Abstract:
The present invention relates to pharmacology, medicine, opthalmology, and, in particular, concerns a class of chemical compounds of structure (I) and also their solvates, isomers or prodrugs applicable when incorporated into pharmaceutical compositions also containing pharmaceutically acceptable carrier which can be useful for prophylaxis and treatment of different eye pathologies such as cataract and macular dystrophy.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to pharmacology, medicine, opthalmology, and, in particular, concerns a class of chemical compounds of structure (I) which being incorporated into pharmaceutical compositions can be used for prophylaxis and treatment of different eye pathologies such as cataract and macular dystrophy. 
       BACKGROUND 
       [0002]    At present, various methods of treatment of eye pathologies—surgical and medicamental, are applied in medical practice. Medicamental methods usually comprise natural and synthetic compounds possessing antioxidant properties (antioxidants). 
         [0003]    In pathogenesis of many eye pathologies (including cataract and macular dystrophy), the oxidative stress—disruption of the balance between production of free radicals and their elimination by antioxidants, plays an important role. 
         [0004]    Only bioactive nutrients containing natural carotenoids possessing antioxidant properties—lutein and zeaxanthin have been available in Russia to date. Said compounds also contain plant carotenoid beta-carotene (1.5 mg) that plays an important role in the formation of a visual pigment rhodopsin providing an eye with adaptation to the lowered lighting; antioxidants—vitamins E and C, micronutrients zinc and copper which are also important to maintain the health of eyes. 
         [0005]    Age-related macular degeneration (AMD) occupies a highly important place in the world among disorders leading to persistent deterioration of visual functions and blindness (J. Evans, C. Rooney, F. Ashood, 1996). AMD is one of the eye diseases which are difficult to treat (L. N. Marchenko, 2001). The Russian Central Scientific Research Institute of Expertise of Work Capability and Organization of Labor of the Disabled reported in 1997 that the vascular diseases of retina resulting in eye disability in particular comprise nonexudative age-related macular degeneration—39.4%, exudative age-related macular degeneration—9.1%, bloodstream disruption in great retina vessels—51.5%. Age-related macular degeneration constituted about 10% of blindness registered in the Western Europe 25 years ago, this value has increased up to 50% to date (V. S. Akopyan, 2004). According to the reports of WHO/OMS (1986), increase in proportion of elders within the human population leads to annual increase in said disease. The history of macular degeneration problem originated from 1855 when F. S. Donders described macular drusen. The term “senile macular degeneration” was first introduced by O. Haab in 1885. Later on, C. Behr (1920) and H. F. Falls (1949) assigned said pathology to hereditary familial diseases. Taking into account a variety of clinical and opthalmoscopic data, different terms have been applied to age-related macular degeneration in the literature. To date a consensus exists among ophthalmologists that all these pathology types are a manifestation of the same disease that now is often designated in the literature as “age-related macular degeneration” (AMD). 
         [0006]    AMD is a pathology of central photoactive area of retina. The disease is a chronic dystrophic process when choriocapillaries, Bruch&#39;s membrane and pigment retinal epithelium are predominantly affected followed by the affection of photoreceptors (V. S. Lysenko et al., 2001). The extent of the process severity and the loss of central vision depends on AMD type and vicinity of dystrophic process to central fossa of retina. AMD is most commonly double-sided process. The second eye was observed to be affected within 5 years after the affection of the first eye (H. C. Zweng, 1977). 
         [0007]    Progression of macular degeneration results in increased light sensitivity, eyesight degradation, gradual loss of eyeshots, and finally appearance of turbid spot in the center of visual field (relative or absolute scotoma). The reasons resulting in macular degeneration are different. However the role of genetic factors and damaging action of light are undoubted. At present, the consequences of negative effect of free oxygen radicals are often discussed in the scientific literature. Photochemical reaction induced by light and oxygen results in the formation of highly reactive free radicals which are capable for damaging light sensitive cells of eye retina. The older is a person, the more dangerous is the effect of free radicals—natural aging correlates with decline of the activity of intrinsic protective antioxidant system of an organism that accelerates dystrophic processes. 
         [0008]    Prolonged computer work also leads to eyesight degradation. Computer monitor is a source of serious hazard to eyes since it radiates ultraviolet light, the effect of the latter is enhanced when luminescent lamps are used. Coupled with hard work of eyes, this can cause fast exhaustion, headaches, decrease in capability for work, eye pain, lachrymation. According to statistics, from 50% to 90% of persons engaged in computer working have such complaints when see a doctor. These complaints are combined into the term “computer vision syndrome”. To increase antioxidant protection of eyes, persons engaged in computer working need additional administration of antioxidants. 
         [0009]    Vitamins-antioxidants such as vitamins C and E, bioflavonoids, beta-carotene also protect eyes from damaging and facilitate anabolic processes supporting collagen biosynthesis. Combined administration of N-acetyl-cysteine, lipoic acid and vitamins C and E stimulates biosynthesis of antioxidant enzymes of eye tissue, glutathione. 
       DESCRIPTION 
       [0010]    One of the aspects of the present invention is a pharmaceutical composition for prophylaxis and treatment of different eye pathologies comprising a compound that includes targeting moiety, linker group and antioxidant. In general, such a compound can be described by the following structure (I): 
         [0000]    
       
                 
         
             
             
         
       
     
         [0011]    wherein A is an effector—antioxidant of structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0012]    and/or reduced form thereof, 
         [0013]    wherein m is an integer from 1 to 3; each Y is independently selected from the group consisting of: lower alkyl, lower alkoxy; or two adjacent Y groups, together with carbon atoms to which they are attached form the following structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0014]    and/or reduced form thereof, 
         [0015]    wherein R1 and R2 may be the same or different and are each independently lower alkyl or lower alkoxy; 
         [0016]    L is a linker group, comprising: 
         [0017]    a) straight or branched hydrocarbon chain optionally substituted with one or more substituents and optionally containing one or more double or triple bonds; or 
         [0018]    b) natural isoprene chain; and 
         [0019]    n is integer from 1 to 20; 
         [0020]    B comprises: 
         [0021]    a) a Skulachev-ion Sk: 
         [0000]      Sk + Z −   
         [0022]    where Sk is a lipophilic cation, and Z is a pharmacologically acceptable anion; and/or 
         [0023]    b) a charged hydrophobic peptide containing 1-20 amino acid residues; 
         [0024]    with proviso that in compound of structure (I) A is neither ubiquinone (e.g. 2-methyl-4,5-dimethoxy-3,6-dioxo-1,4-cyclohexadienyl) nor tocopherol or a mimetic of superoxide dismutase or ebselen; when L is neither divalent decyl nor divalent pentyl nor divalent propyl radical; and when B is triphenylphosphonium cation; including solvates, isomers or prodrugs thereof. 
         [0025]    A further aspect of the present invention is a pharmaceutical composition for prophylaxis and treatment of different eye pathologies comprising a compound of structure (I), wherein A is a plastoquinone of structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0026]    wherein Y is methyl, m=2; 
         [0027]    L is a linker group, comprising: 
         [0028]    a) straight or branched hydrocarbon chain optionally substituted with one or more substituents and optionally containing one or more double or triple bonds; or 
         [0029]    b) natural isoprene chain; 
         [0030]    n is integer from 1 to 20; 
         [0031]    B comprises: 
         [0032]    a) a Skulachev-ion Sk: 
         [0000]      Sk + Z −   
         [0033]    where Sk is a lipophilic cation, and Z is a pharmacologically acceptable anion; and/or 
         [0034]    b) a charged hydrophobic peptide containing 1-20 amino acid residues; 
         [0035]    with proviso that in compound of structure (I) A is neither ubiquinone (e.g. 2-methyl-4,5-dimethoxy-3,6-dioxo-1,4-cyclohexadienyl) nor tocopherol nor mimetic of superoxide dismutase or ebselen; when L is neither divalent decyl nor divalent pentyl nor divalent propyl radical; and when B is triphenylphosphonium cation; including solvates, isomers or prodrugs thereof. 
         [0036]    A further aspect of the present invention is a pharmaceutical composition for prophylaxis and treatment of different eye pathologies comprising a compound of structure (I)—SkQ1: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0037]    A further aspect of the present invention is a pharmaceutical composition for prophylaxis and treatment of different eye pathologies comprising therapeutically or prophylactically justified amount of a compound of Structure (I) and at least one pharmacologically acceptable solvent or carrier. A pharmacologically acceptable solvent or carrier may present a filler, a diluent (solvent) or their mixture. “Therapeutically justified” amount of a compound is amount of a compound of Structure (I) that causes desired biological or medical response in a patient treated by a doctor or a veterinarian. “Prophylactically justified” amount of a compound is amount of a compound of Structure (I) that prevents or suppresses the disease, or relieves progress of the disease in a patient suffering from a medical state that is tried to be prevented, suppressed or relieved by a doctor or a veterinarian. 
         [0038]    A patient is a human in one of the aspects of the present invention. 
         [0039]    “Eye pathologies” comprise but are not limited by: different forms of macular degeneration (MD) and other related symptoms, namely: atrophic (dry) MD, exudative (wet) MD, age-related macular retinopathy (ARM), choroidal neovascularization, detached pigment retinal epithelium (PED), atrophy of pigment retinal epithelium (RPE). The term “macular degeneration (MD)” also comprises all eye diseases irrelevant to age-related changes in a human organism, namely: vitelliform degeneration of Best, Stargardt disease, juvenile macular dystrophy, Behr&#39;s disease, Sorsby&#39;s dystrophy, Doyne honeycomb retinal dystrophy. “Symptoms related to macular degeneration” comprise but are not limited by: drusen surrounded by white-yellow spots, submacular discoid scar of tissues, choroidal neovascularization, detached pigment retinal epithelium (PED), atrophy of pigment retinal epithelium (RPE), anomalous expansion of choroidal blood vessels, blurred or disturbed vision area, central dead point, pigment anomalies, mixed layer of thin granulation located on the inner side of Bruch&#39;s membrane, thickening and lowered permeability of Bruch&#39;s membrane. 
         [0040]    Said compositions are particularly useful for treatment and/or prophylaxis of such disorders as: cataract including senile cataract, diabetic cataract, retinopathy, detached retina, pathology of retinal vessels, eye vascular envelope, optic nerve including atrophy of optic nerve, central and peripheral chorioretinal dystrophies, in particular, uveitis; intraocular hemorrhage, traumatic hemorrhage; conjunctivitis; ophthalmic ulcer; keratitis including filamentary keratitis; glaucoma. 
         [0041]    The reasons causing macular degeneration include but are not limited by: genetic or physical trauma, diseases such as diabetes, or infections, in particular, bacterial. 
         [0042]    The compounds of structure (I) can be applied to efficient prophylaxis and therapy of all forms of macular degeneration (MD) and other MD related syndromes or symptoms irrespective of the reasons which have caused them. 
         [0043]    Application of the pharmaceutical compositions of the present invention can be both somatic and local. Administration methods comprise enteral such as oral, sublingual and rectal; local such as through-dermal, intradermal and oculodermal; and parenteral. Acceptable parenteral methods of administration comprise injections, for example, intravenous, intramuscular, hypodermic injections et cetera, and noninjection methods such as intravaginal and nasal. Per ocular or per oral administration of the compounds and the pharmaceutical compositions of the present invention is more preferable. In particular, the administration can be carried out in the form of eye drops or tablets, granules, capsules or other pressed or compressed form. 
         [0044]    When a compound of structure (I) is administered as a pharmaceutical composition, the compound of structure (I) should be mixed according to formula with a suitable amount of pharmacologically acceptable solvent or carrier so that to have the appropriate form for administration to a patient. The term “solvent” relates to diluent, auxiliary medicinal substance, filler or carrier which is mixed with the compound of structure (I) for administration to a patient. Liquors like water, and oils including petrolic, animal, vegetative and synthetic such as peanut oil, soybean oil, mineral oil and other similar oils can be used as said pharmacological carriers. Normal saline solution, acacia pitch, gelatin, starch, talc, keratin, colloid silver, urea etc can serve as said pharmacological solvents. 
         [0045]    Said composition can also include auxiliary substances, stabilizers, thickeners, lubricant and coloring agents. 
         [0046]    The compounds and compositions of the present invention can be administered in the form of capsules, tablets, pills, pillets, granules, syrups, elixirs, solutions, opthalmologic solutions, suspensions, emulsions, suppositories or retarded release substances, or in any other form suitable for administration to a patient. 
         [0047]    One of the aspects of the present invention is application of the compounds of structure (I) and compositions in the form of solutions for per oral and per ocular administration. 
         [0048]    Therapeutically justified amount of a compound of Structure (I) required for treatment of a specific disease or symptom, depends on the nature of disease or symptom and a method of administration and should be determined at consultation with a physician in charge. In principle, upon per oral administration, acceptable doses are from 1 to 500 μg/kg of a patient body weight, 25 μg/kg of a patient body weight is more preferable, and 125 μg/kg of a patient body weight is the most preferable. 
         [0049]    Example of Pharmaceutically Acceptable Composition in the Form of Solution for Per Oral Administration. 
         [0050]    10 mM sodium phosphate buffer, pH 6.0 
         [0051]    SkQ1 at concentration of 125 μg/mL 
         [0052]    Aqueous solution 
       An Example of Pharmaceutically Acceptable Composition in the Form of Opthalmologic Solution (Eye Drops). 
       [0053]    10 mM sodium phosphate buffer, pH 6.5 
         [0054]    Aqueous solution of 250 nM SkQ1 
         [0055]    Aqueous solution of 0.9% NaCl 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0056]      FIG. 1  shows the influence of the compounds on the cataract morbidity in OXYS rats. 
           [0057]      FIG. 2  demonstrates the influence of the compounds on the macular dystrophy morbidity in OXYS rats. 
           [0058]      FIG. 3  shows the influence of the compound on the cataract progression in OXYS rats. 
           [0059]      FIG. 4  shows the influence of the compound on the macular degeneration progression in OXYS rats. 
           [0060]      FIG. 5  compares the state of crystalline lens of OXYS rats before administering and after 45-day course of KBr, SkQ1 or vitamin E. 
           [0061]      FIG. 6  shows degenerative changes in macular region of retina of OXYS rats before administering and after 45-day course of KBr, SkQ1 and vitamin E. 
           [0062]      FIG. 7  demonstrates the therapeutic effect of SkQ1 on the state of crystalline lens of OXYS rats. 
           [0063]      FIG. 8  demonstrates the therapeutic effect of SkQ1 on the state of retina of OXYS rats. 
       
    
    
       [0064]    The following non-limiting Examples illustrate the preparation and use of the compounds of structure I but should not be understood as limiting the invention as modifications in materials and methods will be apparent to the skilled person. The following examples should not be construed as limiting the scope of this disclosure. 
       EXAMPLES 
     1. Prophylactic Effect of SkQ1 Antioxidant of the Present Invention Against Age-Related Eye Diseases 
       [0065]    The study was carried out using OXYS and Wistar male rats. The animals were housed in cages (five rats per a cage) and kept under standard laboratory conditions (at 22±1° C., 60% relative humidity, and natural light), provided with a standard rodent diet (PK-120-1, Ltd. ‘laboratorsnab’, Russia), and given water ad libitum. At the age of 1.5 months after preliminary pupil dilation with 1% tropicamide ophthalmic the rats were examined by ophthalmologist. During the period from 1.5 to 3 months, which is critical for the development of pronounced changes in eye organ of OXYS rats, the animals were given either SkQ1 (50 nmol per kg of body weight), or KBr (50 nmol per kg of body weight) or vitamin E (alfa-tocopherol acetate, 20 mg per kg). We use Vitamin E for a comparison with test antioxidants. Animals received the compounds on a small piece of dried bread before a regular meal, and the control group of animals received the same piece of bread without any compound. After completing the course of antioxidants the animals were weighed and retested with opthalmoscope. To avoid human factor in the evaluation of compound effects, the researcher who conducted the opthalmoscopic examination was not told which of the animals received antioxidants. 
         [0066]    The opthalmoscopic examination was carried out using direct opthalmoscope “Betta”, Germany. In selected animals under fluorotane narcosis (1-1.5 minutes) eyeground was photographed, fluorescent angiography with the use of “Opton” fundus-camera was conducted or crystalline lenses were examined by means of slitlamp “Opton SL30” using system of automatic image registration (biomicroscopic research). 
         [0067]    The lens state was evaluated according to the classification system accepted in clinical practice (L. A. Katsnelson, T. I. Forofonova, A. Ya. Bunin, 1990) with grades ranging from 0 to 3: score 0—the lens is clear; score 1—spotted weak cloudiness; score 2—multiple spots of cloudiness and score 3—intense cloudiness of the lens core and nucleus. The presence and the degree of spotted changes in macular area were evaluated according to accepted classification: score 0—no changes; score 1—the 1 st  stage of pathology, when small yellow deposits, known as “drusen” appear underneath the macula; score 2—2 nd  stage, the development of prominent yellow spot with sharp edges with the size of 0.5 to 1 of the disk diameter (exudative detachment of pigment retinal epithelium); and score 3—3 rd  stage with extensive hemorrhage into macular area. 
         [0068]    Statistical processing of the results was carried out using the factorial dispersive analysis (ANOVA/MANOVA, Statistica, 5) with post hoc comparison of group average (Newman-Keul test) considering genotype and preparation as independent factors. 
         [0069]    Results Obtained 
         [0070]    Opthalmoscopic examination did not reveal any changes in the lenses or in the macular area of the retina in 1.5 and 3 month-old Wistar rats. In contrast, in OXYS rats early cataract (score 1) was observed in 20% of cases ( FIG. 1 ) and macular degeneration of the 1 st  stage—in 10% of cases at the age of 1.5-months ( FIG. 2 ). 
         [0071]    At the age of 3 months in the control intact group of OXYS rats pathological changes of lenses were observed in 90% of examined eyes, including 35% of eyes with 2 nd  stage of cataract, with ring-shaped and nuclear cataracts prevailed ( FIG. 1 ). 
         [0072]    Macular dystrophy was observed in 85% of eyes from control group of animals of which 16% corresponded to the 2 nd  stage of this pathology ( FIG. 2 ). In the group of OXYS rats supplemented with KBr, lens changes were observed in 93% of eyes, with 57% of total number of eyes having 2 nd  stage of cataract progression. Changes in the macular area of the retina were observed in 87% of eyes of animals from this group and 13% of these changes corresponded to the 2 nd  stage of the disease. Taking into account that cataract already affected 20% of eyes, 73% of rat eyes have been newly affected, and respectively macular dystrophy has affected 77% of eyes. 
         [0073]    In animals supplemented with SkQ1 ( FIG. 1 ) some lens changes were registered in 46% of cases, however these changes corresponded to the 1 st  stage of cataract. Changes in the macular area of the retina in OXYS rats of this group were revealed in 38% of cases and also were defined as the 1 st  stage of macular degeneration ( FIG. 2 ). Of this group of rats supplemented with SkQ1, cataract was revealed in 26% of cases (2.8 times less than in the group of rats supplemented with KBr), macular dystrophy was detected in 28% of cases (also 2.8 times less than in the control group). 
         [0074]    In the group of rats supplemented with vitamin E, lens changes were registered in 58% of cases (38% has been added, 1.8 times less than in the control intact group), with 12% of changes corresponding to the 2 nd  stage of the cataract. Changes in the macular area of the retina were revealed in 54% of OXYS rats from this group (1.5 times less than in the control intact group), including 8% corresponding to the 2 nd  stage of macular degeneration. Administration of SkQ1 not only decreased the cataract and macular dystrophy morbidity but also essentially affected their progression (see  FIG. 3  and  FIG. 4  respectively). 
         [0075]    It is remarkable that in one month after the end of the course of SkQ1 administration, no any changes in the state of retina and crystalline lens of the rats supplemented with SkQ1 have been observed, in contrast to the control group of animals. 
         [0076]    Thus, the investigations performed prove the efficiency of SkQ1 application for prophylaxis of age-related eye diseases including prophylaxis of cataract and macular dystrophy—the main age-related eye pathologies in elders. 
       2. Therapeutic Effect of SkQ1 Antioxidant of the Present Invention Against Age-Related Eye Diseases 
       [0077]    The experiment followed the same pattern as said investigation demonstrating prophylactic effect of SkQ1 except that in this experiment OXYS and Wistar rats at the age of 10.5 months were used. 
         [0078]    Results 
         [0079]    Table 1 shows the results of examination of animals before administering at the age of 10.5 months and after the therapy course. In Wistar rats, changes of crystalline lenses and retina exceeding characteristic parameters for the appropriate age were revealed that is due to specific conditions of cage keeping of these animals. Examination of Wistar rats in 45 days did not reveal any changes in the state of crystalline lenses, the compounds also did not affect substantially the state of lenses. Among Wistar rats supplemented with SkQ1, animals with changes of retina which could be qualified as appropriate to even the most initial stage of disease were practically absent. 
         [0080]    Pair comparisons showed that in the control intact group of OXYS rats, pathological changes of lenses and retina for 1.5 months have authentically aggravated (p&lt;0.04 and p&lt;0.01 accordingly). In animals supplemented with KBr, changes of lenses have authentically aggravated whereas no any changes of retina have been observed. It should be emphasized that the state of eyes before and after the therapy course has been compared therefore when the average values are compared (Table 1,  FIGS. 7 and 8 ), in OXYS rats supplemented with SkQ1 these pathological changes have really been much less pronounced. In retina of this group of animals, significant reduction of puffiness was observed; there was also reduction of quantity and area of ischemic centers, resolution of hemorrhages. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 The state of animal eyes before and after course of SkQl 
               
               
                 (50 nmol per kg of body weight). Changes of lenses and 
               
               
                 macular area of retina are given with grades (score). 
               
             
          
           
               
                   
                 Preliminary 
                   
               
               
                   
                 examination at 
                 Examination after therapy course at 
               
               
                   
                 the age of 10.5 
                 the age of 12 months 
               
             
          
           
               
                   
                 months 
                 Intact 
                 KBr 
                 SkQl 
               
               
                   
                   
               
             
          
           
               
                   
                 OXYS 
               
             
          
           
               
                 Macular 
                 1.46 ± 1.18 
                 1.90 ± 0.10 
                 1.13 ± 0.17 
                 0.32 ± 0.13 
               
               
                 Lenses 
                 1.19 ± 0.12 
                 1.41 ± 0.19 
                  1.6 ± 0.23 
                 0.41 ± 0.13 
               
             
          
           
               
                   
                 Wistar 
               
             
          
           
               
                 Macular 
                 0.48 ± 0.19 
                  0.5 ± 0.25 
                 0.25 ± 0.10 
                 0.09 ± 0.06 
               
               
                 Lenses 
                 0.40 ± 0.23 
                  0.5 ± 0.22 
                  0.5 ± 0.15 
                 0.54 ± 0.14 
               
               
                   
               
             
          
         
       
     
         [0081]    The data obtained proves the therapeutic effect of SkQ1-based pharmaceutical composition on animals suffering from cataract or retinopathy corresponding to macular dystrophy of retina in humans.