The need for new antibacterial drugs is justified because many pathogens are currently resistant to available antibacterial drugs, and this is an alarming threat to the health of future generations. 1, 3, 4-Oxadiazole has been shown to pose a wide range of antibacterial activity. Some of the marketed drugs also possess this heterocyclic moiety.
Materials & Methods:The new derivatives of 1, 3, 4-oxadiazole were synthesized using a single-stage, high-yield method. Then, to measure the antibacterial activity of prepared derivatives agar well diffusion method was employed, and the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined at a concentration of 1mg/mL with three replications. Findings: Compounds 4a, 4d, and 4i exhibited a promising antibacterial activity against Acinetobacter baumannii PTCC1855. Among the three compounds mentioned, compound 4i showed the best performance with IZ=22±0.75 m.m , MIC=500µg/mL and MBC=125µg/mL at a concentration of 1mg/mL.
Conclusion:The new 1, 3, 4-Oxadiazole derivative (4i) was shown to be a promising compound for pharmaceutical applications, by adding other functional groups to its structure, it is possible to increase the destructive power of the compound.
Background: The enterococcal surface protein (Esp) is a high-molecular-weight surface protein of biofilm creating agent in Enterococcus faecalis. Oxadiazoles have a wide range of biological activities. Objective: This research aimed to examine the impact of new oxadiazole derivatives on the expression of Esp, playing an important role in promoting the biofilm formation ability of drug-resistant E. faecalis strains. Method: 1, 3, 4-oxadiazole derivatives were synthesized through a one-step synthesis. E. faecalis strains were collected and isolated from hospitals in Tehran. The antimicrobial properties of the synthesized materials against the isolated strains were investigated. RNA, DNA, and cDNA were extracted, and the relative expression of Esp in E. faecalis isolates was evaluated by real-time PCR. Docking study was performed by AutoDock vina software, and the resulting docking poses were analyzed using Discovery Studio 4.5 Client software. Results: The use of synthesized derivatives changed the Esp expression level in different isolates compared to the control sample. The two compounds containing naphthalene (4f) and methoxyphenyl (4g) caused respectively a 2-fold and a 3-fold decrease in Esp expression compared to the control sample. The compound 4f with the best binding energy among the compounds (-9.2) had the most hydrogen and hydrophobic bonds with the receptor-binding site. Conclusions: 1, 3, 4-oxadiazole derivatives, especially naphthalene and methoxyphenyl, act as inhibitors of bacterial biofilm formation and can be used in the pharmaceutical and biological industries.
Background: New drugs must be designed and synthesized for combating resistant pathogens. In this study, antibacterial and antifungal activities of 4 new derivatives of 1,3,4-oxadiazole were assessed against 8 bacterial and 2 fungal pathogens. Methods: To this end, the cinnamic acid derivatives were dissolved in acetonitrile solvent and N-iso-ciano-imino-triphenyl-phosphorane was added to the above-mentioned solution, followed by applying Petroleum ether and Ethyl acetate as solvent and base. Then, antimicrobial susceptibility tests were used to determine inhibition zone diameter, minimum inhibitory concentration, the minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) values. Results: The chemical structure of all compounds was characterized with infrared spectra, 1H-NMR, and 13C-NMR. A variety of inhibitory effects were observed by the synthesized compounds. Methoxyphenyl derivative (3c) affected bacterial strains, especially Streptococcus mutans. Other compounds also had antibacterial properties. Additionally, compound 3c showed the greatest effect on fungal samples, especially Aspergillus flavus. Conclusions: In general, our new derivatives of 1,3,4-oxadiazole are able to destroy Gram-positive bacteria. In addition, developing new derivatives of 1,3,4-oxadiazole in future research can improve therapeutic properties. It seems that with the addition of other functional groups and increasing the destructive power of compounds, inhibitory effects on fungal samples can also be observed.
Background: Oxadiazoles are a group of anti-inflammatory compounds that have a wide range of activity due to their higher efficacy. Pseudomonas aeruginosa is an opportunistic pathogen and a major pathogen of nosocomial infections. This study aimed to evaluate the antibacterial and investigation of the molecular docking of new derivatives of 1, 3, 4-oxadiazole against P. aeruginosa, in vitro & in silico. Materials and Methods: Four new derivatives were synthesized and added to our previous synthetic derivatives of 1, 3, 4-oxadiazole. The antibacterial activity of all derivatives was measured based on three standard species of P. aeruginosa using inhibition zone (IZ) and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. Then, employing the computational design of the drug by the molecular docking method, the inhibitory effect of synthetic compounds on the LasR regulatory protein of P. aeruginosa quorum sensing system was investigated, which plays an important role in regulating the expression of pathogenic genes in bacteria. Results: The chemical structures of new compounds were characterized by IR spectra and 1H-NMR. A variety of inhibitory effects were observed by the synthesized compounds – compound 4d and 4g, in particular. Also, the inhibitory effect of these two compounds on the LasR regulatory protein under the control of the quorum sensing system in P. aeruginosa was demonstrated by molecular docking. Conclusions: The results of this study showed that the two compounds containing the functional group of naphthalene and fluorophenyl have a significant effect on the inhibition of P. aeruginosa, as well as on the LasR protein of this bacterium.
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