scholarly journals Synthesis and Antibacterial, Antioxidant, and Molecular Docking Analysis of Some Novel Quinoline Derivatives

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Digafie Zeleke ◽  
Rajalakshmanan Eswaramoorthy ◽  
Zerihun Belay ◽  
Yadessa Melaku

2-Chloroquinoline-3-carbaldehyde and 2-chloro-8-methylquinoline-3-carbaldehyde derivatives were synthesized through Vilsmeier formulation of acetanilide and N-(o-tolyl)acetamide. Aromatic nucleophilic substitution reaction was used to introduce various nucleophiles in place of chlorine under different reaction conditions. The carbaldehyde group was oxidized by permanganate method and reduced with metallic sodium in methanol and ethanol. The synthesized compounds were characterized by UV-Vis, IR, and NMR. The antibacterial activity of the synthesized compounds was screened against two Gram-positive bacteria (Bacillus subtilis ATCC6633 and Staphylococcus aureus ATCC25923) and two Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). Most of the compounds displayed potent activity against two or more bacterial strains. Among them, compounds 6 and 15 showed maximum activity against Pseudomonas aeruginosa with mean inhibition zones of 9.67 ± 1.11 and 10.00 ± 0.44 mm, respectively, while ciprofloxacin showed mean inhibition zone of 8.33 ± 0.44 mm at similar concentration. On the other hand, compound 8 exhibited maximum activity against Escherichia coli with inhibition zones of about 9.00 ± 0.55 mm at 300 μg/mL and 11.33 ± 1.11 mm at 500 μg/mL. The radical scavenging activity of these compounds was evaluated using 1,1-diphenyl-2-picryl hydrazyl (DPPH), and all of them displayed moderate antioxidant activity, with compound 7 exhibiting the strongest activity. The molecular docking study of the synthesized compounds was conducted to investigate their binding pattern with DNA gyrase, all of them were found to have minimum binding energy ranging from –6.0 to –7.33 kcal/mol, and the best result was achieved with compound 11. The findings of the in vitro antibacterial and molecular docking analysis demonstrated that the synthesized compounds have potential of antibacterial activity and can be further optimized to serve as lead compounds.

Author(s):  
O B Oloyede

This study investigated phytochemical content, radical scavenging and antibacterial activities of aqueous extract of leaves of Jatropha curcas Linn. Quantitative phytochemical analyses of alkaloids, phenols, tannins and flavonoids contents were carried out; radical scavenging activity was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and hydrogen peroxide inhibition assays while Disc diffusion and Agar well (ditch) diffusion methods were used for antibacterial activity against Klebsiella pneumonia, Escherichia coli, Pseudomonas aeruginosa, Staphilococcus aureus and Proteus species at 62.5, 125, 250 and 500 mg/mL. The extract contained alkaloids (1.600± 0.58 %), tannins (0.121 ± 0.00 mg/mL), phenols (0.463 ± 0.06 mg/mL) and flavonoids (0.672 ± 0.00 mg/mL), and showed radical scavenging activities against DPPH (IC50 = 21.24) and hydrogen peroxide (15.67 mg/mL) which were less than that of Butylated hydroxyanisole (BHA); IC50 = 3.92 (DPPH) and 6.19 mg/mL (hydrogen peroxide) respectively. It also showed antibacterial activity against Klebsiella pneumonia, Escherichia coli, and Pseudomonas aeruginosa at 250 and 500 mg/ml (MIC = 125 mg/mL), which were resistant to ampicillin, chloxacillin and erythromycin, and the extract was inactive against Staphilococcus aureus and Proteus species at these concentrations, though all were sensitive to gentamycin. This shows that the aqueous extract of leaves of Jatropha curcas Linn may possess some of the folkloric properties claimed.


Author(s):  
Nourhan G. Naga ◽  
Dalia E. El-Badan ◽  
Heba S. Rateb ◽  
Khaled M. Ghanem ◽  
Mona I. Shaaban

The last decade has witnessed a massive increase in the rate of mortalities caused by multidrug-resistant Pseudomonas aeruginosa. Therefore, developing new strategies to control virulence factors and pathogenicity has received much attention. One of these strategies is quorum sensing inhibition (QSI) which was developed to control Pseudomonas infection. This study aims to validate the effect of one of the most used β-lactam antibiotics; cefoperazone (CFP) and its metallic-derivatives on quorum sensing (QS) and virulence factors of P. aeruginosa. Assessment of quorum sensing inhibitory activity of CFP, cefoperazone Iron complex (CFPF) and cefoperazone Cobalt complex (CFPC) was performed by using reporter strain Chromobacterium violaceum ATCC 12472. Minimal inhibitory concentration (MIC) was carried out by the microbroth dilution method. The influence of sub-MICs (1/4 and 1/2 MICs) of CFP, CFPF and CFPC on virulence factors of P. aeruginosa was evaluated. Data was confirmed on the molecular level by RT-PCR. Also, molecular docking analysis was conducted to figure out the possible mechanisms of QSI. CFP, CFPF, and CFPC inhibited violacein pigment production of C. violaceum ATCC 12472. Sub-MICs of CFP (128- 256 μg/mL), and significantly low concentrations of CFPC (0.5- 16 μg/mL) and CFPF (0.5- 64 μg/mL) reduced the production of QS related virulence factors such as pyocyanin, protease, hemolysin and eliminated biofilm assembly by P. aeruginosa standard strains PAO1 and PA14, and P. aeruginosa clinical isolates Ps1, Ps2, and Ps3, without affecting bacterial viability. In addition, CFP, CFPF, and CFPC significantly reduced the expression of lasI and rhlI genes. The molecular docking analysis elucidated that the QS inhibitory effect was possibly caused by the interaction with QS receptors. Both CFPF and CFPC interacted strongly with LasI, LasR and PqsR receptors with a much high ICM scores compared to CFP that could be the cause of elimination of natural ligand binding. Therefore, CFPC and CFPF are potent inhibitors of quorum sensing signaling and virulence factors of P. aeruginosa.


2013 ◽  
Vol 9 (3) ◽  
pp. 116-120
Author(s):  
Aman Gupta ◽  
◽  
Vanashika Sharma ◽  
Ashish Kumar Tewari ◽  
Vipul SurenderKumar ◽  
...  

2018 ◽  
Vol 13 (11) ◽  
pp. 1934578X1801301 ◽  
Author(s):  
Yike Yue ◽  
Yongsheng Chen ◽  
Sheng Geng ◽  
Guizhao Liang ◽  
Benguo Liu

Fisetin is a flavonoid widespread in vegetables, fruits and medicinal plants. The in vitro antioxidant and α-glucosidase inhibitory activities of fisetin were systemically investigated in this study. The DPPH and ABTS radical scavenging performance of fisetin was higher than that of BHA. In the ORAC and PSC assays, fisetin also exhibited strong antioxidant activity. The α-glucosidase inhibitory activity of fisetin (IC50, 9.38±0.35 μg/mL) was significantly superior to that of acarbose (IC50, 1.07±0.15 mg/mL). Its inhibition type was determined to be a mixed competitive and non-competitive inhibition mode. Molecular docking analysis suggested it could exert the α-glucosidase inhibitory role by forming hydrogen bonds with the TRP391, ASP392, ARG428 and ASP568 residues of α-glucosidase.


Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3373 ◽  
Author(s):  
Xuan Zhang ◽  
Yijia Jia ◽  
Yanli Ma ◽  
Guiguang Cheng ◽  
Shengbao Cai

The present study investigated the phenolic profiles and antioxidant properties of different fractions from Prinsepia utilis Royle fruits using molecular docking analysis to delineate their inhibition toward digestive enzymes. A total of 20 phenolics was identified and quantified. Rutin, quercetin-3-O-glucoside, and isorhamnetin-3-O-rutinoside were the major phenolic compounds in the total phenolic fraction and flavonoid-rich fraction. The anthocyanin-rich fraction mainly contained cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside. All of the fractions exhibited strong radical scavenging activities and good inhibition on cellular reactive oxygen species (ROS) generation in H2O2-induced HepG2 cells, as evaluated by DPPH and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. Moreover, the powerful inhibitory effects of those fractions against pancreatic lipase and α-glucosidase were observed. The major phenolic compounds that were found in the three fractions also showed good digestive enzyme inhibitory activities in a dose-dependent manner. Molecular docking analysis revealed the underlying inhibition mechanisms of those phenolic standards against digestive enzymes, and the theoretical analysis data were consistent with the experimental results.


2020 ◽  
Vol 15 (2) ◽  
pp. 127-142 ◽  
Author(s):  
Sunil K Bose ◽  
Monika Chauhan ◽  
Neelima Dhingra ◽  
Sanjay Chhibber ◽  
Kusum Harjai

Aim: To investigate the effects of Terpinen-4-ol on quorum sensing (QS)-regulated biofilm formation and virulence factors production in Pseudomonas aeruginosa. Materials & methods: QS inhibition, molecular docking analysis and gene expression studies were performed to check attenuation effect of Terpinen-4-ol on virulence of P. aeruginosa. Production of various virulence factors and biofilm formation were studied at sub-MIC of Terpinen-4-ol alone and in combination with ciprofloxacin. Results: Terpinen-4-ol at sub-MIC exhibited QS inhibition and downregulated all key QS genes. Molecular docking analysis showed high binding affinities of Terpinen-4-ol with QS receptors. Terpinen-4-ol exhibited synergistic interaction with ciprofloxacin and further reduced production of all the virulence factors and biofilms formation. Conclusion: Terpinen-4-ol could be developed into antivirulence drug after its in vivo evaluation for treatment strategies.


2018 ◽  
Vol 16 (S1) ◽  
pp. S155-S163 ◽  
Author(s):  
S. Mehalaine ◽  
O. Belfadel ◽  
T. Menasria ◽  
A. Messaili

The present study was carried out to determine, for the first time, the chemical composition and antibacterial activity of essential oils derived from the aerial parts of three aromatic plants Thymus algeriensis Boiss & Reut, Rosmarinus officinalis L., and Salvia officinalis L. growing under semiarid conditions. The essential oils were chemically analyzed and identified by gas chromatography (GC) and GC/ mass spectrometry (GC/MS) and their antimicrobial activity was individually evaluated against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa using both agar disk diffusion and agar dilution methods. The major constituents of Thymus algeriensis essential oil were identified as camphor (13.62%), 1,8-cineol (6.00%), borneol (5.74%), viridiflorol (4.00%), and linalool (3.93%). For Rosmarinus officinalis essential oil, 48 compounds were characterized, of which the main constituents were camphor (17.09%), Z-β-ocimene (10.88%), isoborneol (9.68%), α-bisabolol (7.89%), and borneol (5.11%). While, Salvia officinalis essential oil was characterized by β-thujone (16.44%), followed by viridiflorol (10.93%), camphor (8.99%), 1,8-cineol (8.11%), trans-caryophyllene (5.85%), and α-humulene (4.69%) as the major components. Notably, results from antibacterial screening indicated that Thymus algeriensis and Salvia officinalis essential oils exhibited a strong inhibitory effect against both Escherichia coli and Staphylococcus aureus compared to Rosmarinus officinalis essential oil. Further, less activity was recorded against Pseudomonas aeruginosa for the three tested essential oils.


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