Halogenated (HAH) and polycyclic (PAH) aryl hydrocarbons, polyaromatic hydrocarbons, polychlorinated biphenyls (PCB) and other industrial chemicals that bind to the aryl hydrocarbon receptor (AhR) are environmental contaminants which will be collectively referred to hereinafter by the term AhR ligands.

AhR ligands have attracted much attention and concern recently because of their resistance to degradation, resulting in a long biologic half-life (> 10 years) in soil (see ref. 1) and between 4 and 12 years in human blood and fat (2).

Every person on earth is continually exposed to AhR ligands which are present in cigarette smoke, in exhaust fumes from both gasoline and diesel engines, in furnace gases, in cooked meat and fish, in dairy products, and even in mother's milk.

There is sufficient evidence to link exposure to AhR ligands to the development of numerous pathologies such as atherosclerosis, cancer, immunosuppression, skin disorders, reproductive failure, and diminished resistance to viral infection.

Attempts to reduce exposure to said environmental toxins have not been successful, nor are they likely to be until internal combustion engines, the use of fossil fuels, and cigarette smoking are eliminated.

It is, therefore, imperative to develop methods to antagonize the adverse effects of toxic AhR ligands. In WO 99/56737 in the name of INSERM, co-inventors of the present patent application disclosed the potent anti-dioxin effects of resveratrol and analogs and gave a valid response to this challenge.

The inventors have elaborated new stilbene derivatives and have surprisingly found more active and more selective AhR antagonists than resveratrol.

Advantageously contrary to resveratrol, such derivatives are devoid of affinity for the estrogen receptor (ER).

Accordingly, the primary object of the invention is to provide new stilbene derivatives with antagonist properties with respect to AhR ligands.

Another object of the invention is to provide drugs for preventing or treating pathologies and poisoning induced by exposure to AhR ligands.

The stilbene derivatives of the invention have formula I: wherein R3, R4 and R5 and R3', R4'and R5'are identical or different and represent H, OH, 0-alkoxy or hal, said alkoxy group being a Cl-C6 alkoxy and"hal"being F, Cl or CF3, with the proviso that one of R4', R3 and R5 or R4, R3'and R5'does not represent OH, OCH3, or ROCHA CH3 when the two other substituents are OH, OCH3, or OCH2 CH3, respectively, and the symmetrical derivatives.

As shown by the results given in the Examples, said derivatives have a high affinity for the AhR, but without detectable affinity for the ER.

Said derivatives are in racemic form or in the form of geometric cis or trans isomers.

Preferred stilbene derivatives are trans isomers.

In a preferred group, R3 and R5 are hal.

In advantageous derivatives of said group R3'or R4'is hal, alkoxy or hydroxy, and R5'is H.

Preferably R3 and R5 are Cl and in particularly preferred derivatives R3'is H and R4'or R5' is methoxy or Cl.

The invention particularly relates to (E)-1- (4'-trifluoromethylphenyl)-2- (3, 5- ditrifluoromethylphenyl)-ethene, (E)-1- (4'-methoxyphenyl)-2- (3, 5-dichlorophenyl) -ethene, and (E)-l- (4'-chlorophenyl)-2- (3, 5-dichlorophenyl) -ethene which bound to AhR with respective relative binding affinity (RBA) of 52.1, 112.0 and 130.0 without detectable affinity for ER.

The invention also relates to the symmetrical compounds, the positions 4'-3,5 and 4-3', 5' with respect to said substituents being identical. The invention particularly relates to the derivatives wherein R3', R5' and R4 represent hal or R3'and R5'are hal and R4 is OH or alkoxy.

Advantageously, said compounds are not toxic on cell culture up to 10AM.

They are particularly useful to investigate further the role of AhR both at the physiological level and in pathologies in which this receptor is involved through activation by xenobiotics.

Said derivatives are useful as antagonists to AhR ligands for binding to the AhR receptor.

Their absence of toxicity make them of interest as active principle in therapeutic and nutritional fields, and in general for the prevention or treatment of disorders due to the toxic effects resulting from exposure to AhR ligands.

The pharmaceutical compositions of the invention comprise an effective amount of at least one stilbene derivative as above defined with pharmaceutically acceptable carrier.

Said pharmaceutical compositions are advantageously in a form for administration by the oral, nasal, parenteral or topical route.

The drugs thus developped are presented in forms appropriate for administration by the oral route, such as drops, gel capsules, syrup or alcohol syrup, by the nasal route, such as spray or drops, by the parenteral route, in the form of a solution in an appropriate solvent, or again by the topical route, such as cream, ointment, shampoo or lotion. The pharmaceutically acceptable vehicles or excipients used are based on oils authorized in the pharmacopoeia, or on an alcohol such as ethanol or propylene-glycol (from 10% to 100%) or on DMSO. In general, they are non-aqueous solvents. Use can also be made of a lipid preparation such as IntralipidR.

It will be noted that said antagonistic stilbenes are soluble in the excipients and/or vehicles used for the preparation of drugs.

The dosage in the different forms and for daily administration will be established, in the standard way, depending on the type of effects to be treated. By way of example, the said drugs based on the said antagonists will be administered in an amount of from 0.1 mg to 500 mg/day, especially from 20 mg to 200 mg/day, and in particular from 10 to 100 mg/day.

Higher doses of stilbene derivatives, up to 5 g per day, can be administered as an antidote for acute intoxication by AhR ligands.

The drugs developed on the basis of these antagonists can be used in various pathologies involving AhR ligands, such as atherogenesis, immunosuppression, cancer, viral infections such as AIDS, allergies and dermatological diseases associated with dioxin and the AhR ligands and with osteoporosis.

The inhibitory effects of the said stilbenes towards the AhR ligands are also advantageously exploited in dietetics.

The invention also concerns the use of the above-defined antagonists as food additives.

Thus it concerns foods characterized in that they contain at least one antagonist such as defined above in a quantity allowing it to exert an inhibitory effect towards AhR ligands, so as to prevent their harmful effects. These foods are intended for adults or for children and infants.

These additives are incorporated in the food, for example in powdered milk, liquid or solid preparations (cereals) or canned foods.

They can also be dissolved in oil for administration as drops or as a food additive.

They can be incorporated during the production of the foods or when they are packaged, or by using preparations with the antagonists already formulated, making it possible to effect the desired supplementation.

The dose used will be reduced compared to that adopted for an adult, taking account of the weight of the child and its food, so as to obtain an effective plasma concentration (of the order of micromolar).

The antagonists of the invention are likewise of great value for combating the effects of smoking, which corresponds to chronic exposure to AhR ligands.

The advantageous properties of the antagonists of the invention are exploited by using them to impregnate cigarette filters, so as to deliver a dose of stilbene derivatives proportional to the concentration of the poisons absorbed with the smoke, and leading to a blood concentration making it possible to inhibit toxic effects of AhR ligands.

Other characteristics and advantages of the invention are given in the examples that follow, which, by way of illustration.

Experimental Section Chemicals: 2,3, 7,8-tetrachloro (1,6-3H) dibenzo-p-dioxin, 28 Ci/mmole was purchased from Terrachem (Lenexa, KS). Dioxin stock solutions were initially dissolved in dimethylsulfoxide and handled under a fume hood. TCDD stock was subsequently diluted in ethanol for use in

experiments described below. Steroids were purchased from Steraloids (Wilton, NH). All other chemicals were purchased from Sigma Chemicals.

Chemistry 1H NMR were recorded at 200 MHz on a Brucker AC200 spectrometer. Chemical shifts are given in parts per million and tetramethylsilane was used as the internal standard for spectra obtained in acetone-d6. All J values are given in Hz. Mass spectra were recorded on a variant MAT 311 A mass spectrometer. Elementar analysis was carried out by the microanalytical service laboratory of the Ecole Supérieure de Chimie of the Université Paul Sabatier, France and all values were within +-0. 4% of the calculated composition. Reagents and solvents were used as obtained from commercial suppliers without further purification. Reaction progress was determined by TLC analysis on silica gel coated aluminium plates. Visualization with UV light (254 nM). All stilbene were purified by RP HPLC and detected by UV light (254 nM). Melting points were uncorrected and measured on a Kofler apparatus. Phosphonium chloride 2a-g were prepared by refluxing a stirred mixture of triphenylphosphine and the corresponding benzyl chloride in toluene. Yields were better than 50% for all experiments.

General procedure for the preparation of stilbenes (Z) and stilbenes (E) Phosphonium salt (lmmol) was dissolved in dichloromethane (lml). Aryl aldehyde (lmmol), 18 crown 6 (0,1 mmol) and potassium hydroxyde (3mmol) was added to the solution.

Reaction mixture was stirred at room temperature and periodically monitored by TLC (toluene or hexane) until complete consumption of the aldehyde. The mixture was dilute with dichloromethane and filtered. The organic layer was washed with, dried over MgSO4 and evaporated under vacuum. Purification by RP HPLC (Ultrasep ES 100 RP 18,250 x 8 mm, 6.0 pm ; methanol : water, 80: 20 or 85: 15 ; flow rate lml/min) afford pure product.

)-1-(4-methoxyphenyl)-2-(3, 5-dimethoxyphenyl) -ethene (4a)

Mp: 55-57°C ; Rf (toluene): 0,4 ; 1H NMR (acetone-d6) a 3.808 (s, 6H), 3.813 (s, 3H), 6. 387 (t, J=2.25Hz, 1H), 6.743 (d, J=2. 5Hz, 2H), 6.94 (m, 2H), 7.05 (d, J=16.5Hz, 1H), 7.17 (d, J=16.5Hz, 1H), 7.53 (m, 2H) ; 13C NMR a (acetone-d6) : 55.575, 100.245, 105.056, 114.957, 127.285, 128.661, 129.463, 130.876, 140.746, 160,489, 162.081 ; MS (DCI/NH3): m/z 271 (M+1) ; UV : kl= 307 nm s= 24 600 M-1.cm-1, #2= 317 nm s= 23 800 M-l. cm-1 (E)-l- (4-chlorophenyl)-2- (3, 5-dichlorophenyl)-ethene (4b) Mp: 94-96°C ; Rf (hexane): 0.56 ; 1H NMR a (acetone-d6) : 7.257 (d, 1H, J= 16.44Hz, 1H), 7. 369 (t, J= 1.9 Hz, 1H), 7.4-7. 49 (m, 2H), 7. 448 (d, 1H, J= 16. 32Hz, 1H), 7.62 (d, J= 1.9 Hz, 2H), 7.625-7. 68 (m, 2H); 13C NMR 9 (acetone-d6) : 125.84, 127.361, 127.77, 129.292, 129.727, 135.872 ; MS (DCI/CH4): m/z : 247 (MH+-HC1 ; 47), 283 (MH+ ; 100), 311 (M.... C2H5+ ; 35), 323 (M....C3H5+ ; 2.2) ; UV: #1=301 nm #=20 500 M-1.cm-1,#2=313 nm #= 20 500 M-cm (E)-l- (4-methoxyphenyl)-2- (3, 5-difluorophenyl)-ethene (4c) Mp: 108-110°C ; Rf (toluene 1/hexane 1): 0.58 ; 1H NMR a (acetone-d6) : 3.826 (s, 3H), 6.85 (tt, 1H, Jl=10. 1 Hz, J2=2.3 Hz, 1H), 6.96 (m, 2H), 7.57 (m, 2H), 7.09 (d, J= 16.4 Hz, 1H), 7.34 (d, J= 16.4 Hz, 1H), 7.21 (dt, J1=7. 14 Hz,, J2= 1.6 Hz, 2H) ; 13C NMR a (acetone- d6) : 55,619, 102.607, 109.56, 115.052, 124.834, 129.115, 130.119, 132.122, 142.894, 161.011, 164.23 ; MS (DCI/CH4): m/z=227 (MH+-HF ; 15.8), 246 (M+ ; 100), 275 (M.... C2H5+ ; 13.5) ; UV: kl= 308 nm s= 46 320 M-1. cm-1,#2= 320 nm s= 49 800 M-l. crri l.

(E)-1- (4-fluorophenyl)-2- (3, 5-difluorophenyl)-ethene (4d) Mp: 47 °C ; Rf (hexane): 0.34 ; 1H NMR a (acetone-d6) : 6.91 (tt, Jl= 9.5 Hz, J2=2. 2Hz, 1H), 6.743 (d, 2H, J= 2.5Hz, 2H), 7.17-7. 28 (m, 5H), 7.41 (d, J=16. 42Hz, 1H), 7.68 (m, 2H); 13C NMR # (acetone-d6) : 103.1, 109.9, 116.445, 127.123, 129.63, 131.23, 142.364, 163.56, 164.2 MS (DCI/CH4): m/z=215 (MH+-HF ; 38), 234 (M+ ; 100), 263 (M.... C2H5+ ; 23.47), 275 (M.... C3H5+ ; 1.04) ; LTV : % I= 295 nm s= 23 900 M-1. cm-1, #2= 307 nm s= 22 100 M-l. cm-1

(E)-1-(4-trifluoromethylphenyl)-2-(3,5-ditrifluoromethylphen yl)-ethene (4e) Mp: 99-100°C ; Rf (hexane): 0.39 ; 1H NMR 8 (acetone-d6) : 7.65 (d, J=16.6 Hz, 1H), 7.77 (d, J=16. 6 Hz, 1H), 7.76 (m, 2H), 7.91 (m, 2H), 7.96 (s, lH), 8 31 (s, 2H); 13C NMR a (acetone d6) 121.870, 126.541, 127.857, 128.371, 129.136, 132.051 ; MS (DCI/CH4) : m/z = 365 (MH+-HF ; 100), 385 (MH+ ; 23.58), 413 (M.... C2H5+ ; 12.5), 425 (M.... C3Hs+ ; 1. 95); UV : i-297 nm s= 28 200 M-l. cm-1, % 2= 307 nm s= 25 800 M-1. cm-1 (E)-l- (4-fluorophenyl)-2- (3, 5-dimethoxyphenyl) -ethene (4f) Mp: 46-48°C ; Rf (toluene): 0.53 ; 1H NMR 8 (acetone-d6) : 3.81 (s, 6H), 6.42 (t, J=2. 25 Hz, 1H), 6.77 (d, J=2. 26 Hz, 2H), 7.08-7. 182 (m, 3H), 7.269 (d, J= 16. 4Hz, 1H), 7.635 (m, 2H); 13C NMR: 55.601, 100.666, 105.347, 116.28, 128.591, 129.172, 129.522 ; MS (DCI/NH3) : m/z = 259 (MH+ ; 100); UV : kl= 297 nm s= 22 900 M-l. cm-1,#2= 308 nm £= 21 200 M-1.cm-1 (E)-1- (4-ethoxyphenyl)-2- (3, 5-dimethoxyphenyl)-ethene (4g) Mp: 54-55°C ; Rf (toluene): 0.45 ; 1H NMR a (acetone-d6) : 1.366 (t, J= 6.955 Hz, 3H), 3.808 (s, 6H), 4.06 (q, J= 6.98 Hz, 2H), 6.385 (t, J=2.25 Hz, 1H), 6.741 (d, J=2.23 Hz, 2H), 6.44 (d, J= 16.1 Hz, 1H), 6. 55 (d, J= 16.1 Hz, 1H), 6.918 (m, 2H), 7.513 (m, 2H); 13C NMR a (acetone-d6) : 15.094, 55,564, 64.012, 100.196, 105.022, 115.441, 127.157, 128.661, 129.492, 130.725, 140.757, 159.812, 162.07 ; MS (DCI/NH3) : m/z 285 (M+1, 100); UV: #1= 307 nm s= 36 900 M-1. cm-1, #2= 320 nm s= 36 800 M-1.cm-1 (E)-1- (4-butoxyphenyl)-2- (3, 5-dimethoxyphenyl)-ethene (4h) Mp: 54-56°C ; Rf (toluene): 0.51 ; 1H NMR a (acetone-d6) : 0.9666 (t, J= 7.28Hz, 3H), 1.49 (m, 2H) 1.755 (m, 2H), 3.808 (s, 6H), 4.007 (t, J= 6. 35Hz, 2H), 6.3866 (t, J=2.24 Hz, 1H), 6.742 (d, J=2. 25 Hz, 2H), 6.927 (m, 2H), 7.512 (m, 2H) 7.016 (d, J= 16.36 Hz, 1H), 7.2 (d, J= 16.36 Hz, 1H) ; 13C NMR # (acetone-d6) : 14.109, 19.888, 32.076, 55,566, 68.256, 100.206, 105.035, 115.485, 127.148, 128.653, 129.505, 130.712, 140.76, 159.995, 162.075 ; MS

(DCI/NH3): m/z 313 (M+1, 100); UV: #1= 307 nm #= 40 100 M-1. cm-1,#2=320 nm #= 40 000 M-1.cm-1.

(E)-1-(4-trifluoromethylphenyl)-2-(3,5-dichlorophenyl)-ethen e (4i) Mp: 98-100°C ; Rf (hexane): 0.43 ;'H NMR a (acetone-d6) : 7.395 (d, J= 16.54 Hz, 1H), 7.561 (d, J= 16.54 Hz, 1H), 7.4107 (t, J=1.87 Hz, lH), 7.674 (d, J=1.84 Hz, 2H), 7.74 (m, 2H), 7.86 (m, 2H) ; 13C NMR a (acetone-d6) : 126.116, 126.569, 128.223, 129.352, 131.098, 135.93 MS (DCI/CH4) : m/z 281 (MH+-HC1 ; 11.8), 297 (MH+-HF ; 100), 317 (MH+ ; 79.7), 345 (M.... C2H5+ ; 24.8) ; UV: #1=297 nm #= 41 000 M-1.cm-1,#2= 309 nm s= 41 100 M'l. cm~ , % 3= 324 nm s= 25 000 M-cm (E)-1- (4-methoxyphenyl)-2- (3, 5-dichlorophenyl)-ethene (4j) Mp: 62-64°C ; Rf (toluene/hexane): 0.7 ; 1H NMR a (acetone-d6) : 3.828 (s, 3H), 6.96 (m, 2H), 7.07) ; 13C NMR a (acetone-d6) : 55.621, 115.045, 124.118, 125.382, 127.011, 129.161, 132.419 ; MS (DCI/NH3): m/z 278 (MH+ ; 100), 296 (MH+.... NH3; 15.4) ; UV: kl= 309 nm s= 44 400 M''. cm-1,#2= 325 nm £= 51 600 Milz cm-1 (Z)-1-(4-methoxyphenyl)-2-(3, 5-dimethoxyphenyl) -ethene (5a) colourless oil; Rf (toluene): 0,4 ;'H NMR a (acetone-d6) : 3.66 (s, 6H), 3.77 (s, 3H), 6.34 (t, J=2.16Hz, 1H), 6.429 (d, J=2.7Hz, 2H), 6.45 (d, J=12. 4Hz, 1H), 6.556 (d, J=12.4Hz, 1H), 6.824 (m, 2H), 7.218 (m, 2H) ; 13C NMR 9 (acetone-d6) : 55.418, 55.47, 100.085, 107.372, 114.387, 129.443, 130.315, 130.883, 131.014, 140.307, 159.925, 161.706 ; MS (DCI/NH3): m/z 271 (MH+) ; UV: BmaX= 286 nm # = 25 500 M-1. cm-1 (Z)-1- (4-chlorophenyl)-2- (3, 5-dichlorophenyl)-ethene (5b) colourless oil; Rf (hexane): 0.63 ;'H NMR a (acetone-d6) : 6.63 (d, J= 12.18Hz, 1H) 6.77 (d, J= 12.18Hz, 1H), 7.19 (d, J=1.9 Hz, 2H), 7.23-7. 36 (m, 5H) ; 13C NMR # (acetone-d6) : 127.748, 128.087, 128.932, 129.467, 131.327, 132.398, 133.899, 135.494, 135.87, 141.375

MS (DCI/CH4): mlz : 283 (MH+ ; 100), 311 (M....C2H5+ ; 46), 323 (M.... C3H5+ ; 3.6) ; UV: #max = 286 nm s= 13 600 M'l. cm-1 (Z)-1-(4-methoxyphenyl)-2-(3, 5-difluorophenyl) -ethene (5c) colourless oil; Rf (toluene 1/hexane 1): 0.62 ; 1H NMR 9 (acetone-d6) : 3.788 (s, 3H), 6. 497 ( d, J = 12.15 Hz, 1H), 6.706 (d, J = 12.15 Hz, 1H), 6.819-6. 88 (m, 5H), 7.19 (m, 2H) ; 13C NMR 9 (acetone-d6) : 55,506, 102.915, 112.3, 114.678, 127.067, 130.97, 133.103 ; MS (DCI/CH4) : m/z=227 (MH+-HF ; 30.37), 247 (MH+ ; 100), 275 (M.... C2Hs+ ; 18.28), 287 (M.... C3Hs+) ; UV: Xmax= 291 nm £= 14 000 M-cm (Z)-1-(4-fluorophenyl)-2-(3,5-difluorophenyl)-ethene (5d) colourless oil; Rf (hexane): 0. 41 ; 1H NMR a (acetone-d6) : 6.62 (d, J= 12.2Hz, 1H), 6. 81- 6. 9 (m, 4H), 7.25-7. 32 ( m, 2H) ; 13C NMR a (acetone-d6) : 103.2, 112.4, 116.16, 128.86, 131.63, 132.3 ; MS (DCI/CH4): m/z= 215 (MH+-HF ; 17), 234 (M+ ; 100), 263 (M.. C2H5+ ; 7), 275 (M.... C3Hs+ ; 0.45) ; UV: ? Ina, = 277 nm £= 6000 M'l. cm-1 (Z)-1-(4-trifluoromethylphenyl)-2-(3,5-ditrifluoromethylphen yl)-ethene (5e) colourless oil; Rf (hexane): 0.39 ; 1H NMR a (acetone-d6) : 6.97 (d, J=12.2 Hz, 1H), 7.05 (d, J=12.2 Hz, 1H), 7. 48 (m, 2H), 7.66 (m, 2H), 7.797 (s, 2H), 7.89 (s, 1H) ; 13C NMR a (acetone-d6) : 121.697, 126.403, 130.089, 130.277, 133.211 ; MS (DCI/CH4): m/z= 365 (MH+-HF ; 100), 385 (MH+ ; 17.9), 413 (M....C2H5+ ; 15.5), 425 (M.... C3Hs+ ; 3.7) ; UV: Xmax= 276 nm £= 9000 Milz cm-1 (Z)-1-(4-fluorophenyl)-2-(3, 5-dimethoxyphenyl) -ethene (5f) colourless oil; Rf (toluene): 0.59 ; 1H NMR a (acetone-d6) : 3.657 (s, 6H), 6.362 (t, J =2. 25 Hz, 1H), 6.39 (d, J =2. 2 Hz, 2H), 6.556 (d, J = 12. 2 Hz, 1H), 6.625 (d, J = 12.2 Hz, 1H), 7.037 (m, 2H), 7.306 (m, 2H) ; 13C NMR 8 (acetone-d6) : 55.425, 100.378, 107.421, 115.81, 130.068, 131.194, 131.647 ; MS (DCI/NH3): nilz = 259 (MH+ ; 100); UV: #max= 277 nm #= 39 000 M-1.cm-1

(Z)-1- (4-ethoxyphenyl)-2- (3, 5-dimethoxyphenyl)-ethene (5g) colourless oil; Rf (toluene): 0.5 ; 1H NMR 9 (acetone-d6) : 1.34 (t, J = 6.96 Hz, 3H), 3.66 (s, 6H), 4.02 (q, J = 6.98 Hz, 2H), 6.337 (t, J =2. 27 Hz, 1H), 6.428 (d, J =2.28 Hz, 2H), 6.44 (d, J= 12.28Hz, 1H), 6.55 (d, J= 12.28Hz, 1H), 7.192 (m, 2H), 7.225 (m, 2H) ; 13C NMR a (acetone-d6) : 15.059, 55,414, 63.913, 100.073, 107. 357, 114.886, 129.355, 130.75, 130.926, 131.02, 140.321, 161.703 ; MS (DCI/NH3) : m/z 285 (M+1, 100); 302 (MH+.... NH3); UV : #max=285 nm #= 24 000 M-'. cm' (Z)-1- (4-butoxyphenyl)-2- (3, 5-dimethoxyphenyl)-ethene (5h) colourless oil; Rf (toluene): 0.56 ;'H NMR a (acetone-d6) : 0.952 (t, J= 7.27Hz, 3H), 1.47 (m, 2H) 1.688-1. 76 (m, 2H), 3.662 (s, 6H), 3.968 (t, J= 7. 1Hz, 2H), 6.339 (t, J=2.28 Hz, 1H), 6.435 (d, J=2.68 Hz, 2H), 6.44 (d, J= 12.3 Hz, 1H), 6.55 (d, J= 12.3 Hz, 1H), 6.815 (m, 2H), 7.209 (m, 2H) ; 13C NMR (acetone-d6) : a 14.103, 19.866, 32.041, 55,413, 68.152, 100.053, 107.357, 114.918, 129.338, 130.154, 130.932, 131.013, 140.329, 159.416, 161.691 MS (DCI/NH3): m/z 313 (M+1, 100); UV: #max= 286 nm #= 38 200 M-1. cm-1 (Z)-1- (4-trifluoromethylphenyl)-2- (3, 5-dichlorophenyl)-ethene (5i) colourless oil; Rf (hexane): 0.48 ; 1H NMR a (acetone-d6) : 6.764 (d, J= 12.52 Hz, 1H), 6.891 (d, J= 12.52 Hz, 1H), 7.195 (d, J=1.9 Hz, 2H), 7.3646 (t, J=1.93 Hz, 1H), 7.47 (m, 2H), 7.66 (m, 2H) ; 13C NMR 8 (acetone-d6) : 126.216, 127.962, 128.147, 130.348, 132.251 MS (DCI/CH4) : m/z 281 (MH+-HCI ; 8.5), 297 (MH+-HF ; 100), 317 (MH+ ; 68.4), 345 (M.... C2Hs+ ; 28.96) ; LTV : 276 nm F, = 38 900 M-1. cm-1 (Z)-1- (4-methoxyphenyl)-2- (3, 5-dichlorophenyl)-ethene (5j) colourless oil; Rf (toluene/hexane) : 0.75 ; 1H NMR 9 (acetone-d6) : 3.79 (s, 3H), 6.476 (d, J= 12.12Hz, 1H), 6.716 (d, J= 12.12Hz, 1H), 6.857 (m, 2H), 7.2 (m, 4H), 7.313 (t, J=1.93 Hz, 1H) ; 13C NMR # (acetone-d6) : 55.529, 114.7, 126.407, 127.332, 128.026, 133.384, 135.353

MS (DCI/NH3): nilz 278 (MH ; 100), 296 (MH+.... NH3; 16.24) ; UV: Xmax= 296 nm s= 12 3COM'', cm'' AhR and ER-mediated transactivation.

Cis and Trans isomers were then tested for transcriptional modulatory activity in a DRE-TK- CAT containing stable cell line treated with TCDD. All the compounds displayed antagonist activities on AhR.

To assay the (3 estrogenic properties of resveratrol, tests were performed with a stable cel line expressing an ERE-driven Luciferase reporter gene for ER-mediated transcriptional regulation. Results showed that the presence of oxygen atom on substituants yielded compounds with weak agonistic activities with regard to estradiol through ER. None of the other compounds displayed any antogonistic activities through ER. Results for both lines of experiments are summarized on Tables I and II.

Table I: Characteristics of trans-Stilbenes derivatives. mp°C : melting point. Ago: agonist. N. M.: not measurable. RBA: relative binding affinity of the compound for the given receptor (AhR or ER). The estimated in vitro affinity of resveratrol for the AhR (calculated as ICso) was 6. 10-6 M. R. T. A.: Residual Transcriptional Activity: This is calculated as the residual induction of the stably transfected DRE-TKCAT reporter gene when 10-9 M of TCDD is challenged by 10-7 M of the compound, expressed as average +/-SEM, (n = 3 to 6 determinations). AhR ER Compounds Rl R2 MP °C RBA T. A. RBA T. A. Resveratol 4'-OH 3, 5-OH 1 Ant 0. 01 Ago 4a 4'-OMe 3,5-OMe 55-57 21.0 Ant 0.03 Ago 4b 4'-Cl 3, 5-Cl 94-96 130.0 Ant N. M N. M 4c 4'OMe 3,5-F 108-110 17.5 Ant N. M N. M 4d 4'-F 3,5-F 47-48 39.1 Ant N. M N. M 4e 4'-CF3 3, 5-CF3 99-100 52.1 Ant N. M N. M 4f 4'-F 3,5-OMe 46-48 32.1 Ant N. M N. M 4g 3', 5'-OMe 4-OEt 54-55 39.8 Ant N. M N. M. 4h 3', 5'-OMe 4-OBu 54-56 8.1 Ant N. M N. M. 4i 4'-CF3 3, 5-Cl 98-100 791.0 Ago N. M N. M. 4j 4'-OMe 3, 5-Cl 62-64 112.0 Ant N. M N. M. 4k 3'CF3 3, 5-Cl 110-111 26.3 Ant N. M N. M. 41 3'-OMe 3, 5-Cl 68-70 37. 2 Ant N. M N. M.

Table II : Characteristics of cis-Stilbenes derivatives. mp°C : melting point. Ago: agonist N. M.: not measurable. RBA: relative binding affinity of the compound for the given receptor (AhR or ER). The estimated izz vitro affinity of resveratrol for the AhR (calculate as ICso) was 6. 10-6 M. R. T. A.: Residual Transcriptional Activity: This is calculated as the residual induction of the stably transfected DRE-TKCAT reporter gene when 10-9 M of TCDD is challenged by 10-7 M of the compound, expressed as average +/-SEM, (n = 3 to 6 determinations). AhR ER Compounds Rl R2 mp°C RBA TA RBA TA 5a 4'-OMe 3,5-OMe Oil 2.1 Ant 0.06 Ago 5b 4'-C1 3, 5-Cl Oil 12.4 Ant N. M N. M 5c 4'-OMe 3,5-F Oil 7.2 Ant N. M N. M 5d 4'-F 3,5-F Oil 2.6 Ant N. M N. M 5e 4'-CF3 3,5-CF3 Oil 2.7 Ant N. M N. M 5f 4'-F 3,5-OMe Oil 1.7 Ant N. M N. M 5g 3', 5'-OMe 4-OEt Oil 2.5 Ant N. M N. M 5h 3', 5'-OMe 4-OBu Oil 3.7 Ant N. M N. M 5i 4'-CF3 3, 5-Cl Oil 10.9 Ant N. M N. M 5j 4'-OMe 3, 5-Cl Oil 13.0 Ant N. M N. M 5k 4'-OMe 3, 5-CF3 Oil 6.3 Ant N. M N. M 51 3'-OMe 3, 5-CI Oil 7.1 Ant N. M N. M

Measurements of cytotoxicity Cytotoxicity was evaluated on the A549 cell line. Resveratrol and its halogenated homologs were not toxic up to a 10 microM concentration.

Cell culture and gene reporter assays.

The human adenocarcinoma breast cell line MCF-7 was obtained from the American Tissue Culture Collection (Rockville, USA). The cells were established by stably transfecting MCF- 7 cells with the ERE-globin-tk-luc-SV-Neo plasmid and thus expressed luciferase in an estrogen dependent manner MCF-7-Luc. MCF-7 cells were grown routinely in RPMI 1640 medium and (MCF-7-Luc) cells in DMEM medium, supplemented with 5% FBS (Gibco BRL, Life Technologies, Cergy Pontoise, France). Cells were incubated at 37°C in a humidified 5% C02 incubator. For experiments, cells were grown for 5 days in phenol red- free medium, containing 5% dextran-coated charcoal treated FCS (DCC-FCS). Medium was changed after 2 days. At day 5, cells were treated or not with compounds. Compounds were dissolved in ethanol.

Luciferase assay: For each condition, 15.103 cells were seeded per well in 12-well plates and treated, as described above, during 16 hours in a final volume of 0.5 mL. At the end of the treatment, cells were washed with PBS and lysed in 150 u. l of lysis buffer (Promega, Charbonnières, France). Luciferase activity was measured using the luciferase assay reagent (Promega), according to the manufacturer's instructions. Protein concentrations were measured using Bradford technique, to normalize the luciferase activity data. For each condition, average luciferase activity was calculated from the data of 3 independent wells.

The stable cell line 47DRE bearing the TCDD-responsive CAT construct was previously described (3). It was routinely grown in DMEM medium supplemented with 10 % fetal calf serum (FCS), 4,5 g/L glucose, and 0.6 units/ml (10-6 M) insulin. Unless stated otherwise, cells were established 24 hours before any experiment in a modified medium (stripped condition) containing 5% Dextran-charcoal-treated newborn calf serum instead of 10 % FCS. All other components remained unchanged. Assays for Dioxin inducibility of the integrated DRE-TK- CAT construct were performed after a 48 hour treatment with Dioxin plus or minus resveratrol derivatives as described in the text. All chemicals applied to the cells were diluted in ethanol, control cells received ethanol alone. CAT expression was assayed on whole cell

extracts (100 ug protein) with a CAT-ELISA assay (Roche, Meylan, France) according to supplier's specifications. Experiments were done in triplicate.

Ligand binding competition assay (Aryl Hydrocarbon Receptor) Experiments were conducted exactly as previously described by Savouret et al., (3). Briefly, binding competition was performed using female New Zealand rabbit liver cytosol as the receptor source. The cytosol was prepared at 4°C in Hepes 20 mM pH 7.6, EDTA 1.5 mM, glycerol 10 %, P-mercapto-ethanol 10 mM, with Complete protease cocktail (Roche, Meylan, France) by homogenisation in a Ultra-Turax homogenizer (Bioblock Scientific, Illkirch, France) followed with 20 strokes in a Dounce Homogenizer with the tight pestle. The homogenate was centrifuged 30 min at 20,000 g. The supernatant was centrifuged at 105,000 g for 65 min. The cytosol was aliquoted, snap-frozen in liquid nitrogen and kept at- 80 °C. Cytosol aliquotes (4.5 ml) were thawed on ice, diluted ten-fold in Hepes 20 mM pH 7.6, 5 mM CaCl2, containing Complete protease cocktail and 10 mM mercapto-ethanol, and recentrifuged 30 min. at 105,000 g. The cleared cytosol dilution was adjusted to 0.85 mg proteins/ml. 930 ! 11 of diluted cytosol were preincubated with the desired amounts of unlabeled competitors in ethanol solutions for 1 hour at 4°C. Subsequently, 2,3, 7,8-tetrachloro (1,6-3H) dibenzo-p-dioxin (28 Ci/mmole) was added at 0.2 nM and incubation continued for 3 hours at 4°C. Non-displaceable binding was assessed by incubating the aliquotes with 70 gl of a 2% activated charcoal suspension in Hepes 20 mM pH 7.6 for 90 minutes at 4°C, followed by centrifugation at 15,000 g for 10 minutes. 500 RI of the supernatants were counted in 5 ml of Ultima Gold cocktail (Packard, Meridien, CT) in a Beckman liquid scintillation Counter (45 % counting efficiency). Binding competition assays were repeated at least twice for each competitor and each point was performed in triplicate.

Ligand binding competition assay (Estrogen Receptor) ER binding experiments were conducted using Estrogen Receptors extracted from MCF-7 cells as previously described (4). Briefly MCF-7 (from ATCC) were grown to 80% confluency in DMEM medium (GiBCO BRL) suplemented with 10 % FCS. Cells were then scraped, and washed twice with PBS. After centrifugation for 10 minutes at 1500 rpm, the cells were resuspended in TM buffer (20 mM Tris, HCl pH 7.4 ; sodium molybdate, 20mM).

Cells were broken by freeze-thaw lysis of the cell pellets in an equal volume of TM buffer.

Cytosolic receptors were prepared by a 105,000 g x 60 minutes centrifugation at 0°C, and then stored at-80°C. This cytosolic receptor solution was diluted to 60% in TM buffer, and

then incubated with the corresponding ligand for 18 hr at 4°C in a volume of 100 pI with 50 gg of protein and 2 nM of [3H] Estradiol and two concentrations (1 and 10pM) of unlabeled test ligand. Assays were terminated by loading 65 gel of the incubate on a 1.. 2 ml SephadexTM LH-20 column equilibrated with the TM buffer. The flow through was collected and counted for radioactivity in ready safe scintillant (Beckman).

Cytotoxicity Assays A MTT colorimetric assay was employed as described in (5) according to the established procedure 1. Drug stock solutions were prepared in EtOH and the final solvent concentration was = 1% EtOH (v/v), a concentration without effect on cell replication. Drugs were tested at 10CM on the human tumor cell line panel constituted of human lung carcinoma (A-549).

Cells were cultured at 37°C in RPMI-1640 medium with streptomycin/penicillin and 5% (v/v) FCS in a humidified atmosphere containing 5% CO2. Initial seeding densities varied among the cell lines to ensure a final absorbance reading in control cultures in the range of 0.7-1 A562 units. After the addition of the samples to the cell culture, the cells were incubated for 5 days before the MTT reagent was added. Each test was performed in duplicate and absorbance readings varied no more than 5%.

Biological effects of the stilbene derivatives of the invention A. Dioxins and other AhR ligands The biological effects of AhR ligands have been disclosed (ref. 1). Briefly, they are mediated by AhR present in the cytosol of mammalian cells of almost all organs and tissues bound to heat shock protein 90 (hsp90). Upon binding to ligand, AhR dissociates from hsp90 and the ligand-AhR complex is translocated to the nucleus through association with a structurally related protein, the AhR nuclear translocator (Arnt). Inside the nucleus, the heteromeric ligand/AhR/Arnt complex regulates gene transcription by binding to DNA at dioxin- responsive enhancers (DRE) located within, or upstream of, a number of genes coding for phase 1 (cytochrome P-450) enzymes such as CYPIA1, 1A2, and 1B1 and phase 2 (detoxification) enzymes such as glutathione S-transferase Ya, aldehyde-3-dehydrogenase, and NAD (P) H: quinone oxidoreductase.

The most important phase 1 enzyme is CYPIA1 which is part of the aryl hydrocarbon hydrolase activity (AHH) and leads to the oxidative metabolism of AhR ligands, often to

more pro-carcinogenic compounds. Phase 1 enzymes also increase the production of reactive oxygen (ROS) which have been shown to be associated with lipid peroxidation, oxidative DNA damage and other pathologic effects AhR ligands also induce phase 2 enzymes responsible for detoxification and excretion of environmental toxicants.

Therefore, a complex activation of gene transcription occurs following exposure to AhR ligands, which may initiate toxic effects as well as attempts to clear the ligand or its active metabolites from the body.

The prototype AhR ligand is 2,3, 7,8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin) which binds to the AhR with the highest affinity of all known compounds (Kd = 10-10 to-"M in mice and 10-9 M in humans).

It results from the inventor's demonstration of the AhR inhibitory activity of stilbene derivatives that a variety of AhR ligand-induced genes can be repressed. This directs the uses of stilbene derivatives into a number of different areas. By searching gene databanks (such as EMBL and Genbank) for genes containing one or several putative dioxin responsive elements (DRE) presenting the consensus sequence TNGCGTG, or GNGCGTG in any orientation, preferentially in their promoter region.

Outside of the already known phase 1 and phase 2 enzymes, it was discovered that a number of genes contain DRE's and, thus are likely to be regulated by AhR ligands and resveratrol. A number of these genes are listed in two tables according to their relationship to distinct physiological or pathological events.

Table 3 lists various genes involved in hormonal control, lipid metabolism and inflammation, genetic or degenerative diseases, proliferative diseases and cancers.

Table 3: Human genes containing DRE's in their regulatory regions. The bovine prion gene is also shown. Cds: coding sequence. GENES Access Nr Sites Location Comments Enzymes Inducible NOS X97821 4 promoter Endothelial NOS U24214 1 promoter Cyclooxygenase 2 U20548 1 promoter PG H Synthase U44805 1 promoter PG endoperoxide synthase M31812 D64068 1 promoter 5-Lipoxygenase M38191 5 promoter cds 15-Lipoxygenase U63384 6 promoter cds Phospholipase A2. U11239 2 promoter Thromboxane A2 receptor D15054 1 promoter Disease-related proteins [CAM (CD54) ] M65001 promoter 2 Adenomatous polyposis protein U02509 2 promoter cds Non-coding Adenomatous polyposis protein D13981 1 supplementary Brain specific exon in Multiple variants Adenomatous polyposis protein D13980 1 5'UTR Creutzfeld-Jacob Human Prion protein D00015 2 cds Bovine gene [Bovine Prion protein] D26150 4 intron 1 Obesity Ob (leptin) U43589 5 promoter, cds Alzheimer Presenilin L76518 5 promoter Familial STM2 U50871 7 promoter Alzheimer GADD p 153 540707 2 promoter DNA damage Oncogenes WT lb S77896 1 promoter Wilm'fumor WNT-5A U39837 3 promoter PCNA J05614 1 promoter apoptosis p53 J04238 17 complete gene cell cycle p53 J04238 1 promoter c-Ha-Ras M13221 1 promoter c-jun U60581 3 promoter c-myc p64 M13930 4 promoter promoter promoter ATF3 U37542 2 Table 4: Viral genes or genomes containg DRE's UTR: untranslated region LTR: long terminal repeat. IE: immediate early. Cds: coding sequence. VIRAL GENE ACCESS LOCATION SITES COMMENT NO Nr Cytomegalovirus 1E-1 M64941 promoter 1 HTLV-1 S76263 5'LTR 1 HTLV-1 S76263 TAX gene 1 HTLV-4 X06392 5'LTR 2 HIV 1 isolate BRU (LAV-1) K02013 3'LTR 1 repeatedly found in all isolates HIV 2 U22047 genone 2 HIV 2 EHO U27200 genone 1 CD 4 U01066 promoter 1 HIV receptor CXCR4 AF005058 promoter, cds 9 HIV co-receptor Human Papilloma Virus (HPV) X52061 genonelcr 1 long control region HPV 11 J04351 genone 2 HPV 16 M33616 genone 1 3'flanking region HPV 25 M50264 promoter 1 gene E6 HPV 33, 47,58, 59 genone Human poliovirus 1 X70509 5'UTR 1 Human rhinovirus 1 B D00239 genone 2 Human rhinovirus 2,14, 89 genone Herpes virus HSV1 U18080 genone 1 IE transactivator Herpes virus HSV1 M13885 genone 1 gene "a"segment Hepatitis A virus K02990 genone 1 Hepatitis B virus X98077 genone 1 Hepatitis C virus D30613 genone 4 Adenovirus type 2 J01917 genone 21 Adenovirus type 12 J01910 genone 1 right terminal repeat Adenovirus type 12 X14757 promoter 1 ElA gene Adenovirus type 19A X95259 early region 3 1 HLA binding protein gene region E1A gene Adenovirus type 41 M18289 cds 1 attachment protein Human respiratory syncitial virus M17212 1 gene genone M1, M2 proteins Human influenza virus multiple sites in matrix proteins, all registered subtypes various genes hemagglutinin, neuraminidase RNA polymerase

B. Cardiovascular effects of AhR ligands Cigarette smoke contains benzo [a] pyrene (BaP) and other AhR ligands such as polychlorinated dibenzo-p-dioxins (PCDD) in the tar fraction. It has been estimated that the amount of BaP in mainstream cigarette smoke is between 40 and 100 ng per cigarette and that up to 460 ng of BaP per hour can be inhaled by non-smokers in a smoking

environment. Daily intake of PCDDs by smoking 20 cigarettes a day has been estimated to be 4.3 pg/kg body weight/day. In heavy smokers, daily exposure to BaP could be as high as 0.05 mg/kg in addition to other unquantifiable AhR ligand exposure from cigarettes and from the environment. The AhR ligands in cigarette smoke are present in high enough concentrations to induce CYP1A1 and AHH activity in the lungs placenta kidney ovary and in the endothelial cells lining blood vessels AHH metabolism of BaP results in reactive carcinogenic intermediates which bind to DNA forming predominantly covalent adducts. Cigarette smoking has been identified as the direct cause of at least eight different human cancers including lung, bladder, gastrointestinal tract, and leukemia, as well as ischemic heart disease. There is also epidemiologic evidence linking smoking with accelaration of acquired immune deficiency (AIDS) and with osteoporosis and increased risk of fractures in both men and women.

In the cardiovascular system, AhR ligands may be atherogenic by disrupting the functions of endothelial cells in blood vessels. AhR ligands have been shown to induce CYP1A1/AHH in porcine aortic endothelial with ED50 values of 180 nM for BaP and 0.015 nM for TCDD. Stimulation of these phase lenzymes leads to increased ROS production which may cause endothelial cell membrane damage and lipid oxidation.

Oxidized LDL formed by this mechanism undergoes unregulated uptake by a scavenger receptor in vascular endothelial cells leading to over-accumulation and the formation of "foam cells". It has also been demontrated that AhR ligands can disrupt endothelial integrity and permeability, which could allow increased uptake of cholesterol-rich lipoprotein remnants into the arterial wall leading to atheroma formation. This effect was only seen with PCBs that bind the AhR and induce CYP1A1. In addition, the same PCBs increased oxidative stress and lipid peroxidation in cultured endothelial cells, which may be the mechanism of cell injury, and which was correlated in time increases in CYP1A1 induction.

C. Activation of the progression of HIV and other viral infection bv AhR ligands AhR ligands are known to enhance the replication of viruses in animals.

It is believed that activation of latent human immunodeficiency virus type 1 (HIV-1) expression by AhR ligands, is important for the progression of acquired immune

deficiency disease (AIDS). Il has been shown that dioxin and other AhR ligands activate HIV-1 expression by induction of CYPlAl and by activation of the cellular transcription factor, nuclear factor kappa (NF-kappa-B). The genes for both of these factors (CYP1A1, NF-Kappa B), as well as the long terminal repeat (LTR) of the HIV gene promoter itself, contain DRE's consistent with their modalution by AhR ligands. Moreover, the two know entryways of HIV into lymphocytes, the CXCR4 chemokine receptor and the CD4 glycoprotein also present multiple DRE's in their promoters (see table 4).

D. Skin disorders associated with dioxins exposure AhR ligands, especially dioxins, are potent inducers of chloracne. In every industrial accident involving these environmental toxins, chloracne was considered the hallmark of dioxin intoxication and was consistently observed in the majority of exposed individuals.

This acneiform eruptive skin condition occurs as a result of an altered pattern of differentiation of the basal cells of sebaceous glands and an altered rate of differentiation of keratinocytes. These cells express increasing concentrations of AhR during ongoing differentiation and, moreover, AhR ligands themselves enhance keratinocyte terminal differentiation. It is likely that AhR ligands elicit specific skin responses through activation of the AhR resulting in modified levels of gene expression in the skin.

E. Osteoporosis and exposure to AhR ligands There are epidemiologic data to support cigarette smoking as a risk factor for osteoporosis in both men and women. The plausibility of this relationship is strengthened by the dose- response relationship between the number of cigarettes smoked per day and the decrease in bone mineral density, and by the association between smoking and increased fracture risk. In addition, studies of twins discordant for cigarette smoking have demonstrated that bone density of women who smoked, or who smoked more heavily, was found to be significantly lower than that of their twin sisters. The pairs with the largest difference in smoking had the largest difference in bone density. The mechanism by which smoking and osteoporosis are related remains unknown. However, it is unlikely to be a simple direct effect since the relationship of ovarian steroids and bone turnover is so important.

It is believed by the inventors that AhR ligands present in cigarette smoke, and in the environment, are responsible for loss of bone density through 3 different interconnected effects.

1) An anti-estrogenic effect of AhR ligands in bone since AhR ligands have been shown to inhibit a broad spectrum of estrogen-induced responses in rodents and in breast cancer cell lines.

2) A direct toxic effect of AhR ligands on bone. Both AhR and Arnt have been found to be expressed in bone tissue of mice during embryonic development. The effect of TCDD was examined on the organization of bone tissue in vitro using primary cultures of normal diploid calvarial-derived rat osteoblasts. It was found that TCDD inhibited formation of bone tissue-like multicellular nodules suggesting a direct association with reduced bone mass.

3) A direct toxic effect of AhR ligands on the ovary. There is compelling evidence for a direct toxic effect of AhR ligands on the ovary. Women who smoke undergo menopause at an earlier age (between 1 and 4 years earlier) than non-smokers. In addition, the incidence of ovarian cancer in women is highest in industrialized urban areas and in women working in rubber, electrical or textile industries where exposure to AhR ligands are increased compared to other industries. Experimental data in animals showing direct toxic effects of BaP and other AhR ligands on oocytes support these epidemiological studies.

F. Resveratrol, the natural molecule The low rate of coronary heart disease in France compared to otherr western countries, despite the presence of similar risk factors (high animal fat intake, low exercise levels, and high rate of smoking) has been called the French paradox. However, France was found to have the highest consumption of wine of any of the countries studied, leading to the speculation that wine may contain cardioprotective compounds. In addition to ethanol, which in moderate consumption appears to reduce mortality from coronary heart disease by increasing high-density lipoprotein cholesterol and inhibiting platelet aggregation.

Two flavonoids (catechin, quercetin) and the tri-hydroxystilbene, resveratrol, inhibit the synthesis of thromboxane in platelets and leukotriene in neutrophils, and modulate the synsthesis and secretion of lipoproteins in animals and human cell lines.

However, flavonoids should be avoided in the treatment of human diseases due to their numerous harmful side-effects.

Resveratrol (3,5, 4'-trihydroxystilbene) is the parent compound of a family of molecules, including glucosides and polymers, existing in cis and trans configurations in a variety of plants classified as spermatophytes of which vines, peanuts and pines are the prime representatives. Resveratrol is produced by plants as a phytoalexin or antifungal agent.

Resveratrol is usually present in red wine in concentrations between 1 and 8 mg/L (trans- resveratrol: 1 to 5 mg/L; and cis-resveratrol 0,5 to 4 mg/L).

Another recent study demonstrated that resveratrol prevented chemical induction of preneoplastic lesions in a mouse mammary gland culture model and could slow down the growth of skin tumors which had been initiated in mice by a two step carcinogenic stimulus. This effect was proposed to act through the inhibition of cyclo-oxygenase and hydroperoxidase enzymes, by induction of phase 2 drug-metabolising enzymes, by anti- oxidant activity and by inducing differentiation of cancer cells.

Since resveratrol is highly lipophilic, it is poorly absorbed from fruit and vegetables in the diet. However, it is readily soluble in alcohol, and is present in therapeutic levels in many red wines which prove to be a good delivery system. This fact may be an advantage for wine drinkers such as the majority of the adult French population, but means that abstainers and small children are not exposed to the protective effects of resveratrol against AhR ligands. In addition, since dioxin and other hydrophobic AhR ligands are also soluble in alcohol, an alcoholic delivery system will increase the absorption of the very toxins one is trying to antagonize. It is preferable for resveratrol to be administrated as a dietary supplement, dissolved in a small volume of oil or other inocuous lipophilic solvent.

The discovery by the inventors of the potent anti-dioxin effects of reveratrol, has important medical socioeconomie implications. It has been demonstrated that resveratrol, in concentrations easily obtained clinically, cas inhibit dioxin-induced phase I enzymes activity as well as interleukin-I beta production and HIV promoter induction. It can therefore protect against a variety of diseases and toxic effects related to exposure to AhR ligands.

The obtained data show that the known AhR associations with immunosuppression, cancer and viral infections such as HIV-induced AIDS may be preventel by AhR antagonists such as resveratrol. In addition, the constant presence of DRE's in inflammatory related genes such as IgE, cytokines, chemokines, their receptors and the iNOS gene suggests a role of AhR and its ligands in inflammatory diseases. Examples of such iNOS-mediated diseases include atopic dermatitis, rheumatoid and osteo-arthritis, neurodegenerative diseases (multiple scleroris, amyotrophic, lateral sclerosis), diabetes, recurrent abortion, and likely, several others. The presence of DRE's in genes for chemokines and their receptors further supports the link between AhR ligands and inflammation and fever.

Final, the presence of DRE's in the intronic enhancer of the bovine Prion gene (responsible for bovine spongiformis encephalaitis and highly suspected to be involved in the new variant of human Creutzfeld-Jacob's disease) and in the promoter region of presenilin and STM2 genes (Alzheimer's disease) suggests that AhR ligands may aggravate these neurodegnerative conditions.

BIBLIOGRAPHIC REFERENCES 1. Rowlands JC, Gustafsson J-A (1997). Aryl hydrocarbon receptor-mediated signal transduction. Crit Rev Toxicol 27,109-134.

2. Bock, K. W. (1994). Aryl hydrocarbon or dioxin receptor: biologic and toxic responses. Rev. Physiol Biochem Pharmacol 125,1-42.

3. Savouret, J. -F. ; Antenos, M.; Quesne, M. ; Xu, J.; Milgrom, E.; Casper, R.

F. J. Biol Chem 2001,276, 3054-3059.

4. Poirot, M.; De Medina, P.; Delarue, F. Perie, J. J.; Klaebe, A.; Faye, J. C.

Bioorg Med Chem 2000,8, 2007-2016.

5. Alley, M. C. ; Scudiero, D. A.. ; Monks A. ; Hursey, M. L.; Cserwinski, M. J. ; Fine. D. L. ; Abbott, B. J.; Mayo, J. G. ; Shoemaker, R. H.; Boyd, M. R.

Cancer Res 1988,48, 589-601.