4,5-diaryl-pyrrole derivatives,their preparation and pharmaceutical compositions containing them

Background of the Inven.tion

This invention relates to antiinflammatory pyrroles.

J. Szmuszkovicz et al. J. Med. Chem., 9, (4), 527-36 (1966) describe synthesis and biological activity of a clinically tested antiinflammatory agent of the formula

<img file="IL61768A_D0001.tif" />

Yoshida et al. U.S.P. 3,709,906 disclose 2-alkyl-

4,5-diphenylpyrrole derivatives which are useful as antiinflammatory agents.

There is a continuing need for safe and effective antiinflammatory agents. Inflammation is a disease process characterized by redness, fever, swelling, and pain. Arthritis, in its various forms, is the most prevalent, chronic, and severe of the inflammatory diseases. Traumatic injury and infection also involve inflammation, and antiinflammatory drugs are often used in their treatment. The usefulness of most commercial antiinflammatories is limited because of toxicity and adverse side-effects. Many produce gastric irritation and other effects, such as changes in blood cells and central nervous system. Adreno-cortical steroids produce gastric irritation and suppression of normal adrenal function.

־ 61768/2

Israeli Patent No. 56856 discloses diaryl substitutedthio pyrrole compounds useful for treating arthritis and inflammation. The compounds of the instant application are different from those disclosed in the 56856 Patent in that they all possess an alkyl substituted sulfur radical on one of the aiaryl moieties of the molecule.

Summary of the Invention

This invention relates to compounds of formula I, pharmaceutical compositions containing them and methods of use of these compounds to treat arthritis or alleviate pain in non-human mammals.

61765-/2

The invention provides a compound of formula I:

where = C.j—alkyl or polyfluoroalkyl;

R₂ and R₃

Y = F or R_tS(0) , כ m wherein R^ = methyl, and m = 0, 1 or 2;

. ^R4 ^{= H;} n = 0, 1 or 2;

provided that at least one of R₂ and R^ must be

<img file="IL61768A_D0002.tif" />

where R^ is methyl and m = 0 or 2.

Detailed Description of the Invention Preferred Compounds

Compounds preferred for their degree' of activity, safety and/or ease of synthesis include those where independently:

a) R^ « methyl or trifluoromethyl; or

h) R^ s methyl.and n = 2; or .

c) Rj־ = trifluoromethyl and n = 2; or

d) R₂ and R^, independently are and at least one of R₂^{and R}3 contains . Y = CH-S(0) ; 3 m and the other of R₂ and R^ contains

Y. = F,

e) R^ = H; or

f) n = 0 or 2 and more preferably n = 2.

Compounds of a preferred scope include those where: !

R^ . methyl or trifluoromethyl;

<img file="IL61768A_D0003.tif" />

and at least one of R₂ and R₃ must contain:

Y = CH-S(0) ; ־ m

and the other and contain:

Y = F,

R^ - H; and n = 0 or 2 and more preferably n = 2.

Ο 5

Examples of compounds preferred for their activity are

<img file="IL61768A_D0004.tif" />

H where m = 0;

m = 2.

Synthesis

The compounds of this invention can be prepared from 2,3-diarylpyrroles. One method of preparation of

2,3-aiarylpyrroles involves reaction of substituted ^-ammodeoxyfaenzoins with acetylene diesters, followed by hydrolysis and decarboxylation according to the procedure used by J. Szmuszkovicz et al, J. Med. Chert., 9, 547 (1966) and U.S. Patent 3,462,451 for the synthesis of 2,3-bis(4-methoxyphenyl)pyrrole. (Scheme!).

¹⁰ Scheme I

ArCHNH-’HCl . ״ ״ ן NaOAc \ Ar

<img file="IL61768A_D0005.tif" />

Another method of preparation of 2,3-diarylpyrroles is a modification of the procedure of T. Severin and

H. Poehlmann, Chem. Ber., 110, 491 (1977), which describes the preparation of monoaryl pyrroles. By using substituted desoxybenzoins, the desired 2,3diarylpyrroles result (Scheme II).

Scheme II

ArCH₂

ArC־CH-CH־r.T(CH₃)₂

Ar'C=C

HC־־O

NaOEt

Ar'C־O

--_ר(,HCCH + NH-N (CH z כ * ft ו!

⁵¾⁰4

Preparation of 4,5-diaryl-3-aiky!pyrroles can be accomplished by several methods. First, 4,5-diarylpyrrole-3-carboxylate esters, prepared, for instance, by the method of A. M. van Leusen et al., ^,Tet. Letters, 5337 (1972) can be reduced to the 4,5-diaryl-3-methylpyrroles by lithium aluminum hydride [following the general procedure of R. L. Hinman and S. Theodoropulos,

J. Or?. Chem., 28, 3052 (1963)].

LiAlH,

Secondly, 4,5-diary1-3-propylpyrroles can be prepared by the thio-Claisen rearrangement of 2-allylthiopyrroles, followed by Raney nickel reduction (general procedure of K. Teo et al. Can. J, Chem., 56, 221 (1978)].

<img file="IL61768A_D0006.tif" />

Ac 20 quinoline

Δ

<img file="IL61768A_D0007.tif" />

Thirdly, 4,5-diaryl-3-alkylpyrroles can be pre15 pared by the general procedure of N. Engel and,

W. Steglich, Angew. Chem. Int. Ed. Engl.» 17, 676 (1978), from N-ally!carboxamides.

R.

in 1 י

Ar-C-NHCH₂C־CHAr

COCI

<img file="IL61768A_D0008.tif" />

ArC*NCH--C=CHAr &amp;

KOtBu

<img file="IL61768A_D0009.tif" />

<img file="IL61768A_D0010.tif" />

Introduction of an alkylthio functionality is accomplished in several ways. First, trifluoromethanesulfenyl chloride reacts directly and nearly 30 quantitatively with diarylpyrroles, to give the 2-trifluoromethylthio substituted compounds.

<img file="IL61768A_D0011.tif" />

CF₃SC1 ^Ar ץ____z^R4

-------> |i

Na₂C0₃ /ך -Λ

Ar ׳ έ SCF ether

Secondly, other alkylthio pyrroles can also he prepared directly by the reaction of an alkanesulfenyl chloride (such as methanesulfenyl chloride) with a

2,3-diarylpyrrole in an inert organic solvent, such as 1C tetrahydrofuran, diethyl ether, or dioxane, at temperatures from -80°C to 25°C.

IS

<img file="IL61768A_D0012.tif" />

R_XSC1 Na_?CO.

ether

<img file="IL61768A_D0013.tif" />

Thirdly, introduction of other alkylthio groups is also accomplished in a two step procedure involving substitution by cupric thiocyanate, thiocyanogen or ²⁰ the like to give the 2-thiocyanate derivative, then hydrolysis in the presence of an alkyl halide, e.g., methyl iodide, or fluorinated olefin, e.g., tetrafluoroethylene.

<img file="IL61768A_D0014.tif" />

G OH

R I or C?₂ = cf₂

Fourthly, trifluoromethanesulfenyl chloride reacts with 4,5-diarylpyrrole-2-carboxaldehydes and 4,5diarylpyrrole-2-carboxylic acids to give 4,5-diaryl-2(trifluoromethylthio)pyrroles directly (with. con¹Γ³ °^{f ־}“^{bOn B0n0Xide and} ־*»־η dioxide respectively).

<img file="IL61768A_D0015.tif" />

<img file="IL61768A_D0016.tif" />

Oxidation of the 2-alkylthio compounds with suitable oxidizing agents, such as m-chloroperoxybenzoic acid 20 (mClPBA) gives the corresponding sulfoxides and sulfones.

<img file="IL61768A_D0017.tif" />

mClPBA

<img file="IL61768A_D0018.tif" />

(a־l,2)

The Rg-substituent other than hydrogen of formula ₍Γ can he introduced hy direct alkylation, acylation, or sulfonylation of the compounds of formula Γ where = H. This reaction can he carried out in the absence or presence of a base, such as potassium carbonate, pyridine, triethylamine, potassium t-butoxide, methyl lithium, dimsyl sodium or the like. The reaction can be run neat, using the reagent as solvent, or in the presence of an inert solvent, including but not limited to dimethylformamide, glyme, THF, pyridine and methylene chloride. The temperature of the reaction can be in the range -78°C to the boiling point of the solvent or reagent, if used in excess as the solvent. Examples of alkylating, acylating and sulfonylating agents that can be employed are allyl halides; alkyl halides such as methyl iodide; dimethylaminoethyl chloride; alkoxymethyl halides, such as benzyloxymethyl chloride; acyloxymethyl halides, such as chloromethylpivalate; dihydropyran; ethyl vinyl ether; 2-chlorotetrahydrofuran; alkyl chloroformates, such as ethyl chloroformate; dialkylcarbamoyl chlorides, such as diethylcarbamoyl chloride; dialkylthiocarbamoyl chlorides such as diethylthiocarbamoyl chloride;, alkanoic anhydrides and alkanoyl halides, such as acetic anhydride; aroyl halides, such as benzoyl chloride; alkanesulfonyl halides such as methanesulfonyl chloride; ary!sulfonyl halides, such as benzenesulfonyl chloride.

Preparation of pharmaceutically suitable salts of compounds of formula I can be in accordance with well-known techniques of forming salts.

The preparation of these compounds is further illustrated by the following Examples. All parts are by weight and temperatures are in degrees centigrade unless otherwise specified.

⁰ ); ¹² /// Examole 1

----- KiStliyl

3- Oj4-Fluorophenyl) -2- (4-metiiaxi/thioqhenyl) -5(trifluoromethylthio)-IH-pyrrole_____________

A?^ 2-(4-Fluorophenyl)-1-(4-methylthiophenyl)5 ethanone___________________________________

To a stirred mixture of 75.4 g (0.438 mole) of 4-fluorophenylacetyl chloride and 54.4 g (0.438 mole) of thioanisole in 500 mlmethylene chloride, chilled in an ice bath, was added in portions over 10 approximately twenty minutes a quantity of 58.3 g (0.438 mole) of aluminum chloride. The resulting mixture was stirred in an ice bath another 1.5 hours, then was poured into 1 liter of IN hydrochloride acid. ־ The mixture was extracted with methylene 15'Chloride three times. The combined organic layers were washed successively with saturated aqueous sodium bicarbonate, 5% sodium hydroxide solution, saturated salt solution then dried and concentrated by rotary evaporation. The residue was triturated 20with cold ethanol and collected to give 99.7 g (88%) of off-white solid, m.p. 135-138°.

B. 2-(4-Fluorophenyl-4-(dimethylhydrazono)-1(4-methylthiophenyl)-2-buten-l-one

To a mixtureof52 g (0.2 mole) of 2-(4-fluoro25phenyl)-1-(4-methyIthiophenyl)ethanone and 22 g (0.22 mole) of glyoxal mono(dimethylhydrazone) [prepared by the method of T. Severin and H. Poehlmann, Chem. Ber., 110, 491 (1977)] in _Λ 200 ml ethanol was added dropwise a solution of 30sodium ethoxide prepared from 5.1 g (0.22 mole) of sodium in 200 ml ethanol. The mixture was heated at reflux for three hours, then stirred at room temperature overnight. The mixture was concentrated by rotary evaporation. The residue 35was diluted with water and extracted three times with methylene chloride. The organic layers were combined, dried and concentrated. The residue was recrystallized from methyl cyclohexane to give 46.4 g (68%) of yellow solid, m.p. 129-130°.

C. 3-(4-Fluorophenyl)-2-(4-methylthiophenyl)-1H- pyrrole_______________________________________

To a stirred mixture of 46.4 g (0.136 mole) of 2-(4-fluorophenyl)-4-(dimethylhydrazono)-1(4-methylthiophenyl)-2-buten-l-one in 400 ml ethanol and 250 ml water was added all at once

153. 8 g (0.884 mole) of sodium hydrosulfate.

The mixture was heated at reflux for three hours, then cooled to room temperature. A quantity of 50 ml water was added, then the mixture was poured into 2 liters of ice water, the solid which precipitated was collected, washed with water, dried, then recrystallized from ethanol/water to give 28.2 g (87%) of white solid, m.p. 164-165°.

D. 3-(4-Fluorophenyl)-2-(4-methylthiophenyl)-5(trifluoromethylthio)-lH-pyrrole

To a stirred mixture of 2.8 g (0.01 mole) of 3- (4-fluorophenyl)-2-(4-methylthiophenyl)-1Hpyrrole and 2.1 g (0.02 mole) of sodium*carbonate in 50 ml ether at -78° and under a dry ice condenser was added a solution of 1.5 g (0.011 mole) of trifluoromethanesulfenyl chloride in 2 ml of cold ether. The mixture was stirred at -78° for one hour, then allowed to warm to room temperature. The mixture was filtered to remove the inorganic salts. The filtrate was concentrated and the residue was purified by chromatography on silica gel, eluting with hexane/toluene mixtures (60/40). The chromatographed product was recrystallized from ethanol/water to give 3.5 g of white solid, m.p. 106-107°.

ο 14

Anal. Calcd. for ^c1g^H₁₃^F4^NS2^{: c}56.39 ׳; H, 3.42;

N, 3.65.

Found: C, 56.30; H, 3.52;

N, 3.71.

Example 2

3-(4-Fluorophenyl)-2-(4-methylsulfonylphenyl)-

5-(trifluoromethylthio)-IH-pyrrole

A. 3- (4-Fluorophenyl)-2- (4-methylsulfonylphenyl)10 1H-pyrrole______________________________________

To a stirred mixture of 28.3 g (0.1 mole) of

3-(4-fluorophenyl)-2-(4-methy1thiophenyl)-1Hpyrrole in 850 ml ethyl acetate in an ice bath was added dropwise a solution of 50 g (/v0.25 mole) 15 of ׳v 85% m-chloroperoxybenzoic acid in 500 ml ethyl acetate. The mixture was stirred at 0° for three hours, then at room temperature overnight. The mixture was cooled back to 0° and the crystalline product was collected, washed with cold ethyl 20 acetate, then dried. F-NMR indicated the solid contained 80% sulfone and 20% sulfoxide, so the solid was dissovled in 2 liters of hot ethyl acetate (at 65°) and a quantity of 4.0 g of m-chloroperoxybenzoic acid was added. The mixture was allowed to cool to room temperature, then chilled in an ice abth. The crystalline precipitate was collected, washed with cold ethyl acetate, then air dried to give 17.1 g (54%) of off-white product; m.p. 268-270°.

ο 15

Β. 3-(4-Fluorophenyl)-2-(4-methylsulfonylphenyl)-

5- (trifluoromethylthio)-lH-pyrrole

To a mixture of 15.8 g (0.05 mole) of 3-(4fluoropheny1)-2-(4-methylsulfonyIpheny1)-IH-pyr5 role and 10.6 g (0.1 mole) of sodium carbonate in 300 ml tetrahydrofuran and 300 ml ether at -78° and under a dry ice condenser was added as a gas 12.8 g (0.095 mole) of trifluoromethanesulfenyl chloride. The mixture was allowed to warm IQ to room temperature (with the dry ice condenser still attached) and stirred for three hours. The mixture was chilled again to -78” and another -3.0^׳ g of trifluoromethanesulfenyl chloride was added as a gas. The mixture was stirred overnight 15 at room temperature (with dry ice in the condenser for several hours). Another 3.0 g trifluoromethanesulfenyl chloride was added as above and the mixture was stirred for three days at room temperature. The mixture was filtered to remove the inorganics 20 and the filtrate was concentrated to give 21.8 g of solid. This was purified by chromatography on silica gel, eluting with toluene containing 4 to 8% ethyl acetate to give, after recrystallization from ethanol/water, 18.2 g (88%) of product 25 as a white solid, m.p. 204-206°. A previous sample prepared by a similar procedure had m.p. 203-204° and gave the microanalytical results shown below.

Anal. Calcd. for C. _OH. ,F.NO,S״: C, 52.04; H, 3.15; ——— 18 13 4 2 2

N,- 3.37.

Found: C, 52.29; H, 3.17;

N, 3.25.

a Examples 3 and 4

1983.15.X ־- —ι ־״ α0״_Λ. A Act, ^{As c0>}»3״ ״ * ® * B E

Example 3 (n־״l) Example 4 (n«2)

Product of ־ Example 2

3.7 grams (9 m.moles) of the compound of example 2 were stirred under nitrogen in ethyl acetate (200 ml) at room temperature while a solution of 85% m-chloroperoxy-benzoic acid (2.0 grams in 50 ml of ethyl acetate) was added over a 35 minute period. Stirring was continued at room temperature for 5.5 hours, after which time the reaction mixture was diluted with ethyl acetate, washed three times with a 10% solution of sodium bicarbonate, dried over MgSO^, and evaporated.

The residue was purified by high-performance liquid chromatography (95:5 methylene chloride-ethyl acetate eluent). Two pure product fractions were obtained from recrystallization from a solution of ethanol in water (801 by volume):

• 0.6 gram (161 yield) of the compound of Example

3, a.p. 220-221*C1 • 0.75 gram (19% yield) of the compound of Example

4, m.p. 2802״B2״C.

b 15.X.1983

Example 5

5-(Trifluoromethylthio)-3(4-fluorophenyl)-2-(4-aethyl8ulfinylphenyl)pyrrole

A .uspenslon of 2-(4-®ethylsulfinylphenyl)-3'4)־-fluorophenyl)pyrrole (2.5 g, 8 mole) in 100 1 diethyl ether and 100 1 tetrahydrofuran vas treated with .odium carbonate (1.7 g, 16 .mole), cooled to -78° and treated with gaseous trifluoromethyl .ulfenyl chloride (1.4 g, 10 nmole). The reaction ixture was .tirred .t -78° for 7.5 hours and then allowed to varn to room temperature overnight. The reaction mixture vas filtered and concentrated in vacuo. Chromatography on .illca gel and recrystallization from nethylcyclohexane/toluene gave the title compound (2C1 g), np 226-228°. Infrared and proton and fluorine NMR spectra were consistent with the assigned structure. MS: n/z 399 (M⁺). Yield was 66%.

Anal. Calcd. for ^c1B^H13^N0S2^F4^{: C}’ ⁵⁴*¹⁴ί ®²⁸.³ יί ^κ» ³.⁵¹J Found: C, 54.3, .54.5; H, 3.4, 3.3; R, 3.4, 3.4.

c Example 6 15.X.1983 -----^c-----

5-(Trlf3uoro_Mtl₁>lthlo)-2,3-H_t(₁^_tthylthloph<._ny״p)lrrole

A aolutlon of 2,3-bls(4-»ethylthlophenyl)pyrrole (4 g, u mole) Io 100 al diethyl ether and 50 ai tetrahydrofuran vaa treated with .odium dathonate (2.8 _t, 26 eaole), cooled to -78. and treated with gaseous trlfluoroaethyl «ulfenyl chloride (2.1 g, 15 ־״ole). There.ctlon mixture was stirred at -78. for 1.5 hours, filtered and concentrated in vacuo. Chromatography on alllca gel and ״crystallisation froa hexane gave the title compound (3.6 g), ap 110-111. Infrared and proton and fluorine NMR apectra were consistent with the be signed .tructure. MS: n/z 411 Yield was 68%. ' Anal. Calcd. for C, 55.48; B, 3.92; N, 3.40;

Found: C, 55.8, 55.6; H. 4.0, 4.0; N, 3.7, 3.7.

d Example 7

3-(4-Fluorophenyl)-2-(4-methylsulfonylphenyl)-5(methylthio)-1H-pyrrole

3-(4-Fluorophenyl)-2-(4-methylsulfonylphenyl)-5thiocyano-1H-pyrrole (24.0 g) was suspended in methanol (200 ml and treated with KOH (1.1 eq) in water (100 ml). After stirring 1 hour and removing some solid by filtration, the filtrate was concentrated and the residue dissolved in toluene (150 ml). After the solution stood overnight, 4.0 g of product precipitated. Chromatography of the mother liquor (SiO₂6:4 ־׳ toluene-ethyl acetate) provided additional product which was combined with the first crop, triturated with ether and petroleum ether, and dried to provide 11.8 g of the title product, mp. 168-171° (dec). The product was also obtained when methyl iodide was added to the methanolic reaction mixture after buffering with CO₂.

Dosage Forms

The anti-arthritic agents of this invention can be administered to treat arthritis by any means that produces contact of the active agent with the agent's site of action in the body of a mammal. They can be administered by any conventional means available for use in conjunction with pharmaceuticals; either as individual therapeutic agents or in a combination of therapeutic agents. They can be administered alone, but are generally administered with a pharmaceutical carrier selected on the basis of the chosen route of a±ninistration and standard pharmaceutical practice.

The dosage administered will, of course, vary 15 depending upon known factors such as the pharmacodynamic characteristics of the particular agent, and its mode and route of administration; age, health, and weight of the recipient; nature and extent of symptoms, kind of concurrent treatment, frequency of treatment, and the 20 effect desired. Usually a daily dosage of active ingradient can be about 0.05 to 40 milligrams per kilogram of body weight. Ordinarily 0.1 to 20, and preferably 0.2 to 10 milligrams per kilogram per day given in divided doses 2 to 4 times a day or in sustained re25 lease form is effective to obtain desired results.

Dosage forms (compositions) suitable for internal administration contain from about 5 milligrams to about 500 milligrams of active ingredient per unit. In these pharmaceutical compositions the active ingredient 30 will ordinarily be present in an amount of about 0.5 95% by weight based on the total weight of the composition.

The active ingredient can be׳ administered orally in solid dosage forms, such as capsules, tablets, and

35. powders, or in liquid, dosage forms, such as elixirs־, syrups, and suspensions, it can also be administered parenterally, in sterile liquid dosage forms.

Gelatin capsules contain the active ingredient and powdered carriers, such as lactose, sucrose, mannitol, 5 starch, cellulose derivatives, magnesium suearate, stearic acid, and the like. Similar diluents can be used to make comoressed tables. Both tablets and capsules can be manufactured as sustained release products to provide for continuous release of medication 10 over a period of hours. Compressed tablets can be sugar coated or film coated to mask any unpleasant taste and protect the tablet from the atmosphere, or enteric coated for selective disintegration in the gastrointestinal tract.

Liquid dosage forms for oral administration can contain coloring and flavoring to increase patient acceptance.

In general, water, a suitable oil, saline, aqueous dextrose (glucose), and related sugar solutions and 20 glycols such as propylene glycol or polyethylene glycols are suitable carriers for parenteral solutions. Solutions for parenteral administration contain preferably a water soluble salt of the active ingredient, suitable stabilizing agents, and if necessary, buffer 25 substances. Antioxidizing agents such as sodium bisulfite, sodium sulfite, or ascorbic acid either alone or combined are suitable stabilizing agents. Also used are citric acid and its salts and sodium EDTA. In addition parenteral solutions can contain preservatives, 30 such as benzalkonium chloride, methyl- or propyl-paraben, and chlorobutanol.

Suitable, pharmaceutical carriers are described in Remington’s Pharmaceutical Sciences, E. W. Martin, a standard, reference text in this field.

V.

Useful pharmaceutical dosage-forms for administraticn of the compounds of this invention can be illustrated as follows:

Capsules

A large number of unit capsules are prepared by filling standard two-piece hard gelatin capsules each with 50 milligrams of powdered active ingredient, 110 milligrams of lactose, 32 milligrams of talc, and 8 milligrams magnesium stearate.

Caosules

- - --A mixture of active ingredient in soybean oil is prepared and injected by means of a positive displacement pump into gelatin to form soft gelatin capsules containing 50 milligrams of the active ingredient. The capsules are washed in petroleum ether and dried.

Tablets

A large number of tablets are prepared by conventional procedures so that the dosage unit is 50 milligrams of active ingredient, 7 milligrams of ethyl cellulose, 0.2 milligrams of colloidal silicon dioxide, 7 milligrams of magnesium stearate, 11 milligrams of microcrystalline cellulose, 11 milligrams of cornstarch and 93.8 milligrams of lactose. Appropriate coatings may be applied to increase palatability or delay absorption.

Pharmaceutical Utility

A procedure for detecting and comparing the antiinflammatory activity of compounds in this series and standard drugs for which there is a good correlation with human efficacy is the adjuvant-induced arthritis test in rats.

A procedure for detecting and comparing the analgesic activity of compounds in this series and standard drugs for which there is a good correlation with human efficacy is the phenylquinone writhing test.

The test procedures employed for determining anti־־ inflammatory and analgesic activity are described below with test data included in Tables VII and VIII.

Established Adjuvant-Induced Arthritis in Rats

Charles River Lewis male rats (130-150 grams) are injected subcutaneously in plantar area of the right hind paw with 0.1 ml of adjuvant (Difco heat-killed, lyophilized Mycobacterium butyricum suspended in mineral oil 5 mg/ml). 20 Non-arthritic controls are injected with mineral oil. The animals are held for 2 weeks to allow development af arthritis. Paw volumes (uninjected, left hind paw) are measured and the adjuvant injected rats are culled and distributed to treatment groups of 10 of equal disease severity. Non-arthritic controls are distributed to 2 groups of 10. The rats are given oral doses of compound or PVA-Acacia (Polyvinyl Alcohol li. Gum Acacia, U.S.P. 5%, Methylparaben 0.5%) (10 ml/kg) by gavage on that day and on the 6 following days. One day after the last dose the paw volumes (uninjectsd, left hind paw) are measured using a Cgo Basile Volume Differential Meter Model 7101.

Arthritic Control Treatment Group

Mean Paw Volume (ml) - Mean Paw Volume (ml) _eArthritic Control - Non-Arthritic Control _ Mean Paw Volume (ml) Mean Paw Volume (ml) 25 % Decrease from Control Mean Paw Volume.

Dose-response regression lines of the % decrease are plotted on semi-log paper by visual fit and the ED50% decrease from control paw volume is determined by 3° inspection.

Table

Biological Activity

<img file="IL61768A_D0019.tif" />

Adjuvant

<td> Example _^2—</td><td> _J3—</td><td>^R</td><td> n</td><td> R,</td><td>₆ב</td><td> Arthritis ΕΡ,θ</td>

<td> 1 ⁴־rv»</td><td> 4-CH-SC.H. 3 0 4</td><td>^CF3</td><td> 0</td><td> H</td><td> H</td><td> 0.6</td>

<td> 2 4-FC₆H₄</td><td> 4-CH₃SO₂C₆H₄</td><td> eq</td><td> 0</td><td> H</td><td> H</td><td> 0.15</td>

־61768/2