INHIBITION OF ANGIOGENESIS WITH EPIGALLOCATECHIN-3 -GALLATE
The present invention relates to the field of inhibition of angiogenic diseases.
Originating from China, tea has become a popular beverage all over the world. Even though green tea has long been valued in China for its miraculous medicinal properties and for the maintenance of good health, it is not until recently that the beneficial pharmaceutical effects of drinking tea has been appreciated in the Western world. In the course of extensive studies on the medicinal properties of tea components, it has been found that tea catechins, which are a major component of tea tannin, possess strong physiological activity.
Recent studies show that consumption of tea inhibits the growth of several tumour types in animals, including lung and oesophageal cancers (Yang, C. S. & Wang, Z.-Y. J. Natl . Cancer Ins t . 85, 1038-1049 (1993); Wang, Z.-Y. et al . , Carcinogenesis 16, 2143-2148 (1995); and Yang, G.-Y. et al . , Cancer Res . 57, 1889-1894 (1997)). Drinking tea, especially green tea, has been shown to be associated with lower incidence of human cancer in some epidemiological studies (Yang, C. S. & Wang, Z.-Y. J". Natl . Cancer Inst . 85, 1038- 1049 (1993)) . However, the mechanisms of cancer inhibition by
green tea are not known.
US 5 391 568 discloses inhibition of lung tumourigenesis by administration of a polyphenol, such as EGCG, and suggests that the mechanism of inhibition by green tea and EGCG in NNK-induced lung tumourigenesis is due to their antioxidant properties. Further, EGCG has been proposed in methods for treatment of such various conditions as hypertension, mycoplasma infection and influenza virus infection, see US patent no. 4 480 966, 5 104 901 and 5 137 922, respectively. However, none of these patents have succeeded in elucidateing the mechanism behind the effect of EGCG in these methods.
According to the present invention, it has been found that green tea and one of the major green tea catechins, epigallocatechin-3-gallate (EGCG) , significantly prevents angiogenesis. More specifically, the present invention relates to the use of EGCG and/or a catechin-based analogue or functional part thereof in the manufacture of a medicament for the prevention and/or inhibition of diseases associated with angiogenesis.
BRIEF DESCRIPTION OF THE FIGURES
Figure la shows results of BCE cell proliferation assay performed as previously described (Cao, Y. et al . , J". Biol .
Chem . 271, 29461-29467 (1996) ) . Cells at the density of 10,000 cells/well were seeded in gelatinized 24-well plates and grown in DME medium containing 5% bovine calf serum. EGCG (Sigma) samples in triplicates and FGF-2 at a final concentration of 1 ng/ml were added to each well. After 72 -h incubation, cells were counted with a Coulter counter. Values represent the mean of three determinations (O SEM) as the number of cells. * *P< 0 . 005 , * * *P< 0 . 0001 .
Figures lb-le show suppression of VEGF-stimulated neovascularization by green tea in the mouse corneal model. The Chinese green tea water extract was prepared according to published protocols (Yang, C. S. et al . , Exp . Lung Res . 24, 629-639 (1998); and Wang, Z-Y. et al . , Cancer Res. 52, 1162- 1170 (1992)) and mice drank tea starting at day 3 before VEGF implantation and throughout the experiment. Pellets containing 160 ng of VEGF, sucrose aluminum sulfate and hydron were implanted into corneal micropockets as previously described (Cao, Y.et al . , J. Exp . Med . 182, 2069-2077 (1995) ) .
Figure lb shows measured vessel length in the mouse corneal model for mice treated with water and mice treated with tea.
Figure lc shows measured vessel clock-hour in the mouse
corneal model for mice treated with water and mice treated with tea.
Figure Id shows measured vessel area in the mouse corneal model for mice treated with water and mice treated with tea.
Figure le shows results of the CAM assay that was performed as previously described (Cao, Y.et al . , J. Exp . Med . 182, 2069-2077 (1995)). Disks of methylcellulose containing various doses of EGCG dried on nylon meshes were implanted on the CAMs of individual embryos . Embryos and CAMs were examined after 48 h for the formation of avascular zones in the field of the implanted disks by a stereoscope. At various doses, the number of CAMs with avascular zones over the total number of CAMs is indicated above each bar.
Figure 2 illustrates general formulae of the major components of green tea; namely (- ) epicatechin, (- ) epicatechin-3- gallate, (-) epigallocatechin and ( - ) epigallocatechin-3- gallate.
As used herein, the term "endothelium" means a thin layer of flat epithelial cells, that lines serous cavities, lymph vessels and blood vessels.
In the present application, a " therapeutically effective dose" is defined as an amount sufficient to prevent, cure or at least partially arrest a disease and its complications.
"Angiogenesis" means the generation of new blood vessels into a tissue or organ and it involves endothelial cell proliferation. Under normal physiological conditions, humans or animals undergo angiogenesis only in very specific restricted situations. For example, angiogenesis is normally observed in wound healing, the female reproductive cycle, fetal and embryonal development and formation of the corpus luteum, endometrium and placenta.
In the present context, it is to be understood that the term "EGCG" encompasses epigallocatechin-3-gallate, epicatechin gallate, epigallocatechin, epicatechin, (+)catechin, theflavin monogallate A, theflavin monogallate B and theflavin digallate as well as any other catechin-based analogue or a functional part thereof, e.g. as defined in Figure 2, or any molecule comprised of the same backbone structure, with the function of inhibition of angiogenesis.
The term "green tea" relates to any tea which has been dried in a well known special way that prevents the tea from the negative effects of fermentation and harmful oxidation. The
processing of green tea according to traditional Chinese methods as well as by further refined techniques is well known and widely described in the literature. In general, 1 g of dry green tea comprises about 73 mg of EGCG.
A "combinatorial library" means a library of molecules containing a large number, typically at least between 103 and 106, of different molecules, typically characterized by different sequences of subunits, or a combination of different sequences of side chains and linkages, or different-substituted compounds in a small -compound library.
In a first aspect, the present invention relates to the use of (-) epigallocatechin-3 -gallate (EGCG) and/or a catechin- based analogue or a functional part thereof, e.g. as defined in Figure 2 , in the manufacture of a medicament for the prevention and/or inhibition of angiogenesis in treatment of a disease. More specifically, said medicament may be effective in treating and/or preventing any disease or process mediated by angiogenesis. Angiogenesis mediated diseases include, but are not restricted to rheumatoid arthritis, psoriasis, ocular angiogenic diseases, for example, diabetic retinopathy, retinopathy of prematurity, macular degeneration, corneal angiogenesis, graft rejection, neovascular glaucoma, retrolental fibroplasia, rubeosis,
Osier-Webber Syndrome, myocardial angiogenesis, plaque neovascularisation, telangiectasia, hemophiliac joints, angiofibroma, and wound granulation. Organ malformation is also angiogenesis dependent.
Further angiogenesis-mediated disease include diabetic neovascularization, scleroderma, leukaemia, pyrogenic granuloma, coronary collaterals, cerebral collaterals, arteriovenous malformations, ischaemic limb angiogenesis, hemangioma, mascular degeneration, fractures, keloids, obesity, scar formation, neuronal diseases such as Alzheimer's disease and Parkinson's disease.
In addition, said medicament may be for the treatment of diseases that have angiogenesis as a pathological consequence, such as cat scratch disease (Rochele minalia quintosa) and peptic ulcers and Helicobacter pylori-related diseases, also pathogenic or undesirable vasculogenesis, haematopoiesis , ovulation, menstruation and placentation.
In embodiments of the present invention, a pharmaceutical or medicament comprising ECGC and/or green tea may not be used in treatment of a tumour or cancer.
In one advantageous embodiment, the use according to the
invention relates to the manufacture of a medicament in the form of an oral preparation, preferably drinking tea, such as green tea. In an especially advantageous embodiment, said tea has been enriched as to the content of epigallocatechin-3- gallate (EGCG) and/or a catechin-based analogue or a functional part thereof. In a specific embodiment, the present use relates to the manufacture of green tea, which has been modified in order to enable a more efficient treatment and/or prevention the desired disease. It may, for example, have been enriched as concerns the content of EGCG, and/or a catechin-based analogue or functional part thereof. Alternatively, the amount of un undesired or toxic component, such as caffeine, may have been lowered or even eliminated. Indeed, it is feasible that certain substances, such as caffeine, may not only be undesired for a specific reason, such as the stimulating effect of caffeine under certain conditions, but they may in addition also deteriorate or even inhibit the desired effect of the present EGCG, and/or the catechin-based analogue or functional part thereof. For example, it may be hypothesized that the vessel dilating effect of caffeine may actually enhance angiogenesis in vi tro . Accordingly, the present invention also relates to the use of a specifically designed tea, preferably green tea, as a functional food for certain purposes, such as improving the health of an individual who does not necessarily have to be
suffering from a disease. Thus, the invention also encompass a functional food, which, alone or in combination with other components, comprises green tea or essential components thereof. In the context of the present invention, it is to be understood that although green tea is preferred, any other tea that comprises a sufficient amount of EGCG and/or catechin-based analogue or functional part thereof may be used for the purposes described herein. In the manufacture of a green tea medicament, which comprises the desired amounts of specific components, concentrations of EGCG and/or catechin-based analogue or functional part thereof, and caffeine, may be determined by methods well known to the skilled in this field, e.g. with reference to methods defined in US 5 391 568.
Green tea is nowadays a commercial product available on all markets, e.g. from Tea Research Institute of the Chinese Academy of Agricultural Sciences, Hangzhou, China. The preparation of tea polyphenols and catechin-based analogues and functional fragments of EGCG which may be used in accordance with the present invention, such as epigallocatechin-3 -gallate (EGCG), epicatechin gallate, epigallocatechin, epicatechin, (+)catechin, theflavin monogallate A, theflavin monogallate B and theflavin digallate, has been disclosed in the literature and is easily
performed by someone skilled in the art with reference thereto. An examples of a process for the production of EGCG by extraction from tea leaves is found in US 4 613 672 in the name of Hara . Further, EGCG and/or the catechin-based analogues or functional parts thereof may be fractionated from a crude catechin mixture (Matsuzaki, T. and Hara, Y., "Antioxidative activity of tea leaf catechins" , Nippon Nogeigaku Kaishi, 59:129-134, 1985) . Alternatively, the EGCG and/or the analogues or parts thereof used according to the invention may be produced synthetically according to methods well known in this field.
As an example, the amount of green tea in drinking water may be about 1.25% (4.69 mg/ml) , thus containing 708 mg/ml of EGCG as previously reported (Yang, C. S. et al . , Exp . Lung Res . 24, 629-639 (1998); and Wang, Z-Y. et al . , Cancer Res. 52, 1162-1170 (1992)). The concentration of EGCG in human plasma after ingestion of 2-3 cups of tea was previously reported to be in the range of 0.1-0.3 mM (Yang, C. S. et al., Cancer Epidemiol . Biomarkers Prev. 7, 351-354 (1998)). Thus, a medicament comprised of green tea will preferably contain any amount from a few, such as 1 or 2 , ng and up to at least 50 or 100 mg, such as about 200-500 mg of EGCG, more preferably about 250-450 and most preferred about 280-425 mg of EGCG in order to provide the above mentioned desired
plasma level. As is well known to the skilled in this field, the curve for human uptake of EGCG will increase steadily with the dose administered up to a certain value, after which it will level out. Consequently, EGCG and/or a catechin-based analogue or functional part thereof according to the invention is preferably used in any concentration up to the value where it is no longer absorbed by the recipient. Thus, the skilled in this field will adapt the amount of EGCG and/or a catechin-based analogue or functional part thereof used as appropriate in each specific case in order to provide the desired concentration and thus effect.
As is clear, other embodiments employ pharmaceuticals and medicaments that do not comprise green tea.
A pharmaceutical or medicament employed in accordance with the present invention may be used in combination with one or more other pharmaceutically active agents or therapies, e.g. radiotherapy, chemotherapy, immunotherapy, anti-inflammatory therapy, anti-infective therapy, hormone therapy and/or surgery .
In a preferred embodiment, the use according to the invention relates to the use of EGCG and/or a catechin-based analogue or functional part thereof in the preparation of a medicament
for the treatment and/or prevention of diabetic retinopathy.
A second aspect of the present invention is a pharmaceutical preparation for use in prevention and/or inhibition of angiogenesis in a disease, which pharmaceutical preparation comprises EGCG and/or a catechin-based analogue or functional part thereof and a pharmaceutically acceptable carrier. In general, the invention relates to any pharmaceutical preparation prepared by the above discussed use. In a preferred embodiment, the preparation according to the invention is suitable for oral administration. Thus, in various embodiments the present preparation is suitable for the treatment and/or prevention of any one of the above mentioned diseases and conditions. Accordingly, the preparation may relate to a medicament for the prevention and/or treatment of an angiogenesis-dependent disease.
More specifically, a pharmaceutical preparation or medicament employed in accordance with the invention will preferably comprise any amount, from a few ng, such as 1 or 2 ng, and up to at least 50 or 100 mg, such as about 200-500 mg, of EGCG, more preferably about 250-450, and most preferably about 280- 425, mg of EGCG in order to provide the above mentioned desired plasma level. In certain cases, depending upon the prevailing conditions, the amount may be much higher, such as
up to about 1000 mg . However, as is well known to the skilled in this field, the curve for human uptake of EGCG will increase steadily with the dose given up to a certain value, after which it will level out. Consequently, EGCG and/or a catechin-based analogue or functional part thereof according to the invention may be used in any concentration up to the value where it is no longer absorbed by the recipient. However, the skilled in this field will realise that the content of EGCG and/or a catechin-based analogues or functional parts thereof should be adapted as appropriate depending e.g. on the patient's age and body weight, the specific condition to be treated and/or prevented etc., in order to provide the desired concentration and thus effect.
Even though an oral preparation is preferred, according to the present invention, EGCG and/or the catechin-based analogue or functional part thereof may be administered by any other route, such as by parenteral , topical, or local administration, such as by aerosol or transdermally, for prophylactic and/or therapeutic treatment. Due to the simplicity thereof, a preparation in the form of a drinking solution, such as tea, is preferred. However, in other embodiments of the invention, the pharmaceutical preparation can be administered in a variety of unit dosage forms depending upon the mode of administration. For example, other
unit dosage forms suitable for oral administration include powder, tablets, pills, capsules and lozenges. Further, a pharmaceutical preparation according to the invention may include additional components, e.g. to render it resistant to acidic and enzymatic hydrolysis. Means and additives to specifically adapt a preparation for a desired administration are well known in the art.
Under certains circumstances, it may also be suitable to administer an preparation comprising EGCG and/or a catechin- based analogue or a functional part thereof according to the invention by parenteral administration, such as intravenous administration or administration into a body cavity or lumen of an organ. Such a consideration is best made by the attending physician, depending e.g. on the disease to be treated and/or prevented etc. Actual methods for preparing parenterally administrable compositions will be known or apparent to those skilled in the art and are described in more detail in such pulications as Remington ' ε Pharmaceutical Science, 15th., Mack Publishing Company, Easton, Pennsylvania (1980) . Thus, the preparation according to the invention will commonly comprise a solution of EGCG and/or a catechin-based analogue or a functional part thereof dissolved in a pharmaceutically acceptable carrier, preferably an aqueous carrier, such as water in the case of a tea preparation. A
variety of alternative aqueous carriers can be used depending on the kind of preparation, e . g. , buffered saline and the like. These solutions may be sterile and are generally free of undesirable matter. The preparation may contain pharmaceutically acceptable auxiliary substances as required to approximate physiological conditions, such as pH adjusting and buffering agents, toxicity adjusting agents and the like, for example, sodium acetate, sodium chloride, potassium chloride, calcium chloride, sodium lactate and the like. The concentration of EGCG and/or a catechin-based analogue or functional part thereof in these formulations can vary widely, and will be selected primarily based on fluid volumes, viscosities, body weight and the like in accordance with the particular mode of administration selected and the patient's needs.
In a third aspect, the present invention relates to a method of treatment of a disease by preventing and/or inhibiting angiogenesis, the method comprising administering to an animal or human patient in need of such treatment of an effective amount of epigallocatechin-3-gallate (EGCG) and/or a catechin-based analogue or functional part thereof. Preferably, said administration is an oral administration. In one embodiment, said treatment is aimed at the prevention or treatment of an angiogenesis-dependent disease, and in a
preferred embodiment, the disease is diabetic retinopathy. However, the method according to the invention may relate to any one of the above mentioned diseases.
The pharmaceutical or medicament for administration in such a method may have any of the properties or purposes disclosed already herein.
Thus, the preparation comprising EGCG and/or a catechin-based analogue or functional part thereof according to the invention can be administered for therapeutic and/or preventive treatments. In the therapeutic methods according to the invention, preparations may be administered to a patient suffering from any one of the above defined diseases in an amount sufficient to cure or at least partially arrest the disease and its complications. Amounts effective for this use will depend upon the severity of the disease, the general state of the patient's health, mode of administration etc..
Single or multiple administrations of the compositions may be administered depending on the dosage and frequency as required and tolerated by the patient. In any event, the composition should provide a sufficient quantity of the EGCG and/or a catechin-based analogue or functional part thereof to effectively treat the patient. Suitable dosages are
determined by the attending physician with reference to suitable literature.
A fourth aspect of the present invention relates to the use of epigallocatechin-3 -gallate (EGCG) and/or a catechin-based analogue or functional part thereof as a tool in drug design, wherein said drugs are preferably suitable for inhibiting endothelial cell proliferation, e.g. any one of the above defined diseases. According to the invention, EGCG and/or a catechin-based analogue or functional part thereof may also be used in methods of combinatorial chemistry and libraries for high throughput screening methods .
Libraries containing small organic molecules may be screened, wherein an organic molecule having a large number of specific parent compound group substitutions are used. A general synthetic scheme may follow the methods described by Brunin and DeWitt. Briefly, at each successive synthetic step, one of a plurality of different selected substituents is added to each of a selected subset of tubes in an array, with the selection of tube subsets being such as to generate all possible permutations of the different substituents employed in producing the library. One suitable permutation strategy is outlined in US patent application with serial no. 08/512 027, filed August 7, 1995: "Methods and Apparatus for
Producing Position-Addressable Combinatorial Libraries" .
As regards the above mentioned uses of EGCG, and/or a catechin-based analogue or functional part thereof, there is a currently widespread interest in using combinatorial libraries of random polypeptides and other organic molecules to search for biologically active compounds, see e.g. Kramer et al . , 1993; Houghten et al . , 1992, 1991; Dooley et al . , 1993a-1993b; Eichler et al . , 1993; Pinilla et al . , 1992, 1993. Ligands discovered by screening libraries of this type may be useful in mimicking or blocking natural ligands or interfering with the naturally occurring interactions of a biological target. More importantly in the present context, they may also be used as a starting point for developing related molecules with more desirable properties, e.g. better biological effect, biological compatibility etc. EGCG and/or a catechin-based analogue or functional part thereof may according to the present invention be used in combinatorial libraries formed by various solid-phase or solution-phase synthetic method (see e.g. US patent 5 763 263) . By use of these techniques, such as the one disclosed in US patent no. 5 753 187, million of new chemical and/or biological compounds may be screened in a few weeks or shorter. Of the large number of compounds produced, only the ones showing interesting biological activity are analyzed for further
testing and experimentation.
As regards the high throughput library screening methods, oligomeric or small -molecule library compounds capable of interacting specifically with a selected biological agent, such as a biomolecule, a macromolecule complex, or cell, are screened employing a combinatorial library device which is easily chosen of the skilled in this field among well known methods, such as described above. In such a method, each member of the library is screened for its ability to interact specifically with the selected agent. In practising the method, a biological agent may be drawn into compound- containing tubes and is allowed to interact with the individual library compound in each tube. The interaction is designed to produce a detectable signal that can be used to monitor the presence of the desired interaction. Preferably, the biological agent is present in an aqueous solution and further conditions are adapted depending on the desired interaction. Detection may e.g. be performed by any well known fluorescence method for detection of substances. Conventional techniques employing a confocal, scanning fluorescence microscope may be used.
Accordingly, the present invention also relates to methods of identifying pharmacological agents or drugs, which exhibit
the pharmacological activities of EGCG and/or a catechin- based analogue or functional part thereof as described above while possessing further, more advantageous properties, such as an easy and cost-effective preparation etc. Screening methods may be used for the testing of other candidate substances, such as EGCG agonists, or agonists for a catechin-based analogue or functional part thereof. The methods according to the invention are amenable to automated, cost-effective high troughput drug screening well known to the skilled in this field, see e.g. US patent 5 710 266.
Thus, the present invention provides the use of ECGC in methods of designing or screening for mimetics of the substances .
Accordingly, the present invention provides a method of designing mimetics of ECGC having the biological activity of inhibition or angiogenesis, said method comprising:
(i) analysing a substance having the biological activity to define a pharmacophore ; and,
(ii) modelling the pharmacophore to design and/or screen candidate mimetics having the biological activity.
Suitable modelling techniques are known in the art. This includes the design of so-called "mimetics" which involves
the study of functional interactions and the design of compounds which contain functional groups arranged in such a manner that they could reproduced those interactions.
The designing of mimetics to a known pharmaceutically active compound is a known approach to the development of pharmaceuticals based on a "lead" compound, here ECGC. Mimetic design, synthesis and testing may be used to avoid randomly screening large number of molecules for a target property.
There are several steps commonly taken in the design of a mimetic from a compound having a given target property. Firstly, the particular parts of the compound that are critical and/or important in determining the target property are determined. These parts constituting the active region of the compound are known as its "pharmacophore" .
Once the pharmacophore has been found, its structure is modelled to according its physical properties, e.g. stereochemistry, bonding, size and/or charge, using data from a range of sources, e.g. spectroscopic techniques, X-ray diffraction data and NMR. Computational analysis, similarity mapping (which models the charge and/or volume of a pharmacophore, rather than the bonding between atoms) and
other techniques can be used in this modelling process.
A template molecule is then selected onto which chemical groups which mimic the pharmacophore can be grafted. The template molecule and the chemical groups grafted on to it can conveniently be selected so that the mimetic is easy to synthesise, is likely to be pharmacologically acceptable, and does not degrade in vivo, while retaining the biological activity of the lead compound. The mimetic or mimetics found by this approach can then be screened to see whether they have the target property, or to what extent they exhibit it. Further optimisation or modification can then be carried out to arrive at one or more final mimetics for in vivo or clinical testing.
The mimetic or mimetics found by this approach can then be screened to see whether they have the target property, or to what extent they exhibit it. Further optimisation or modification can then be carried out to arrive at one or more final mimetics for in vivo or clinical testing.
Mimetics of this type together with their use in pharmaceuticals, medicaments and methods of treatment, form further aspects of the invention and are useful as analogues of ECGC. An analogue of ECGC employed in the present
invention may or may not be a catechin.
In addition, the present invention relates to kits for performing the above described methods .
EXPERIMENTAL
The present invention will now be described by way of examples, which are for illustrative purposes only and not intended to limit the scope of the invention in any way. All references given below and elsewhere in the present application are hereby included by reference.
EXAMPLE 1
EGCG assay on bovine capillary endothelial (BCE) cells EGCG was assayed on bovine capillary endothelial (BCE) cells stimulated with fibroblast growth factor-2 (FGF-2) as previously described (Cao, Y. et al . , J". Biol . Che . 271, 29461-29467 (1996)). As shown in Figure la, EGCG inhibited endothelial cell growth in a dose-dependent manner. The inhibition appeared to be relatively endothelial cell selective since non-endothelial cells including murine T241 fibrosarcoma tumour cells, murine fibroblast cells and rat smooth muscle cells were insensitive to EGCG treatment at concentrations used for BCE cells.
Antiangiogenic effect of EGCG in the chick chorioallantoic membrane (CAM) assay
The effect of EGCG in the chick chorioallantoic membrane (CAM) assay (Cao, Y.et al . , J". Exp . Med . 182, 2069-2077 (1995)) was examined. Over a concentration range of 1-100 mg/CAM, EGCG inhibited new blood vessel growth in a dose- dependent fashion (Figure lg) , as measured by the formation of avascular zones.
Effect of green tea on angiogenesis
Oral consumption of green tea as the sole source of drinking fluid by mice was examined and shown to inhibit corneal neovascularization stimulated by vascular endothelial growth factor (VEGF) . The corneal model is one of the most rigorous antiangiogenic assays that requires systemic administration of a putative angiogenesis inhibitor to suppress neovascularization induced by 160 ng of VEGF in the cornea. The amount of green tea in the drinking water was 1.25% (4.69 mg/ml) containing 708 mg/ml of EGCG as previously reported (Yang, C. S. et al . , Exp . Lung Res . 24, 629-639 (1998); and Wang, Z-Y. et al . , Cancer Res. 52, 1162-1170 (1992)). The concentration of EGCG in the plasma was previously reported to be in the range of 0.1-0.3 inM, which is compatible to human plasma levels after ingestion of 2-3 cups of tea (Yang, C. S. et al . , Cancer Epidemiol . Biomarkers Prev. 7, 351-354
(1998)) . Recent work showed that this tea preparation significantly suppressed lung tumourigenecity and progression in animal models (Wang, Z-Y. et al . , Cancer Res. 52, 1162- 1170 (1992) ) . Drinking this green tea preparation significantly prevented corneal neovascularization induced by VEGF (Figure lc) as compared with the control group that drank water alone (Figure lb) . The vessel length (Figure Id) , clock-hours of corneal circumferential neovascularization (Figure le) and area of neovascularization (Figure If) in 7 corneas of 4 mice in the tea-drinking group were inhibited by approximately 55%, 35% and 70%, respectively .
Results The present invention demonstrates that EGCG, as one of the key catechins in green tea, suppresses endothelial cell growth in vi tro and the new blood vessel formation in the CAM. Drinking green tea containing EGCG significantly prevents corneal neovascularization induced by one of the most potent angiogenic factors, VEGF. The present invention shows, for the first time, that green tea is a natural oral angiogenesis inhibitor and provides indication that drinking green tea is beneficial to prevent the development and progression of angiogenesis-dependent diseases.