ABSTRACT
Context: Extended Spectrum Beta Lactamases (ESBLs) play an important role in pathogenesis of various infections by enabling the bacterial species to be resistant to β-lactam antibiotics including extended-spectrum cephalosporins. Plants were selected on the basis of their traditional applications. Objective: Our investigation screens and evaluates15 Indian medicinal plants for antimicrobial efficacy and synergistic potential against ESBLs producing bacteria. Materials and Methods: 6 bacterial strains were screened for their ability to release ESBLs. Plant extracts in methanol and aqueous solvents were screened for their effect on ESBLs producing bacteria. Antimicrobial-linked ESBLs inhibition activity and minimum inhibitory concentration (MIC) of extracts were evaluated by agar well diffusion and microdilution method. Synergistic interactions between plant extracts exhibiting good antimicrobial activity and extended spectrum cephalosporins were explored by Checkerboard method. Results: Three strains were detected as ESBL positive. The results of susceptibility assay clearly showed strong ESBLs inhibitory effect of Crinum latifolium, Oroxylem indicum, Punica granatum, Sapindus emarginatus and Terminalia chebula and their MIC values ranged from 1.87-30 mg/ml. In vitro interactions between plant extracts and antibiotics cefotaxime and ceftaizidime evaluated in terms of fractional inhibitory concentration (FIC) indices indicated synergism. Discussion and Conclusion: Higher resistance of ESBLs positive strains to β-lactam antibiotics encourages us to search the novel ESBLs inhibitors. Maximum 10-fold decline in the MIC of antibiotics cefotaxime and ceftaizidime was achieved in combination with plant extracts. Owing to enormous clinical significance of ESBL-producing organisms coupled with limited therapeutic options, the results revealed by present study are of paramount importance.
ABSTRACT
Aims: The study was aimed to evaluate the antibacterial, synergistic and β-lactamase inhibitory potential of O. indicum against ampicillin resistant and Extended Spectrum β- lactamase (ESBL) producing bacterial strains. Methods: Bacterial strains were screened for ampicillin resistance and ESBL production by disk diffusion method and modified double disc synergy test respectively. Antibacterial and synergistic activities of O. indicum methanol extract and ethyl acetate sub fraction of methanol extract were explored by agar well diffusion method and Checkerboard method respectively. Extracts were subjected to Gas chromatography and Mass spectroscopy (GC-MS) analysis to identify the bioactive compounds. Molecular docking studies were carried out to verify the β-lactamase inhibitory potential of the bioactive compounds. Results: All bacterial strains were found to be resistant to ampicillin and only one strain was detected as ESBL positive. Ethyl acetate sub fraction exhibited strong antibacterial and synergistic activity than the methanol extract. Zone of inhibition and Minimum inhibitory concentration for ethyl acetate sub fraction was 16 mm and 15mg/ml respectively. In vitro interactions between plant extracts and ampicillin evaluated in terms of fractional inhibitory concentration (FIC) indices revealed synergistic effects of plant extracts. The molecular docking studies of major bioactive compounds depicted by GCMS analysis revealed that Wogonin, a flavonoid (GLIDE Score-5.77) possessed the best inhibitory profile against β–lactamase. Conclusion: Synergistic activity of O. indicum may be attributed to the β–lactamase inhibitory potential of the bioactive compounds present in the extract. The findings provide substantial basis for the future use of O. indicum crude extracts as potential antibacterial and antibiotic modulating agent.
ABSTRACT
Virus encoded RNA-silencing suppressors (RSSs) are the key components evolved by the viruses to counter RNA-silencing defense of plants. Whitefly-transmitted begomoviruses infecting tomato crop code for five different proteins, ORF AC4, ORF AC2 and ORF AV2 in DNA-A component, ORF BV1 in DNA-B and ORF βC1 in satellite DNA β which are predicted to function as silencing suppressors. In the present study suppressor function of ORF βC1 of three betasatellites Tomato leaf curl Bangalore betasatellite ToLCBB-[IN:Hess:08], Cotton leaf curl Multan betasatellite CLCuMB–[IN:Sri:02] and Luffa leaf distortion betasatellite LuLDB-[IN:Lu:04] were examined. Agroinfiltration of GFP-silenced Nicotiana tabaccum cv. Xanthi with the cells expressing βC1 protein resulted in reversal of silenced GFP expression. GFP-siRNA level was more than 50-fold lower compared to silenced plants in plants infiltrated with βC1 gene from ToLCBB. However, in the case of 35S-βC1 CLCuMB and 35S-βC1 LuLDB construct, although GFP was expressed, siRNA level was not reduced, indicating that the step at which βC1 interfere in RNA-silencing pathway is different.