INTRODUCTION:

Non steroidal anti-inflammatory agents continue to be one of the most widely used groups of therapeutic agents. They are used for the treatment of inflammation including pain releasing, antipyretic and rheumatoid arthritis. With a greater life expectancy, it is not surprising that the development of newer NSAIDs continues at a rapid pace. Almost all the NSAIDs under clinical usage are highly acidic in nature and suffer from a common drawback of gastrointestinal toxicity¹.

Indole alkaloids have been proved to be medicinally important natural compounds. Indole ring constitutes an important template for drug design such as the classical NSAIDs indomethacin and indoxole.

Further indole derivatives have been reported to possess promising biological activities including analgesic, anti-inflammatory^2,3,4,5, antihypertensive⁶, anticonvulsant⁷ antimicrobial^8,9 and selective COX 2 inhibitory activities^10,11,12. Thus the efficient synthesis of novel substituted indole derivative compounds still represent highly pursued target. The substitution of heterocyclic moiety at the 2- position of indole ring markedly influences the anti inflammatory activity ¹³.

The area of design and synthesis of novel NSAIDs is being explored for drugs with better efficacy and safety profile. Diarylheterocycle class of compounds has been investigated extensively as COX 2 inhibitors. In contrast, relatively few reports document structural modifications of the existing NSAIDs into better drugs¹⁴. Thus we decide to explore indole nucleus of indomethacin (NSAID) for structural modifications in order to produce potential anti inflammatory agents.

Moreover pyrimidine derivatives have also been reported to possess potent anti inflammatory activity ^{15, 16, 17}. With the view to develop better anti inflammatory agents we have therefore synthesized some indole derivatives possessing pyrimidine moiety at 2- position and sulfonyl group at 1-position of 3-phenyl indoles to get compounds (6a-6l) with higher biological significance.

In this paper we report derivatives of 6-(indol-2-yl)-pyrimidine-2-amines as safer agents for treatment of inflammatory conditions. The synthesized compounds were found to possess an interesting profile of anti inflammatory and analgesic activities with significant decrease in ulcerogenic effect.

MATERIAL AND METHODS:-

Equipment and Materials:-

All the reagents and solvents used in synthesis were of laboratory grade and procured from SD Fine Chemicals, Qualigens and Sigma, India. All the solvents were dried and distilled before use. Animals were procured from institute animal house. The melting points were determined in open capillary on Veego (model:-VMP-D) electronic apparatus and are uncorrected. The IR spectra of synthesized compounds were recorded on Shimadzu 8400-S FT-IR Spectrophotometer using potassium bromide. The ¹H NMR were recorded in DMSO-d₆ using NMR Varian-Mercury 300 MHz spectrometer and chemical shifts are reported as parts per million (ppm) using tetramethylsilane (TMS) as an internal standard. C, H and N analysis were carried out on a CE Instruments EA 1110 analyzer. To monitor the reactions and to establish the identity and purity of reactants and products, thin layer chromatography (TLC) was performed on microscopic glass slides (2 x 7.5 cm) coated with silica gel-G (Merck), using toluene-methanol and chloroform-methanol as the solvent systems and the spots were visualized by exposure to iodine vapours or spraying dilute sulfuric acid or UV.

Methods:-

Synthesis of N-(2-benzoylphenyl)methanesulfonamide (2a) and N-(2-benzoylphenyl) tolylsulfonamide (2b)

Synthesis of N-(2-benzoylphenyl)methanesulfonamide (2a) and N-(2-benzoylphenyl)tolylsulfonamide (2b) was carried out by sulfonylation of o-aminoketones.

2a: m.p.: 158-160ºC; yield: 72 %; IR (cm^-1, KBr): 3266, 3187, 3049, 1685, 1628, 1540, 1331 and 1145 (SO₂ asymmetric and symmetric); ¹H NMR (DMSO-d₆): δ 3.05 (s, 3H, CH₃), 7.10-7.89 (m, 9H, aromatic), 6.69 (s, 1H, NH).

2b: m.p.: 191-193ºC; yield: 78 %; IR (cm^-1, KBr): 3236, 3127, 3019, 1681, 1630, 1545, 1335 and 1160 (SO₂ asymmetric and symmetric); ¹H NMR (DMSO-d₆): δ 2.61 (s, 3H, CH₃), 7.10-8.12 (m, 13H, aromatic), 6.75 (s, 1H, NH).

General procedure for synthesis of N-(2-benzoylphenyl)-N-(2- oxopropyl)methanesulfonamide (3a) N-(2-benzoylphenyl)-4-methyl-N-(2-oxopropyl) benzenesulfonamide (3b)

The sulfonamide (0.25mol) (2a-2b) was suspended in anhydrous DMF (100 mL) at 0⁰C. With stirring, NaH (0.25 mol) was added in small portions and the mixture was kept at 0ºC for an additional 30 min. The resulting yellow amide anion solution was added drop wise over period of 30 min to a stirred solution of chloroacetone (0.25 mol) in 20 mL of DMF. After the solution was stirred for 1 h at room temperature, the DMF was evaporated and water was added. The precipitated product (3a-3b) was collected on a filter and recrystallized from methanol.

3a: m.p.: 142-144ºC; yield: 68 %; IR (cm^-1, KBr):3312, 3069, 1710, 1685, 1638, 1565, 1398, 1332 and 1158 (SO₂ asymmetric and symmetric); ¹H NMR (DMSO-d₆): δ 2.60 (s, 3H, COCH₃) 3.10 (s, 3H, SO₂CH₃), 4.58 (s, 2H, CH₂CO), 7.10-7.79 (m, 9H, aromatic).

3b: m.p.: 165-167ºC; yield: 71 %; IR (cm^-1, KBr): 3346, 3019, 1702, 1681, 1632, 1545, 1402, 1332 and 1161 (SO₂ asymmetric and symmetric); ¹H NMR (DMSO-d₆): δ 2.58 (s, 3H, COCH₃), 2.68 (s, 3H, C₆H₄CH₃), 4.62 (s, 2H, CH₂CO), 7.12-8.03 (m,13H, aromatic).

General procedure for synthesis of N 1-(1-(methylsulfonyl)-3-phenyl-1H-indol-2-yl)ethanone (4a) 1-(3-phenyl-1-tosyl-1H-indol-2-yl)ethanone (4b)

To alkylated sulfonanilide (3a-3b) (0.025 mol) suspended in methanol (400 mL) was added NaOMe (0.025 mol). After the suspension was stirred for 2 h, the solvent was evaporated on a rotary and the residue was dissolved in a mixture of water (300mL) and chloroform (200mL). The chloroform layer was washed with water (50mL), dried over MgSO₄ and evaporated to dryness. The residue was dissolved in benzene (100mL) and pyridine (0.05 mol) was added. After the mixture was chilled to 5ºC, SOCl₂ (0.025 mol) was added drop wise and the mixture was stirred for 1 h at room temperature. Ice and water were then added; the benzene layer was separated, washed with 5 % NaHCO₃ and water and dried over MgSO₄. Evaporation of the benzene, trituration with methanol and recrystallization from solvent provided the product (4a-4b) in good yield.

4a: m.p.: 131-133ºC; yield: 64 %; IR (cm^-1, KBr):3312, 3061, 1711, 1648, 1560, 1391, 1334 and 1154 (SO₂ asymmetric and symmetric); ¹H NMR (DMSO-d₆): δ 2.61 (s, 3H, COCH₃) 3.12 (s, 3H, SO₂CH₃), 7.10-7.71 (m, 9H, aromatic).

4b: m.p.: 115-117ºC; yield: 69 %; IR (cm^-1, KBr): 3326, 3019, 1708, 1636, 1545, 1401, 1341 and 1157 (SO₂ asymmetric and symmetric); ¹H NMR (DMSO-d₆): δ 2.61 (s, 3H, COCH₃), 2.64 (s, 3H, C₆H₄CH₃), 7.10-8.05 (m, 13H, aromatic).

General procedure for synthesis of (E)-3-(4-sunstitutedphenyl)-1-(1-(substitutedsulfonyl)-3-phenyl-1H-indol-2-yl) prop-2-en-1-one (5a-5l)

0.01 mole of 4a-4b, dissolved in DMF (25 mL) was stirred with 5 mL (10%) sodium hydroxide solution in a conical flask; under cold conditions for 10 min. Substituted benzaldehyde (0.01 mol) was added and the reaction mixture was stirred at room temperature for 12 -14h. It was slowly poured over the crushed ice with constant stirring and the solid separated out was filtered, washed with water and recrystallized with ethanol. The physical and spectral data of the compounds are given in Table 1 and Table 2.

Table 1 Physical data of (E)-3-(4-sunstitutedphenyl)-1-(1-(substitutedsulfonyl)-3-phenyl-1H-indol-2-yl) prop-2-en-1-one (5a-5l)

Compound	R	R’	Molecular formula	MP (⁰C)	Yield (%)	Rf values
5a	-CH₃	H	C₂₄H₁₉NO₃S	151-153	66.33	0.75
5b	-CH₃	Cl	C₂₄H₁₈ClNO₃S	127-129	58.23	0.69
5c	-CH₃	Br	C₂₄H₁₈BrNO₃S	144-146	70.56	0.66
5d	-CH₃	OCH₃	C₂₅H₂₁NO₄S	150-153	62.73	0.67
5e	-CH₃	N(CH₃)₂	C₂₆H₂₄N₂O₃S	142-156	58.19	0.73
5f	-CH₃	NO₂	C₂₄H₁₈N₂O₅S	169-172	64.84	0.63
5g	-C₆H₄ p-CH₃	H	C₃₀H₂₃NO₃S	162-164	78.34	0.74
5h	-C₆H₄ p-CH₃	Cl	C₃₀H₂₂ClNO₃S	159-161	68.12	0.68
5i	-C₆H₄ p-CH₃	Br	C₃₀H₂₂BrNO₃S	196-198	72.18	0.72
5j	-C₆H₄ p-CH₃	OCH₃	C₃₁H₂₅NO₄S	189-192	66.28	0.68
5k	-C₆H₄ p-CH₃	N(CH₃)₂	C₃₂H₂₈N₂O₃S	174-176	68.61	0.73
5l	-C₆H₄ p-CH₃	NO₂	C₃₀H₂₂N₂O₅S	167-170	65.14	0.67

Table 2 Spectral data of (E)-3-(4-sunstitutedphenyl)-1-(1-(substitutedsulfonyl)-3-phenyl-1H-indol-2-yl) prop-2-en-1-one (5a-5l)

Code no.	IR (cm^-1 , KBr)	¹H NMR (DMSO-d₆) (δ ppm)
5a	3063 (Ar stretch); 1670 (C=O stretch); 1635 (C=C stretch); 1541 (C=C aromatic ring); 1471 (C-N stretch); 1331 and 1152 (SO₂ asymmetric and symmetric)	3.12 (s, 3H, SO₂CH₃), 6.98 (d, J=7Hz, 1H,=CH-Ar), 7.10-8.23 (m, 14H, aromatic). 8.08 (d, J=7Hz, 1H-COCH=)
5b	3073 (Ar stretch); 1675 (C=O stretch); 1628 (C=C stretch); 1542 (C=C aromatic ring); 1470 (C-N stretch); 1336 and 1151 (SO₂ asymmetric and symmetric), 736 (C-Cl stretch)	3.07 (s, 3H, SO₂CH₃), 6.96 (d, J=7Hz, 1H,=CH-Ar), 7.11-8.13 (m, 13H, aromatic). 8.06 (d, J=7Hz, 1H-COCH=)
5c	3066 (Ar stretch); 1671 (C=O stretch); 1629 (C=C stretch); 1541 (C=C aromatic ring); 1468 (C-N stretch); 1335 and 1155 (SO₂ asymmetric and symmetric), 657 (C-Br stretch)	3.05 (s, 3H, SO₂CH₃), 6.98 (d, J=7Hz, 1H,=CH-Ar), 7.16-8.14 (m, 13H, aromatic). 8.04 (d, J=7Hz, 1H-COCH=)
5d	3056 (Ar stretch); 1674 (C=O stretch); 1634 (C=C stretch); 1549 (C=C aromatic ring); 1462 (C-N stretch); 1330 and 1153 (SO₂ asymmetric and symmetric),1243 (C-O-C stretch)	3.08 (s, 3H, SO₂CH₃), 3.65 (s, 3H, -OCH₃), 6.78 (d, J=7Hz, 1H,=CH-Ar), 7.11-8.19 (m, 13H, aromatic). 8.11 (d, J=7Hz, 1H-COCH=)
5e	3061 (Ar stretch); 1670 (C=O stretch); 1628 (C=C stretch); 1551 (C=C aromatic ring); 1478 (C-N stretch); 1342 (N(CH₃)₂ -stretch); 1333 and 1155 (SO₂ asymmetric and symmetric)	2.96 (s, 6H, CH₃), 3.10 (s, 3H, SO₂CH₃), 6.88 (d, J=7Hz, 1H,=CH-Ar), 7.20-8.11 (m, 13H, aromatic). 8.12 (d, J=7Hz, 1H-COCH=)
5f	3028 (Ar stretch); 1678 (C=O stretch); 1629 (C=C stretch); 1540 (C=C aromatic ring); 1556 (NO₂ stretch); 1467 (C-N stretch); 1334 and 1154 (SO₂ asymmetric and symmetric)	3.06 (s, 3H, SO₂CH₃), 6.86 (d, J=7Hz, 1H,=CH-Ar), 7.23-8.14 (m, 13H, aromatic). 8.10 (d, J=7Hz, 1H-COCH=)
5g	3046 (Ar stretch); 1677 (C=O stretch); 1633 (C=C stretch); 1551 (C=C aromatic ring); 1468 (C-N stretch); 1334 and 1161 (SO₂ asymmetric and ymmetric)	2.64 (s, 3H, C₆H₄CH₃), 6.78 (d, J=7Hz, 1H,=CH-Ar), 6.98-8.12 (m, 18H, aromatic), 8.01 (d, J=7Hz, 1H-COCH=)
5h	3073 (Ar stretch); 1675 (C=O stretch); 1628 (C=C stretch); 1542 (C=C aromatic ring); 1470 (C-N stretch); 1336 and 1151 (SO₂ asymmetric and symmetric), 736 (C-Cl stretch)	2.61 (s, 3H, C₆H₄CH₃), 6.88 (d, J=7Hz, 1H,=CH-Ar), 7.01-8.02 (m, 17H, aromatic), 8.12 (d, J=7Hz, 1H-COCH=)
5i	3035 (Ar stretch); 1676 (C=O stretch); 1622 (C=C stretch); 1544 (C=C aromatic ring); 1468 (C-N stretch); 1335 and 1151 (SO₂ asymmetric and symmetric), 657 (C-Br stretch)	2.68 (s, 3H, C₆H₄CH₃), 6.87 (d, J=7Hz, 1H,=CH-Ar), 6.88-8.07 (m, 17H, aromatic), 8.07 (d, J=7Hz, 1H-COCH=)
5j	3023 (Ar stretch); 1673 (C=O stretch); 1621 (C=C stretch); 1541 (C=C aromatic ring); 1466 (C-N stretch); 1338 and 1145 (SO₂ asymmetric and symmetric),1245 (C-O-C stretch)	2.62 (s, 3H, C₆H₄CH₃), 3.65 (s, 3H, -OCH₃), 6.78 (d, J=7Hz, 1H,=CH-Ar), 6.94-8.01 (m, 17H, aromatic), 8.10 (d, J=7Hz, 1H-COCH=)
5k	3019 (Ar stretch); 1658 (C=O stretch); 1624 (C=C stretch); 1543 (C=C aromatic ring); 1468 (C-N stretch); 1342 (N(CH₃)₂ -stretch); 1336 and 1148 (SO₂ asymmetric and symmetric)	2.70 (s, 3H, C₆H₄CH₃), 2.96 (s, 6H, CH₃), 6.68 (d, J=7Hz, 1H,=CH-Ar), 7.09-8.03 (m, 17H, aromatic), 8.06 (d, J=7Hz, 1H-COCH=)
5l	3065 (Ar stretch); 1677 (C=O stretch); 1628 (C=C stretch); 1541 (C=C aromatic ring); 1556 (NO₂ stretch); 1460 (C-N stretch); 1331 and 1154 (SO₂ asymmetric and symmetric)	2.68 (s, 3H, C₆H₄CH₃), 6.80 (d, J=7Hz, 1H,=CH-Ar), 7.02-8.08 (m, 17H, aromatic), 8.09 (d, J=7Hz, 1H-COCH=)

Table 3 Physical data of 4-(4-substitutedphenyl)-6-(1-(methylsulfonyl)-3-phenyl-1H-indol-2-yl) pyrimidin-2-amine (6a-6f) and 4-(4-substitutedphenyl)-6-(3-phenyl-1-tosyl-1H-indol-2-yl) pyrimidin-2-amine and (6g-6l)

Compound	R	R’	Molecular formula	MP (⁰C)	Yield (%)	Rf values
6a	-CH₃	H	C₂₅H₂₂N₄O₂S	112-117	64.33	0.74
6b	-CH₃	Cl	C₂₅H₂₁ClN₄O₂S	139-142	55.23	0.69
6c	-CH₃	Br	C₂₅H₂₁BrN₄O₂S	120-122	73.06	0.62
6d	-CH₃	OCH₃	C₂₆H₂₄N₄O₃S	136-138	66.13	0.61
6e	-CH₃	N(CH₃)₂	C₂₇H₂₇N₅O₂S	124-126	54.19	0.70
6f	-CH₃	NO₂	C₂₅H₂₁N₅O₄S	142-145	61.64	0.64
6g	-C₆H₄ p-CH₃	H	C₃₂H₂₈N₄O₂S	132-134	67.34	0.72
6h	-C₆H₄ p-CH₃	Cl	C₃₁H₂₅ClN₄O₂S	129-131	63.12	0.68
6i	-C₆H₄ p-CH₃	Br	C₃₁H₂₅BrN₄O₂S	156-158	59.18	0.62
6j	-C₆H₄ p-CH₃	OCH₃	C₃₂H₂₈N₄O₃S	157-159	53.28	0.69
6k	-C₆H₄ p-CH₃	N(CH₃)₂	C₃₃H₃₁N₅O₂S	131-133	58.63	0.73
6l	-C₆H₄ p-CH₃	NO₂	C₃₁H₂₅N₅O₄S	147-149	63.14	0.68

Table 4 Spectral data 4-(4-substitutedphenyl)-6-(1-(methylsulfonyl)-3-phenyl-1H-indol-2-yl) pyrimidin-2-amine (6a-6f) and 4-(4-substitutedphenyl)-6-(3-phenyl-1-tosyl-1H-indol-2-yl) pyrimidin-2-amine and (6g-6l)

Code No	IR (cm^-1 , KBr)	¹H NMR (DMSO-d₆)	Elemental Analysis
6a	3380 (NH₂ pyrimidine); 2920 (Ar stretch); 1641 (C=N str pyrimidine); 1577 (C=C aromatic ring); 1470 (C-N stretch); 1331 and 1152 (SO₂ asymmetric and symmetric)	3.12 (s, 3H, SO₂CH₃), 5.52 (s, 2H, NH₂), 7.10-8.23 (m, 15H, aromatic).	Calcd:- C, 67.85; H, 5.01; N, 12.66 Found:- C, 67.81; H, 5.08; N, 12.62
6b	3390 (NH₂ pyrimidine); 2928 (Ar stretch); 1640(C=N str pyrimidine); 1578 (C=C aromatic ring); 1471 (C-N stretch); 1333 and 1156 (SO₂ asymmetric and symmetric), 736 (C-Cl stretch)	3.10 (s, 3H, SO₂CH₃), 5.53 (s, 2H, NH₂), 7.11-8.03 (m, 14H, aromatic).	Calcd:- C, 62.95; H, 4.44; N, 11.75 Found:- C, 62.96; H, 4.40; N, 11.78
6c	3381 (NH₂ pyrimidine); 2926 (Ar stretch); 1642 (C=N str pyrimidine); 1578 (C=C aromatic ring); 1472 (C-N stretch); 1331 and 1152 (SO₂ asymmetric and symmetric), 658 (C-Br stretch)	3.09 (s, 3H, SO₂CH₃), 5.51 (s, 2H, NH₂), 7.11-8.14 (m, 14H, aromatic).	Calcd:- C, 57.59; H, 4.06; N, 10.74 Found:- C, 57.58; H, 4.02; N, 10.77
6d	3379 (NH₂ pyrimidine); 2938 (Ar stretch); 1644 (C=N str pyrimidine); 1571 (C=C aromatic ring); 1473 (C-N stretch); 1331 and 1154 (SO₂ asymmetric and symmetric), 1240 (C-O-C stretch)	3.08 (s, 3H, SO₂CH₃), 3.65 (s, 3H, -OCH₃), 5.52 (s, 2H, NH₂), 7.05-8.16 (m, 14H, aromatic).	Calcd:- C, 66.08; H, 5.12; N, 11.86 Found:- C, 66.05; H, 5.15; N, 11.88
6e	3370 (NH₂ pyrimidine); 2909 (Ar stretch); 1643 (C=N str pyrimidine); 1572 (C=C aromatic ring); 1478 (C-N stretch); 1342 (N(CH₃)₂ -stretch); 1334 and 1155 (SO₂ asymmetric and symmetric)	2.96 (s, 6H, CH₃), 3.12 (s, 3H, SO₂CH₃), 5.50 (s, 2H, NH₂), 7.13-8.10 (m, 14H, aromatic).	Calcd:- C, 66.78; H, 5.60; N, 14.42 Found:- C, 66.74; H, 5.61; N, 14.46
6f	3368 (NH₂ pyrimidine); 2944 (Ar stretch); 1642 (C=N str pyrimidine); 1578 (C=C aromatic ring); 1555 (NO₂ stretch); 1467 (C-N stretch); 1330 and 1151 (SO₂ asymmetric and symmetric)	3.05 (s, 3H, SO₂CH₃), 5.52 (s, 2H, NH₂), 7.10-8.12 (m, 14H, aromatic).	Calcd:- C, 61.59; H, 4.34; N, 14.36 Found:- C, 61.55; H, 4.36; N, 14.38
6g	3391 (NH₂ pyrimidine); 2958 (Ar stretch); 1646 (C=N str pyrimidine); 1572 (C=C aromatic ring); 1476 (C-N stretch); 1336 and 1152 (SO₂ asymmetric and symmetric)	2.65 (s, 3H, C₆H₄CH₃), 5.49 (s, 2H, NH₂), 7.10-8.23 (m, 19H, aromatic).	Calcd:- C, 72.16; H, 5.30; N, 10.52 Found:- C, 72.15; H, 5.31; N, 10.54
6h	3325 (NH₂ pyrimidine); 2908 (Ar stretch); 1652 (C=N str pyrimidine); 1576 (C=C aromatic ring); 1479 (C-N stretch); 1336 and 1152 (SO₂ asymmetric and symmetric), 756 (C-Cl stretch)	2.61 (s, 3H, C₆H₄CH₃), 5.55 (s, 2H, NH₂), 7.16-8.11 (m, 18H, aromatic).	Calcd:- 67.32; H, 4.56; N, 10.13 Found:- 67.36; H, 4.54; N, 10.11
6i	3336 (NH₂ pyrimidine); 2898 (Ar stretch); 1641 (C=N str pyrimidine); 1576 (C=C aromatic ring); 1475 (C-N stretch); 1330 and 1152 (SO₂ asymmetric and symmetric), 658 (C-Br stretch)	2.69 (s, 3H, C₆H₄CH₃), 5.48 (s, 2H, NH₂), 7.06-8.03 (m, 18H, aromatic).	Calcd:- C, 62.31; H, 4.22; N, 9.38 Found:- C, 62.36; H, 4.20; N, 9.36
6j	3325 (NH₂ pyrimidine); 2907 (Ar stretch); 1642 (C=N str pyrimidine); 1580 (C=C aromatic ring); 1469 (C-N stretch); 1332 and 1154 (SO₂ asymmetric and symmetric), 1242 (C-O-C stretch)	2.66 (s, 3H, C₆H₄CH₃), 3.68 (s, 3H, -OCH₃), 5.57 (s, 2H, NH₂), 7.10-8.19 (m, 18H, aromatic).	Calcd:- C, 70.05; H, 5.14; N, 10.21 Found:- C, 70.09; H, 5.10; N, 10.24
6k	3367 (NH₂ pyrimidine); 2918 (Ar stretch); 1646 (C=N str pyrimidine); 1578 (C=C aromatic ring); 1471 (C-N stretch); 1344 (N(CH₃)₂ -stretch); 1325 and 1149 (SO₂ asymmetric and symmetric)	2.63 (s, 3H, C₆H₄CH₃), 2.86 (s, 6H, CH₃), 5.59 (s, 2H, NH₂), 7.08-8.03 (m, 18H, aromatic).	Calcd:- C, 70.56; H, 5.56; N, 12.47 Found:- C, 70.58; H, 5.52; N, 12.44
6l	3360 (NH₂ pyrimidine); 2933 (Ar stretch); 1643 (C=N str pyrimidine); 1571 (C=C aromatic ring); 1554 (NO₂ stretch); 1463 (C-N stretch); 1331 and 1155 (SO₂ asymmetric and symmetric)	2.68 (s, 3H, C₆H₄CH₃), 5.58 (s, 2H, NH₂), 7.11-8.01 (m, 18H, aromatic).	Calcd:- C, 66.06; H, 4.47; N, 12.43 Found:- C, 66.07; H, 4.45; N, 12.44

Animals:-

Wistar rats (150-200 g) and Albino mice (25-30g) of either sex were selected for the experiments. Animals were kept for a period of two weeks in our laboratory environment prior to study. Animals were housed in polypropylene cages and maintained under standard laboratory conditions. The animals were fed with standard diet and water ad libitum. The principles of NIH Guide for Care and Use of Laboratory Animals (pub No. 85-23 revised 1985) and the instructions given by our institutional Animal Ethical Committee (CPCSEA) were followed throughout the experiment. The animal experiments were previously approved by Institutional Ethical Committee (IEC) and followed CPCSEA requirements.

Anti-inflammatory activity:¹⁹

The anti-inflammatory activity was evaluated using carrageenan induced rat paw edema on rat method. Wistar rats (150-200 g) were divided into groups of six animals each. Group 1 served as control group without using drug, group 2 received indomethacin 10 mg/kg and other groups received test drugs in dose equivalent to the indomethacin. The drugs were prepared as homogenous suspensions in saline (0.9 % NaCl) and were administered orally to animals. One hour after administration of drugs, each rat received a sun planter injection of 0.1 ml of 1 % carrageenan solution in its left paw. The measurement of the hind paw volume was carried out using Plethysmometer before any treatment (Vo) and in any interval (Vt) after the administration of the drugs. (Table 5)

Table 5 Anti-inflammatory effects of the newly synthesized pyrimidinyl indoles derivatives in carrageenan induced rat’s edema

Compound	Dose	Percentage inhibition (mean± SEM)
Compound	Dose	2h	3h
6a	20 mg/kg	61.91 ± 2.71	73.73 ± 3.32**
6b	20 mg/kg	76.70 ± 1.67	88.21 ± 1.52**
6c	20 mg/kg	70.32 ± 2.40	85.89 ± 2.71**
6d	20 mg/kg	73.36 ± 1.63	87.46 ± 1.43**
6e	20 mg/kg	69.41± 2.14	81.68 ± 3.18**
6f	20 mg/kg	59.36 ± 2.54	68.81 ± 1.18
6g	20 mg/kg	56.31 ± 1.58	60.84 ± 1.44
6h	20 mg/kg	57.22 ± 2.49	67.69 ± 2.48**
6i	20 mg/kg	52.59 ± 1.56	61.10 ± 2.83
6j	20 mg/kg	60.33 ± 0.64	77.38 ± 2.08**
6k	20 mg/kg	67.82 ± 2.25	78.35 ± 1.28**
6l	20 mg/kg	49.95 ± 2.36	58.36 ±1.66
Control	-
Indomethacin	5 mg/kg	83.10 ± 1.04	91.73 ± 1.79

Data are analyzed by one way ANOVA followed by Dunnett’s test.

** Values are significant at P<0.01.

Analgesic activity: ²⁰

All the compounds were tested for analgesic activity which was carried out by using acetic acid induced writhing method in albino mice (25-30 g) of either sex. A 0.6 % v/v solution of acetic acid was used as writhing inducing agents. The test compounds were administered orally 1 h prior to acetic acid injection. Mice were divided into groups of six animals each. Group 1 served as control group without using drug, group 2 received indomethacin 10 mg/kg and other groups received test drugs in dose equivalent to the indomethacin. All the drugs were prepared as homogenous suspensions in saline (0.9 % NaCl) and were administered orally to animals. Acetic acid was administered intraperitonially. The number of writhing were counted for 20 min in control, standard and test compounds and compared. Analgesic activity was measured as percent decrease in writhing in comparison to control. (Table 6)

Table 6 Analgesic effects of newly synthesized pyrimidinyl indole derivatives in acetic acid induced writhing in rats

Compound	Dose	Analgesic activity
Compound	Dose	Number of writhings (mean± SEM)	% Protection
6a	20 mg/kg	13.33 ± 0.60	63.81
6b	20 mg/kg	6.16 ± 0.47	83.27**
6c	20 mg/kg	7.94 ± 0.74	78.44**
6d	20 mg/kg	9.12 ± 0.83	75.24**
6e	20 mg/kg	8.46± 0.61	77.03**
6f	20 mg/kg	20.33 ± 0.52	44.81
6g	20 mg/kg	12.67 ± 0.66	65.60**
6h	20 mg/kg	11.20 ± 0.57	69.59**
6i	20 mg/kg	14.67 ± 0.74	60.17
6j	20 mg/kg	14.50 ± 0.31	60.64**
6k	20 mg/kg	15.16 ± 0.27	58.84
6l	20 mg/kg	16.83± 0.19	54.31
Control	-	36.84 ± 0.88	-
Indomethacin	5 mg/kg	6.00 ± 0.42	83.71

Data are analysed by one way ANOVA followed by Dunnett’s test.

** Values are significant at P<0.01.

Acute ulcerogenesis: ²¹

The studies were carried out on healthy Wistar rats (150-200g) at a dose two times the anti inflammatory dose viz. 60 mg/kg. The animals were divided into different groups of six each. Group 1 served as control and received vehicle only, group 2 received standard drug indomethacin 60 mg/kg and other groups were administered test compounds in dose molecularly equivalent to 60 mg/kg of indomethacin. The animals were fasted 6 hrs before giving a single dose of each of vehicle, standard and test compounds respectively and sacrificed 14 hr later when food and water was given. The gastric mucosa of the rats was examined by means of magnifier. For each stomach the severity of mucosal damage was assessed according to the following scoring system: 0 - no lesions of upto five punctiform lesions; 1 - more than five punctiform lesions; 2 - one to five small ulcers; 3 - more than five small ulcers of one large ulcer; 4 – more than one large ulcer [ ]. The mean score of each treated group minus the mean score of the control group was considered as the ‘severity index’ of gastric damage (level of significance p< 0.001). (Table 7)

Table 7 Ulcerogenic activity observed on gastric mucosa of rats

Compound	Dose	Ulcerogenic activity (S. I.)
6a	60 mg/kg	1.21 ± 0.22
6b	60 mg/kg	1.02 ± 0.33**
6c	60 mg/kg	0.73 ± 0.30**
6d	60 mg/kg	0.94 ± 0.21**
6e	60 mg/kg	0.86 ± 0.24**
6f	60 mg/kg	1.23 ± 0.27**
6g	60 mg/kg	1.61 ± 0.33**
6h	60 mg/kg	1.29 ± 0.19
6i	60 mg/kg	1.65 ± 0.34**
6j	60 mg/kg	1.71 ± 0.30
6k	60 mg/kg	0.84 ± 0.47**
6l	60 mg/kg	1.53± 0.40
Control	-	-
Indomethacin	60 mg/kg	2.34 ± 0.30**

Data are analyzed by one way ANOVA followed by Dunnett’s test.

** Values are significant at P<0.01.

Statistical Analysis:

Data were analysed by one way ANNOVA followed by Dunnet’s t-test using computerized GraphPad Prism Version 5 (Graph Pad software). All the results are expressed as mean ± SEM. The P values < 0.01 were considered significant.

RESULTS:-

The results of biological activity are reported in Table 5, 6 and 7 which record the effects of standard drug Indomethacin included for comparison. The synthesized test compounds exhibited significant pharmacological properties in animal models used for study.

Anti inflammatory activity:

The anti inflammatory activity of compounds was carried out at an equimolar oral dose relative to 10 mg/kg of indomethacin. The percent edema inhibition relative to control was measured after 2 h and 3 h of the treatment. The inhibition of swelling in carrageenan induced edema in rat paw brought about by oral administration of the drug is shown in Table 5. The percentage of swelling by the drugs was calculated using eq. (1)

Inhibition % = {[(Vt- Vo) control-(Vt-Vo) treated]/ (Vt- Vo) control} x100 ------------------------- (1)

(Vt and Vo relates to the average volume in the hind paw of the rats (n=6) before any treatment and after anti-inflammatory agent treatment, respectively).

All the synthesized compounds tested for anti-inflammatory activity showed inhibition of edema ranging from 58.36 to 88.21 %. Compounds (4 b, c, d, e, j, k) showed very good anti-inflammatory activity. 6-(4-chlorophenyl)-4-(1-(methylsulfonyl)-3-phenyl-1H-indol-2-yl)-1,2-dihydropyrimidin-2-amine (6b) (88.21%) and 6-(4-methoxyphenyl)-4-(1-(methylsulfonyl)-3-phenyl-1H-indol-2-yl)-1,2-dihydropyrimidin-2-amine (6d) (87.46%) were equipotent to indomethacin (91.73%) in inhibiting the paw edema in rats. Compounds 6-(4-bromophenyl)-4-(1-(methylsulfonyl)-3-phenyl-1H-indol-2-yl)-1,2-dihydropyrimidin-2-amine (6c) and 6-(4-(dimethylamino)phenyl)-4-(1-(methylsulfonyl)-3-phenyl-1H-indol-2-yl)-1,2-dihydropyrimidin-2-amine (6e) showed anti-inflammatory activity 85.89 % and 81.68 % respectively compared to the standard drug. Compounds 6j and 6k showed inhibition in edema equivalent to 75% of inhibition by indomethacin. Pyrimidines having substituted phenyl ring at 6^th position were in general more active than unsubstituted ones, indicating that the presence of functional group may be helpful in orienting the molecule in active site. Pyrimidines having chloro and methoxy group substituted at para position of phenyl ring at position-6 found to be more active than others, indicating that the presence of electron withdrawing groups bonds may be helpful in more efficient binding with the receptors. The presence of methylsulfonyl group at 1- position of indole nucleus seems to be important for good anti inflammatory action. The statistical significance testing using one way analysis of variance showed that the anti inflammatory activity of indomethacin and all the newly synthesized compounds were effective in comparison with the control group (p<0.01).

Analgesic activity:

Compounds (6a-6l) were further tested for analgesic activity at the same dose as used for anti-inflammatory activity. The percent protection in mice brought about by administration of the drugs is shown in Table 6. The compounds tested showed analgesic activity in the range of 44.81 to 83.27 %. The percent protection was calculated using Eq (2).

Protection (%) = 100-[number of writhing in test/ number of writhing in control x 100]- (2)

Compounds 6b and 6c showed 83.27 and 78.44% of protection respectively against acetic acid induced writhing compared to 83.71 % protection with indomethacin. The analgesic effect was observed in the compounds in the similar way to anti-inflammatory effects. The compounds with 4-chlorophenyl and 4-bromophenyl ring at 6^th position of pyrimidine ring were in good in analgesic effect compared to other substitutions.

Acute ulcerogenesis:

The compounds were screened further for their gastric irritation activity. The ulcerogenic effect of indomethacin and newly synthesized compounds were studied at 60 mg/kg in rats. It was observed that the ulcerogenic effect of the test compounds (6a-6l) was appreciably less than indomethacin. Less number of ulcers was observed in animals treated with test compounds compared with the animals treated with indomethacin. The tested compounds showed severity index ranging from 0.73 to 1.71 whereas the standard drug indomethacin showed high severity index of 2.34 (Table 7). The compounds 6b, 6c, 6d, 6e, and 6k showed severity index of 1.02, 0.73, 0.94, 0.86 and 0.84 respectively which is less than that of indomethacin. These findings suggest that the newly synthesized compounds will produce less gastric irritation and may be considered as safer drugs for treating inflammatory conditions.

DISCUSSION:-

The purpose of the present study was to examine whether molecular modification of indole and pyrimidine result in molecules with good analgesic and anti inflammatory actions with lesser ulcerogenic side effects. A series of compounds was synthesized and evaluated for biological activities. The data reported indicate that the compounds having indole nucleus with sulfonylmethyl group at 1-position and substituted pyrimidine ring at 2-position are safer analgesic and anti-inflammatory agents which is supported by their less ulcerogenic effect. Pyrimidines having substituted phenyl ring at 6^th position were in general more active than unsubstituted ones, indicating that the presence of functional group may be helpful in orienting the molecule in active site. Pyrimidines having chloro and methoxy groups substituted at para position of phenyl ring at position-6 found to be more active than others, indicating that the presence of electron withdrawing groups may be helpful in more efficient binding with the receptors. The presence of sulfonylmethyl group at 1-position of indole nucleus seems to be important for good anti inflammatory action. The statistical significance testing using one way analysis of variance showed that the anti inflammatory activity of indomethacin and all the newly synthesized compounds were effective in comparision with the control group (p<0.01).

ACKNOWLEDGEMENT:-

The authors are thankful to Poona District Education Association’s Seth Govind Raghunath Sable College of Pharmacy, Saswad and Department of Chemistry, University of Pune.

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Received on 23.01.2011 Modified on 15.02.2011

Asian J. Research Chem. 4(7): July, 2011; Page 1180-1187