Synthesis, Characterization And Biological Evaluation Of N-Mannich Bases Of 5-Amino-4-[2-(6-Bromo-1, 3-Benzothiazol-2-Yl) Hydrazinylidene]-2, 4-Dihydro-3h-Pyrazol-3-One.

Bugga Reddy, S (2012) Synthesis, Characterization And Biological Evaluation Of N-Mannich Bases Of 5-Amino-4-[2-(6-Bromo-1, 3-Benzothiazol-2-Yl) Hydrazinylidene]-2, 4-Dihydro-3h-Pyrazol-3-One. Masters thesis, KMCH College of Pharmacy, Coimbatore.


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In the present work twelve title compounds were synthesised by subject 5-amino- -[2-(6- bromo-1,3-benzothiazol-2-yl)hydrazinylidene]-2,4-dihydro-3H-pyrazol-3-one (BTZP) to mannich reaction with 12 different amines. The intermediate 5-amino-4-[2-(6-bromo-1,3- benzothiazol- 2-yl)hydrazinylidene]-2,4-dihydro-3H-pyrazol-3-one(BTZP) was synthesized from ethyl[2-(6-bromo-1,3-benzothiazol-2-yl) hydraziny lidene](cyano)acetate (BTZE) by cyclising with hydrazine hydrate. Ethyl[2-(6-bromo-1,3-benzothiazol-2-yl) hydraziny lidene](cyano) acetate was synthesized by coupling through diazonium salts of 6- bromobenzo[d]thiazol-2-amine with ethylcyanoacetate. The compound diazonium salts of 6- bromobenzo [d]thiazol-2-amine was formed by reacting 6-bromobenzo[d]thiazol-2-amine (BTZ) with sodium nitrite in concentrated hydrochloric acid, which in turn was synthssized from 4-bromo aniline and thiourea. The yield was found to be 55-75% in all the stage. Most of the newly synthesized compounds were found to be soluble in semi polar solvents. Thin layer chromatography was used to confirm the reaction time and purity of the compounds synthesized. Melting point was determined by one end open glass capillary tubes and was uncorrected. The UV spectrum values observed between 400-800nm and IR spectra of synthesized compounds were exhibited 3372.82cm-1 for associated NH of amines, 840-790cm-1 for Ar, CH=CH stretching, 1640-1620cm-1 and 1600-1400cm-1for C=O stretching. The 1H NMR spectra all the synthesized compounds showed multiplets in the range δ 7.5-8.04 for the protons of aromatic ring In addition, 1H NMR spectra of these compounds signals arising from possible –CH2– structure at 3.3 ppm .The Ar-NH– proton structure of synthesized was also supported by 1H-NMR spectra. Mass spectrums of the synthesized compounds were in full agreement with their molecular weights and studies showed satisfactory results. Disc Diffusion Method All the newly synthesized compounds were screened for their preliminary anti-bacterial activity against Six gram-positive bacteria strains, Micrococcus luteus NCIM 2169, staphylococcus aureus NCIM 2079, Bacillus subtilis NCIM 2063, Cornybacterium NCIM 2640, Bacillus lintus NCIM 2018 and Staphylococcus albus NCIM 2178, and six gramnegative bacteria strains, Escherichia Coli NCIM 2065, Pseudomonas aruginosa NCIM 2018, Rhodosporum ruberum NCIM 5128, Vibrio cholera NCIM 1738, Salmonella Paratyphii NCIM 2075, Klbsellia pneumonia NCIM 2957 by disc diffusion method at a concentration of 100μg/disc. Among the synthesized compounds, compound B1P, B1PB, B1AZ, B1T and B1B at 100μg/disc was found to be significant active against most of the screened bacteria when compared with standard drug (Ciprofloxacin 5μg/disc). Twelve N-mannich bases of 5-amino-4-[2-(6-bromo-1,3-benzothiazol-2-yl)hydraziny lidene]-2,4-dihydro-3H-pyrazol-3-one (BTZP) were prepared. The structure of the compounds were characterized by UV, IR, NMR and Mass spectral data, and evaluated for their in-vitro anti-microbial, in-vitro anti-oxidant and invitro cytotoxicity activity. The compounds containing substitution of electron donating groups present at phenyl ring (B1P, B1M, B1AZ, B1AP, B1T and B1B) imparted significant anti-bacterial activity against compared with electron withdrawing group attached compounds (B1Br, B12C, B14C, B12N, B14N). Particularly, the 2nd position of pyrazolone ring containing bulky group link through –CH2-NH- Bridge (B1AZ and B1B) showed anti-bacterial activity and anti-fungal against all tested strains at 100μg/disc level. The compounds containing electron withdrawing group (B1PB, B1Br, B12C, B12N and B14N) imparted moderate anti fungal activity, particularly aspergillus niger, aspergillus fumigates, and aspergillus arasites to the resulting N-mannich base containing pyrazolone derivatives. The DPPH and ABTS in-vitro anti-oxidant methods result of the synthesised compound review that the electron withdrawing groups attached at the para position of Nmethyl benzenamine ring compounds (B12N, B14N, B1Br, B12C, B1PB, B14C and B1AP) showed better anti -oxidant activity. All the tested compounds showing the in-vitro cytotoxicity activity except B1B compound but this compound showing moderate to significant anti microbial activity aganist all the tested strains. So this compound may consider for further modification for its biological activity.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Synthesis; Characterization; Biological Evaluation; N-Mannich Bases; 5-Amino-4-[2-(6-Bromo-1, 3-Benzothiazol-2-Yl; Hydrazinylidene; -2, 4-Dihydro-3h-Pyrazol-3-One
Subjects: PHARMACY > Pharmaceutical Chemistry
Depositing User: Ravindran C
Date Deposited: 17 Aug 2017 07:07
Last Modified: 13 Oct 2017 00:12

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