Synthesis, structure and pharmacological studies of methyl esters of 3,5-dibromo-n-phenylanthranilic acids

SUMMARY

The methyl esters of 3,5-dibromo-N-phenylanthranilic acids have been synthesized. The structure of the compounds was confirmed by elemental analysis, IR- and NMR-spectroscopy, and individuality by chromatography in a thin layer of sorbent. The results of pharmacological studies suggest that esterification of the carboxyl group of 3,5- dibromo-N-phenylanthranilic acids leads to the decrease in anti-inflammatory, analgesic and diuretic activity, and leads to the increase of toxicity compared to the initial acids.

Key words: synthesis, N-phenylanthranilic acid, methyl esters, pharmacological properties.

Introduction. Derivatives of N- phenylanthranilic acids are used in medicine as a nonsteroidal antiinflammatory drugs. Some of them have proven to be most severe for nonspecific actions, and those that do not cause a degradation of glycosaminoglycans and kolagen of joints [1,7]. Today, derivatives of N- phenylanthranilic acids investigated as potential anti-cancer drugs, as well as those which could be applied in Alzheimer's disease and cardiovascular disease, that is very relevant and necessary, given the increase in morbidity data nosological forms [2-6, 8].

Given the above, the aim of our work was to obtain a number of biologically active compounds - methyl esters of 3,5-dibromo-N-phenylanthranilic acids and study of their pharmacological properties.

Substituted 3,5-dibromo-N-phenylanthranilic acids have been obtained by the Ullmann reaction by the interaction of 3,5 dybromo-2-chlorobenzoic acid with arylamines (method 1) and by arylation of 3,5-dibromoanthranilic acid by halogenbenzenes derivatives (method 2) in the media of n-amyl alcohol (way 1A, 2A), ) in the media of

dimethylformamide (way 1B, 2B), without solvent (way 1C, 2C) in the presence of copper or copper (II) oxide [6,8]. Also as a counter synthesis of 3,5-dibromo-N-phenylanthranilic acids condensation of N-acetyl-3,5-dybromoanthranilic acid with substituted halogenbenzene followed by hydrolysis of N-acyl derivatives has been used (method 3).

In order to increase the solubility of copper ions in aprotic low-polar phase to accelerate the arylation reaction various solubilizers (Tween-80, sodium salts of stearic acid, oleic acid) have been used, which have been added to the reaction mixture in an amount of 2-5 weight percent. Use of sodium oleate as a phase transfer catalyst allows to faster the arylation reaction in 1,7-3,5 times [9].

The synthesis of methyl esters of 3,5-dibromo-N-phenylanthranilic acids has been carried out by Fischer esterification in the media of absolute methanol in the presence of concentrated sulfuric acid (Table 1, Scheme 1):

Br H

CHOH

(k. H2SO4)

І. ІІ. (2.1-2.11)

Scheme 1

The structure and identity of 3,5-dibromo-N-phenylanthranilic acids have been confirmed by elemental analysis, IR- and NMR-spectroscopy, chromatographic analysis and qualitative reactions.

In the NMR-spectra of esters signals of aromatic protons in 6,61-8,37 ppm have been identified. Secondary amino group’s proton signal appears as a broad singlet in the region of 8,32-9,38 ppm. Characteristic signal of methyl esters is a signal of OCH3 - group, which is registered in the 3,57-3,75 ppm (Table 2).

IR-spectra of the methyl esters of 3,5-dibromo-N-phenylanthranilic acids are characterized by a number of intense bands, which correspond to the main structural fragments of molecules of synthesized substances. In the area of 1704-

1670 cm -1 an intense band corresponding to stretching vibrations ester carbonyl group has been interpreted (vC - O). In been detected, respectively. The first band refers to the stretching vibration of C-O-C - group, to which the main

спирт.

і С-О ) have

the areas of 1250-1270 cm -1 and 1090-1050 cm -1 the stretching vibration bands of C-O-C (

ки сл .

vC - O

contribution is made by the fluctuations of “acidic” fragment of the molecule, the main contribution to the second band oscillations is made by the “alcoholic” fragment of the molecule. Stretching vibrations of the C-Br - bond with a band of medium intensity at 628-532 cm -1 (VC - Br). Symmetric and asymmetric vibrations of nitrogroup in the spectrogram yaa ya

(6-8) appear in the areas1525-1516 cm -1 ( NO2 ) and 1325-1306 cm -1 ( NO2 ) (Table 2).

An anti-inflammatory, analgesic, diuretic and bacteriostatic properties of synthesized methyl esters of 3,5- dibromo-N-phenylanthranilic acids have been studied.

Studies on anti-inflammatory and analgesic activities have revealed that methyl esters did not exceed the reference drug, and some of them never showed these activities (Table 3), the original acids’ pharmacological activities had same or even higher activities than reference drugs (Table 4).

Methyl esters exhibited bacteriostatic activity in relation to Staphylococcus aureus, Bacillus subtilis, Echerichia coli and Pseudomonas aureginosa.

The esterification of the carboxylgroup of 3,5-dibromo-N-phenylanthranilic acids results in toxicity increase (Table 3 and 4).

Table 1 - Methyl esters of 3,5-dibromo-N-phenylanthranilic acids

Br

Co mpo -und

R

Yeild, %

Melting point оС1

Quantified, %

Gross formula

Calculated, %

Rf2

N

C

N

C

1

2

2.1

H

88

162-164

3,7

1

43,80

С14Н11

Br2NO2

3,63

43,66

0,3 9

0,5 0

2.2

2’-CH3

84

187-189

3,4

5

45,03

C15H13

Br2NO2

3,50

45,14

0,3

8

0,4 9

2.3

4’-CH3

87

154-157

3,5

4

45,21

C15H13

Br2NO2

3,50

45,14

0,4 0

0,4 7

2.4

3’,4’- CH3

87

204-207

3,4 3

46,58

C16H15

Br2NO2

3,38

46,51

0,3

5

0,4 5

2.5

4’-

OCH3

82

195-197

3,3

2

43,44

C15H13

Br2NO3

3,37

43,40

0,3

7

0,4 4

2.6

4’-

OC2H5

85

109-111

3,3

4

44,75

C16H15Br2

NO3

3,26

44,78

0,6 2

-

2.7

2’-NO2

80

120-122

6,5 9

39,14

C14H10Br2

N2O4

6,51

39,09

0,5 7

-

2.8

3’-NO2

74

102-103

6,5 8

39,01

C14H10Br2

N2O4

6,51

39,09

0,5 8

-

2.9

4’-NO2

80

88-90

6,5 5

39,03

C14H10Br2

N2O4

6,51

39,09

0,5 5

-

2.10

4’-Br

78

155-158

3,4 9

40,12

C14H10Br3

NO2

3,33

40,08

0,3

0

0,3

8

2.11

4’-Cl

79

159-161

2,9 8

36,22

C14H10Br2

ClNO2

3,01

36,24

0,2 8

0,3

5

Note: 1 Crystallized from aqueous methanol;

2Rf values are given in solvent systems: 1. Methanol-hexane (1:3).

2.ethyl acetate- methanol -ammonia (8,5:1:0,5)

Table 2. - IR- and NMR-data of methyl esters of 3,5-dibromo-N-phenylanthranilic acids

R

IR-spectra

NMR -spectra

Absorption freq

uency

Chemical shift, 5, m.p.

Vnh

acidvC=O

vC - О

acacidvC - О

clcohi vC - О

'l as

v no 2

s

^NH

vC - Br

vC - P

NH

1 (1H, s.br. )

-CH3

-

OCH2

-

COOC H3 (3H,c)

Ar-H

Н

332

2

1658

1702

1279

1082

-

1588

584

160

5

9,32

-

-

3,61

6,917,93 (7H,m )

2’-

CH3

333 0

1662

1699

1274

1085

-

1575

605

160 0

9,19

2,07 (3H,s)

-

3,62

6,937,91 (6H,m )

4’-

CH3

333

4

1664

1700

1272

1085

-

1576

618

159

8

-

-

-

-

-

3’,4’

CH3

334

2

1670

1695

1280

1087

-

1574

620

160

5

9,05

2,19 (3H,s)

2,25 (3H,s)

-

3,62

6,707,93 (5H,m )

4’-

OC

H3

333

8

1672

1704

1285

1090

-

1578

624

160

7

-

-

-

-

-

4’-

OC2

H5

332

5

1648

1688

1276

1057

1516

1306

1570

532

159

8

8,32

1,31 (3H,s)

3,90 (2H,s)

3,57

6,828,10 (6H,m )

2’-

NO2

331 0

1626

1675

1270

1052

1525

1312

1574

540

160 0

9,01

-

-

3,75

6,618,37 (6H,m )

3’-

NO2

332 0

1624

1670

1272

1050

1520

1310

1578

545

150 0

-

-

-

-

-

4’-

NO2

329

5

1625

1685

1272

1056

-

1572

540

159

6

-

-

-

-

-

4’-

Br

334

8

1650

1695

1285

1072

-

1576

622

159

8

9,40

-

-

3,61

6,907,94 (6H,m )

Д’-

Cl

335

8

1648

1698

1290

1082

-

1578

628

160 0

9,38

-

-

3,60

6,747,88 6H,m)

Table 3. - pharmacological activities of methyl esters of 3,5-dibromo-N-phenylanthranilic acids

Compound

R

Anti- inflamma tory, % in a dose of 10

mg/kg

Analgesic, % in a

dose of 20 mg/kg

Diuretic, % in a dose of 50 mg/kg (control group 100%)

Bacteriostatic, MIC, Lg/ml

DL50, mg/kg intra gastri cally (on mice)

 

Staphylo coccus aureus, ATCC 25923

Bacteriu m subtilis, ATCC 6639

Echerich ia coli, ATCC 25922

Pseudomo nas aureginosa

ATCC 97853

2.1

H

6,8

12,4

122

125

250

125

250

-

2.2

2’-CH3

12,7

19,3

78

125

250

125

250

-

2.3

3’-CH3

0

0

134

250

500

125

250

-

2.4

3’,4’- CH3

31,2

34,8

95

250

500

62,5

62,5

>1500

2.5

4’-

OCH3

24,5

0

75

250

500

125

250

-

2.6

4’-

OC2H5

0

36,1

108,4

62,5

62,5

62,5

250

>1200

2.7

2’-NO2

0

0

98,3

62,5

62,5

31,2

125

-

2.8

3’-NO2

0

0

-

31,2

62,5

31,2

125

-

2.9

4’-NO2

0

0

-

31,2

62,5

31,2

125

-

2.10

4’-Br

22,1

29,3

-

125

250

125

250

-

2.11

4’-Cl

29,5

35,1

132

125

250

125

250

>1500

Diclofenac (ED50=8 mg/kg)

37,5

-

-

-

-

-

-

360

Mefenamic acid in a dose of 100 mg/kg

30

-

-

-

-

-

-

628

Metamizole sodium

ED50=55 mg/kg

-

52,0

-

-

-

-

-

1197

Hydrochlorothia zide in a dose of 50 mg/kg

-

-

212

-

-

-

-

320

Ethacridine

-

-

-

31,2

15,6

31,2

62,5

-

Phthalylsulfathia zole

-

-

-

7,8

7,8

250

-

-

Conclusions. A synthesis of methyl esters of 3,5-dibromo-N-phenylanthranilic acids has been carried out.

By means of physico-chemical methods - elemental analysis, IR and NMR spectroscopy, TLC the structure of compounds have been confirmed. Pharmacological studies of methyl esters of 3,5-dibromo-N-phenylanthranilic acids have been carried out. The esterification of the carboxylgroup of 3,5-dibromo-N-phenylanthranilic acids results in toxicity increase and in reduce of pharmacological activity.

Table 4. - pharmacological activities of 3,5-dibromo-N-phenylanthranilic acids

Com pound

R

Antiinflammatory, % in a dose of

Analgesi c, % in a dose of 20 mg/kg

Diuretic, % in a dose of

50 mg/kg

Bacteriostatic, MIC, pg/ml

DL50, mg/kg intra Gastri cally (on mice)

10

mg/kg

20

mg/k g

St. Aureus, ATCC 25923

Bacte rium subtilis, ATCC 6639

Ech. Coli, ATCC 25922

Pseud. Auregi nosa, ATCC 97853

2.1

Н

-

12,6

20,5

132,9

250

500

250

250

-

2.2

2’-CH3

-

14,2

22,7

180,2

250

250

250

500

-

2.3

3’-CH3

-

34,5

39,8

216,2

250

500

250

250

>3000

2.4

3’,4’- CH3

39,5

44,2

40,5

218,5

250

500

125

125

>3500

2.5

4’-OCH3

0

10,2

0

225

250

500

250

250

-

2.6

4’-

OC2H5

14,1

-

0

185,6

62,5

125

125

125

>3000

2.7

2’-NO2

26,7

-

9,5

120,5

62,5

31,2

62,5

125

>2500

2.8

3’-NO2

21,6

-

-

140,0

31,2

62,5

125

125

-

2.9

4’-NO2

11,6

-

-

-

31,2

62,5

125

125

-

2.10

4’-Br

25,1

35,4

39,2

284,5

250

250

125

125

>3500

2.11

4’-Cl

32,5

40,8

30,4

290

250

250

125

125

>3500

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Year: 2013
City: Shymkent
Category: Medicine