02521nas a2200277   4500008004100000022001400041245012800055210006900183260007300252300001200325490000700337520149500344653003001839653002601869653002401895653001901919100002001938700002801958700001401986700001702000700002602017700002102043700003102064700002002095856012802115       2008                        eng d  a0924-857900aPotential plasmid-curing agent, 8-epidiosbulbin E acetate, from dioscorea bulbifera L. against multidrug-resistant bacteria0 aPotential plasmidcuring agent 8epidiosbulbin E acetate from dios  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcNOV  a405-4100 v323 a<p>Bioassay-guided fractionation of an aqueous methanolic extract of Dioscorea bulbifera L. bulbs was performed using organic solvents. A novel plasmid-curing compound was identified as 8-epidiosbulbin E acetate (EEA) (norditerpene) on the basis of modern spectroscopic analysis and X-ray crystallography. EEA exhibited broad-spectrum plasmid-curing activity against multidrug-resistant (MDR) bacteria, including vancomycin-resistant enterococci. EEA cured antibiotic resistance plasmids (R-plasmids) from clinical isolates of Enterococcus faecalis, Escherichia coli, Shigella sonnei and Pseudomonas aeruginosa with 12-48% curing efficiency. The reference plasmids of Bacillus subtilis (pUB110), E. coli (RP4), P. aeruginosa (RIP64) and Salmonella typhi (R136) were cured with efficiency ranging from 16% to 64%. EEA-mediated R-plasmid curing decreased the minimal inhibitory concentration of antibiotics against MDR bacteria, thus making antibiotic treatment more effective. The antibiotic resistance pattern revealed that the compound was effective in the reversal of bacterial resistance to various antibiotics. In addition, the compound did not show any cytotoxicity against a broad range of human cancer cell lines, namely MCF-7 (breast cancer), SiHa (cervical cancer) and A431 (epidermal carcinoma), and hence has the potential to be used as a lead compound for drug discovery programmes. (C) 2008 Elsevier B. V. and the International Society of Chemotherapy. All rights reserved.</p>10a8-Epidiosbulbin E acetate10aAntibiotic resistance10aDioscorea bulbifera10aPlasmid curing1 aShriram, Varsha1 aJahagirdar, Sheetal, S.1 aLatha, C.1 aKumar, Vinay1 aPuranik, Vedavati, G.1 aRojatkar, Supada1 aDhakephalkar, Prashant, K.1 aShitole, M., G.  uhttps://library.ncl.res.in/content/potential-plasmid-curing-agent-8-epidiosbulbin-e-acetate-dioscorea-bulbifera-l-against-003186nas a2200289   4500008004100000022001400041245006600055210006300121260008700184300001000271490000800281520220700289653002702496653002602523653002502549653002102574653002902595653001902624100002002643700002802663700001402691700001702705700003102722700002102753700002502774856009702799       2010                        eng d  a0971-591600aAntibacterial & antiplasmid activities of Helicteres isora L.0 aAntibacterial antiplasmid activities of Helicteres isora L  aPO BOX 4911 ANSARI NAGAR, NEW DELHI 110029, INDIAbINDIAN COUNCIL MEDICAL REScJUL  a94-990 v1323 a<p>Background &amp; objectives: The multiple drug resistance (MDR) is a serious health problem and major challenge to the global drug discovery programmes. Most of the genetic determinants that confer resistance to antibiotics are located on R-plasmids in bacteria. The present investigation was undertaken to investigate the ability of organic extract of the fruits of Helicteres isora to cure R-plasmids from certain clinical isolates. Methods: Active fractions demonstrating antibacterial and antiplasmid activities were isolated from the acetone extracts of shade dried fruits of H. isora by bioassay guided fractionation. Minimal inhibitory concentration (MIC) of antibiotics and organic extracts was determined by agar dilution method. Plasmid curing activity of organic fractions was determined by evaluating the ability of bacterial colonies (pre treated with organic fraction for 18 h) to grow in the presence of antibiotics. The physical loss of plasmid DNA in the cured derivatives was further confirmed by agarose gel electrophoresis. Results: The active fraction did not inhibit the growth of either the clinical isolates or the strains harbouring reference plasmids even at a concentration of 400 mu g/ml. However, the same fraction could cure plasmids from Enterococcus faecalis, Escherichia coli, Bacillus cereus and E. coli (RP4) at curing efficiencies of 14, 26, 22 and 2 per cent respectively. The active fraction mediated plasmid curing resulted in the subsequent loss of antibiotic resistance encoded in the plasmids as revealed by antibiotic resistance profile of cured strains. The physical loss of plasmid was also confirmed by agarose gel electrophoresis. Interpretation &amp; conclusions: The active fraction of acetone extract of H. isora fruits cured R-plasmids from Gram-positive and Gram-negative clinical isolates as well as reference strains. Such plasmid loss reversed the multiple antibiotic resistance in cured derivatives making them sensitive to low concentrations of antibiotics. Acetone fractions of H. isora may be a source to develop antiplasmid agents of natural origin to contain the development and spread of plasmid borne multiple antibiotic resistance.</p>10aantibacterial activity10aAntibiotic resistance10aantiplasmid activity10aHelicteres isora10amultiple drug resistance10aplasmid-curing1 aShriram, Varsha1 aJahagirdar, Sheetal, S.1 aLatha, C.1 aKumar, Vinay1 aDhakephalkar, Prashant, K.1 aRojatkar, Supada1 aShitole, Mahadeo, G.  uhttps://library.ncl.res.in/content/antibacterial-antiplasmid-activities-helicteres-isora-l-0