Biological important Co(II) ternary complexes of 2-substituted benzazoles and amino acids

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1 Available online Journal of hemical and Pharmaceutical esearch, 2013, 5(11): esearch Article I : DE(UA) : JP5 Biological important o(ii) ternary complexes of 2-substituted benzazoles and amino acids handni Jain, Meena agar and Gita eth* Department of hemistry, University of ajasthan, Jaipur, India ABTAT ome new ternary complexes of o(ii) with 2-mercapto benzoxazole, 2-amino benzothiazole and 2-(4 aminophenyl)-6-methyl benzothiazole and with some amino acids (Leucine, Isoleucine) were synthesized and characterized by elemental analysis, I, 1 H M spectral studies. The antibacterial activity of these metal complexes has been evaluated against pathogenic bacteria taphylococcus aureus (+ve) and Escherichia coli (-ve). The antifungal activity of these metal complexes has been evaluated against pathogenic fungi Aspergillus niger and Fusariumoxy sporium. The results indicate that the metal complexes are found more active than the parent ligands. Keywords: Benzoxazole, Benzothiazole, Amino acids, Antibacterial activity, Antifungal activity. ITDUTI It is well known that mixed ligand ternary complexes of some metal plays an important role in the activation of enzymes. [1] It is studied that mixed ligand complexes are biologically active against pathogenic microorganisms [2-3]. The studies transition metal complexes of benzoxazole and benzothiazole have gained importance because of their biological significance [4-10]. It was observed that biological activities of these ligand increased on complexation with metal ion [11-12]. The ligation behaviour of benzoxazole, benzimidazole and benzothiazole and their derivatives have been reported by eth et al. [13-16]. We described here the synthesis, characterization and biological activity of o(ii) ternary complexes derived from 2-mercapto benzoxazole, 2-amino benzothiazole and 2-(4 -aminophenyl)-6-methyl benzothiazole and amino acids Leucine and isoleucine ligands. The resulting mixed ligand complexes may be of potential biological importance. The structure of ligands used to synthesize the metal complexes and chemical structure of o(ii) ternary complexes are shown in Fig. 1,2 and 3. H H 2 H 3 H 2 2-Mercapto Benzoxazole (MB) 2-Aminobenzothiazole (ABT) 2-(4 -aminophenyl)-6-methyl benzothiazole (APMBT) Fig.-1 : tructure of Ligands 501

2 Gita eth et al J. hem. Pharm. es., 2013, 5(11): H 2 H H Leucine (Leu) Isoleucine (Ileu) H 3 H H 2 H(H 3) 2 H 2 H 3 Fig. 2 tructure of amino acid F H 2 H 2 o H 2 l o H 2 H 2 H 2 H H H 2 H 3 l H 2 o H 2 H Fig.-3 The uggested hemical tructure of o(ii) Ternary omplexes EXPEIMETAL ETI All the chemicals used were of reagent grade. ol 2.6H 2, MB, ABT and APMBT were purchased from sigma- Aldrich. All the solvents were distilled before use. Infrared spectra was recorded (with KBr pellets) on HIMADZU 8400 FT-I spectrophotometer. 1 H M spectra were recorded on a JEL AL 300 MHz FT-M spectrometer in Dl 3 using TM as an internal reference. Melting points were determined on a capillary melting point apparatus and are uncorrected. Molecular weight were determined by the ast camphor method. itrogen was determined by the Kjeldahl's method and sulphur was estimated by messenger's method. hlorine was estimated volumetrically by using volhard method. obalt was estimated by gravimetrically. Preparation of obalt(ii) ternary complexes olution of ol 2.6H 2 (0.1 mol) in dry MeH (10 ml) was added to MB (0.1 mol)/abt (0.1 mol)/apmbt (0.1 mol) and leucine (0.1mol)/Iso-leucine (0.1 mol) in dry methanol MeH (10 ml). Then the reaction mixture was refluxed with continuous stirring for 4 hours and allowed to stand at room temperature overnight. These were filtered, recrystallized from EtH and dried in vaco. 502

3 Gita eth et al J. hem. Pharm. es., 2013, 5(11): EULT AD DIUI The o(ii) ternary complexes were synthesized by ol 2.6H 2 with 2-substituted benzazoles (MB, ABT, APMBT) or amino acids (Leu, Ileu) in 1:1:1 molar ratio according to the following equation. ol 2.6H 2 + (L-L) + (A-A) Methanol [o(l-l)(a-a)(h 2 ) 2 ] eflux ol 2.6H 2 + (L-L ) + (A-A) L-L = MB L-L = ABT, APMBT A A = Leu, Ileu Methanol eflux [ol(l-l )(A-A)(H 2 )] These reactions processed easily and lead to the formation of coloured solid which are stable to air and moisture. The resulting o(ii) ternary complexes are soluble in methanol, ethanol, DM and DMF. The analytical data and physical properties of o(ii) ternary complexes of 2-substituted benzazoles are given in Table-1. Table-1 Analytical data and physical properties of o(ii) ternary complexes of 2-substituted benzazoles with leucine & isoleucine ompound 1. o(mb)(leu)(h 2) 2 o 13H o(mb)(ileu)(h 2) 2 o 13H ol(abt)(leu)(h 2) ol 13H ol(abt)(ileu)(h 2) ol 13H ol(apmbt)(leu)(h 2) ol 20H ol(apmbt)(ileu)(h 2) ol 20H olour Purple Purple Pinkish Pinkish Pale violet Yield (%) M.P. (º) Blue Elemental analysis (%) Found (alcd.) H l o (41.60) (41.60) (39.75) (39.75) (49.75) (49.75) 5.24 (5.37) 5.25 (5.37) 5.00 (5.13) 5.03 (5.13) 5.19 (5.43) 5.30 (5.43) 7.22 (7.46) 7.34 (7.46) (10.70) (10.70) 8.49 (8.70) 8.49 (8.70) 8.21 (8.54) 8.25 (8.54) 8.02 (8.16) 8.05 (8.16) 6.31 (6.64) 6.33 (6.64) (9.02) 9.00 (9.02) 7.12 (7.34) 7.13 (7.34) (15.70) (15.70) (15.00) (15.00) (12.20) (12.20) Mol. Wt. Found (alcd) (375.31) (375.31) (392.77) (392.77) (482.90) (482.90) I PETA The important I spectral bands and their tentative assignments are summarized in Table 2. The ligand MB, ABT and APMBT, Leu and Ileu act as bidentate ligands in their o(ii) ternary complexes. The absorption band at ~ 3350 and ~ 3250 cm 1 are assigned to ν as ( H) and ν s (-H) vibrations of -H 2 group of amino acid & ABT & APMBT, indicating the coordination of nitrogen atom to the metal atom without any deprotonation. This gets further supported by the appearance of non ligand bands of medium intensity in the region ~ cm -1 due to v(o ) vibration. This is further supported by the presence of non ligand band in the region ~ cm -1 due to ν( H) vibration of the free ligand MB, disappears in the spectra of respective ternary metal complexes indicating the deprotonation of the H group and simultaneous formation of o- band. This is further supported by the appearance of new band of medium intensity in the region ~ cm -1 due to ν(o-) vibration. In the I spectra of metal complexes the absorption bands observed in the region ~ cm -1 are assigned to ν(=) vibration. Table-2 I pectral data (cm 1 ) of ternary complexes of o(ii) ompound ν(h 2) Asy. ymm. ν(=) ν(=) ν(=) o- o- o- o-l 1. o(mb)(leu)(h 2) o(mb)(ileu)(h 2) ol(abt)(leu)(h 2) ol(abt)(ileu)(h 2) ol(apmbt)(leu)(h 2) ol(apmbt)(ileu)(h 2)

4 Gita eth et al J. hem. Pharm. es., 2013, 5(11): H M PETA The 1 H M spectra of the ligands (MB, ABT, APMBT) and their o(ii) ternary complexes were recorded in Dl 3. (Table-3). The 1 H M spectrum of ligand MB exhibit broad singlet at δ 3.80 ppm due to -H proton but it disappears in the spectra of metal complexes, thereby suggesting the deprotonation of the -H group on complexation with the metal ion. The ligand ABT and APMBT exhibit singlet at δ 3.68 ppm and δ3.80 ppm due to H 2 proton respectively but it shifted slightly downfield in the metal complexes, suggesting the coordination of nitrogen of the -H 2 group with the metal. The aromatic protons of the ligand (MB, ABT and APMBT) were observed as multiplets atδ ppm shifted downfield in their respective o(ii) ternary complexes which may be possible due to deshielding on coordination of ligands with metal. Table-3 1 H M spectral data (ppm) of the ligands (MB, ABT, APMBT) and their o(ii) complexes ompound -H -H 2 -H 3 -H 2 -H Aromatic proton 1. MB 3.80 (bs) ABT APMBT o(mb)(leu)(h 2) o(mb)(ileu)(h 2) ol(abt)(leu)(h 2) ol(abt)(ileu)(h 2) ol(apmbt)(leu)(h 2) ol(apmbt)(ileu)(h 2) (bs = broad singlet) ATIBATEIAL ATIVITY The results of antibacterial activity of 2-substituted benzazole ligands and their o(ii) ternary complexes are summarized in Table-4. The organism selected for the studies are taphylococcus aureus (+ve) and Escherichia coli(-ve). The antibacterial activity was evaluated by Inhibition zone technique. Table-4 Antibacterial creening data of the ligands (MB, ABT, APMBT) and their o(ii) ternary complexes Diameter inhibition zone (mm) ompounds taphylococcus aureus Escherichia coli MB ABT APMBT o(mb)(leu)(h 2) o(mb)(ileu)(h 2) ol(abt)(leu)(h 2) ol(abt)(ileu)(h 2) ol(apmbt)(leu)(h 2) ol(apmbt)(ileu)(h 2) treptomycin (tandard) Table-5 Fungcidal creening Data for the ligands(mb, ABT & APMBT) and their o(ii) ternary complexes Average % inhibitor concentration (in ppm) after 72 hours ompound Aspergillus niger Fusarium oxysporium MB ABT APMBT o(mb)(leu)(h 2) o(mb)(ileu)(h 2) ol(abt)(leu)(h 2) ol(abt)(ileu)(h 2) ol(apmbt)(leu)(h 2) ol(apmbt)(ileu)(h 2) Dithane M-45 (tandard) Antifungal activity The results of antifungal activity of 2-substituted benzazole ligands and their o(ii) ternary complexes were summarized in Table-5. 2-substituted benzazole derivatives and their o(ii) ternary complexes have been screened 504

5 Gita eth et al J. hem. Pharm. es., 2013, 5(11): for fungicidal properties against Aspergillus nigerand Fusarium oxysporium at concentration 50, 100 and 200 ppm.the radial growth method was used to check an activity against fungi by taking Dithane M-45 as a standard. The antifungal screening data reveals that o(ii) ternary complexes are more fungitoxic than the parent ligand (MB, ABT & APMBT). The enhanced activity of the o(ii) ternary complexes may be described to the increased liophilic nature of these complexes arising due to the chelation. The toxicity increased with increasing concentration. Acknowledgements The authors are thankful to the Head, Department of hemistry, University of ajasthan, Jaipur, India for providing necessary facilities to carry out this research work. handni Jain is grateful to university grant commission, ew Delhi, India for the financial support in the form of I-JF wide grant number 09/149(0591)/2011 EM-I. EFEEE [1] MHughes oordination ompounds in Biology In :G Wilkinson, D Gillard, JAMcleverty, Editors. omprehensive oordination hemistry, Vol. 6, xford, U.K. : Pergamon Press; 1987, P [2] JThakkar; VThakkar.ynthesis and eactivity in Inorganic and Metal rganic hemistry, 2000, 30(10), [3] Vhivankar; VThakkar.ActaPoloniaePharmaceutica,2003, 60(1), [4] PPattanayak; JLPratihar; DPatra; Lin; Paul; Khakraborty. Polyhedron, 2013, 51, [5] ZQu; J u; Z Mao; X Le.ynthesis and eactivity in Inorganic, Metal-rganic and ano-metal hemistry, 2013, 43(6), [6] Z Qu; Huang; X Le. Wuji Huaxue Xuebao, 2012, 28(8), [7] Premlata; G eth, J. hem. Pharm. es.,2012, 4(5), [8] KDubey; UKDubey; KMishra, J. oord. hem.,2011, 64(13), [9] H Gu; Z Wang; W henasian J. hem.,2012, 24(2), [10] H Gu;Z Wang; W hen, WujiHuaxueXuebao, 2012, 28(3), [11] Mhivakumaraiah; Gowda.Indian J. hem.,2003, 42A, [12] Bharti; MMaurya; L aqui; AAzam.Bioorg. Med. hem.lett., 2000, 10, [13] J Kaur; MKamota;jha;VKabra. eth, G. Phosphorus ulfur ilicon elat. Elem.,2006, 181, [14] MKamota; Geth.Heteroatom hem.,2010, 21(1), [15] Verma ;Geth.J. Indian hem. oc., 2011, 88(9), [16] Pal; M Kumar; G Eeth.J. hem., 2011, 8(3),