synthesis and biological activity of novel bis and mono heterocycles

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Indo American Journal of Pharmaceutical Research, 2015 ISSN NO: 2231-6876

SYNTHESIS AND BIOLOGICAL ACTIVITY OF NOVEL BIS AND MONO

HETEROCYCLES OF THIENOPYRIMIDINE DERIVATIVES

Kerru Nagaraju, Nallapaneni Harikrishna, Kasturi Vasu and Chunduri Venkata Rao* Sri Venkateswara University Tirupati 517 502, Andhra Pradesh, India.

Corresponding author

Chunduri Venkata Rao

Department of Chemistry,

Sri Venkateswara University Tirupati 517 502,

Andhra Pradesh, India.

+91-877-2289303;

+91-877-2249532;

[email protected]

Copy right © 2015 This is an Open Access article distributed under the terms of the Indo American journal of Pharmaceutical

Research, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ARTICLE INFO ABSTRACT

Article history

Received 05/04/2015

Available online

05/05/2015

Keywords

Thienopyrimidine,

Isoxazole-5-One,

Triazole,

Oxadiazole,

Thiadiazole,

Antioxidant And

Antibacterial Activity.

A new series of structurally diverse thienopyrimidines have been synthesized with the

annulations of heterocyclic structural pharmacophores. All the newly synthesized compounds

were characterized by IR, 1H and

13C NMR and LC-MS spectral studies and tested for their

antioxidant and antibacterial activity. The 3-amino-4-(1-phenyl-2-(thieno[3,2-d]pyrimidin-4-

ylsulfonyl)ethyl)isoxazol-5(4H)-one (14) showed excellent radical-scavenging activity when

compared with the standard BHT. Hence the novel thienopyrimidine derivatives are

considered as potent antioxidant and antibacterial agents.

Please cite this article in press as Kerru Nagaraju et al. Synthesis and biological activity of novel bis and mono heterocycles of

thienopyrimidine derivatives. Indo American Journal of Pharm Research.2015:5(04).

mailto:[email protected]

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Vol 5, Issue 04, 2015. Kerru Nagaraju et al. ISSN NO: 2231-6876

INTRODUCTION The annulations of two or more heterocyclic systems (pharmacophoric structures) has been one of the best approaches in

rational drug design in generating new structurally diverse drugs as structural diversity is obviously directly related to the compounds

potentiality able with pharmacological activities. In fast few decades there is remarkable growth in the development of antimicrobial

drugs. However development of the resistance against these antimicrobial is in an alarming stage. Moreover, the antioxidant of

reactive oxygen species (ROS) capable of causing damage to DNA has been associated with carcinogenesis, coronary heart disease

and many other health problems related to advancing nature [1]. They make use of their effects by scavenging or preventing the

invention of ROS which can protect the formation of free radicals and retard the growth of many chronic diseases including cancer

[2], neurodegenerative, inflammation and cardiovascular diseases [3]. Recently, qualitative SARS and rational-design strategies for

antioxidants have been used to join multiple functions including a diversity of multiple antioxidant properties such as radical-

scavenging ability and diversified pharmacological activities to numerous functions during one molecule scaffold [4].

The rapid developments in the literature dealing with the synthesis and biological activities of the thienopyrimidine

derivatives encouraged us to carry out the synthesis of novel fused thienopyrimidine derivatives. However, the development of simple,

facile and efficient methods to give five member triazoles, oxadiazoles, thiadizoles and isoxazole containing thienopyrimidine

heterocycles is one of the major aspects in organic synthesis. Indeed, numerous series of thienopyrimidine heterocyclic compounds

possessing a bridgehead triazole moiety play an imperative role in lots of biological activities such as fungicidal, anti-inflammatory

and analgesic agents [5]. In the past few years, thienopyrimidines have attracted great attention owing to their inspiring array of

pharmacological activities. They were found to demonstrate antioxidant [6, 7], cyclin D1-CDK4 [8], adenosine A2A receptor [9],

antituberculosis [10], antihypertensive [11], 5-HT1A receptor [12], antiproliferative [13], anti viral, antitumor and antibacterial activity

[14]. An extensive multiplicity of heterocyclic systems has been explored for growing pharmaceutically essential molecules. Along

with the derivatives of oxadiazoles, triazoles and thiadiazoles have played an important task in the medicinal chemistry. These

heterocycles have been originated to acquire broad spectrum anti bacterial and nonulcerogenic anti-inflammatory activity [15, 16] and

also the 1,2,4-triazole and 1,3,4-thiadiazole rings with sulfone nucleus possess significant anti-inflammatory and analgesic activity

[17]. In addition, compounds bearing the isoxazole ring also have a noteworthy number of biological applications displaying PTP1B

[18], antifungal [19], HDAC inhibitors [20] and antitumor activity [21]. In view of this intelligence and a range of applications of

thienopyrimidine heterocycles, we herein report the synthesis of a series of novel thienopyrimidine mono and bis triazole, oxadiazole,

thiadiazole and isoxazole heterocycles by incorporating the bioactive groups attached to corresponding sulfone moiety, which

fortunately resulted in noticeable antioxidant and antibacterial properties.

METERIAL AND METHODS

Chemistry

Melting points were determined in open capillaries on a Mel-Temp apparatus and are uncorrected. All the reactions were

monitored by thin layer chromatography (TLC) on precoated silica gel 60 F254 (mesh); spots were visualized with UV light. Merck

silica gel (60-120 mesh) was used for column chromatography. The IR spectra were recorded on a Perkin-Elmer BX1 FTIR

Spectrophotometer as KBr pellets and the wave numbers were given in cm-1

. 1H NMR (400 MHz), and

13C NMR (100 MHz) spectra

were recorded on a Bruker AMX 400 MHz NMR spectrometer in CDCl3/DMSO-d6 solution using TMS as an internal standard. The

mass spectra were recorded on Agilent 1100 LC/MSD instrument with method API-ES at 70 eV. All chemical shifts are reported in δ

(ppm) using TMS as an internal standard.

Preparation of compounds (2-6)

These compounds were prepared in our laboratory, according to reported procedure [27-30]

General Procedure for the preparation of compounds (7 and 7a)

Potassium hydroxide (1.68 g, 30 mmol) was dissolved in absolute ethanol (50 mL). The solution was cooled in ice bath and

solutions of (6 and 6a) (5.56 g, 20 mmol) were added with stirring. To this carbon disulphide (1.5 mL, 25 mmol) was added in small

portions with constant stirring. The reaction mixture was stirred continuously for 12 h at room temperature. The precipitated

potassium dithiocarbazinate was collected by filtration, washed with anhydrous ether (100 mL) and dried in vacuum. The potassium

salts (7 and 7a) thus obtained and were used in the next step without further purification.

General Procedure for the preparation of compounds (8 and 9)

A suspension of potassium dithiocarbazinate salts (7 and 7a) (7.84 g, 20 mmol) in water (50 mL) and hydrazine hydrate (1.9

mL, 40 mmol) was refluxed for 16-20 h with occasional shaking. The colour of the reaction mixture changed to green with the

evolution of hydrogen sulfide gas. A homogenous reaction mixture was obtained during the reaction process. The reaction mixture

was cooled to room temperature and diluted with cold water (20 mL). On acidification with acetic acid the required triazoles 8 and 9

were precipitated out, respectively. It was filtered, washed thoroughly with cold water, dried and recrystallized from ethanol.

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4-Amino-5-[2-phenyl-3-(thieno[3,2-d]pyrimidine-4-sulfonyl)-propyl]-4H-[1,2,4] triazole-3-thiol (8)

Yield: 81% (pale brown color solid); mp 238-240 0C; IR (KBr) (νmax/cm

-1): 3373, 2823, 2357, 1659, 1544, 1174;

1H NMR

(400 MHz; DMSO-d6): δH 1.21 (d, JHH = 8.0 Hz, 2H, CH2), 2.30 (d, JHH = 16.0 Hz, 2H, CH2), 3. 02 (m, 1H, CH), 5.75 (s, 2H, NH2),

7.18 (d, JHH = 8.0 Hz, 1H, Ar-CH), 7.50 (d, JHH = 8.0 Hz, 1H, Ar-CH), 7.91-8.47 (m, 5H, Ar-H), 8.82 (s, 1H, pyrimidine-CH), 9.06 (s,

1H, SH); 13

C NMR (100 MHz; DMSO-d6): δC 17.93, 45.64, 97.14, 108.18, 110.36, 113.06, 122.36, 126.05, 132.34, 151.46, 153.61,

155.31, 160.49, 162.35, 171.35; LC-MS (70 eV): m/z = 433 (M+H)+.

5,5'-((Thieno[2,3-d]pyimidine-2,4-disulfonyl)bis(2-phenylpropane-3,1-diyl))bis(4-amino-4H-1,2,4-triazole-3-thiol) (9)

Yield: 82% (pale yellow color solid); mp 253-255 0C; IR (KBr) (νmax/cm

-1): 3362, 2933, 2360, 1645, 1557, 1140;

1H NMR

(400 MHz; DMSO-d6): δH 1.30 (d, JHH = 4.0 Hz, 4H, 2 × CH2), 2.82 (d, JHH = 8.0 Hz, 4H, 2 × CH2), 4.21 (m, 2H, 2 × CH), 6.85 (d,

JHH = 8.0 Hz, 1H, Ar-CH), 7.54-7.61 (m, 10H, 2 × Ar-H), 7.80 (s, 4H, 2 × NH2), 8.11 (d, JHH = 8.0 Hz, 1H, Ar-CH), 13.72 (s, 2H, 2 ×

SH); 13

C NMR (100 MHz; DMSO-d6): δC 20.78, 33.69, 96.32, 99.43, 107.338, 109.50, 125.58, 128.06, 143.79, 150.64, 152.72,

154.46, 159.63, 160.79, 170.07; LC-MS (70 eV): m/z = 727 (M-H)-.


A mixture of (7 and 7a) (0.0l mol) was added portion wise to 15 mL of 98% H2SO4 and the resulted clear solution was stirred

at room temperature for 24 h. After the reaction was completed, the reaction mixture was poured into ice water and the obtained solid

was filtered off, washed thoroughly with cold water, dried and recrystallized from ethanol to afford 10 and 11, respectively.

5-[2-Phenyl-3-(thieno[3,2-d]pyramidine-4-sulfonyl)-propyl]-[1,3,4]thiadiazole-2-thiol (10)

Yield: 76% (yellow color solid); mp 226-228 0C; IR (KBr) (νmax/cm

-1): 2828, 2359, 1645, 1506, 1165;

1H NMR (400 MHz;

DMSO-d6): δH 2.35 (d, JHH = 4.0 Hz, 2H, CH2), 2.88 (m, 1H, CH), 3.68 (d, JHH = 8.0 Hz, 2H, CH2), 7.03-7.11 (m, 5H Ar-H), 7.37 (d,

JHH = 4.0 Hz, 1H, Ar-CH), 8.04 (d, JHH = 8.0 Hz, 1H, Ar-CH), 8.33 (s, 1H, pyrimidine-CH), 8.62 (s, 1H, SH); 13

C NMR (100 MHz;

DMSO-d6): δC 20.75, 48.02, 97.75, 110.88, 126.51, 130.64, 132.78, 134.43, 138.33, 152.04, 154.20, 155.95, 161.24, 163.02, 170.34;

LC-MS (70 eV): m/z = 435 (M+H)+.

5,5'-((Thieno[2,3-d]pyimidine-2,4-disulfonyl) bis(2-phenylpropane-3,1-diyl))bis (1,3,4-thiadiazole-2-thiol) (11)

Yield: 83% (pale brown color solid); mp 219-221 0C; IR (KBr) (νmax/cm

-1): 2989, 2363, 1647, 1548, 1144;

1H NMR (400

MHz; DMSO-d6): δH 1.78 (m, 2H, 2 × CH), 2.76 (d, JHH = 4.0 Hz, 4H, 2 × CH2), 2.78 (d, JHH = 12.0 Hz, 4H, 2 × CH2), 6.94 (d, JHH =

8.0 Hz, 1H, Ar-CH), 7.23-7.34 (m, 10H, 2 × Ar–H), 8.12 (d, JHH = 8.0 Hz, 1H, Ar-CH), 12.32 (s, 2H, 2 × SH); 13

C NMR (100 MHz;

DMSO-d6): δC 18.77, 34.50, 98.00, 101.19, 111.20, 124.38, 126.88, 129.37, 132.88, 152.28, 154.41, 156.14, 161.32, 161.75, 172.35;

LC–MS (70 eV): m/z = 732 (M+H)+.


A mixture of (7 and 7a) (0.0l mol) in water and 15 mL of HCl was added and the resulted clear solution was stirred at 70 C

for 12 h. The reaction mixture was poured into ice water and solid was obtained. It was filtered, washed thoroughly with cold water,

dried and recrystallized from ethanol to give 12 and 13, respectively.

5-[2-Phenyl-3-(thieno[3,2-d]pyrimidine-4-sulfonyl)-propyl]-[1,3,4]oxadiazole-2-thiol (12).

Yield: 71% (pale yellow color solid); mp 216-218 0C; IR (KBr) (νmax/cm

-1): 2881, 2307, 1641, 1523, 1178;

1H NMR (400

MHz; DMSO-d6): δH 2.68 (d, JHH = 12.0 Hz, 2H, CH2), 3.32 (m, 1H, CH), 4.14 (d, JHH = 4.0 Hz, 2H, CH2), 6.85 (d, JHH = 4.0 Hz, 1H,

Ar-CH), 7.18 (d, JHH = 8.0 Hz, 1H, Ar-CH), 7.64-7.84 (m, 5H, Ar-H), 8.97 (s, 1H, pyrimidine-CH), 11.43 (s, 1H, SH); 13

C NMR (100

MHz; DMSO-d6): δC 17.36, 40.98, 96.61, 121.71, 124.94, 125.48, 128.44, 130.66, 132.34, 150.87, 153.02, 154.74, 159.93, 160.04,

171.03; LC-MS (70 eV): m/z = 419 (M+H)+.

5,5'-(Thieno[2,3-d]pyimidine-2,4-disulfonyl) bis(2-phenylpropane-3,1-diyl)) bis (1,3,4-oxadiazole-2-thiol) (13)


-1): 2939, 2359, 1645, 1558, 1172;

1H NMR (400 MHz;

DMSO-d6): δH 2.03 (d, JHH = 8.0 Hz, 4H, 2 × CH2), 2.83 (m, 2H, 2 × CH), 3.83 (d, JHH = 8.0 Hz, 4H, 2 × CH2), 7.23-7.36 (m, 10H, 2 ×

Ar-H), 7.93 (d, JHH = 8.0 Hz, 1H, Ar-CH), 8.76 (d, JHH = 8.0 Hz, 1H, Ar-CH), 12.72 (s, 2H, 2 × SH); 13

C NMR (100 MHz; DMSO-

d6): δC 23.22, 32.95, 78.49, 99.90, 107.91, 109.97, 126.15, 126.50, 150.15, 151.09, 153.01, 154.98, 160.15, 161.25, 170.46; LC-MS

(70 eV): m/z = 701 (M+H)+.

Procedure for the synthesis of 3-amino-4-(1-phenyl-2-(thieno[3,2-d]pyrimidin-4-ylsulfonyl)ethyl)isoxazol-5(4H)-one (14)

A mixture of 5b (0.0.1 mol), hydroxylamine hydrochloride (0.01 mol) and triethylamine (0.01 mol) were refluxed together in

methanol (15 mL) in 15 min. The reaction mixture was poured into ice cold water and extracted with diethyl ether. The ethereal layer

was removed, washed successively with cold water, 5% aq. Sodium bicarbonate, dried and evaporated to obtain compound 14 and

purified by column chromatography.

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-1): 3445, 2834, 1647, 1511, 1137;

1H NMR (400 MHz;

DMSO-d6): δH 1.49 (d, JHH = 4.0 Hz, 2H, CH2), 1.75 (m, 1H, CH), 3.73 (d, JHH = 8.0 Hz, 1H, CH), 6.02 (brs, 2H, NH2), 6.43 (d, JHH =

12.0 Hz, 1H, Ar-CH), 6.61 (d, JHH = 12.0 Hz, 1H, Ar-CH), 6.84-6.95 (m, 5H, Ar-H), 8.64 (s, 1H, pyrimidine-CH); 13

C NMR (100

MHz; DMSO-d6): δC 19.21, 28.90, 97.12, 123.90, 126.03, 127.35, 130.00, 136.99, 138.58, 151.48, 153.58, 155.30, 160.48, 161.68,

170.82; LC-MS (70 eV): m/z = 403 (M+H)+.

Biological assays

Antioxidant testing

The compounds 8-14 are tested for antioxidant property by DPPH, nitric oxide and H2O2 methods.

DPPH radical scavenging activity

The hydrogen atom or electron donation ability of the compounds was measured from the bleaching of the purple colour

methanol solution of 2,2,-diphenyl-1-picrylhydrazyl (DPPH) radical. The spectrophotometric assay uses the stable radical DPPH as a

reagent. 1 mL of various concentrations of the test compounds (25, 50, 75 and 100 µg/mL) in methanol were added to 4 mL of

0.004% (w/v) methanol solution of DPPH. After a 30 min incubation period at room temperature, the absorbance was read against

blank at 517 nm. The percent of inhibition (I %) of free radical production from DPPH was calculated by the following equation

% of scavenging = [(A control - A sample)/A blank] × 100

Where a control is the absorbance of the control reaction (containing all reagents except the test compound) and a sample is the

absorbance of the test compound. Tests were carried at in triplicate.

Nitric oxide (NO) scavenging activity

Nitric oxide scavenging activity was measured by slightly modified methods of Green et al. and Marcocci et al. Nitric oxide

radicals (NO) were generated from sodium nitroprusside. 1 mL of sodium nitroprusside (10 mM) and 1.5 mL of phosphate buffer

saline (0.2 M, pH 7.4) were added to different concentrations (25, 50, 75 and 100 µg/mL) of the test compounds and incubated for 150

min at 25 0C. After incubation, 1 mL of the reaction mixture was treated with 1 mL of Griess reagent (1%sulfanilamide, 2% H3PO4

and 0.1% naphthyl ethylenediamine dihydrochloride). The absorbance of the chromatophore was measured at 546 nm. Butylated

hydroxyl toluene (BHT) was used as standard. Nitric oxide scavenging activity was calculated by the following equation




Hydrogen peroxide (H2O2) scavenging activity

The H2O2 scavenging ability of the test compound was determined according to the method of Ruch et al. A solution of H2O2

(40 mM) was prepared in phosphate buffer (pH 7.4). 10, 25, 50, 75 &100 µg/mL concentrations of the test compounds in 3.4 ml

phosphate buffer were added to H2O2 solution (0.6 mL, 40 mM). The absorbance value of the reaction mixture was recorded at 230

nm. The percent of scavenging of H2O2 was calculated by the following equation




Antibacterial activity

A total of four bacterial strains viz. Bacillus subtilis (MTCC-1133), Staphylococcus aureus (MTCC-7443), Escherichia coli

(MTCC-1668), Salmonella typhimurium (MTCC-98) were used in the investigation for antimicrobial assay. Ampicillin was used as

standard drug for antibacterial activity and Minimum inhibitory concentration (MIC) of all compounds was determined by micro-

dilution method using serially diluted compounds. MIC of the compounds was determined by series of dilution at various

concentrations. Different concentration of the compounds (100 µg/mL, 50 µg/mL, 25 µg/mL, 12.5 µg/mL, 6.25 µg/mL, 3.12 µg/mL,

1.56 µg/mL) was serially diluted in microtiter plate. Specifically, 0.1 mL of standardized inoculums (1-2 × 107 cfu/mL) was added in

each tube of microtiter plate. The plates were incubated aerobically at 37 0C for 18-24 h. The lowest concentration (highest dilution)

of the compounds showed no visible bacterial growth no turbidity in the solution when it was compared with the control was regarded

as the MIC. Mueller-Hinton agar and Luria broth (Hi-media, Mumbai, India) was used for antibacterial activity.

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RESULT AND DISCUSSION

Chemistry

The synthetic strategies adopted for the synthesis of the intermediate and final compounds are depicted in Scheme 1.

Thieno[2,3-d]pyrimidine-2,4-diol (2) and thieno[3,2-d]pyrimidin-4-ol (2a) were prepared [9, 27] from compound 1. Compound 2 and

2a on refluxion with phosphorous oxychloride yielded 3 and 3a which on further treatment with sodium (E)-2-phenylethenesulfinate

with catalytic amount of triethylamine formed the corresponding 4 and 4a, respectively. Compounds 4 and 4a on treatment with

diethylmalonate and sodium methoxide gave the corresponding solids 5 and 5a, respectively. Further 4 on reaction with ethyl

cyanoacetate with catalytic amount of sodium methoxide at 60 0C afford ethyl 2-cyano-3-phenyl-4-(thieno[3,2-d]pyrimidin-4-

ylsulfonyl)butanoate (5b). Compounds 6 and 6a were prepared from 5 and 5a with hydrazine hydrate followed by treatment with

carbon disulphide in the presence of alcoholic potassium hydroxide yielded potassium dithiocarbazinate salts 7 and 7a, respectively.

Next 7 and 7a were transformed to the corresponding triazole derivatives 8 and 9 on treatment with hydrazine hydrate. The

condensation of 7 and 7a with 98% sulphuric acid yielded thiadiazole derivatives 10 and 11, respectively. Similarly, oxadiazole

derivatives 12 and 13 were respectively prepared by the cyclization of 7 and 7a. Finally, compound 5b on reflexion with

hydroxylamine hydrochloride yielded isoxazole derivative 14 (Scheme 1). All the reactions were monitored by TLC and the newly

synthesized compounds were purified by column chromatography. The structure elucidations of the newly synthesized compounds

were carried out by modern spectroscopic techniques like IR, 1H and

13C NMR and LC-MS spectrum.

Scheme 1. Synthetic pathway for the preparation of mono and bis triazole, thiadiazole, oxadiazoles and isoxazole of

thienopyrimidine.

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Biological assays

Antioxidant activity

The compounds 8-14 are tested for antioxidant property by DPPH [22, 23], nitric oxide [24, 25] and H2O2 [26] methods. We

investigated all the newly synthesized compounds 8-14 were tested for antioxidant property by 1,1-diphenylpicrylhydrazyl (DPPH)

(Table 1), hydrogen peroxide (Table 2) and nitric oxide (Table 3) methods. All the pharmacological data are expressed as mean ± SD,

BHT (butylated hydroxytoluene) was used as a positive control and measurements was run in triplicate. Among all the tested

compounds, thieno[3,2-d]pyrimidin-4-ylsulfonylethylisoxazol-5-one 14 displayed excellent radical-scavenging activity in all three

methods, when compared with the standard BHT. The compounds 8 and 9 showed moderate antioxidant activity whereas the other

compounds 10-13. The compound isoxazol-5-one in combine with sulfone moiety 14 exhibited great activity which may be due to the

presence of two oxygen atoms than the compounds having thiadiazole and oxadiazole. The IC50 value of the standard BHT in DPPH

method was found to be 25.19 µg/mL where as the IC50 values of the compounds 8, 9 and 14 were found to be 27.69, 31.11 and 26.95

µg/mL, respectively. Further, the analysis of table 1, 2 and 3 indicates that radical scavenging activity in DPPH, hydrogen peroxide

and nitric oxide methods increases with increase in concentration. BHT (butylated hydroxytoluene) was used as a positive control and

measurements was run in triplicate. The percentage of scavenging activity was calculated.

Antibacterial activity

All the synthesized compounds (8-14) were screened for their antibacterial activity determined by micro-dilution method

[31]. The potentiality of the synthesized compounds studied against various Gram+Ve such as Bacillus subtilis and Staphylococcus

aureus and Gram–Ve such as Escherichia coli and Salmonella typhimurium strains of human pathogens. The result obtained as MIC is

presented in Table 4. It is more attractive to speculate the observation that the result of the antibacterial activity of the various

derivatives appeared to be related the nature of five member rings attached to thienopyrimidine moiety. It is evident from Table 4 that

two compounds viz. 8 and 14 were found more potent with either less or equal MIC as compared to control drug ampicillin. DMSO

was also taken in a control experiment which showed no effect in the experiment. The compound 8 containing [1,2,4]triazole ring

tagged sulfonyl thienopyrimidine was found potent activity against B.subtilis with MIC 3.12 µg mL–1

while the standard ampicillin

showed 6.25 µg mL–1

. Further, the compounds 14 having isoxazole ring tagged sulfonyl thienopyrimidine found potent activity

against E.coli at MIC 3.12 µg mL–1

.

Table 1. The in vitro antioxidant activity of 8-14 in DPPH method.

(–) Showed no scavenging activity.

Results are expressed as means of three replicates ± standard deviation.

Table 2.The in vitro antioxidant activity of 8-14 in hydrogen peroxide method.

Compound Concentration (µg/mL)

25 50 75 100 IC50

8 47.10 ± 0.45 52.73 ± 0.71 60.04 ± 0.46 66.19 ± 0.15 26.53 ± 0.46

9 41.28 ± 0.24 47.12 ± 0.62 48.30 ± 1.11 53.39 ± 1.11 30.28 ± 0.87

10 30.22 ± 1.05 36.03 ± 0.87 40.26 ± 0.99 48.14 ± 0.87 41.36 ± 0.28

11 31.21 ± 1.11 35.96 ± 0.91 36.68 ± 0.59 38.06 ± 1.00 40.05 ± 1.00

12 33.16 ± 1.01 40.26 ± 0.23 43.19 ± 1.05 50.13 ± 0.30 37.69 ± 1.05

13 32.08 ± 1.01 37.47 ± 0.42 40.14 ± 1.03 45.37 ± 0.34 38.96 ± 0.79

14 49.27 ± 0.14 56.18 ± 0.11 65.21 ± 0.18 68.26 ± 0.22 25.37 ± 0.24

BHT 53.60 ± 0.04 60.81 ± 0.05 68.19 ± 0.16 72.28 ± 0.07 23.32 ± 0.03

Blank ‒ ‒ ‒ ‒ ‒

(–) Showed no scavenging activity.



25 50 75 100 IC50

8 45.13 ± 0.11 53.28 ± 0.15 59.02 ± 0.87 63.19 ± 0.16 27.69 ± 0.36

9 40.18 ± 0.14 49.34 ± 0.22 56.17 ± 0.14 59.01 ± 1.00 31.11 ± 1.05

10 32.45 ± 0.39 43.20 ± 0.17 45.92 ± 0.79 50.23 ± 1.01 38.52 ± 0.47

11 30.37 ± 0.32 42.18 ± 1.01 44.33 ± 1.00 48.23 ± 1.13 41.15 ± 0.08

12 38.19 ± 0.16 46.54 ± 0.49 48.28 ± 1.04 52.39 ± 1.17 32.73 ± 1.07

13 31.23 ± 1.11 43.49 ± 0.51 46.90 ± 0.78 50.28 ± 0.24 40.02 ± 1.01

14 46.38 ± 0.08 57.16 ± 0.05 61.32 ± 0.11 65.27 ± 0.06 26.95 ± 0.13

BHT 49.62 ± 0.05 58.28 ± 0.14 65.51 ± 0.04 70.39 ± 0.07 25.19 ± 0.07

Blank ‒ ‒ ‒ ‒ ‒

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Table 3. The in vitro antioxidant activity of 8-14 in nitric oxide method.


25 50 75 100 IC50

8 48.42 ± 0.41 56.26 ± 0.23 63.14 ± 0.12 66.29 ± 0.43 25.81 ± 0.76

9 45.16 ± 0.14 49.73 ± 0.64 51.25 ± 0.22 59.01 ± 1.01 27.67 ± 0.49

10 31.29 ± 1.05 33.02 ± 1.00 46.51 ± 1.32 52.09 ± 1.00 39.94 ± 1.06

11 30.22 ± 1.05 34.40 ± 1.11 44.03 ± 1.01 50.11 ± 1.02 41.36 ± 0.31

12 32.58 ± 0.54 36.91 ± 0.79 50.70 ± 0.62 56.22 ± 1.12 38.36 ± 1.07

13 31.46 ± 0.43 38.12 ± 1.05 48.28 ± 1.05 53.24 ± 0.22 39.73 ± 0.67

14 50.36 ± 0.33 61.14 ± 0.12 68.31 ± 0.18 70.42 ± 0.41 24.82 ± 0.37

BHT 55.76 ± 0.05 63.24 ± 0.11 70.64 ± 0.03 73.17 ± 0.06 22.41 ± 0.04

Blank ‒ ‒ ‒ ‒ ‒

(–) Showed no scavenging activity


Table 4. The in vitro antibacterial activity of compounds 8-14.

Minimum inhibitory concentration (MIC) µg/mL

Compounds Antibacterial activity

Gram +ve bacteria Gram –ve bacteria

B.subtilis

(MTCC-1133)

S.auears

(MTCC-7443)

E.coli

(MTCC-1668)

S.typhimurium

(MTCC-98)

8 3.12 6.25 6.25 6.25

9 50.00 25.00 50.00 100.00

10 12.50 12.50 25.00 12.50

11 25.00 50.00 12.50 50.00

12 6.25 25.00 12.50 12.50

13 12.50 50.00 25.00 25.00

14 6.25 6.25 3.12 6.25

Ampicillin 6.25 12.50 6.25 6.25

Control - - - -

CONCLUSION

The present study reports the synthesis of new class of thienopyrimidine sulfonyl mono and bis heterocycles-triazole,

thiadiazole, oxadiazole and isoxazole were prepared from the synthetically vulnerable intermediate 4-(styrylsulfonyl)thieno[3,2-

d]pyrimidine and studied their antioxidant and antibacterial activities were successfully achieved. In this study, the synthesized

compounds may be used as lead compounds for anti-bacterial and antioxidant activity and may be evaluated further towards antifungal

and anticancer activity studies.

ACKNOWLEDGEMENTS The authors would like acknowledge the Council of Scientific and Indusrial Research (CSIR), New Delhi, for financial

assistance under major research project CSIR Lr. No.02 (0065)/12/EMR-II and Prof. Ch. Appa Rao, Department of Biochemistry, S V

University, Tirupati for their help in antioxidant activity study.

Authors’ Statements

Competing interests

The authors no conflict of interest

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synthesis and biological activity of novel bis and mono heterocycles