Iraqi J Pharm Sci, Vol.24(1) 2015 Antibacterial evolution of bis heterocyclic derivatives 59 Synthesis and Antibacterial Activity of bis Heterocyclic Derivatives of 1,3,4-thiadiazole Ahlam A. Al-jubouri ٭ ,1 and Ahlam J. Qasir٭٭ .Department of Registration , Ministry of Health, Baghdad, Iraq ٭ .Department of Pharmaceutical Chemistry, College of Pharmacy, University of Baghdad, Baghdad, Iraq ٭٭ Abstract The Chemistry of heterocyclic sulphur and nitrogen containing compounds have a great role in the field of scientific studies, The 2-amino 5-mercapto-1,3,4-thiadiazole ring for instance, has gained more importance in recent years because they are considered as potent biologically active nucleus. In this study disulfide derivative can be obtained by oxidation with hydrogen peroxide of thiol group of the heterocyclic 2-amino 5-mercapto-1,3,4-thiadiazole ring to obtain compound (3) with expected antibacterial activity. In order to use it as a diazo component to prepare some new bis azo compounds as possible antibacterial agents, the reaction of two primary amino groups on both sides of disulfide dimer with sodium nitrite was carried out to prepare diazounium salt which was coupled with different coupling compounds to form the azo linkage. The reaction steps and the purity of the products were confirmed by thin layer chromatography (TLC) and melting points measurement .The chemical structure of the final compounds were characterized and confirmed by measuring their FT-IR spectroscopy and elemental microanalysis(C, H, N &S).These compounds were screened for their antibacterial activity which was done on four different strains of bacteria by well diffusion method. These compounds show moderate to good activity against tested gram positive bacteria and low or no activity against gram negative bacteria compared to the standard compounds. Key words: Disulfide dimer, Diazo compound, Antibacterial activity. - ٤, ١,٣كمشتقاث مركباث ثنائيت حهقيت غير متجانست ن بكتريانه ةفعانيت مضادو خهيقت زول ياثياد احالو عذنان انجبوري ،*٣ جميم قصيرو احالو ٭٭ ٭ انؼشاق. ،بغذاد ،ٔصاسة انصحت انخسجٍم،لسى ٭٭ . قانؼشا ،دبغذا ،جايؼت بغذاد ،كهٍت انصٍذنت ،فشع انكًٍٍاء انصٍذالٍَت الخالصة ٕي انكبشٌج ٔانُخشٔجٍٍ حًخهك دٔس ػظٍى فً يجال انذساساث انؼهًٍت , فؼهى خاٌ كًٍٍاء انًشكباث انحهمٍت غٍش انًخجاَست انخً حح اكخسبج اًٍْت اكبش فً انٕلج انشاٍْ الَٓا حؼخبش َٕاة فؼانت صٔل ٌاثٍاد - ٤, ١,٣يٍشكبخٕ – ٥ايٍُٕ -۲سبٍم انًثال انحهمت صٔل باكسذة يجًٕػت ٌاثٍاد - ٤, ١,٣يٍشكبخٕ – ٥ايٍُٕ -۲ فً ْزِ انذساست حى ححعٍش يشخك ثُائً انكبشٌج نهحهمت .˝بإٌنٕجٍا كب انُٓائً االٔل رٔ فؼانٍت يخٕلؼت كًعاد انثإٌل فً ْزِ انحهمت غٍش انًخجاَست بٕاسطت بٍشٔكسٍذ انٍٓذسٔجٍٍ نهحصٕل ػهى انًش اصٔ نخحعٍش بؼط يشكباث ثُائً االصٔ انجذٌذة راث فؼانٍت يعادة ثُائً ْزا انًشكب كًكٌٕ نًشكباث ؼًال.نغشض اسخبكخشٌانه نذاٌا صٍَٕٔو انزي حى ػهى جٓخً ثُائً انكبشٌج يغ َخشٌج انصٕدٌٕو نخحعٍش يهح ا االٔنٍتار حى يفاػهت يجًٕػخً االيٍٍ بكخشٌانه حى انخاكذ يٍ خطٕاث انخفاػم َٔمأة انُٕاحج بٕاسطت كشٔياحٕغشافٍا انطبمت انشلٍمت) .سبطّ بًشكباث يخخهفت نخكٌٍٕ اصشة االصٔ TLC) نٓا .انخشاكٍب انكًٍٍائٍت نهًشكباث انُٓائٍت لذ حى حشخٍصٓا ٔانخاكذ يُٓا بٕاسطت لٍاط اغٍاف االشؼت سٔ لٍاط دسجاث االَصٓا اسبؼت ؼًال( .كزنك حى انخؼشف ػهى فؼانٍخٓا كًعاداث نهًٍكشٔباث باسخC,H,N&Sش)ححج انحًشاء ٔانخحهٍم انكًً انذلٍك نهؼُاص لهٍهت أ نًشكباث فؼانٍت يخٕسطت انى جٍذة ظذ انبكخشٌا يٕجبت انغشاو ٔفؼانٍتزِ اْ اظٓشثانمشص .نمذػضالث يخخهفت بطشٌمت اَخشاس فً ْزِ انذساست بانًماسَت يغ انًشكباث انمٍاسٍت.ؼًهت يؼذٔيت حجاِ انبكخشٌا سانبت انغشاو انًسخ ثنائي داي سهفايذ ، مركباث انذايازو، انفعانيت انمضادة نهبكتريا .انكهماث انمفتاحيت : Introduction The rapidly expanding population of immunocompromised patient results in a corresponding increase of diseases caused by bacteria, fungi and other yeast. Infections caused by these microorganisms pose a serious challenge to the medical community and highlight the importance and urgent need for new, more potent and selective antimicrobial agents. The incidence of bacterial infections has increased dramatically in recent years (1) . Drug resistance by microorganisms is of increasing importance as the phenomenon has considerable impact on human and animal health. The prevalence of clinical drug resistance has unfortunately increased significantly in recent decades due to the use 1 Corresponding author E-mail: ahlamaljubouri@yahoo.com Received:14 /1/2015 Accepted: 18/5/2015 Iraqi J Pharm Sci, Vol.24(1) 2015 Antibacterial evolution of bis heterocyclic derivatives 60 and misuse of antimicrobial drugs and many infectious diseases can no longer be treated effectively with common anti-infective drugs. Antimicrobial resistance is not limited to bacterial species and in the 1990s resistance emerged to one of the most potent antifungal agents, fluconazole. Antifungal resistance is particularly problematic as diagnosis is often delayed and there are relatively few antifungal treatments approved for use by the FDA (2) .Heterocyclic play an important role in biochemical processes because the side groups of the most typical and essential constituents of living cells are based on aromatic heterocycles. Between them, sulfur and nitrogen-containing heterocyclic compounds have maintained the interest of researchers through the development of organic synthesis. Some of them are tetrazoles, fused thiazoles, thiadiazoles, oxadiazoles, triazoles, which are structural subunits of several biologically active compounds (3) . Thiadiazole derivatives possess biological activity probably conferred to them by the strong aromaticity of this ring system, which leads to great in vivo stability and generally, a lack of toxicity for higher vertebrates, including humans. Thiadiazole can act as the bio-isosteric replacement of the thiazole moiety. So it acts like third and fourth generation cephalosporin (4) . 1, 3, 4- Thiadiazole ring containing compounds represent an important class of heterocyclic nitrogen compounds and their derivatives are characterized with a broad spectrum of biological activity in both agrochemical and pharmaceutical fields (5,6) . Many 1,3,4- thiadiazoles derivatives have been used as “privileged” scaffolds to produce substances of interest in numerous therapeutic areas (7) such as antituberculosis (8,9) , anti-inflammatory (10) ,analgesic (11) ,anticonvulsants (12) , antihypertensive (13) , antioxidant (14) , anticancer (15) ,antiviral (16) ,antidepressant (17) , anti-HIV, antiproliferative activities (18) . Compounds possessing 1, 3,4-thiadiazole ring system show antifungal, bacteriostatic as well as anthelmintic effects (19,20) . Furthermore, Five membered heterocyclic compounds show various types of biological activity among them 2,5-disubstituted 1,3,4-thiadiazoles are associated with diverse biological activities probably, due to –N=C-S- grouping (21) . Hence the current work is the need for the development of novel antimicrobial agents to combat the bacterial infections. Materials and Methods Aceticanhydride, 4-aminophenol, carbon disulfide, 1-naphthol, 2-naphthol, thiosemicarbazide. All the solvents and materials used were of analar type and used without further purification. The ascending TLC was run on silica gel F-254 (type 60) pre- coated aluminum sheets, for checking the purity of the products as well as monitoring the progress of the reaction. The final products and their intermediates were detected by reacting with iodine vapor or by irradiation with UV light. Infrared spectral determination was performed for all compounds in KBr disk, using FTIR at the college of pharmacy, university of Baghdad and at the College of Science Al-Mustansiriya University. Elemental microanalysis has been done using elemental analyzer Euro vector, and was done at the College of Science, Al-Mustansiriya University. Chemical synthesis Synthesis of p-Hydroxy acetanilide (Compound 1) (22) . In a 100 ml conical flask containing p- aminophenol (25 mmole, 2.725g) and water (7.5ml). Acetic anhydride (31.7 mmole, 3ml) was added with constant shaking. The mixture was stirred vigorously and warmed on a water bath for about 15 minutes until the solid dissolves completely. Upon Cooling, p- hydroxy acetanilide was precipitated which was collected by suction filtration , then washed with a little cold water, drained well and recrystallized from hot water (about 18.5ml) and dried.The physical appearances, percentage yield, melting point,and Rf values are listed in table 1. Synthesis of 5-amino-1, 3, 4-thiadiazole-2- thiol (compound 2) ( 23) . To thiosemicarbazide (100 mmole, 10g) suspended in absolute ethanol (40 ml), anhydrous sodium carbonate (54 mmole, 5.82 g) were added and carbon disulfide (120 mmole, 10.1 g). The reaction mixture was heated with stirring under reflux for five hours .The completion of the reaction was indicated by TLC. The solvent was largely removed by rotatory evaporator and the residue was dissolved in water (44 ml), then acidified with concentrated hydrochloric acid (8.8 ml). The product was recrystallized from ethanol/water to give a pure compound. The physical appearances, percentage yield, melting point, and Rf values are listed in table 1, the elemental analysis results are presented in table 2 while the IR data are shown in table 3. Synthesis of 5, 5’- dithiobis (2-amine -1, 3, 4- thiadiazole) (Compound 3) ( 24) . Hydrogen peroxide (3.1ml, 30%) was added drop wise to a suspension of compound (2) (10 mmole, 1.33g) in ethanol (30ml) with continuous stirring for 1 hour at room temperature, a yellow precipitate was formed, this precipitate was collected by filtration, Iraqi J Pharm Sci, Vol.24(1) 2015 Antibacterial evolution of bis heterocyclic derivatives 61 washed with hot ethanol to afford the pure product and dried in oven at 60 o C to provide compound (3).The physical appearances, percentage yield, melting point and Rf value are listed in table 1, the elemental analysis results are presented in table 2 while the IR data are shown in table 3. Synthesis of 5, 5’ - dithiobis ( 2- amino -1, 3, 4-thiadiazole) diazonium salt (Compound 4) ( 25 ) . Compound 3 (1.32 g, 5mmole) was dissolved in 6 ml of concentrated hydrochloric acid and 6 ml of water in a suitable beaker; the resulting solution was stirred and cooled by immersing in a bath of crushed ice; throughout the reaction the temperature was kept below 5 o C. A cold solution of (0.75g, 11mmole) sodium nitrite in (5 ml) water was placed in a dropping funnel which was cooled using crushed ice, then it was added dropwise into the first solution in the ice bath with continues stirring ,the temperature should not be allowed to rise above 10°C.The last quantity of the sodium nitrite solution was added more slowly and after stirring for 3-4 minutes, a drop of the solution diluted with 4 drops of water was tested with potassium iodide-starch paper; if no immediate blue color was obtained at the point of contact with the paper, a further amount of sodium nitrite solution was added. The testing was continued every 5 minutes until an immediate blue color was obtained. A solution of sulfamic acid (1.5ml) of 2% w/v was added and stirring was continued for 20 minutes. The diazonium salt formed was used immediately in the following synthesis of Compounds (4A- 4C). Synthesis of 1,1'-(1Z,1'Z)- disulfanediyl- bis(1,3,4thiadiazole-5,2-diyl)bis(diazene-2,1- diyl)dinaphthalen-2-ol(Compound 4A) (26) . 2-Naphthol (1.44 g, 10 mmole) was dissolved in (8 ml) of (10 %) NaOH in a suitable beaker immersed in an ice bath. The solution was stirred vigorously and the temperature was kept below 5°C by the addition of crushed ice. The cold diazonium salt solution from the previous step (compound 4) was placed in a dropping funnel, then it was added drop by drop to the cooled, stirred 2- Naphthol solution; a deep red color was developed and a red crystals soon separated. At the end of the addition the mixture was stirred for 3hours in the ice bath. Then the solution was filtered through Buchner funnel, washed well with water, and recrystallized from glacial acetic acid (3ml); washed with a little absolute ethanol to eliminate acetic acid and dried. The physical appearances, percentage yield, melting point and Rf value are listed in table 1, the elemental microanalysis results are presented in table 2 while the IR data are shown in table 3. Synthesis of 4,4'-(1Z,1'Z)-5,5'-disulfanediy- lbis(1,3,4-thiadiazole-5,2-diyl)bis(diazene-2,1- diyl)dinaphthalen-1-ol (Compound 4B) ( 26) . 1-Naphthol (1.44 g, 10 mmole) was dissolved in (8 ml) of (10 %) NaOH in a suitable beaker immersed in an ice bath. The solution was stirred vigorously and the temperature was kept below 5°C by the addition of crushed ice. The same procedure was carried out as in the synthesis of compound (4A). The deep bluish violet color was developed and a deep blue crystals soon separated. At the end of the addition the mixture was stirred for 3 hours in the ice bath. Then the solution was filtered through Buchner funnel, washed well with water, and recrystallized from glacial acetic acid (3ml); washed with a little ethanol to eliminate acetic acid and dry upon filter paper. The physical appearances, percentage yield, melting point and Rf value were listed in table1, the elemental microanalysis results are presented in table 2 while the IR data are shown in table3. Synthesis of N , N '- ( 3 , 3 '- ( 1 Z , 1 'Z)-5,5'- disulfanediylbis(1,3,4-thiadiazole- 5,2diyl)bis(diazene-2,1-diyl)bis(4-hydroxy- 3,1-phenylene)) diacetamide (Compound 4C) (26) . p-Hydroxyacetanilide (compound 1) (1.51 g; 10 mmole) was dissolved in (8 ml) of (10 %) NaOH in a suitable beaker immersed in an ice bath. The solution was stirred vigorously and the temperature was kept below 5°C by the addition of crushed ice. The same procedure was carried out as in the synthesis of compound (4A and4B) .The deep brown color was developed and a brown crystals soon separated. At the end of the addition the mixture was stirred for 1h in the ice bath. Then the solution was filtered through Buchner funnel, washed well with water, and recrystallized from glacial acetic acid (3ml); washed with a little absolute ethanol to eliminate acetic acid and dried. The physical appearances, percentage yield, melting point and Rf value are listed in table 1, the elemental microanalysis results are presented in table 2 while the IR data are shown in table 3. Iraqi J Pharm Sci, Vol.24(1) 2015 Antibacterial evolution of bis heterocyclic derivatives 62 Table (1): Physical appearance, percentage of yield, melting points, Rf values of intermediates and final compounds. Compound No. Physical appearance %Yield Observed melting point (˚C) Reported melting point (C) Rf values Solvent system 1 grey crystal 83.6% 168-169 169 0.72 A 2 Pale yellow powder 73.4% 241-243 240-242 0.87 B 3 Yellow powder 58.7% 233-235 233-235 0.92 C 4A Deep red powder 81.8% 81 (decom.) --------- 0.92 D 4B Deep blue powder 66.1% 170 (decom.) --------- 0.71 D 4C Brown crystal 85.3% 201-203 -------- 0.88 A A) Toluene: Methanol (9:1), B) Chloroform: Ethylacetate: Methanol (2:2:1) C) n-Hexane: Isopropanol: Methanol (9: 0.9:0.1), D) Chloroform: Ethanol (8:2) Table (2): Elemental microanalysis of the final compounds Table (3): Characteristic IR absorption bands of intermediates and final compounds Elemental microanalysis % Empirical formula Molecular weight Compound Observed Calculated Element 18.201 18.181 C C4H4N6S4 264 3 1.465 1.515 H 31.943 31.818 N 48.391 48.48 S 50.167 50.174 C C24H14O2N8S4 574 4A 2.434 2.439 H 19.521 19.512 N 22.288 22.299 S 50.079 50.174 C C24H14O2N8S4 574 4B 2.441 2.439 H 19.57 19.512 N 22.331 22.299 S 40.798 40.816 C C20H16O4N10S4 588 4C 2.712 2.721 H 23.912 23.809 N 21.698 21.768 S Compound Band(cm -1 ) Interpretation 1 3321 3109 2991, 2881 1651 1608 ,1560 1506 1437 1437 ,1369 1255 , 1224 1170 1107 ,1014 853 ,802 O-H Stretching of phenol and N-H Stretching of amide. C-H Stretching of aromatic ring. C-H asymmetrical and symmetrical stretching of CH3. C=O Stretching of Amide and C=N Stretching of heterocyclic ring Aromatic C=C stretching N-H bending of amide. O-H in plane bending C-H bending of CH3. Aromatic C-H in-plane bending. C-O Stretching of phenol Aromatic C-H out of plane bending. Iraqi J Pharm Sci, Vol.24(1) 2015 Antibacterial evolution of bis heterocyclic derivatives 63 Table (3): Continued characteristic IR absorption bands of intermediates and final compounds Antibacterial activity assessment (27) . The antibacterial activity of the synthesized compounds was investigated in comparison with cefotaxime (30 μg/ disc) and amoxicillin (25 μg/disc) which were used as a reference antibacterial activity against Gram- positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis) and Gram- negative bacteria (Escherichia coli, Klebsiella pneumonia ) Antibacterial activities of each compound were evaluated by well diffusion method using Mueller–Hinton agar as culture media (27) . The synthesized compounds were dissolved in dimethylsulfoxide to prepare the stock solution (20mg/ml) and the solution was diluted with dimethylsulfoxide: distilled water (1:5) to obtain the required concentrations of 0.4, 0.8and 1.0 mg/ml. The petri dishes were inoculated with (30 μl) separately of each concentration of the synthesized compounds for each well and incubated at 37 °C for 24 h. To ensure that the solvent had no effect on the bacterial growth, a control was performed with the test medium supplemented with DMSO at the same dilutions as used with the tested compounds. At the end of the period the inhibition zones formed on media were measured with a zone reader in millimeters. The inhibition zone values are summarized in table 4. Compound Band(cm -1 ) Interpretation 2 3329 ,3246 2642 1606 1548 1172 N-H stretching vibration of primary amines. S-H Stretching of thiol. C=N Stretching of heterocyclic ring. N-H bending of primary amine. C-N Stretching of heterocyclic ring 3 3255 1635 1134 N-H stretching vibration of primary amines. C=N Stretching of thiadiazole ring moiety. C-N Stretching of thiadiazole ring moiety. 4A 3286 3053 1627 1508 ,1600 1464 1274 ,1242 1213 844 , 813 O-H stretching vibration of 2-Naphthol. C-H Stretching of aromatic ring. C=N Stretching of aromatic ring. C=C Stretching of heteroaromatic ring. N=N Stretching. Aromatic C-H in-plane bending. C-N Stretching. Aromatic C-H out of plane bending. 4B 3248 3061 1620 1595,1541 1498 1253 ,1230 1207 871 ,839 ,748 682 O-H stretching of 1-Naphthol. C-H Stretching of aromatic ring. C=N Stretching of aromatic ring. C=C Stretching of heteroaromatic ring. N=N Stretching. Aromatic C-H in-plane bending. C-N Stretching. Aromatic C-H out of plane bending. C=C bending of aromatic ring. 4C 3284 ,3306 3091 2933 1637 1608 1560 1535 1500 1386 ,1367 1257 , 1224 1170 871 ,839 ,748 677 O-H stretching and N-H stretching of amide. C-H Stretching of aromatic ring. C-H Stretching of CH3. C=O stretching of amide. C=N Stretching of heteroaromatic ring. C=C Stretching of aromatic ring. N-H bending of amide. N=N Stretching. C-H bending of CH3. Aromatic C-H in-plane bending. C-N Stretching. Aromatic C-H out of plane bending. C=C bending of aromatic ring. Iraqi J Pharm Sci, Vol.24(1) 2015 Antibacterial evolution of bis heterocyclic derivatives 64 Table (4): The antibacterial screening data for final compounds. Zone of inhibition in mm Compound No. Klebsiella pneumonia Escherichia coli Staphylococcus epidermidis Staphylococcus aureus -ve -ve 19 19 12 μg/ well 3 -ve -ve 22 22 24 μg/ well -ve -ve 22 23 30 μg/ well -ve -ve -ve 20 12 μg/ well 4A -ve -ve -ve 20 24 μg/ well 8 8 -ve 22 30 μg/ well -ve -ve -ve 7 12 μg/ well 4B -ve -ve -ve 8 24 μg/ well -ve -ve -ve 16 30 μg/ well -ve -ve 25 25 12 μg/ well 4C -ve -ve 29 26 24 μg/ well -ve -ve 30 29 30 μg/ well -ve -ve -ve -ve ------- DMSO 26 25 18 -ve 30 μg/ disc Cefotaxime 15 -ve 13 15 25 μg/ disc Amoxicillin Results and Discussion The synthesis of the designed compounds was successfully achieved by following the stated procedures as shown in (Scheme 1). The Fourier transform infrared (FT-IR) spectra of the final synthesized compounds and their intermediates showed the characteristic bands of absorption by which they were identified.IR data help not only to identify the final compounds, but also they are advantageous to follow up the reactions depending on the appearance or disappearance of specific group frequencies. The values of the interesting bands of these spectra are presented in table (3). for compound (3),we noticed the absence of the S-H stretching band at 2624 cm -1 and the compound was insoluble in 5% KOH solution but soluble in 5% HCl solution due to presence of basic group (NH2) on both sides of compound and absence of acidic group ( -SH) ,for compound (4A), we noticed the appearance of N=N stretching band at 1464 cm -1, ,The disappearance of N-H primary amine stretching bands of dimer at 3255 cm -1 and appearance of O-H of 2- naphthol stretching bands at 3286 cm -1 ; and the color of the compound was changed from yellow to deep red and it was soluble in 5% KOH solution but for compound (4B),we noticed the appearance of N=N stretching band at 1498 cm -1 ,the disappearance of N-H primary amine stretching bands of dimer at 3255cm -1 and appearance of O-H of 1-naphthol stretching bands at 3248 cm -1 ; the color of the compound was changed to deep blue and it was soluble in 5% KOH solution, and for compound (4C),we noticed the appearance of N=N stretching band at 1500 cm -1 ,the disappearance of N-H primary amine stretching bands of dimer at 3255 cm -1 and the appearance of O-H of phenol stretching bands and N-H secondary amide stretching band at 3306 -3284cm -1 ;the color of the compound was changed to brown and it was soluble in 5% KOH solution. The newly synthesized compounds were screened for their antibacterial activity. From the result in table (4),compound 4C showed highly antibacterial activity against gram positive bacteria ( Iraqi J Pharm Sci, Vol.24(1) 2015 Antibacterial evolution of bis heterocyclic derivatives 65 Staphylococcus aureus, Staphylococcus epidermidis ) tested in all three concentrations used compared with the standard (Amoxicillin) and no activity against gram negative bacteria (Klebsiella pneumonia., Escherichia coli ) at tested concentrations compared with the standard (Cefotaxime).Final compounds except 4B showed high activity at all concentrations against gram positive bacteria (Staphylococcus aureus). The tested compounds except compound 4C (at concentration 30μg/ml) showed no activity against gram negative bacteria (Klebsiella pneumonia, Escherichia coli) in all three concentrations. . Scheme (1): Synthesis of intermediates and final compounds. Conclusion The synthesis of the designed compounds was successfully achieved by following the stated procedures as previously described. Characterization and structural formulas of the synthesized compounds were characterized and confirmed by determination their melting points, decomposition points, Rf values, infrared spectroscopy (IR) and elemental microanalysis. Most of these compounds showed good antibacterial activity comparable with the standard compounds. The zone of inhibition of the final compounds shows the disulfide dimer of 2-amino 5- mercapto 1, 3, 4-thiadiazole ring and its derivatives exhibit potent bioactivities against gram positive bacteria. This is may be attributed to the different groups substituted on the amino groups of dimer through diazotization reaction. However, for compounds 4A and 4B, the position of hydroxyl group in naphthol ring showed wide variation in potency against bacteria. This may be reflected by differences in physiochemical properties or may have different affinity for bacterial cell wall that favor compound 4A compared to compound 4B. Iraqi J Pharm Sci, Vol.24(1) 2015 Antibacterial evolution of bis heterocyclic derivatives 66 Acknowledgment The authors gratefully thank the college of pharmacy, university of Baghdad, for supporting this research. References 1. Narendra S., Uma Sh., Niranjan S., Sushil K.and Umesh K. Sh.;Synthesis and antimicrobial activity of some novel 2- aminothiazolederivatives; J. Chem. Pharm. Res., 2010; 2(3):691-698. 2. Bernadette S. C., Brian D., Denise A. E., Kevin K., Georgina R., Venkat R.and Maureen W., Anticancer and antifungal activity of copper (II) complexes of quinolin-2(1H)-one-derived Schiff bases. Inorganica Chimica Acta., 2010; 363:4048–4058. 3. Singaravel M. and Sarkkarai A.; A New Approach for the Synthesis of Some Novel Sulphur Bridged Pyrazoles and their Characterization; J. Chem. Pharm. 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