1 Pyrazoline Synthesis Essay

Determination of antibacterial activity by disc-diffusion method

Nutrient agar plates were prepared under sterilized conditions and incubated overnight to detect contamination. About 0.2 mL of working stock culture was transferred into separate nutrient broth and spread thoroughly using a glass spreader. Whatman number 1 discs (6 mm in diameter) were impregnated with the test compounds dissolved in DMSO (200 μg/mL) for about half an hour. Commercially available drug disc (ciprofloxacin 10 mg/disc) was used as positive reference standard. Negative control was also prepared by impregnating the disc of same size in dimethyl sulfoxide (DMSO) solvent. The plates were then incubated overnight for 18 to 24 h. Antibacterial activity was evaluated by measuring the zone of inhibition against the test organism.

Determination of minimum inhibitory concentration of test compounds using twofold serial dilution method

Testing was done in the seeded broth (10−6 to 10−7 cfu/mL). The test compounds were taken at different concentrations ranging from 200, 100, 50, 25, 12.5, 6.25, 3.13, 1.56, 0.78, and to 0.39 μg/mL for finding the minimum inhibitory concentration (MIC) by using seeded broth as diluent. Similarly, the standard solution of ciprofloxacin drug prepared at the concentrations of 200, 100, 50, 25.5, 6.25, 3.13, 1.56, 0.78, and 0.39 μg/mL of sterile distilled water and DMSO were maintained throughout the experiment simultaneously as control.

The study involves a series of 10 assay tubes for the test compounds against each strain. In the first assay tube, 1.6 mL of seeded broth was transferred, and 0.4 mL of the test solution was added, followed by mixing it thoroughly to obtain a concentration of 200 μg/mL. To the remaining nine assay tubes, 1 mL of seeded broth was transferred, and then, from the first assay tube, per milliliter of the content was pipetted out and added into the second assay tube, followed by mixing thoroughly. This type of dilution was repeated up to the 10th assay tube serially. The same procedure was followed for standard drugs. Duplicates were also maintained; these were done under aseptic conditions.

The racks of assay tubes were placed inside the incubator at 37 ± 1°C for 24 h. After the incubation period, the assay tube concentrations were again streaked into the nutrient agar plate due to turbidity of the drug microorganism mixture. The lowest concentration of the test compounds, which caused apparently a complete inhibition of growth of organisms, was taken as the MIC. The solvent control tube was also observed to find whether there was any inhibitory action. The sterile distilled water and DMSO did not show any inhibition.

The antimicrobial activity of all the synthesized pyrazolines (entries 1 to 8) were examined by disc diffusion and two fold serial dilution methods. Bacterial strains, viz. S. aureus, E. coli, K. pneumonia, S. typhi, and Pseudomonas species, and fungal strains, viz. Candida albicans, Mucor species, Rhizopus species, Aspergillus niger. In the present study, DMSO is used as control, while ciprofloxacin and ketoconazole are used as standards for bacterial and fungal strains, respectively. The zone of inhibition and MIC values of compounds (entries 1 to 8) against both the tested bacterial strains are given in Table ​4. The representative photographs of disc diffusion and serial dilution methods are depicted in Figure ​3.

Table 4

The antibacterial and antifungal activities of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substitutedphenyl)-2-pyrazolines by disc diffusion method

Figure 3

Antibacterial activities by zone of inhibition of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazoline petri dishes (AB1 to AB10).

The antibacterial activity of all pyrazolines produced a maximum zone of inhibition against all the bacterial strains except compounds 3 and 4 against S. typhi and Pseudomonas spp., compounds 4 against S. aureus, and compounds 7 and 8 against Pseudomonas spp. which showed maximum zone of inhibition than the standard (ciprofloxacin).

Antibacterial activity of all synthesized pyrazolines was measured by serial dilution method, and the MICs are presented in Table ​5. From Table ​5, compounds 1 to 8 showed the growth inhibitory concentration against the tested organism fall in the range of 1.5 to 200 μg/mL. However, compounds 1 to 4 showed the inhibition against all bacterial strains in the range from 25 to 100 μg/mL. The rest of the compounds are more effective against all bacterial strain MICs at 1.5 to 25 μg/mL.

Table 5

The antibacterial and antifungal activities of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines by serial dilution method

Antifungal activity

The following fungal strains C. albicans, Mucor spp, Rhizopus spp, and A. niger were used for the present study. Sabouraud dextrose agar (SDA) medium was used for the growth of fungi, and testing was done in Sabouraud dextrose broth (SDB) medium.

The subculture and the viable count were carried out by the same procedure as done in antibacterial studies except for the temperature which should be maintained at 28 ± 1°C for about 72 h. Similarly, for the disc diffusion method, the petri dishes were incubated at 28 ± 1°C for about 72 h. The same concentration of the test compound, solvent (DMSO), and ketoconazole (standard) prepared previously were used for the antifungal studies.

The antifungal activities of synthesized pyrazolines 1 to 4 exhibited a similar inhibition activity as that of the standard (15 mm) against all fungal strains, whereas pyrazoline 2 exhibited against C. albicans and A. niger (20 mm), and pyrazoline 5 to 8 against all the fungal strains showed maximum zone of inhibition (17 to 20 mm) than the standards (15 mm, ketoconazole). The measured antifungal activities of pyrazolines are presented in Table ​4. The representative photographs of disc diffusion methods are depicted in Figure ​4.

Figure 4

Antifungal activities of spectrum of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazoline pretri dishes (AF1 to AF8).

The antifungal activities of all synthesized pyrazolines were measured by serial dilution method. Among the compounds under study, compounds 1 to 8 were found to be effective against all the fungal strain MICs at 3.13 to 6.25 μg/mL. MIC values of compounds 1 to 4 against all the tested fungal strains are in the range of 25 to 50 μg/mL except for compound 2 against C. albicans (12.5 μg/mL) and compound 4 against A. niger (3.13 μg/mL). The measured antifungal activities of all compounds are presented in Table ​5.

Citation data is made available by participants in Crossref's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search inSciFinder.

  • Improved Photoinduced Fluorogenic Alkene–Tetrazole Reaction for Protein Labeling


    Bioconjugate Chemistry201728 (11), 2859-2864

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • Self-Reporting Fluorescent Step-Growth RAFT Polymers Based on Nitrile Imine-Mediated Tetrazole-ene Cycloaddition Chemistry

    DiegoEstupiñánThomasGegenhuberJames P.BlincoChristopherBarner-KowollikLeonieBarner

    ACS Macro Letters20176 (3), 229-234

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • Photochemically Induced Folding of Single Chain Polymer Nanoparticles in Water

    CarolinHeilerJanin T.OffenlochEvaBlascoChristopherBarner-Kowollik

    ACS Macro Letters20176 (1), 56-61

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • Novel Strategy for Preparing Dual-Modality Optical/PET Imaging Probes via Photo-Click Chemistry


    Bioconjugate Chemistry201627 (5), 1200-1204

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • Photochemical Microcontact Printing by Tetrazole Chemistry

    BenjaminVonhörenOliverRolingChristophButenMartinKörsgenHeinrich F.ArlinghausBart JanRavoo

    Langmuir201632 (9), 2277-2282

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • Intramolecular Cross-Linking Methodologies for the Synthesis of Polymer Nanoparticles

    SudheendranMavilaOrEivgiInbalBerkovichN. GabrielLemcoff

    Chemical Reviews2016116 (3), 878-961

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • [Cu(OH)(TMEDA)]2Cl2-Catalyzed Regioselective 2-Arylation of 5-Substituted Tetrazoles with Boronic Acids under Mild Conditions


    The Journal of Organic Chemistry201479 (14), 6703-6707

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • Developments in the Field of Bioorthogonal Bond Forming Reactions—Past and Present Trends


    Bioconjugate Chemistry201425 (5), 825-839

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • Cellular Incorporation of Unnatural Amino Acids and Bioorthogonal Labeling of Proteins

    KathrinLangJason W.Chin

    Chemical Reviews2014114 (9), 4764-4806

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • Design and Synthesis of Laser-Activatable Tetrazoles for a Fast and Fluorogenic Red-Emitting 1,3-Dipolar Cycloaddition Reaction


    Organic Letters201315 (21), 5496-5499

    Abstract | Full Text HTML | PDF | PDF w/ Links

  • Photo-Induced Ligation of Acrylonitrile-Butadiene Rubber: Selective Tetrazole–Ene Coupling of Chain-End-Functionalized Copolymers of 1,3-Butadiene

    Christoph J.DürrPaulLederhoseLebohangHlaleleDorisAbtAndreasKaiserSvenBrandauChristopherBarner-Kowollik

  • 0 thoughts on “1 Pyrazoline Synthesis Essay

    Leave a Reply

    Your email address will not be published. Required fields are marked *