H, d, J = 8.5 Hz, Ar-H), 8.03 (1H, ddd, J = 8.5, 7.3, 1.3 Hz, Ar-H), 7.98 - 7.74 (5H, m, Ar-H), 4.75 (t, 2H, CH 2 ), 3.32 - 3.22 (2H, m, CH 2 ), 2.42 - 2.31 (2H, m, CH 2 )。

[0242] 3-(3-Fluoropropyl)-2-phenylbenzo[d]thiazol-3-ium trifluoromethanesulfonate (FM073)

[0243]

[0244] The title compound was synthesized using the above method (c) and isolated in 20% yield (crude product).

[0245] 1 1H NMR (400 MHz, DMSO-d 6 ) δ 8.51 (1H, dd, J = 8.2, 1.2 Hz), 8.43 (1H, d, J = 8.6 Hz), 7.95 (1H, ddd, J = 8.6, 7.3, 1.3 Hz), 7.90 - 7.69 (6H, m), 4.78 - 4.70 (2H, m), 4.49 - 4.33 (2H, m), 2.30 - 2.14 (2H, m).

[0246] 19 19F NMR (376 MHz, DMSO-d 6 ) δ -77.79.

[0247] 3-(3-Iodopropyl)-2-phenyl-2,3-dihydrobenzo[d]thiazole (FM069)

[0248]

[0249] The title compound was synthesized using the above method (d) and isolated in 56% yield.

[0250] 1 1H NMR (400 MHz, DMSO-d 6) δ 7.60 - 7.52 (2H, m, Ar-CH), 7.51 - 7.40 (3H, m, Ar-CH), 7.14 - 7.01 (2H, m, Ar-CH), 6.76 - 6.68 (1H, m, Ar-CH), 6.64 (1H, d, J = 7.9 Hz, Ar-CH), 6.41 (1H, s, CH), 3.27 (2H, q, J = 7.0 Hz, Ar-CH 2 ), 3.02 (2H, ddd, J = 14.6, 8.8, 5.8 Hz, CH 2 ), 2.10 - 1.90 (2H, m, CH 2 )。

[0251] 13 C NMR (101 MHz, DMSO-d 6 ) δ 146.63 (qC), 140.60 (qC), 128.76 (CH), 128.70 (CH), 126.90 (CH), 125.76 (CH), 124.63 (qC), 121.20 (CH), 118.63 (CH), 107.16 (CH), 72.30 (CH), 46.60 (CH 2 ), 29.38 (CH 2 ), 4.97 (CH 2 )。

[0252] 3-(3-Fluoropropyl)-2-phenyl-2,3-dihydrobenzothiazole (FM074)

[0253]

[0254] The title compound was synthesized using method (d) above and isolated in 52% yield.

[0255] 1 H NMR (400 MHz, DMSO-d 6 ) δ 7.60 - 7.51 (m, 2H, Ar-CH), 7.50 - 7.38 (m, 3H, Ar-CH), 7.12 - 7.01 (m, 2H, Ar-CH), 6.70 (td, J = 7.5, 1.1 Hz, 1H, Ar-CH), 6.58 (dd, J = 8.0, 1.1 Hz, 1H, Ar-CH), 6.41 (s, 1H, CH), 4.59 - 4.38 (m, 2H, CH 2 ), 3.03 (ddd, J = 14.7, 8.8, 6.0 Hz, 2H, CH 2 ), 1.97 - 1.71 (m, 2H, CH 2 )。

[0256] 13 C NMR (101 MHz, DMSO-d 6 ) δ 146.64 (qC), 140.56 (qC), 128.76 (CH), 128.70 (CH), 126.91 (CH), 125.80 (CH), 124.60 (qC), 121.18 (CH), 118.55 (CH), 107.06 (CH), 82.55 and 80.94 (CF), 72.22 (CH 2 ), 42.19 (CH 2 ), 26.51 (CH 2 )。

[0257] 19 F NMR (376 MHz, DMSO-d 6 ) δ -106.93。

[0258] 2-(4-Methoxyphenyl)benzothiazole (FM054)

[0259]

[0260] The title compound was synthesized using the above method (a) and isolated in 63% yield.

[0261] 1 H NMR (400 MHz, DMSO-d 6 ) δ: 8.13 - 8.07 (1H, m, ArH), 8.07 - 7.98 (3H, m, ArH), 7.52 (1H, ddd, J = 8.3, 7.2, 1.3 Hz, ArH), 7.43 (1H, ddd, J = 8.3, 7.2, 1.2 Hz, ArH), 7.15 - 7.08 (2H, m, ArH), 3.85 (3H, s, CH 3 )。

[0262] 13 C NMR (101 MHz, DMSO-d 6 ) δ 167.01 (qC), 161.73 (qC), 153.61 (qC), 134.17 (qC), 128.83 (CH), 126.48 (CH), 125.46 (qC), 125.07 (CH), 122.42 (CH), 122.15 (CH), 114.70 (CH), 55.45 (CH 3 )。

[0263] 3-(3-Fluoropropyl)-2-(4-methoxyphenyl)benzothiazol-3-ium trifluoromethanesulfonate (FM107)

[0264]

[0265] The title compound was synthesized using the above method (c) and used in the next step without purification.

[0266] 3-(3-Fluoropropyl)-2-(4-methoxyphenyl)-2,3-dihydrobenzo[d]thiazole (FM108)

[0267]

[0268] The title compound was synthesized using the above method (d) and isolated in 58% yield.

[0269] 1 HNMR(400MHz,DMSO-d 6 ) δ 7.56 - 7.48 (2H, m), 7.09 - 6.99 (4H, m), 6.68 (1H, td, J = 7.5, 1.1 Hz), 6.63 (1H, dd, J = 7.9, 1.0 Hz), 6.34 (1H, s), 4.69 - 4.39 (m, 2H, CH2), 3.88 (3H, s), 3.01 (m, 2H, CH2), 1.99 - 1.75 (m, 2H, CH2).

[0270] 13 C NMR(101MHz,DMSO-d 6 ) δ 159.61 (qC), 146.58 (qC), 132.06 (qC), 128.59 (CH), 125.65 (CH), 124.73 (CH), 121.16 (CH), 118.52 (CH), 114.04 (CH), 107.07 (CH), 72.29 (CH), 82.56 and 80.95 (CF), 72.21 (CH2), 55.15 (CH 3 ), 42.20 (CH2), 26.53 (CH2).

[0271] 3-(3-Iodopropyl)-2-(4-methoxyphenyl)benzo[d]thiazol-3-ium trifluoromethanesulfonate (FM071)

[0272]

[0273] The title compound was synthesized using the above method (c) and used in the next step without purification.

[0274] 3-(3-Iodopropyl)-2-(4-methoxyphenyl)-2,3-dihydrobenzo[d]thiazole (FM083)

[0275]

[0276] The title compound was synthesized using the above method (d) and isolated in 36% yield.

[0277] 1 HNMR (400 MHz, DMSO-d 6 ) δ 7.55 - 7.45 (2H, m), 7.08 - 6.97 (4H, m), 6.69 (1H, td, J = 7.5, 1.1 Hz), 6.60 (1H, dd, J = 7.9, 1.0 Hz), 6.37 (1H, s), 3.82 (3H, s), 3.30 - 3.20 (2H, m), 3.04 - 2.84 (2H, m), 2.03 - 1.83 (2H, m).

[0278] 13 C NMR (101 MHz, DMSO-d 6 ) δ 159.57 (qC), 146.57 (qC), 132.00 (qC), 128.49 (CH), 125.70 (CH), 124.71 (CH), 121.14 (CH), 118.51 (CH), 114.01 (CH), 107.06 (CH), 72.26 (CH), 55.14 (CH 3 ), 46.25 (CH 2 ), 29.21 (CH 2 ), 5.02 (CH 2 ).

[0279] 2. Radiochemistry

[0280]

[0281] Scheme 3

[0282] As shown in Scheme 3 above, the precursor compound was radiolabeled to form 18 F-labeled compounds. These 18 F-labeled compounds were then oxidized to obtain their oxidized analogs.

[0283] Radioactive Labeling

[0284] Radiofluorination was carried out by nucleophilic substitution of alkyl iodides in the precursor compounds FM069 and FM083.

[0285] The 18Fluoride (ca. 200 - 1200 MBq) was trapped in a carbonated QMA cartridge (Waters Sep-Pak Light) pretreated with water (10 mL) and released with 1.0 mL of a mixture of Kryptofix 222 and potassium carbonate (30:15 mM) dissolved in acetonitrile / water (85:15). After removal of the solvent by heating under a nitrogen stream at 110 °C for 15 min, azeotropic distillation was repeated twice with anhydrous acetonitrile (400 μL) at 90 °C for 15 min. Then a solution of the precursor (16 μmol) in anhydrous acetonitrile (400 μL) was added and heated at 80 °C for 15 min in a sealed Wheaton bottle. The reaction was cooled to room temperature and quenched by the addition of water (100 μL) and purified by semi-preparative HPLC. The radiolabeled product was collected from the HPLC column and diluted to 10% acetonitrile in water. It was trapped onto a Sep-Pak C-18 light cartridge (pre-activated with 5 mL of methanol followed by 5 mL of water). The cartridge was washed with 2 mL of water and then the product was released with 1 mL of absolute ethanol. The separated tracer in ethanol was used for subsequent assays.

[0286] 18 F]3-(3-Fluoropropyl)-2-phenyl-2,3-dihydrobenzothiazole( 18 F-FM074) and 18 F]3-(3-Fluoropropyl)-2-(4-methoxyphenyl)-2,3-dihydrobenzothiazole( 18 F-FM108) were each purified using a ZORBAX column (300SB-C18, semi-preparative 9.4X 250 mm, 5 μm) with AcCN and water as mobile phases at a flow rate of 3 mL / min. The following gradient was used: from 50% to 90% AcCN in 15 min; hold at 90% AcCN for 10 min; from 90% to 50% AcCN in 5 min.

[0287] Radiosynthesis of 18 F-FM074 and 18 F-FM108 was achieved with radiochemical conversions approaching quantitation (as indicated by radio-HPLC) (Figure 2(A) and Figure 2(C)) and non-decay corrected isolated radiochemical yields of 10 ± 3% (n = 10) and 18 ± 5% (n = 5), respectively, from the end of bombardment until formulation for injection.

[0288] The identity of 18 F-FM074 and 18 F-FM108 was confirmed by HPLC co-elution with the corresponding non-radioactive reference compounds (Figure 2(B) and Figure 2(D)).

[0289] ​Molar Activity

[0290] Determination 18 The molar activities of F-FM074 and 18 F-FM108. The molar activity (A m ) is the measured radioactivity per mole of compound, usually measured in Bq / mol or GBq / μmol.

[0291] When starting with approximately 1 GBq of 18 F-fluoride, 18 the molar activities of F-FM074 and 18 F-FM108 were measured to be 168 ± 39 GBq / μmol (n = 3) and 136 ± 17 GBq / μmol (n = 3), respectively.

[0292] Since F radiolabeling is achieved with near-quantitative radiochemical yields, F tracers with high molar activities can be produced. 18 18

[0293] Oxidation

[0294] By reacting 18 F-FM074 or 18 F-FM108 (approximately 50 MBq, 1000 μL in PBS containing 10% ethanol) with potassium superoxide (approximately 10 mg) until complete oxidation was observed by radio-HPLC, the oxidized analogs 18 F-FM074-Ox and 18 F-FM108-Ox were obtained.

[0295] 3. LogD Measurement

[0296] 18 The lipophilicity of F-FM074 and 18 F-FM074-Ox was determined by measuring their logD values using a variation of the conventional shake-flask method, i.e., the conventional partition method between 1-octanol and phosphate-buffered saline (PBS) (pH 7.4). The 1-octanol was saturated with PBS before use. A radioactive tracer (1 μL) in ethanol was added to a mixture of PBS (200 μL) and 1-octanol (200 μL) in 1.5 mL Eppendorf vials (n = 6). The vials were sealed and shaken, then centrifuged at 3000 g for 10 min. A 100 μL aliquot was taken from each layer and added to separate tubes. The radioactive content of each fraction was measured in a gamma counter. LogD oct / PBS ​​Calculate as follows: log[(cpm in 1-octanol layer - cpm in 1-octanol blank) / (cpm in PBS layer - cpm in PBS blank)].

[0297] 18 The logD of F-FM074 was 1.00 ± 0.08 (n = 12), and its oxidized form 18 The logD of F-FM074-Ox was significantly lower at -1.00 ± 0.04 (n = 6). These suggest 18 F-FM074 will enter cells by passive diffusion, while 18 The cell membrane permeability of F-FM074-Ox is much smaller. 18 The log D of F-FM108 was also determined to be 0.83 ± 0.12 (n = 12).

[0298] 4. Stability Test

[0299] Stability tests monitored by HPLC showed that 18 F-FM074 was stable for 4 h both in pure ethanol and in 1% ethanol in PBS in the presence of ascorbic acid (0.01 mg / mL) (no longer times were tested). When incubated in rat serum at 37 °C, 90% of 18 F-FM074 was intact within 1 h (Figure 3(A)). The stability of 18 F-FM108 in PBS was also determined, and it was stable within 30 min (Figure 3(B)).

[0300] 5. Chemoselectivity Study

[0301] We investigated 18 F-FM074 and 18 the in vitro chemoselectivity of F-FM108 towards various ROS.

[0302] Prepare different oxidants in PBS (900 μL). Add 18 the F-labeled compound formulated at 0.5 - 2 MBq in 100 μL ethanol to the oxidant PBS solution. The final reaction mixture contained 18 the F-labeled compound (0.5 - 2 MBq) in the presence of 100 μM oxidant in PBS with 10% ethanol (final volume 1000 μL). Keep the reaction at room temperature for 5 min, then inject it into HPLC for analysis.

[0303] Superoxide (O 2 - ): Add 18The F-labeled compound was added to PBS (900 μL), and then the resulting solution was added to a vial containing solid KO 2 (1 mg) to form a reaction mixture having 10 mM O 2 - .

[0304] Hydrogen peroxide (H 2 O 2 ): H 2 O 2 (10 mM stock solution, 10 μL) was diluted in PBS (890 μL), and then the F-labeled compound in ethanol (100 μL) was added to a final concentration of 100 μM. 18

[0305] Hydroxyl radical (·OH): Hydroxyl radical was generated in situ by reacting hydrogen peroxide (H 2 O 2 , 100 μM) with iron II (1000 μM). FeSO 2 ·7H 2 O (5 mM stock solution, 200 μL) was diluted in PBS (690 μL), and H 2 O 2 (10 mM stock solution, 10 μL) was added, followed by the F-labeled compound in 100 μL ethanol. 18

[0306] Iron(II) sulfate heptahydrate (Fe 2+ )(control): FeSO 2 ·7H 2 O (5 mM stock solution, 200 μL) was diluted in PBS (700 μL) to a final concentration of 1000 μM, and then the F-labeled compound in 100 μL ethanol was added. 18

[0307] tert-Butyl hydroperoxide (TBHP): TBHP (10 mM stock solution, 10 μL) was diluted in PBS (890 μL), and then the F-labeled compound in ethanol was added to a final concentration of 100 μM. 18

[0308] tert-Butoxy radical (t-BuO·): tert-Butoxy radical was generated in situ by reacting tert-butyl hydroperoxide (TBHP, 100 μM) with Fe 2+ (1000 μM). FeSO 2 ·7H 2 ​​​​O (stock solution of 5 mM, 200 μL) was diluted in PBS (690 μL), and TBHP (stock solution of 10 mM, 1 μL) was added, followed by the addition of the 18 F-labeled compound in ethanol.

[0309] Peroxynitrite (ONOO - ): Peroxynitrite was generated in situ by the spontaneous decomposition of 3-morpholinosydnomine (SIN-1) in solution. SIN-1 (stock solution of 5 mM, 1 μL) was diluted in PBS (989 μL) containing the 18 F-labeled compound in ethanol (10 μL), resulting in a final concentration of 50 μM ONOO - in the solution.

[0310] Nitric oxide (NO·): NO was generated in situ from the NO donor drug diethylamine NONOate (DEA / NO). A 33 mM stock solution of DEA / NO in 10 mM NaOH was used. 1 μL was diluted in PBS (990 μL) containing the 18 F-labeled compound in ethanol (10 μL), resulting in a final concentration of 33 μM DEA / NO in the solution. Before HPLC analysis, the reaction was allowed to proceed at room temperature (ca. 20 °C) for 32 min to allow DEA / NO to decompose to diethylamine and nitric oxide radical (NO) at a concentration of 50 μM.

[0311] 18 F-FM074 showed rapid oxidation (within 5 min) and selective oxidation of 58 ± 8% (n = 4) by superoxide (spontaneous decomposition of 1 mg / mL KO 2 O in solution) compared to other endogenous ROS such as hydroxyl radical (·OH), hydrogen peroxide (H 2 O - ), nitric oxide (·NO), and peroxynitrite (ONOO 2 ) (no oxidation or less than 10%). Additionally, in the presence of ascorbic acid (1 mg / mL), 18 F-FM074 oxidation by superoxide (KO 2 ) could be partially inhibited to 31 ± 5% (n = 2) ( Figure 4 (A)). In contrast, 18 F-FM074 showed little or no reactivity towards other biologically relevant ROS.

[0312] 18 F-FM108 showed oxidation by superoxide (1 mg / mL KO 2Spontaneous decomposition) rapidly (within 5 min) and selectively oxidizes 54 ± 4% (n = 3). In addition, in the presence of (ascorbic acid, 1 mg / mL), 18 F-FM108 is oxidized by superoxide (KO 2 ) and can be partially inhibited to 38% (n = 1) ( Figure 4 (B)). In contrast, 18 F-FM108 has little or no reactivity towards other biologically relevant ROS.

[0313] When 18 F]FM074 is incubated with xanthine oxidase, xanthine (1 mM) and catalase in PBS buffer at 37 °C for 5 min, 53% oxidized 18 F]FM074 is observed in the radio-HPLC chromatogram. This indicates that 18 F]FM074 can be oxidized by superoxide generated by the xanthine oxidase / xanthine system, providing an 18 F]FM074 in vitro biological evaluation against ROS.

[0314] 6. In Vivo Experiments

[0315] All experiments were conducted in accordance with the Animals (Scientific Procedures) Act 1986 under project license numbers PPLP96678ED7 and PPL 70 / 8482. Male Wistar rats were obtained from Envigo Ltd. and underwent a 7-day acclimatization period in the Biological Services Department of St Thomas' Hospital prior to any experiments.

[0316] 6.1 Studies in Healthy C57Bl6 Mice

[0317] Wild-type C57BL / 6J mice (male, 26 ± 2 g) were intravenously injected via the tail vein with 18 F]FM074 (1.2 ± 1.1 MBq) in PBS containing sodium ascorbate (0.01 mg / mL). Animals were sacrificed (n = 3 per group) 3 min or 60 min after injection following PET. Target organs and tissues were collected, weighed, and radioactivity was measured in a gamma counter. Organ uptake was calculated as the percentage of injected dose per gram of tissue block (%ID / g). Data are reported as mean ± SD.

[0318] The above PET imaging studies in healthy C57Bl6 mice (n = 3) showed that 18 F-FM074 has rapid blood clearance and excellent tissue penetration. Regions of interest (ROIs) were drawn on the major organs, and the PET signal was quantified in the form of a time-activity curve using the standardized uptake value (SUV). 18F-FM074 is rapidly taken up by the heart and the brain, and no non-specific background retention is observed. The radiotracer is excreted by both renal and hepatobiliary pathways within less than 1 hour ( Figure 5 ).

[0319] 18 A common concern with F-radiotracers is defluorination in vivo, resulting in 18 deposition of F-fluoride in bone. In our study, bone uptake was minimal after 1 hour, indicating that the radiotracer is stable to defluorination in vivo.

[0320] 6.2 Biodistribution in Healthy Rats

[0321] Biodistribution studies were performed in healthy rats.

[0322] Male Wistar rats (290 - 355 g) were placed in an incubator at 37 °C and then transferred to an anesthesia induction chamber at a flow rate of 1 L / min and an isoflurane level of 5%. The anesthetized rats were transferred to an anesthesia mask at a flow rate of 1 L / min and an isoflurane level of 2.5%. The radiotracer (0.5 - 2.2 MBq, 200 - 600 μL, maximum 5% EtOH in PBS) was injected intravenously via a cannula inserted into the tail vein. The animals (n = 3 per group) were sacrificed by cervical dislocation at 1, 5, and 30 min after injection. The heart was immediately removed and rinsed with saline to wash out the blood. The target organs, as well as blood and urine, were collected and the radioactivity was measured in a gamma counter. 2 2 18

[0323] Figure 6 Biodistribution studies performed in healthy Wistar rats showed that 18 F-FM074 was rapidly and initially taken up by the major organs including the brain, heart, lungs, and spleen, and was rapidly cleared from the blood pool at 1 min after injection ( Figure 6 (A)). The radiotracer was cleared from these organs by hepatic and renal metabolism within 30 min and was excreted into the small intestine and urine. In addition, 18 F-FM074 was taken up by bone and muscle only minimally within 30 min.

[0324] Biodistribution studies were also performed with the oxidized radiotracer 18 F-FM074-Ox. 18 F-FM074-Ox showed significantly reduced uptake in the major organs and was rapidly cleared by the kidneys and excreted in the urine ( Figure 6 (B)).

[0325] Doxorubicin-Induced Cardiotoxicity Rat Model

[0326] To evaluate18 PET imaging was performed in a rat model of doxorubicin-induced cardiotoxicity to determine whether F-FM074 has increased uptake in tissues under oxidative stress. Some studies have shown that ROS production is a key regulatory mechanism in doxorubicin-induced cardiotoxicity.

[0327] Wistar rats were randomly divided into two groups, and Alzet osmotic minipumps containing doxorubicin (30 mg / kg) in saline (n = 6) or saline only as a control (n = 4) were implanted. The minipumps released the drug at a constant rate over seven days, after which PET / CT imaging was performed.

[0328] Echocardiography

[0329] To evaluate cardiac function, all rats received echocardiography (Vevo 770 TM , VisualSonics) one day before osmotic pump implantation and a second echocardiogram one day before PET / CT imaging. The rats were anesthetized with 2% isoflurane in 100% oxygen and maintained at 37 °C via a thermostatic platform and rectal thermometer. High-resolution parasternal left ventricular (LV) long-axis M-mode and B-mode images were obtained using an RMV710B transducer. The images were analyzed offline using Vevo software to determine LV function.

[0330] Micro-Pump Implantation

[0331] Male Wistar rats (280 - 300 g) were used in all experiments. Subcutaneous 7-day osmotic pumps (Alzet) containing doxorubicin (Cambridge Bioscience, 30 mg / kg cumulative dose) or vehicle (sterile 0.9% NaCl) were inserted into the rats under 2% isoflurane in 100% oxygen.

[0332] Doxorubicin (30 mg / kg) or vehicle only (saline) was delivered to the animals using an osmotic minipump for seven days, after which PET / CT imaging was performed.

[0333] PET / CT Imaging

[0334] The animals were placed in an incubator at 37 °C and then transferred to an anesthesia induction chamber at a flow rate of 1 L / min of O 2 and an isoflurane level of 5%. The anesthetized rats were transferred to the PET bed and maintained at a flow rate of 1 L / min of O 2Flow rate, 2.5% isoflurane level anesthesia. Radiotracer (0.5-2.2MBq, 200-600μL, maximum 5% EtOH in PBS) was injected intravenously via a cannula inserted into the tail vein. The injection start time coincided with the start of PET acquisition to obtain dynamic tracer uptake information. PET scans were obtained for 30min, followed by CT scans, after which the animals were sacrificed and organs were harvested according to the biodistribution scheme. PET data were analyzed using VivoQuant.

[0335] Results

[0336] Cardiac function was monitored by ultrasound, and rats treated with doxorubicin showed a statistically significant decrease (15%) in left ventricular ejection fraction on day 6 compared with the baseline on day 0, but no significant difference was found between the doxorubicin-treated and control groups ( Figure 7 ). These data suggest that ultrasound is unable to detect doxorubicin-induced damage to the hearts of treated animals.

[0337] Subsequently, on the seventh day of treatment, both groups underwent a 30-min PET / CT scan with the thorax in the field of view. Figure 8 ) PET images were analyzed in three sections: 18 0 to 3 min, 3 to 10 min, and 10 to 30 min after F-FM074 injection.

[0338] Quantification of left ventricular (LV) and intramyocardial blood pool 18 The uptake of F-FM074 was measured and the ratio of the standardized uptake value (SUV) of LV to blood was used to illustrate the bioavailability of the tracer. Between 3 and 10 min after injection, the uptake of radioactivity was significantly (p < 0.05) higher in doxorubicin-treated rats ( Figure 9 ). However, due to 18 F-FM074 was rapidly cleared, and no significant differences in cardiac uptake were found ex vivo after PET / CT scans. In some PET scans, tracer uptake was visible in the area where the micropump incision was made, which we hypothesize may be due to inflammation and poor perfusion. In addition, high uptake was also observed in the liver, although no significant differences were found between the treatment and control groups.

[0339] The dynamic distribution of radiotracer uptake and washout in the left ventricle (LV) and intramyocardial blood pool was also evaluated to obtain the dynamic distribution of radiotracer uptake and washout in the left ventricle (LV) and intramyocardial blood pool in a rat model of doxorubicin-induced cardiotoxicity. 18 Time-activity curve of F-FM074 uptake (standardized uptake value versus time) ( Figure 10 ). The washout rate from the LV was two-fold slower in the LV of doxorubicin-treated animals compared to controls.

[0340] PET imaging data indicate that the use of 18 F]FM074 can detect doxorubicin-induced damage to the hearts of treated animals. The increased uptake observed in the hearts of doxorubicin-treated rats compared to controls highlights 18 the potential of F-FM074 as a PET tracer for non-invasively detecting oxidative stress in vivo.

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Claims

1. A radiolabeled compound of formula (I): Wherein: X is -S-; Z is absent; R 1 is -H or -D; R 2 and R 3 are connected to form part of a benzene ring; R 4 is wherein R 12 , R 13 , R 15 and R 16 are -H, R 14 is selected from -H and -OR 20 wherein R 20 is C 1 alkyl; R 5 is –(CH 2 ) q –, where q is 3; n is 0; m is 0; and p is 0; or a pharmaceutically acceptable salt thereof.

2. A reference compound of formula (II): wherein X, Z, R 1 , R 2 , R 3 , R 4 , R 5 , n, m and p are as defined in claim 1; or a pharmaceutically acceptable salt thereof.

3. A precursor compound of formula (III): wherein X, Z, R 1 , R 2 , R 3 , R 4 , R 5 , n, m and p are as defined in claim 1; and L is a leaving group, where L is selected from -I, -Br, -Cl, and sulfonate groups; or a pharmaceutically acceptable salt thereof.

4. The precursor compound according to claim 3, wherein L is selected from -I, -Br, -Cl, -OTf, -OMs, and -OTs.

5. The precursor compound according to claim 4, wherein L is -I.

6. A pharmaceutical composition comprising the radiolabeled compound according to claim 1 and a pharmaceutically acceptable carrier.

7. A method of radiolabeling a precursor compound to form the radiolabeled compound according to claim 1, wherein the precursor compound is the precursor compound of formula (III) according to any one of claims 3 - 5, the method comprises the following steps: Reacting the precursor compound of formula (III) with nucleophilic fluoride - 18 according to the following reaction scheme to form the radiolabeled compound of formula (I): wherein X, Z, R 1 , R 2 , R 3 , R 4 , R 5 , n, m and p are as defined in claim 1; and L is as defined in any one of claims 3 - 5.

8. A method for preparing a precursor compound or a reference compound, the method comprises the following steps: (i) Reacting a compound of formula (A) with a compound of formula (E) via a cyclization reaction to form a compound of formula (B); and (ii) Reacting the compound of formula (B) with a compound of formula (F) via a nucleophilic addition reaction to form a compound of formula (C); and (iii) Reducing the compound of formula (C) to form a compound of formula (D); According to the following reaction scheme: where X, Z, R 1 , R 2 , R 3 , R 4 , R 5 , n, m and p are as defined in claim 1; L' is -F or the leaving group L as defined in any one of claims 3 - 5; and L" is a leaving group.

9. The method according to claim 8, wherein the method is for preparing the reference compound according to claim 2, the compound of formula (D) is the reference compound of formula (II), and L' is -F.

10. The method according to claim 8, wherein the method is for preparing the precursor compound according to any one of claims 3 - 5, the compound of formula (D) is the precursor compound of formula (III), and L' is the leaving group L as defined in any one of claims 3 - 5.

11. The method according to claim 10, wherein the leaving group L is selected from -I and -Br.

12. The method according to any one of claims 8 - 11, wherein L" is a sulfonate group selected from -OTf, -OMs, and -OTs.

13. The method according to any one of claims 8 - 11, wherein the method further comprises the step of converting a compound of formula (G) into the compound of formula (F) according to the following reaction scheme: where R 5 , n and m are as defined in claim 1, and L' and L" are as defined in any one of claims 8 - 11.

14. Use of the radiolabeled compound according to claim 1 in the manufacture of a reagent for diagnosing a disease in a diagnostic method carried out on a human or animal body using positron emission tomography (PET), wherein the diagnostic method is a method for diagnosing a condition caused and / or exacerbated by increased production of ROS, and wherein the condition caused and / or exacerbated by increased production of ROS is atherosclerotic plaque or heart disease.

15. Use of the radiolabeled compound according to claim 1 in the manufacture of a reagent for diagnosing a disease in a diagnostic method carried out on a human or animal body using positron emission tomography (PET), wherein the diagnostic method is a method for monitoring the therapeutic efficacy of a therapy, wherein the therapy is cancer chemotherapy, cancer radiotherapy or antioxidant therapy.

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