untitled European Journal of Chemistry 2 (4) (2011) 539‐543 European Journal of Chemistry ISSN 2153‐2249 (Print) / ISSN 2153‐2257 (Online)  2011 EURJCHEM DOI:10.5155/eurjchem.2.4.539‐543.55 European Journal of Chemistry Journal homepage: www.eurjchem.com Synthesis and biological activity of functionalized phosphorus derivatives of isatin imines Emtithal Ahmed El‐Sawi*, Tahia Bayoumy Mostafa and Hyam Ali Radwan Chemistry Department, Faculty of Girls for Arts, Science and Education, Ain Shams University, Heliopolis, Cairo, 11757, Egypt *Corresponding author at: Chemistry Department, Faculty of Girls for Arts, Science and Education, Ain Shams University, Heliopolis, Cairo, 11757, Egypt. Tel.: +2.0224196561; fax: +2.0224157804. E‐mail address: elsawi_e@yahoo.com (E.A. El‐Sawi). ARTICLE INFORMATION ABSTRACT Received: 11 April 2010 Received in revised form: 05 June 2010 Accepted: 05 June 2010 Online: 31 December 2011 KEYWORDS Isatin‐3‐imine derivatives (1a‐d) have been synthesized. These compounds were then converted into phosphorylated products 2a, 2c with triethylphosphite and 3a‐d with triphenylphosphine. The structures of the new compounds were confirmed by elemental analyses, IR, UV/VIS, 1H NMR, 13C NMR and MS studies. The structure of compound 1a was also confirmed by single crystal X‐ray diffraction studies. Compounds 1b‐d and 3c‐d exhibited potent antibacterial activity against Bacillus subtilis and Escherichia Coli. Compound 3a was found to exhibit antifungal activity against the tested organisms. Mass spectroscopy Phosphorylation Triphenylphosphine Schiff bases X‐ray crystallography Antimicrobial activity 1. Introduction The chemistry of isatin and its derivatives is particularly interesting because of their potential applications in medicinal chemistry. The synthetic versatility of isatin has led to the extensive use in organic synthesis. 3‐Imino‐2‐amino‐isatins were obtained by a one‐pot reaction of an excess of aniline (or its derivatives) with 1,2‐bis(dimethylamino)‐1,2‐dichloro‐ ethene followed by hydrolysis to yield the corresponding isatin derivatives [1]. The construction of spiroxindole via imino Diels‐Alder reaction of in‐situ generated isatin imine with dihydropyran [2]. Isatins are known to exhibit variety of biological and pharmaceutical properties [3‐5]. Schiff and Mannich bases of isatin derivatives are also reported to show a variety of biological activities [6‐11]. Some isatin Schiff bases derivatives have been synthesized and realized as anti‐HTV activity [12]. Some organometallic Schiff bases containing Ni(II), Co(II) and Cu(II), were found to be killing agents for Biomphalaria Alexandrina snails without affecting the surrounding environment [13]. Other synthesized Schiff bases from the reaction of isatin with primary aromatic amines were randomly screened for their in vitro anti‐leishmanial potential [14]. 1‐ (Substituted phenylaminomethyl)‐3‐(coumarin‐3‐yl‐ carbohydrazine) isatins were synthesized and exhibited potential anti‐covulsants [15]. The isatin core structure was found to be a novel chemical scaffold in trans‐thyretin fibrillogenesis inhibitor design [16]. Organophosphorus derivatives containing isatin‐3‐ hydrazones were detected as chemotherapeutants against fungal pathogens of sugarcane [17]. Isatin derivatives bearing 1,2,4‐triazole ring were also synthesized [18], where N‐bridged heterocyclic derivatives derived from 1,2,4‐triazoles showed varied biological activities such as: antimicrobial [19], anticonvulsant [20], anticancer [21], analgesic [22], anti‐HIV [23], and anti‐inflammatory [24]. These biological and the other data prompted us to synthesize new isatin derivatives with potential of interesting biological activities. 2. Experimental 2.1. Instrumentation Melting points were determined with Gallen Kamp melting point apparatus and were uncorrected. Elemental analyses were performed by the Microanalytical Center, Cairo University, Giza. FT‐IR spectra were recorded on Mattson 1000 spectrophotometer, Microanalytical Center, Cairo University, Giza. UV/Vis spectra were recorded using Shimadzu UV 1601 Spectrophotometer. Mass spectra were measured on GCMS‐QP 1000 EX Gas Chromatography‐Mass spectrometer, Cairo University, Giza and on Gas chromatography‐Mass spectrometer in National Research Center, Egypt. 1H NMR spectra were recorded on Gemini 200, spectrometer in DMSO‐d6 solution with TMS as internal standard in Cairo University, Giza. X‐ray single crystal diffraction studies were performed in National Research Center, Egypt. A suitable crystal (size 0.50  0.50  0.10 mm) was selected from batch of crystals of compound 1a obtained by crystallization from alcohol. All diagrams and calculations were performed using maxus (Bruker Nonius, Delft & MacScience, Japan), using graphite monochromated MoK radiation (=0.71073 Å). Biological activity was performed in Micro Analytical Center, Cairo University, Giza, Egypt. 540 El‐Sawi et al. / European Journal of Chemistry 2 (4) (2011) 539‐543 Scheme 1 Scheme 2 2.2. Synthesis 2.2.1. Compounds 1a‐d A mixture of (0.001 mol, 0.146 g) of isatin and amine derivatives namely 2,6‐diisopropylaniline, 4‐aminosalicylic acid, 4‐aminodiphenylamine and 4‐amino‐N‐[5‐methoxy‐2‐ pyrimidinyl] benzene sulphonamide in ethyl alcohol (20 mL) was refluxed for 3h. The reaction mixture was cooled and the resulting precipitate was filtered, dried and crystallized from the proper solvent (Scheme 1). (Z)‐3‐((2, 6‐diisopropylphenyl)imino)indolin‐2‐one (1a): Orange crystals from ethanol in 86% yield. M.p.: 264‐265 oC. IR (KBr, max, cm‐1): 3163 (N‐H), 2962‐2866 (C‐H aliph.), 1733 (C=O), 1662 (C=N). UV/Vis (max (nm),  (L/mol.cm)): 459, 11.29x103. 1H NMR (DMSO‐d6, δ, ppm): 8.2 (s, 1H, NH), 7.8‐6.9 (m, 7H, Arom.), 3.1 (m, 2H, 2(CH)), 1.3 (d, 12H, 4(CH3)). Anal. calcd. for C20H22N2O: C, 78.43; H, 7.18; N, 9.15. Found: C, 78.22; H, 7.15; N, 9.00%. (Z)‐2‐hydroxy‐4‐((2‐oxoindolin‐3‐ylidene)amino)benzoic acid (1b): Brown crystals from ethanol in 85% yield. M.p.: >340 oC. IR (KBr, max, cm‐1): 3163 (N‐H), 2962‐2866 (C‐H aliph.), 1733 (C=O), 1683 (C=N). UV/Vis (max (nm),  (L/mol.cm)): 260, 7.2x103; 298, 9.6x103; 314, 10.5x103; 415, 1.8x103. 1H NMR (DMSO‐d6, δ, ppm): 11.2 (s, 1H, COOH), 8.3 (s, 1H, NH), 8.0‐6.9 (m, 7H, Arom.), 4.9 (s, 1H, OH). Anal. calcd. for C15H10N2O4: C, 63.82; H, 3.54; N, 9.92. Found: C, 63.74; H, 3.71; N, 10.24%. (Z)‐3‐((4‐(phenylamino)phenyl)imino)indolin‐2‐one (1c): Black crystals from ethanol in 93% yield. M.p.: 213‐214 oC. IR (KBr, max, cm‐1): 3163 (N‐H), 2962‐2866 (C‐H aliph.), 1733 (C=O), 1663 (C=N). UV/Vis (max (nm),  (L/mol.cm)): 487, 17.15x103, 325, 20.07x103. 1H NMR (DMSO‐d6, δ, ppm): 8.2 (s, 1H, NH‐CO), 7.8‐6.6 (m, 13H, Arom.), 3.8 (s, 1H, NH). Anal. calcd. for C20H15N3O: C, 76.67; H, 4.79; N, 13.41. Found: C, 76.62; H, 4.79; N, 13.20%. (Z)‐N‐(5‐methoxypyrimidin‐2‐yl)‐4‐((2‐oxoindolin‐3‐ ylidene)amino)benzenesulfon amide (1d): Orange crystals from ethanol in 64% yield. M.p.: 188‐189 oC. IR (KBr, max, cm‐ 1): 3163 (N‐H), 2962‐2866 (C‐H aliph.), 1733 (C=O), 1647 (C=N). UV/Vis (max (nm),  (L/mol.cm)): 407, 2.7x103. 1H NMR (DMSO‐d6, δ, ppm): 8.2 (s, 1H, NH), 8.0‐7.2 (m, 10H, Arom.), 3.9 (s, 1H, SO2NH), 3.6 (s, 3H, OCH3). Anal. calcd. For C19H15N5O4S: C, 55.74; H, 3.66; N, 17.11. Found: C, 55.69; H, 3.54; N, 17.23%. 2.2.2. Compounds 2a, c A mixture of (0.001 mol, 0.166 g) triethylphosphite and 3‐ (2, 6‐diisopropoylphenyl‐imino)indolin‐2‐one (1a) or 3‐(4‐ (phenylamino)phenyl‐imino)indolin‐2‐one (1c) in 10 mL THF was stirred for 3 hours at room temperature, then left to stand overnight. The resulting precipitate was filtered and crystallized from petroleum ether (40‐60 oC). It gave one spot on (TLC) (Scheme 2). Compound 2a: Black crystals from THF in 89.47% yield. M.p.: 270‐271 oC. IR (KBr, max, cm‐1): 1758, 1734 (C=O), 1032 (P‐O). 1H NMR (DMSO, δ, ppm): 8.00 (s, 2H, 2NHCO), 7.6‐6.5 (m, 14H, Arom.), 3.6 (q, 6H, 3CH2), 3.2 (m, 4H, 4CH for isopropyl), 1.3 (d, 24H, 8 CH3), 1.0 (t, 9H, 3 (OCH2CH3)). 13C NMR (DMSO, δ, ppm): 163 (C=O), 155.9‐111.5 (aromatic carbons), 40.33‐22.81 (aliphatic carbons). Anal. calcd. for C46H59N4O5P: C, 70.95; H, 7.58; N, 7.19. Found: C, 70.51; H, 7.56; N, 7.12%. El‐Sawi et al. / European Journal of Chemistry 2 (4) (2011) 539‐543 541 H N O N R NH2 OH O OH H2N N H H2N S O O N H N N O H2N R-NH2 = a b c d P 3a, 3b H N O N R P Ph Ph Ph 3c, 3d H N O NPPh Ph Ph R 1a-d Scheme 3 Compound 2c: Deep violet crystals from THF in 77% yield, M.p.: 98‐99 oC. IR (KBr, max, cm‐1): 1727 (C=O (NH‐CO)), 1020 (P‐O). The 1 H NMR (DMSO, δ, ppm): 8.1 (s, 1H, NHCO), 7.6‐6.2 (m, 13H, Arom.), 4.1 (s, 1H, NH), 1.5 (q, 6H, 3CH2), 1.1 (t, 9H, 3 CH3). Anal. calcd. for C26H30N3O4P: C, 65.13; H, 6.26; N, 8.76. Found: C, 65.02; H, 6.17; N, 8.54%. 2.2.3. Compounds 3a‐d A mixture of (0.001 mol, 0.262 g) triphenylphosphine and imine derivatives namely (2, 6‐diisopropoylphenyl‐ imino)indolin‐2‐one (1a), 2‐hydroxy‐4‐(2‐oxoindoylidene‐ amino)benzoic acid (1b), 3‐(4‐(phenylamino)phenyl‐ imino)indolin‐2‐one (1c) and N‐(5‐methoxypyrimidin‐2‐yl)‐4‐ (2oxoindolin‐3‐ylideneamino)‐benzenesulphonamide (1d) in 30 mL THF was stirred for 3 h at room temperature, then left to stand overnight. The resulting precipitate was filtered and crystallized from the proper solvent (Scheme 3). Compound 3a: Yellow crystals from THF in 92% yield, M.p.: 190‐191oC. IR (KBr, max, cm‐1): 1758, 1734 (C=O), 1432 (P‐Ph) [25]. UV/Vis (max (nm),  (L/mol.cm)): 403, 4.65x103; 294, 10.5x103. 1H NMR (DMSO, δ, ppm): 11.01 (s, H, NH), 7.62‐6.70 (m, 22H, Arom.), 2.67 (m, 2H, 2CH), 1.09 (d, 12H, 4CH3). 13C NMR (DMSO, δ, ppm): 163 (C=O), 155.9‐111.5 (Arom.), 40.33‐ 22.82 (Aliphatic). MS (m/z, %): 874 (M+, 0.01), 568 (0.05), 306 (3.00), 304 (8.93), 277 (30), 262 (57, 44), 247 (9.09), 132 (53.05), 108 (100), 107 (98), 77 (83), 55 (55). Anal. calcd. for C38H37N2OP: C, 80.28; H, 6.51; N, 4.92. Found: C, 79.88; H, 6.46; N, 4.86%. Compound 3b: Pale brown crystals from THF in 85% yield, M.p.: 111‐112 oC. IR (KBr, max, cm‐1): 1435 (P‐Ph) [25]. UV/Vis (max (nm),  (L/mol.cm)): 254, 8.4x103; 298, 10.06x103; 315, 10.9x103. 1H NMR (DMSO, δ, ppm): 11.2 (s, 1H, COOH), 10 (s, 1H, NH), 7.8‐6.2 (m, 22 H, Arom.), 4.9 (s, 1H, OH). Anal. calcd. for C33H25N2O4P: C, 72.75; H, 4.58; N, 5.14. Found: C, 72.45; H, 4.56; N, 5.34%. Compound 3c: Black crystals from THF in 81.48% yield, M.p.: 156‐157 oC. IR (KBr, max, cm‐1): 1725 (C=O (NH‐CO)), 1432 (P‐Ph). UV/Vis (max (nm),  (L/mol.cm)): 493, 6.36x103; 309, 12x103. 1H NMR (DMSO, δ, ppm): 8.2 (s, 1H, NHCO), 7.7‐6.2 (m, 28H, Arom.) and 4.2 (s, 1H, NH). MS (m/z, %): 512 (3), 360 (96), 283 (C15H14N3OP+, 100), 277 (6), 179 (34), 164 (50), 77 (13), 51(4). Anal. calcd. for C38H30N3OP: C, 79.30; H, 5.21; N, 7.30. Found: C, 79.20; H, 5.40; N, 7.25%. Compound 3d: Reddish brown crystals from THF in 50% yield, M.p.: 76‐77 oC, IR (KBr, max, cm‐1): 1725 (C=O (NH‐CO)), 1431 (P‐Ph). UV/Vis (max (nm),  (L/mol.cm)): 395, 1.35x103. 1H NMR (DMSO, δ, ppm): 11.00 (s, 1H, (N=C‐OH)), 8.00‐6.57 (m, 25H, Arom.), 4.00 (s, 1H, SO2NH), 3.77 (s, 3H, CH3). 13C NMR (DMSO, δ, ppm): 153 (C=O), 151 (‐S‐NH‐C), 150 (‐N‐C), 149 (benzene‐C‐NH), 144 (pyrimidine‐C‐O); 138‐128 (triphenyl phosphine), 125‐112 (indolyl), 109 ((indolyl) C‐P), 56 ((aliphatic) C‐O). MS (m/z, %): 479 (1.22), 279 (9), 278 (32), 277 (100), 262 (14), 201 (11), 147 (2), 118 (4), 77 (6). Anal. calcd. for C37H30N5O4SP: C, 66.16; H, 4.47; N, 10.43. Found: C, 66.54; H, 4.45; N, 10.32%. 2.3. In vitro antimicrobial activity (Disc diffusion method) A filter paper sterilized disc saturated with measured quantity of the sample is placed on plate containing solid bacterial medium (nutrient agar broth) or fungal medium (Doxs medium) which has been heavily seeded with the spore suspension of the tested organism. After inoculation, the diameter of the clear zone of inhibition surrounding the sample is taken as a measure of the inhibitory power of the sample against the particular test organism [26‐29]. 3. Results and discussion 3.1. Synthesis Isatin reacted with 2,6‐diisopropylaniline, 4‐aminosalicylic acid, 4‐aminodiphenylamine and 4‐amino‐N‐[5‐methoxy‐2‐ pyrimidinyl] benzene sulphonamide in ethyl alcohol under reflux to afford 3‐imine derivatives; 3‐(2,6‐diisopropoylphenyl imino)indolin‐2‐one (1a), 2‐hydroxy‐4‐(2‐oxoindolin‐3‐ylidene amino)benzoic acid (1b), 3‐(4‐(phenylamino)phenyl‐ imino) indolin‐2‐one (1c) and N‐(5‐methoxypyrimidin‐2‐yl)‐4‐(2oxo‐ indolin‐3‐ylideneamino)‐benzenesulphonamide (1d). The structures of these compounds were confirmed by elemental analyses, IR, UV/Vis spectra. All characterization data is given in experimental section. In addition, the structure of the compound 1a is confirmed by X‐ray single crystal diffraction studies. The perspective view of the molecular structure of compound 1a is shown in Figure 1. X‐ray single crystal diffraction data for compound 1a: C20H22N2O; tetragonal; 141/a; unit cell dimensions a = 28.8600(9) Å, b = 28.8600(9) Å, c = 8.7587(5) Å; V = 7295.1(5) Å3; Z = 16; Dx = 1.116 Mg m‐3; 1721 independent reflections; max = 19.57 °; 1158 observed reflections. Refinement method was full matrix least squares refinement, R(all)= 0.087, R(gr)=0.063, wR(ref)=0.128; wR(all)=0.130. wR(gt)=0.128, (ref) = 4.068, S(all) = 3.632, S(gt) = 4.067. Selected geometrical parameters are given in Table 1. 3‐(2,6‐diisopropoylphenylimino)indolin‐2‐one (1a) reacted with triethyl phosphite and triphenylphosphine in tetrahydrofuran to afford two new compounds 2a and 3a containing five‐membered hetero ring similar to dimeric spiro phospholanes [30‐33]. The two suggested structures were inferred from their elemental analyses, IR, UV/Vis, 1H‐NMR, 542 El‐Sawi et al. / European Journal of Chemistry 2 (4) (2011) 539‐543 13C‐NMR and MS spectra. The IR spectra for compound (2a, 3a) showed two C=O at 1758 and 1734 cm‐1 and P‐O‐alkyl at 1032 cm‐1 for 2a, while for compound 3a, it showed P‐Ph at 1432 cm‐1 [25]. Comparing the 1H‐NMR spectra of compounds 2a and 3a, the spectrum of 3a showed fifteen aromatic protons extra than the aromatic protons in 2a due to triphenylphosphinyl protons, also the spectrum of 2a showed signals at δ 4 ppm and 1.2 ppm due to aliphatic protons. The 13C NMR spectrum of compound 3a showed extra carbons between δ 128 and 136 ppm due to phenyl carbons of triphenylphosphinyl. Figure 1. The perspective view of the molecular structure of compound 1a. Table 1. Selected geometrical parameters (Å, °) Bond distance, Å O1‐C1 1.222(2) N1‐C1 1.351(3) N1‐C2 1.411(3) C2‐C7 1.376(3) C7‐C8 1.461(3) N2‐C8 1.269(2) N2‐C9 1.434(3) Bond angles, ° C1‐N1‐C2 110.1(2) C8‐N2‐C9 121.1(2) Triphenylphosphine reacted with 2‐hydroxy‐4‐(2‐ oxoindol in‐3‐y l ideneamino) benzo ic ac id (1b) in tetrahydrofuran to form five membered hetero ring of compound 3b. The IR spectrum showed the absence of one C=O (NH‐CO) and C=N and the presence of a new absorption band at 1435 cm‐1 due to P‐Ph [25]. The reaction of 3‐(4‐(phenylamino)phenylimino)indolin‐2‐ one (1c) with triethylphosphite and triphenylphosphine yielded compounds 2c and 3c, respectively, with three‐ membered hetero rings. The reaction of N‐(5‐methoxypyrimidin‐2‐yl)‐4‐(2oxo‐ indolin‐3‐ylideneamino)‐benzenesulphonamide (1d) with triphenylphosphine yielded compound 3d with three membered hetero ring. IR spectrum showed a new absorption band at 1431 cm‐1 due to P‐Ph. The presence of C=O (NH‐CO) at 1727 cm‐1 confirmed the three membered heterophosphorus form. The UV/Vis spectrum indicated max at 395 nm due to n‐π* transition. 3.2. In vitro antimicrobial activity The synthesized compounds were screened for their anti‐ microbial activity against Bacillus subtilis (G+) and Escherichia Coli (G‐). Control experiment was carried out under similar condition by using tetracycline as standard. The inhibition zone measure in mm showed that compounds 1a, 2a and 3a were inactive towards bacteria. The antifungal activity was tested against the fungal species Aspergillus flavus and Candida albicans at 100 µg concentration. Amphotericin B was used as standard under the same condition. The antifungal data revealed that the compounds 1a‐d, 2a, 3c and 3d showed no effect towards fungus, while the compounds 3a were effective towards the above fungus (Table 2). Table 2. Antibacterial and antifungal activities of compounds. Compound No Inhibition zone diameter (mm/mg sample) Bacillus Subtilis Escherichia Coli Aspergillus flavus Candida albicans 1a 0 0 0 0 1b 14 14 0 0 1c 13 14 0 0 1d 15 13 0 0 2a 0 0 0 0 3a 0 0 13 13 3c 14 14 0 0 3d 16 15 0 0 Tetracycline 32 35 0 0 Amphotericin B 0 0 17 21 Supplementary material CCDC‐766320 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif or by e‐mailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44(0)1223‐336033. References [1]. Huber, S. M.; Hennig, A.; Puhlhofer, F. G.; Weiss R. J. Heterocycl. Chem. 2009, 46, 421‐427. [2]. Raghunathan, R.; Ramesh, E.; Elamparuthi, E. Lett. Org. Chem. 2008, 5, 82‐86. [3]. Un, R.; Ikizler, A. A. Chim. Acta Turc. 1975, 3, 1‐22. [4]. Milcent, R.; Redeuilh, C. J. Heterocycl. Chem. 1979, 16, 403‐407. [5]. Islam, M. R.; Abedin, M. J.; Hossain, M. M.; Duddeck, H. J. Bangladesh Chem. Soc. 1998, 11, 71‐78. [6]. Sarangapani, M.; Reddy, V. M. Indian J. Pharm. Sci. 1994, 56, 174‐177. [7]. Pandeya, S. N.; Sriram, D.; Nath, G.; De Clercq, E. Pharm. Acta Helv. 1999, 74, 11‐17. [8]. Popp, F. D.; Parson, R.; Donigan, B. E. J. Heterocycl. Chem. 1980, 17, 1329‐1330. [9]. Pandeya, S. N.; Sriram, D.; DeClercq, E.; Nath, G. Eur. J. Pharm. Sci. 1999, 9, 25‐31. [10]. Singh, G. S.; Singh, T.; Lakhan, R. Indian J. Chem. 1997, 36B, 951‐954. [11]. Bhattacharya, S. K.; Chakrabarti, S. Indian J. Exp. Biol. 1998, 36, 118‐ 121. [12]. Sridhar, S. K.; Pandeya, S. N.; De Clercq, E. Boll. Chim. Farm. 2001, 140, 302‐305. [13]. El‐Sawi, E. A.; Mostafa, T. B.; Mostafa, B. B. J. Egypt Soc. Parasitol. 1998, 28, 481‐486. [14]. Khan, K. M.; Mughal, U. R.; Samreen, P. S.; Choudhary, M. I. Lett. Drug Des. Discovery 2008, 5, 243‐249. [15]. Imran, M.; Alam, O.; Kaushik, D.; Khan, S. A. Indian J. Heterocycl. Chem. 2007, 16, 251‐254. [16]. Gonzalez, A.; Quirante, J.; Nieto, J.; Almeida, M. R.; Saraiva, M. J.; Arsequell, G.; Valancia, G. Bioorg. Med. Chem. Lett. 2009, 19, 5270‐ 5273. [17]. Pandey, V. K.; Dwivedi, A.; Pandey, O. P.; Sengupta, S. K. J. Agric. Food Chem. 2008, 56, 10779‐10784. [18]. Bekircan, O.; Bektas, H. Molecules 2008, 13, 2126‐2135. [19]. Turan‐Zitouni, G.; Kaplancikli, Z. A.; Yildiz, M. T.; Chevallet, P.; Kaya, D. Eur. J. Med. Chem. 2005, 40, 607‐613. [20]. Chen, J.; Sun, X. Y.; Chai, K. Y.; Lee, J. S.; Song, M. S.; Quan, Z. S. Bioorg. Med. Chem. 2007, 15, 6775‐6781. [21]. Bekircan, O.; Gumrukcuoglu, N. Indian J. Chem. 2005, 44B, 2107‐2113. [22]. Turan‐Zitouni, G.; Kaplancikli, Z. A.; Erol, K.; Kilic, F. S. Farmaco 1999, 54, 218‐223. [23]. Akhtar, T.; Hameed, S.; Al‐Masoudi, N. A.; Khan, K. M. Heteroat. Chem. 2007, 18, 316‐322. [24]. Turan‐Zitouni, G.; Kaplancikli, Z. A.; Ozdemir, A.; Chevallet, P.; Kandilci, H. B.; Gamusel, B. Arch. Pharm. Chem. Life Sci 2007, 340, 586‐ 590. [25]. Williams, D.; Fleming, I. Spectroscopic methods in organic chemistry, 2nd Ed. McGraw‐Hill Book Company (UK), 1973. [26]. Jawetz, E.; Melnick, J. L.; Adelberg, E. A. Review of Medica Microbiology, Lang Medical Publication, Los Altos, California 1974. [27]. Grayer, R. J.; Harbone, J. B. Phytochem. 1994, 37, 19-42. [28]. Muanza, D. N.; Kim, B. W.; Euler, L. L.; Williams, L. J. Pharmacol. 1994, 32, 337‐345. El‐Sawi et al. / European Journal of Chemistry 2 (4) (2011) 539‐543 543 [29]. Irob, O. N.; Moo‐Young, M.; Aperson, W. A. Inter. J. Pharmacol. 1996, 34, 87‐90. [30]. Varma, R. S.; Khan, I. A. J. Indian Chem. Soc. 1979, 56, 1038‐1040. [31]. Riisalu, H.; Vasilev, V. V.; Ionin, B. I. Zh. Obshch. Khim. 1984, 54, 563‐ 569. [32]. Riisalu, H.; VasiIev V. V.; Ionin, B. I. Zh. Obshch. Khim. 1985, 55, 2237‐ 2243. [33]. Sharma, D.; Bansal, R. K. J. Indian Chem. Soc. 1990, 67, 29‐32.