SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF SOME NOVEL 1 ...

4 downloads 112 Views 171KB Size Report
A new series of novel 1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(substituted) thiosemicarbazides were synthesized by the reaction of 3-butyl-2-hydrazino ...
Vol.4, No.4 (2011), 736-743 ISSN: 0974-1496 CODEN: RJCABP http://www.rasayanjournal.com

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF SOME NOVEL 1-(4-OXO-3-BUTYL-3H-QUINAZOLIN-2-YL)-4(SUBSTITUTED) THIOSEMICARBAZIDES V. Alagarsamy * and P. Parthiban Medicinal Chemistry Research Laboratory, MNR College of Pharmacy, Sangareddy, Gr. Hyderabad -502 294, A.P. India. *E-mail: [email protected] ABSTRACT A new series of novel 1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(substituted) thiosemicarbazides were synthesized by the reaction of 3-butyl-2-hydrazino quinazolin-4(3H)-one with various methyl esters of dithiocarbamic acid. The starting material 3-butyl-2-hydrazino quinazolin-4(3H)-one was synthesized from butyl amine. When tested for their in vitro antitubercular activity using H37RV strain on Middle brook 7H11 agar slants with OADC growth supplement, all the test compounds inhibited the growth of Mycobacterium tuberculosis at micro gram concentration. Among the test compounds, 1-(4-oxo-3-butyl-3,4-dihydroquinazolin-2-yl)-4-(2-nitrophenyl) thiosemicarbazide (AS6), 1-(4-oxo-3-butyl-3,4-dihydroquinazolin-2yl)-4-(4-chlorophenyl) thiosemicarbazide (AS7) and 1-(4-oxo-3-butyl-3,4-dihydroquinazolin-2-yl)-4-(2-pyridyl) thiosemicarbazide (AS8) are found to be the most active compounds against M.tuberculosis with the MIC of 6 µg/ml. The title compounds are also screened for the antimicrobial activity against some other gram positive and gram negative bacteria by agar dilution method, compounds AS6 and AS7 showed the most potent activity (MIC in the range of 32-63 µg/ml) against the tested bacteria. Key words: Antitubercular, Quinazolinone, Thiosemicarbazide, Anti-bacterial, M. tuberculosis © 2011 RASĀYAN. All rights reserved.

INTRODUCTION Tuberculosis remains the most important communicable disease in the world1. Tuberculosis (TB) is an infection, primarily in the lungs (a pneumonia), caused by bacteria called Mycobacterium tuberculosis2. Along with the recent increase in cases of tuberculosis, there is a progressive increase in multidrug resistant (MDR) tuberculosis. Some of the MDR isolates are resistant to as many as seven of the commonly employed antimycobacterial drugs3. Quinazolines and condensed quinazolines received the attention of medicinal chemists due to their potential biological activities. Among the biological activities exhibited by quinazolines the antimicrobial activities of 2, 3-substituted quinazolines are interesting4. Literature survey indicates that the quinazoline nucleus substituted at 2,3-position showed significant antitubercular activity5-7. The presence of the functional moiety like thiosemicarbazides and Thiosemicarbazones in different heterocyclic moiety also found to exhibit the antitubercular activity8. Hence the pharmacophore containing quinazolines ring attached with thiosemicarbazides9 or thiosemicarbazones10-12 are expected to possess more pronounce antitubercular and antimicrobial activities13-16. With this aim, in the present study, we have placed the thiosemicarbazides moiety at the C2 position of quinazoline ring and studied their antitubercular and other antimicrobial activity against different gram positive and negative bacteria.

EXPERIMENTAL Melting points (mp) were taken in open capillaries on Thomas Hoover melting point apparatus and are uncorrected. The IR spectra were recorded in film or in potassium bromide disks on a Perkin-Elmer 398 spectrometer. The 1H NMR spectra were recorded on a DPX-500 MHz Bruker FT-NMR spectrometer. The chemical shifts were reported as parts per million (δ ppm) tetramethylsilane (TMS) as an internal

SOME NOVEL THIOSEMICARBAZIDES

V. Alagarsamy and P. Parthiban

Vol.4, No.4(2011), 736-743

standard. Mass spectra were obtained on a JEOL-SX-102 instrument using fast atom bombardment (FAB positive). Elemental analysis was performed on a Perkin-Elmer 2400 C, H, N analyzer and values were within the acceptable limits of the calculated values. The progress of the reaction was monitored on readymade silica gel plates (Merck) using chloroform-methanol (9:1) as a solvent system. Iodine was used as a developing agent. Spectral data (IR, NMR and mass spectra) confirmed the structures of the synthesized compounds and the purity of these compounds was ascertained by microanalysis. Elemental (C, H, N) analysis indicated that the calculated and observed values were within the acceptable limits (± 0.4%). All chemicals and reagents were obtained from Aldrich (USA), Lancaster (UK) or Spectrochem Pvt.Ltd (India) and were used without further purification. Synthesis of 3-butyl-2-thioxo quinazolin-4(3H)-one (4) A solution of butyl amine (1) (0.02 mol) in dimethyl sulfoxide (10ml) was stirred vigorously. To this was added carbon disulphide (1.6ml) and aqueous sodium hydroxide (1.2ml) (20 molar solutions) dropwise during 30 min with stirring. Dimethyl sulphate (0.02 mol) was added gradually keeping the reaction mixture stirring in freezing mixture for 2 h. The reaction mixture was then poured into ice water. The solid obtained was filtered, washed with water, dried and recrystallized from ethanol. Methyl anthranilate (3) (0.01 mol) and the above prepared N-(butyl)-methyl dithiocarbamic acid (2) (0.01 mol), were dissolved in ethanol (20ml). To this anhydrous potassium carbonate (100 mg) was added and refluxed for 22 h. The reaction mixture was cooled in ice and the solid separated was filtered and purified by dissolving in 10% alcoholic sodium hydroxide solution and reprecipitated by treating with dilute hydrochloric acid. The solid obtained was filtered, washed with water, dried and recrystallized from ethanol. Synthesis of 3-Butyl-2-methylsulfanyl quinazolin-4(3H)-one (5) The 3-butyl-2-thioxo quinazolin-4(3H)-one (4) (0.01 mol) was dissolved in 40 ml of 2% alcoholic sodium hydroxide solution. To this dimethyl sulphate (0.01 mol) was added drop wise with stirring. The stirring was continued for 1 h, the reaction mixture was then poured into ice water. The solid obtained was filtered, washed with water, dried and recrystallized from ethanol-chloroform (75:25) mixture. Synthesis of 3-Butyl-2-hydrazino quinazolin-4(3H)-one (6) The 3-butyl-2-methylsulfanyl quinazolin-4(3H)-one (5) (0.01 mol) was dissolved in ethanol (25ml). To this hydrazine hydrate (99%) (0.1 mol) and anhydrous potassium carbonate (100 mg) was added and refluxed for 30 h. The reaction mixture was cooled and poured into ice-water. The solid so obtained was filtered, washed with water, dried and recrystallized from chloroform-benzene (25:75) mixture. General procedure for Synthesis of 1-(4-oxo-3-butyl-3H-dihydroquinazolin-2-yl)-4-(substituted) thiosemicarbazides (AS1-AS10) A solution of primary Alkyl/Aryl amine (0.02 mol) in dimethyl sulfoxide (10ml) was stirred vigorously. To this simultaneously carbon disulphide (1.6ml) and aqueous sodium hydroxide 1.2ml (20ml solution) was added drop wise during 30min with stirring. Dimethyl sulphate (0.02 mol) was added gradually by keeping the reaction mixture stirring in a freezing mixture and continued for further 2 h. The reaction mixture was then poured into ice water and the solid obtained was filtered washed with water, dried and recrystallized from ethanol. 3-Butyl-2-hydrazino-3H-quinazolin-4-one (6) (2.32 gm; 0.01 mole) Methyl N-(substituted) dithiocarbamate (7) (0.01 mol) was dissolved in ethanol and refluxed for 24-30 h (until the methyl mercapton evolution ceases). After completion of the reaction the reaction mixture cooled to room temperature. The solid obtained was filtered, dried and recrystallized from ethanol. By adapting the above procedure the compounds AS1-AS10 were prepared. Pharmacology In vitro antibacterial activity17-18 Evaluation of antibacterial activity done by the agar dilution method. The microorganisms used were procured from Department of Microbiology, MNR medical college. All bacteria were grown on

SOME NOVEL THIOSEMICARBAZIDES

737

V. Alagarsamy and P. Parthiban

Vol.4, No.4(2011), 736-743

Muller-Hinton agar (Hi-media) plates (37oC, 24 h). The minimum inhibitory concentration (MIC) was considered to be the lowest concentration that completely inhibited the growth of bacteria. In vitro M. tuberculosis Activity19-21 (Agar Dilution Method) 10 fold serial dilutions of each test compound/drug were incorporated into Middle brook 7H11 agar slants with OADC Growth Supplement. Inoculums of M. tuberculosis H37Rv were prepared from fresh Middle brook 7H11 agar slants with OADC Growth Supplement adjusted to 1mg/mL (wet weight) in Tween 80 (0.05%) saline diluted to 10-2 to give a concentrate of approximately 107 cfu/mL. A 5µL amount of bacterial suspension was spotted into 7H11 agar tubes containing 10-fold serial dilutions of drug per mL. The tubes were incubated at 37ºC, and final readings were recorded after 28 days. Tubes having the compounds were compared with control tubes where medium alone was incubated with H37RV. The concentration at which complete inhibition of colonies occurred was taken as active concentration of test compound. The minimum inhibitory concentration (MIC) is defined as the minimum concentration of compound required to give complete inhibition of bacterial growth.

RESULTS AND DISCUSSION Synthetic route depicted in Scheme 1 outline the chemistry part of the present work. The key intermediate 3-butyl-2-thioxo quinazolin-4(3H)-one (4) was obtained by reacting butyl amine (1) with carbon disulphide and sodium hydroxide in dimethyl sulphoxide to give sodium dithiocarbamate, which was methylated with dimethyl sulphate to afford the dithiocarbamic acid methyl ester (2). Compound 2 on reflux with methyl anthranilate (3) in ethanol yielded the desired 3-butyl-2-thioxo quinazolin-4(3H)-one (4) via the thiourea intermediate in good yield (86%). It was confirmed by IR spectra of 4, which showed intense peaks at 3250 cm-1 for cyclic thio urea (NH), 1669 cm-1 for carbonyl (C=O) and 1217 cm-1 for thioxo (C=S) stretching. 1H NMR spectra of compound 4 showed multiplet around at δ 0.97-4.55 ppm due to butyl group, a multiplet around δ 7.26 ppm for aromatic (4H) protons and a singlet at δ 10.5 ppm indicating the presence of NH. Data from the elemental analyses have been found to be in conformity with the assigned structure. Furthermore the molecular ion recorded in the mass spectra is also in agreement with the molecular weight of the compound. The 3-butyl-2-methysulfanyl-3H-quinazolin-4-one (5) was obtained by dissolving 4 in 2% alcoholic sodium hydroxide solution and methylating with dimethyl sulphate with stirring at room temperature. The IR spectra of 5 showed disappearance of NH and C=S stretching signals of cyclic thiourea. It showed a peak for carbonyl (C=O) stretching at 1680 cm-1. The 1H NMR spectra of compound 5 showed singlet at δ 2.65 due to SCH3 ppm; and multiplet around δ 0.90-4.15 ppm and δ 7.33-7.69 ppm was observed for butyl group and aromatic (4H) protons respectively. Data from the elemental analysis and molecular ion recorded in the mass spectra further confirmed the assigned structure. Nucleophilic displacement of the methylthio group of 5 with hydrazine hydrate was carried out using ethanol as solvent to afford 3-butyl-2-hydrazino-3H-quinazolin-4(3H)-one (6). The long duration of reaction (30 h) required might be due to the presence of bulky aromatic ring at position 3, which might have reduced the reactivity of quinazolines ring system at C-2 position. The formation of compound 6 was confirmed by the presence of NH and NH2 signals at 3434 and 3200 cm-1 in the IR spectra. It also showed a peak for carbonyl (C=O) at 1656 cm-1. The 1H NMR spectra of the compound 6 showed multiplet around δ 1.37 to 4.13 and δ 4.61 ppm and 10.24 ppm due to NH2 and NH respectively, a multiplet at δ 7.10-7.23 ppm was observed for aromatic (4H) protons. Elemental analyses data and mass spectral data is also in agreement with the assigned structure of the compound. The title compounds 1-(4-oxo-3-butyl-3H-dihydroquinazolin-2-yl)-4-(substituted) thiosemicarbazides (AS1-AS10) were obtained by the condensation of amino group of 3-butyl-2hydrazino quinazolin-4(3H)-one (6) with a variety of methyl ester of dithiocarbamic esters. The formation of title product is indicated by the disappearance of peak due to NH, NH2 of the starting material in IR and 1H NMR spectrum of all the compounds AS1-AS10. The IR and 1H NMR spectrum of these compounds showed the presence of peaks due to thiosemicarbazides, carbonyl (C=O), NH and Aryl groups. The mass spectra of the title compounds showed molecular ion peaks corresponding to their molecular formula. In mass spectrum of compounds AS1-AS10 a common peak at m/z 144 corresponding SOME NOVEL THIOSEMICARBAZIDES

738

V. Alagarsamy and P. Parthiban

Vol.4, No.4(2011), 736-743

to quinazolin-4-one moiety appeared. Elemental (C, H, N) analysis satisfactorily confirmed elemental composition and purity of the synthesized compounds. 3-Butyl-2-thioxo quinazolin-4(3H)-one (4) Yield = 86 %; mp 240-242 0C; IR (KBr) cm-1: 3250 (NH), 1669 (C=O), 1217 (C=S); 1H NMR (CDCl3): δ 0.97-1.02 (t, 3H, CH3), 1.40-1.52 (m, 2H, CH2), 1.74-1.80 (m, 2H, CH2), 4.50-4.55 (m, 2H, CH2). 7.26-7.63 (m, 4H, ArH) and 10.5 (s, 1H, NH); MS (m/z) 234 (M+); Anal. Calcd for C12H14N2OS: C, 61.51; H, 6.02; N, 11.96. Found: C, 61.55; H, 6.05; N, 11.99. 3-Butyl-2-methylsulfanyl quinazolin-4(3H)-one (5) Yield= 88 %; mp 170-172 °C; IR (KBr) cm-1: 1680 (C=O); 1H NMR (CDCl3): δ 0.96-1.01 (t, 3H, CH3), 1.39-1.51 (m, 2H, CH2), 1.73-1.77 (m, 2H, CH2), 2.65 (t, 3H, SCH3), 4.10-4.15 (m, 2H, CH2), 7.337.69 (m, 4H ArH); MS (m/z) 248 (M+); Anal. Calcd for C13H16N2OS: C, 62.87; H, 6.49; N, 11.28. Found: C, 62.85; H, 6.52; N, 11.25. 3-Butyl-2-hydrazino quinazolin-4(3H)-one (6) Yield= 81%; mp 180-182 °C; IR (KBr) cm-1: 3434 & 3200 (NHNH2), 1656 (C=O); 1H NMR (CDCl3): δ 0.96-1.01 (t, 3H, CH3), 1.37-1.50 (m, 2H, CH2), 1.66-1.74 (m, 2H, CH2), 4.04-4.13 (m, 2H, CH2), 4.61 (s, 2H, NH2), 7.10-7.23 (m, 4H, ArH), 10.24 (s, 1H, NH); MS (m/z) 232 (M+); Anal. Calcd for C12H16N4O: C, 62.05; H, 6.94; N, 24.12. Found: C, 62.10; H, 6.96; N, 24.10. 1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(phenyl) thiosemicarbazide (AS1) Yield: 88 %; mp: 115-117 ˚C; IR (KBr) cm-1: 3300 (NH), 3240 (NH), 1674 (C=O), 1252 (C=S); 1 H NMR (300 CDCl3) δ: 1.04-1.09 (t, 3H, CH3), 1.40-1.47 (m, 2H, CH2), 1.55-1.77 (m, 2H, CH2), 4.144.19 (m, 2H, CH2), 6.84-6.87 (d, 2H, Ar-H), 7.08 (br, s, 1H, NH), 7.36 (br s, 1H, NH), 7.43-7.53 (m, 4H, Ar-H), 8.02-8.08 (m, 2H, Ar-H), 8.15-8.19 (d, 1H, Ar-H) 8.77 (br s, 1H, NH); MS (m/z) 367 [M+], 368 [M++1]; Anal. Calcd for C19H21N5OS: C, C, 62.10; H, 5.76; N, 19.06; Found: C, 62.13; H, 5.74; N, 19.01. 1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(2-methyl phenyl) thiosemicarbazide (AS2) Yield: 73 %; mp: 100-102 ˚C; IR (KBr) cm-1: 3300 (NH), 3220 (NH), 1673 (C=O), 1254 (C=O); 1 H NMR (CDCl3): δ 1.05-1.09 (t, 3H, CH3), 1.42-1.55 (m, 2H, CH2), 1.67-1.82 (m, 2H, CH2), 2.46 (s, 3H, CH3), 4.14-4.19 (m, 2H, CH2), 6.84-6.86 (d, 1H, Ar-H), 7.06-7.34 (m, 6H, Ar-H), 7.53 (br, s, 1H, NH), 8.03-8.08 (d,1H, Ar-H), 8.77 (br s, 1H, NH), 11.78 (br s, 1H, NH); MS (m/z): 381 [M+]; Anal. Calcd for C20H23N5OS: C, 62.97; H, 6.08; N, 18.36; Found: C, 62.96; H, 6.11; N, 18.38. 1-(4-oxo-3-butyl-3H - quinazolin-2-yl)-4-(3-methylphenyl) thiosemicarbazide (AS3) Yield: 81 %; mp: 195-197˚C; IR (KBr) cm-1: 3383 (NH), 3240 (NH), 1673 (C=O), 1233 (C=S); 1 H NMR (CDCl3): δ 0.92-0.99 (t, 3H, CH3), 1.31-1.40 (m, 2H, CH2), 1.83-1.89 (m, 2H, CH2), 2.13 (s, 3H, CH3), 4.02-4.09 (m, 2H, CH2), 7.15-7.20 (d, 1H, Ar-H), 7.35-7.42 (m, 6H, Ar-H), 7.92-7.98 (d, 1H, ArH), 8.05 (br s, 1H, NH), 8.49 (br s, 1H, NH), 10.11 (br s, 1H, NH); MS (m/z): 381 [M+]; Anal. Calcd for C20H23N5OS: C, 62.97; H, 6.08; N, 18.36; Found: C, 62.99; H, 6.05; N, 18.34. 1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(4-methylphenyl) thiosemicarbazide (AS4) Yield: 74%; mp: 110-112 ˚C; IR (KBr) cm-1 : 3405 (NH), 3238 (NH), 1673 (C=O), 1253 (C=S); 1H NMR (CDCl3): δ 1.13-1.17 (t, 3H, CH3), 1.53-1.57 (m, 2H, CH2), 1.72-1.78 (m, 2H, CH2), 2.71 (s, 3H, CH3), 4.17-4.21 (m, 2H, CH2), 7.03-7.06 (d, 1H, Ar-H), 7.72-7.83 (m, 6H, Ar-H), 7.93-7.99 (d, 1H, Ar-H), 8.29 (br, s, 1H, NH), 9.12 (br s, 1H, NH), 10.48 (br s, 1H, NH); MS (m/z) : 381; Anal. Calcd for C20H23N5OS: C, 62.97; H, 6.08; N, 18.36; Found: C, 62.99; H, 6.06; N, 18.30. 1-(4-oxo-3-butyl-3H - quinazolin-2-yl)-4-(3-methoxy phenyl) thiosemicarbazide (AS5) Yield: 80 %; mp: 120-122 ˚C; IR (KBr) cm-1: 3365 (NH), 3221 (NH), 1634 (C=O), 1254 (C=S); 1 H NMR (CDCl3): δ 1.05-1.11 (t, 3H, CH3), 1.55-1.61 (m, 2H, CH2), 1.59-1.67 (m, 2H, CH2), 2.32 (s, 3H, OCH3), 3.72-3.76 (m, 2H, CH2), 7.22-7.23 (d, 1H, Ar-H), 7.48-7.55 (m, 6H, Ar-H), 7.73-7.74 (d, 1H, ArH), 8.20 (br s, 1H, NH), 8.25 (br s, 1H, NH), 10.13 (br s, 1H, NH); MS (m/z): 397 [M+]; Anal. Calcd for C20H23N5O2S: C, 60.43; H, 5.83; N, 17.67; Found: C, 60.49; H, 5.87; N, 17.67.

SOME NOVEL THIOSEMICARBAZIDES

739

V. Alagarsamy and P. Parthiban

Vol.4, No.4(2011), 736-743

CH3CH2CH2CH2NH2

+

CS2

+

DMSO

NaOH

S

CH3CH2CH2CH2NH C

S-Na+

(1) (CH3)2SO4 O

O NH

OCH3

EtOH

OCH3 NH CH2CH2CH2CH3

+

CH3CH2CH2CH2NH C

NH2

-CH3SH

S

N

CH2CH2CH2CH3

NaoH/EtoH N

SCH3 (5)

EtOH NH2NH2.H2O

O

N

S

NH NH C NH R

R

NH

S

C

(7)

-CH3SH

O

EtOH

N CH2CH2CH2CH3 N

CH2CH2CH2CH3

N

(CH3)2SO4

N S H (4)

SCH3

(2)

(3)

O

O

S

CH2CH2CH2CH3

N NHNH2

SCH3

(6)

AS1-AS10 H3 C AS1

OCH3

CH3

AS2

AS3

CH3

AS4

AS5

O2 N AS6

AS7

Cl

AS9

AS8 N

CH2

AS10

Scheme-1: Synthesis of 1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(substituted) Thiosemicarbazides

1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(2-nitrophenyl) thiosemicarbazide (AS6) Yield: 70 %; mp: 115-117 ˚C; IR (KBr) cm-1: 3340 (NH), 3239 (NH), 1651 (C=O), 1233 (C=S); 1 H NMR (CDCl3): δ 0.90-0.96 (t, 3H, CH3), 1.53-1.61 (m, 2H, CH2), 1.86-1.91 (m, 2H, CH2), 3.63-3.68 (m, 2H, CH2), 7.19-7.21 (d, 1H, Ar-H), 7.31-7.45 (m, 6H, Ar-H), 7.72-7.73 (d, 1H, Ar-H), 8.05 (br s, 1H, NH), 8.26 (br s, 1H, NH), 10.43 (br s, 1H, NH); MS (m/z): 412; Anal. Calcd for C19H20N6O3S: C, 55.33; H, 4.89; N, 20.38; Found: C, 55.31; H, 4.92; N, 20.41. 1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(4-chlorophenyl) thiosemicarbazide (AS7) Yield: 77 %; mp: 130-132 ˚C; IR (KBr) cm-1: 3380 (NH), 3221 (NH), 1651(C=O), 1272 (C=S); 1 H NMR (CDCl3): δ 1.04-1.09 (t, 3H, CH3), 1.49-1.52 (m, 2H, CH2), 1.74-1.79 (s, 1H, CH2), 4.14-4.19 (m, 2H, CH2), 6.99-7.02 (d, 1H, Ar-H), 7.05-7.10 (m, 2H, Ar-H), 7.26-7.38 (m, 2H, Ar-H), 7.51-7.54 (m, 2H, Ar-H), 7.56-7.59 (d, 1H, Ar-H), 7.99 (br s, 1H, NH), 8.77 (br s, 1H, NH), 11.49 (br s, 1H, NH); MS SOME NOVEL THIOSEMICARBAZIDES

740

V. Alagarsamy and P. Parthiban

Vol.4, No.4(2011), 736-743

(m/z): 401 [M+], 403 [M++2]; Anal. Calcd for C19H20N5OSCl: C, 56.78; H, 5.02; Cl, 8.82; Found: C, 56.83; H, 5.03; Cl, 8.86. 1-(4-oxo-3-butyl-3H - quinazolin-2-yl)-4-(2-aminopyridyl) thiosemicarbazide (AS8) Yield: 80 %; mp: 145-147 ˚C; IR (KBr) cm-1: 3522 (NH), 3365 (NH), 1632 (C=O), 1223 (C=S); 1 H NMR (CDCl3): δ 1.12-1.17 (t, 3H, CH3), 1.68-1.72 (m, 2H, CH2), 2.08-2.15 (m, 2H, CH2), 3.76-3.79 (m, 2H, CH2), 7.21-7.23 (d, 1H, Ar-H), 7.30-7.39 (m, 6H, Ar-H), 7.93-7.97 (d, 1H, Ar-H), 8.12 (br s, 1H, NH), 8.21 (br s, 1H, NH), 10.36 (br s, 1H, NH); MS (m/z): 368; Anal. Calcd for C18H20N6OS: C, 58.68; H, 5.47; N, 22.81: Found: C, 58.66; H, 5.45; N, 22.86; 1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(benzyl) thiosemicarbazide (AS9) Yield: 80 %; mp: 125-127 ˚C; IR (KBr) cm-1: 3380 (NH), 3239 (NH), 1676 (C=O), 1214 (C=S); 1 H NMR (CDCl3): δ 0.93-0.96 (t, 3H, CH3), 1.52 (s, 2H, CH2), 1.76-1.78 (m, 2H, CH2), 2.17-2.20 (m, 2H, CH2), 3.86-3.90 (m, 2H, CH2), 7.15-7.18 (d, 1H, Ar-H), 7.37-7.46 (m, 6H, Ar-H), 7.73-7.76 (d, 1H, ArH), 8.04 (br s, 1H, NH), 8.27 (br s, 1H, NH), 10.48 (br s, 1H, NH); MS (m/z): 381; Anal. Calcd for C20H23N5OS: C, 62.97; H, 6.08; N, 18.36: Found: C, 62.98; H, 6.06; N, 18.45. 1-(4-oxo-3-butyl-3H -quinazolin-2-yl)-4-(cyclohexyl) thiosemicarbazide (AS10) Yield: 80 %; mp: 130-132 ˚C; IR (KBr) cm-1: 3383 (NH), 3299 (NH), 1653 (C=O), 1227 (C=S); 1 H NMR (CDCl3): δ 1.02-1.05 (t, 3H, CH3), 1.55-1.59 (m, 2H, CH2), 1.96-2.01 (m, 2H, CH2), 2.27-2.32 (m, 6H, CH2), 2.31-2.38 (m, 4H, CH2), 2.91-2.94 (m, 1H, CH), 3.81-3.85 (m, 6H, CH2), 7.31-7.42 (m, 4H, Ar-H), 8.05 (br s, 1H, NH), 8.49 (br s, 1H, NH), 10.32 (br s, 1H, NH); MS (m/z): 373; Anal. Calcd for C19H27N5OS: C, 61.10; H, 7.29; N, 18.75: Found: C, 61.16; H, 7.35; N, 18.71.

S.typhi 63 125 63 E.Coli 63 63 63 S.flexneri 125 125 63 P.vulgaris 63 63 125 Enterobacter spp. 125 125 125 K.pneumoniae 63 63 63 S.enteritidis 125 63 63 B.subtilis 125 63 63 S.flexneri 125 125 125 P.aeruginosa 63 125 125 *Gatifloxacin used as a reference standard against standard for other bacteria. MIC of INH = 0.4 µg/mL

6

25

25

125 63 63 32 63 125 63 63 63 32 32 63 63 63 125 63 63 63 125 125 125 125 125 63 63 63 125 63 125 125 63 63 63 125 125 125 63 32 32 63 125 63 63 63 63 32 63 63 63 125 63 63 32 63 63 63 63 125 63 63 125 125 125 63 125 63 63 125 63 125 M. tuberculosis whereas Ciprofloxacin used as a

Standard

6

AS10

6

AS9

AS5 25

AS8

13

AS7

13

AS6

13

AS4

25

AS3

M. Tuberculosis

AS2

Microorganisms

AS1

Table-1: Antibacterial activity (MIC In µg/mL) of 1-(4-oxo-3-butyl-3H-quinazolin-2-yl)-4-(substituted) Thiosemicarbazides (AS1-AS10)

1 4 2 1 1 1 1 1 1 1 1 reference

Antitubercular activity The synthesized compounds were screened for their in vitro antimycobacterial activity against Mycobacterium tuberculosis strain H37Rv at the Tuberculosis Antimicrobial screening centre, Birla Institute of Technology & Sciences, Hyderabad campus, Hyderabad. The results are expressed in terms of Minimum Inhibitory Concentration (MIC). The results of antimycobacterial activity depicted in Table 1, indicate that the test compounds inhibited the growth of mycobacterium in varying degree. Compounds with electron withdrawing SOME NOVEL THIOSEMICARBAZIDES

741

V. Alagarsamy and P. Parthiban

Vol.4, No.4(2011), 736-743

substituent on the aryl ring showed better activity over the unsubstituted or electron donating substituent on the aryl ring. Among the test compounds, 1-(4-oxo-3-butyl-3,4dihydroquinazolin-2-yl)-4-(2nitrophenyl)thiosemi carbazides (AS6), 1-(4-oxo-3-butyl-3,4dihydroquinazolin-2-yl)-4-(4-chloro phenyl) thiosemicarbazides (AS7) and 1-(4-oxo-3-butyl-3,4-dihydroquinazolin-2-yl)-4-(2pyridyl)thiosemicarbazides (AS8) exhibited the antitubercular activity a the minimum micro gram concentration (6µg/ml). Antibacterial activity The title compounds are screened for their antibacterial activity against different gram positive and gram negative bacteria by agar dilution method, the results are depicted in Table-1. Among the different substituents on the aryl ring with electron withdrawing substituent showed better activity over the unsubstituted and electron donating substituent. Compounds AS6 and AS7 emerged as the most active compounds of the series. Compound AS6 shown most potent activity against E. coli and K. pneumoniae while the compound AS7 showed most potent activity against S. typhi, E. coli, K. pneumoniae, S. enteritidis and B. subtilis.

CONCLUSION In summary the synthesis of new series of 1-(4-oxo-3-butyl-3H-dihydroquinazolin-2-yl)-4-(substituted) thiosemicarbazides has been described. These derivatives have exhibited significant antibacterial activity against the various gram positive and gram negative bacteria including M. tuberculosis. Among the series 1-(4-oxo-3-butyl-3,4-dihydroquinazolin-2-yl)-4-(2-nitrophenyl) thiosemicarbazide (AS6), 1-(4-oxo-3butyl-3,4-dihydroquinazolin-2yl)-4-(4-chlorophenyl) thiosemicarbazide (AS7) was found to be the most active antimicrobial agents, with the MIC of 32 µg/ml. Interestingly these compounds also showed significant antitubercular activity (Compound AS6 and AS7 showed activity at 6µg/ml), offering potential for further optimization and development to new antitubercular agents.

ACKNOWLEDGEMENTS The authors gratefully acknowledge the Central Instrumentation Facility, IIT Chennai, India for the spectral analysis of the compounds used in this study; Dr. D. Sriram, Associate Professor, Birla Institute of Technology & Sciences, Hyderabad campus for performing antitubercular screening of the test compounds. The authors are also wish to thank the management of MNR College of Pharmacy for providing infrastructure facilities to carry out this research work.

REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

D.Ang, A.L.Hsu and B.H.Tan, Med. Journal., 47, 747 (2006). E.Houben, L.Nguyen and J.Pieters, Current Opin Microbiol, 9, 76(2001). World Health Organization, Tuberculosis fact sheet (2007). M.Rehman, J.Choudary, S.Ahmad and H.Siddiqui, Chem. Pharm. Bull., 54(8), 1175(2006). A.Gursoy, B.Unal, N.Karali and G. Otuk, Turk J. Chem., 29, 233(2005). S.R.Pattan, V.V.Krishna Reddy, F.V.Manvi, B.G.Desai and A.R.Bhat, Indian J. Chem., 45B, 1778(2006). P.Nandy, M.T.Vishalakshi and A.R.Bhat, Indian J. Heterocycl. Chem., 15, 293(2006). G.Kucukguzel, A.Kocatepe, E.De Clercq, F.Sahin and M.Gulluce, Eur. J. Med. Chem., 41, 353(2006). V.Alagarsamy, V.Rajasolomon, P.Parthiban, K.Dhanabal, S.Murugan, G.Saravanan and G.V.Anjana, J. Heterocyclic Chem., 45, 709 (2008). V.Krishan, S.N.Pandya, U.K.Singh, S.Gupta, P.Prasanth and G.Bhardwaj, Inter. J. Pharma. Sci.,7 Nanotech., 1(4), (2009). A.Sen and T.K.Chaudhuri, Experi. Oncology, 31(1), 22(2009). O.Oniga, C.Moldovan, S.Oniga, B.Tiperciuc, A.Parnau, P.Verite, O.Crisan and I.Ionut, Farmacia, 58, 6 (2010). S.Balasubramanian, C.Ramalingan and S.Kabilan, Synth. Commun., 33(17), 2979(2003).

SOME NOVEL THIOSEMICARBAZIDES

742

V. Alagarsamy and P. Parthiban

Vol.4, No.4(2011), 736-743

14. 15. 16. 17. 18. 19. 20. 21.

C.Ramalingan, S.Balasubramanian and S.Kabilan, Synth. Commun., 34(36), 1105(2004). G.Aridoss, S.Balasubramanian, P.Parthiban and S.Kabilan, Eur. J. Med. Chem., 41, 268 (2006). S.Balasubramanian, C.Ramalingan, G.Aridoss and S.Kabilan, Eur. J. Med. Chem., 40, 694 (2005). V.Alagarsamy, U.S.Pathak, R.Venkateshperumal, S.Meena, K.Thirumurugan, V.Rajasolomon and E.Clercq, Ind. J. Pharma. Sci., , May-June (2003). S.N.Pandya, D.Sriram, G.Nath and E.Clercq. II Farmaco, 54, 624(1999). Antimycobacterial susceptibility testing for M. tuberculosis. T. Villanova, PA: National Committee for Clinical Laboratory Standards, (1995). D.Sriram, P.Yogeeswari, M.Dinakaran and R.Thirumurugan, J. Antimicro. Chemotherapy, 59, 1194(2007). J.Kunes, J.Bazant, M.Pour, K.Waisser, M.Slosarek and J.Janota, II Farmaco, 55, 725(2000). [RJC-838/2011]

International Journal of Chemical, Environmental and Pharmaceutical Research www.ijcepr.com

ISSN: 2229-3892(Print); ISSN: 2229-5283(Online) [Abstracted in : Chemical Abstracts Service , American Chemical Society, USA and CAB(I) , UK] ________________________________________________________________________________________________________

ijCEPr widely covers all fields of Chemical, Environmental and Pharmaceutical Research. Manuscript Categories: Full-length paper, Review Articles, Short/Rapid Communications. Manuscripts should be addressed to: E-mail: [email protected]

Water: Research & Development [Water R&D] www.waterrnd.com ISSN: 2249-2003 [Abstracted in : Chemical Abstracts Service, USA and CAB(I) , UK] ________________________________________________________________________________________________________

WaterR&D is an international Research Journal, dedicated to ‘Water’. It is a truly interdisciplinary journal on water science and technology. It’ll showcase the latest research related to Water in the field of chemistry, physics, biology, agricultural, food, pharmaceutical science, and environmental, oceanographic, and atmospheric science. It includes publication of reviews, regular research papers, case studies, communications and short notes. Manuscript Categories: Full-length paper, Review Articles, Short/Rapid Communications. Manuscripts should be addressed to: E-mail: [email protected]

Adopt GREEN CHEMISTRY Save Our Planet. We publish papers of Green Chemistry on priority.

If you think that you may be a potential reviewer in field of your interest, write us at [email protected] with your detailed resume and recent color photograph.

SOME NOVEL THIOSEMICARBAZIDES

743

V. Alagarsamy and P. Parthiban