The four Schiff bases (I - IV) were synthesized by the condensation reaction of 1(1-hydroxynaphthalen-2-yl)ethanone, 1-(4-chloro-1hydroxynaphthalen-2-yl)ethanone and 1-(4-bromo-1-hydroxynaphthalen-2-yl)ethanone with propane-1,3-diamine and pentane-1,3-diamine. The structural analysis is done by UVvis., FT-IR, 1H NMR, 13C NMR, LCMS and elemental analyses. These compounds were assayed for antibacterial (Escherichia coli and Salmonella Typhi) activity and antioxidant (2,2-Diphenyl-1-Picryl Hydrazyl(DPPH) and Hydroxyl radical scavenging method) activity. The antibacterial and antioxidant activities of synthesized Schiff bases exhibited better degrees of inhibitory effects. Among these, Schiff base 2,2'-((propane-1,3-diylbis(azanylylidene))bis(ethan-1-yl-1-ylidene))bis(4-chloronaphthalen-1-ol) (II) exhibited excellent antibacterial activity with MICs of 0.12, 0.25, 0.5 and 1 mg/ml against E. coli and Salmonella Typhi. Furthermore, two Schiff bases such as, 2,2'-((propane-1,3-diylbis(azanylylidene))bis(ethan-1-yl-1-ylidene))bis(naphthalen-1-ol) (I) and 2,2'-((pentane-1,3-diylbis(azanylylidene))bis(ethan-1-yl-1-ylidene))bis(4-bromonaphthalen-1-ol) (IV) exhibited promising antioxidant activity.
Objectives: The chemistry of chalcones has generated intensive scientific studies throughout the world. Especially interest has been focused on the synthesis and biodynamic activities of isoxazoline derivatives. In recent year numerous isoxazoline derivatives have been synthesized for their anticancer, anti-inflammatory, cytotoxic, antiviral activities. The reaction of substituted chalcones with hydroxylamine hydrochloride in presence of acetic acid gave isoxazoline derivatives. : The five membered oxygen and Nitrogen containing compounds exhibited Material and methods antioxidant, analgesic, antibacterial, antifungal activities. Therefore the attempt have been made to synthesize chlorosubstituted isoxazolines by the reaction of different substituted chalcones with hydroxylamine hydrochloride in presence of few drops of acetic acid. All the synthesized compounds confirmed by TLC and spectral analysis and also screened for their antibacterial activity. : The novel chloro-substituted isoxazolines showed good to moderate Results antibacterial activity against Gram+ve and Gram-ve bacterial strains tested. : These compounds Conclusion containing chloro, bromo, iodo groups were found showed potent antibacterial, antifungal activities. These findings promoted us to to synthesize novel chloro-substituted isoxazolines derivatives which are found to be potential antibacterial agents.
Background: In the present study chalcones were synthesized from 2-hydroxy-1-acetonaphthone and substituted aromatic aldehydes by Claisen Schmidt condensation reaction using potassium hydroxide as a base. The synthesized chalcones were purified by recrystallisation from ethanol and evaluated for antibacterial activity by well diffusion method. The antibacterial activity was evaluated against Bacillus licheniformis, Bacillus species, Escherichia coli and Staphylococcus aureus using Ciprofloxacin as a standard. Method: The target molecules were prepared by reacting 2-hydroxy-1-acetonaphthone and various substituted aromatic aldehyde in the presence of suitable condensing agents. The structure of synthesized compounds were confirmed on the basis of elemental analysis, IR, 1H NMR and 13C NMR spectral data. These synthesized compounds also screened for antibacterial activity. Results: In the present study free hydroxyl group in position 2 or 4 of aldehyde ring of synthesized chalcones appears to be a very important requirement in increasing the activity (2-5 and 8-13). When the hydroxyl group in position 4 is alkylated (14, 15) the chalcones are not more active. When more complex substituent on aldehyde ring (6, 7) there is a decrease in the activity. Conclusion: Newly synthesized chalcones (1-15) shows good and moderate antibacterial activity, we believe that the new hydroxy substituted (in aldehyde ring) chalcones (2-5 and 8-13) reported in this work may provide an interesting insight for further optimization.
A novel series of substituted chalcones containing benzyloxy moiety (3a-3h) was synthesized by microwave induced Claisen-Schmidt condensation of 2-acetyl-1-naphthol and its halo derivatives with different substituted aromatic aldehydes. All the synthesized chalcones were characterized by spectral analysis and screened for their antibacterial and antifungal effectiveness by using standard methods. It is found that the microwave irradiation technique is superior in terms of considerable increase in the reaction rate, yields and shortening the reaction time. The investigation of antimicrobial screening revealed that compounds (3a-3d) containing benzyloxy group at para position of aldehyde ring of chalcones possessing more potent antimicrobial activity.
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