https://ogma.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29353 70/σ^A interaction as determined by ELISA and exhibiting increased inhibition of the growth of Escherichia coli compared to Bacillus subtilis in culture. The structural features of the synthesized transcription initiation inhibitors needed for antibacterial activity were identified employing molecular modelling and structure–activity relationship (SAR) studies.]]> Wed 15 Dec 2021 16:09:32 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:32509 Staphylococcus aureus (MRSA). A pharmacophore model was constructed on the basis of the protein-protein interaction between essential bacterial rRNA transcription factors NusB and NusE and employed for an in silico screen to identify potential leads. One compound, (E)-2-{[(3-ethynylphenyl)imino] methyl}-4-nitrophenol (MC4), demonstrated antimicrobial activity against a panel of S. aureus strains, including MRSA, without significant toxicity to mammalian cells. MC4 resulted in a decrease in the rRNA level in bacteria, and the target specificity of MC4 was confirmed at the molecular level. Results obtained from this work validated the bacterial rRNA transcription machinery as a novel antimicrobial target. This approach may be extended to other factors in rRNA transcription, and MC4 could be applied as a chemical probe to dissect the relationship among MRSA infection, MRSA growth rate, and rRNA synthesis, in addition to its therapeutic potential.]]> Wed 15 Dec 2021 16:07:19 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28155 Staphylococcus aureus (CA-MRSA; strain USA300). From this series, compounds 6 and 15 were found to be the most active, both with MIC values of 2 µg/mL against B. subtilis 168 and 8 µg/mL against S. aureus USA300, respectively. Furthermore, subsequent assays showed that compounds 6 and 15 displayed strong synergistic effects at sub-MIC levels against both S. aureus USA300 and B. subtilis 168 when combined with two commercial antibiotics, kanamycin and chloramphenicol. Preliminary structure-activity relationship studies were also performed.]]> Wed 11 Apr 2018 12:07:46 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29882 gem-dimethyl group), the RCEDYM reaction leads to 14,15-isotaxanes 16 a,b and 18 b with the gem-dimethyl group on the A ring. If the alkyne is at the C11 position (and thus flanked by a gem-dimethyl group), RCEDYM reaction only proceeds in the presence of a trisubstituted olefin at C13, which disfavors the competing diene ring-closing metathesis reaction, to give the tricyclic core of Taxol 44.]]> Wed 11 Apr 2018 11:08:27 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:23749 Wed 11 Apr 2018 09:43:37 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:23516 Wed 10 Nov 2021 15:04:33 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30559 70/σ^A interaction in bacteria. Synthesis was achieved via reactions between a variety of indole-7-carbaldehydes and rhodanine, N-allylrhodanine, barbituric acid or thiobarbituric acid. A library of structurally diverse compounds was examined by enzyme-linked immunosorbent assay (ELISA) to assess the inhibition of the targeted protein–protein interaction. Inhibition of bacterial growth was also evaluated using Bacillus subtilis and Escherichia coli cultures. The structure–activity relationship studies demonstrated the significance of particular structural features of the synthesized molecules for RNA polymerase-σ⁷⁰/σ^A interaction inhibition and antibacterial activity. Docking was investigated as an in silico method for the further development of the compounds.]]> Wed 09 Mar 2022 16:04:39 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:34681 B. subtilis 168 and MRSA USA300) and Gram-negative bacteria (P. aer PAO1 and A. baum ATCC19606) in vitro, the derivatives exhibited good antibacterial activity, particularly against Gram-positive bacteria with an minimum inhibitory concentrations (MIC) value of 2–16 µg/mL. The subsequent synergistic antibacterial assay showed that derivatives 5c and 6c enhanced the susceptibility of B. subtilis 168 and MRSA USA300 to chloramphenicol (CHL) and kanamycin (KAN) (FICI < 0.5). Our data showed that ocotillol-type derivatives with long-chain amino acid substituents at C-3 were good leads against antibiotic-resistant pathogens MRSA USA300, which could improve the ability of KAN and CHL to exhibit antibacterial activity at much lower concentrations with reduced toxicity.]]> Wed 04 Sep 2019 10:06:26 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:34052 Escherichia coli and Gram-positive Bacillus subtilis species, these analogues showed up to 100% growth inhibition at 200 μM. 2-((Z)-4-(((Z)-4-(4-((E)-(Carbamimidoylimino)methyl)phenoxy)but-2-en-1-yl)oxy)benzylidene)hydrazine-1-carboximidamide 22 showed excellent activity against important pathogens. With minimum inhibitory concentration values of ≤3 μg/mL for Gram-positive Streptococcus pneumoniae and methicillin-resistant Staphylococcus aureus and ≤51 μg/mL for Gram-negative Pseudomonas aeruginosa and Acinetobacter baumannii, 22 is a potent lead for a novel antibacterial target. Epifluorescence studies in live bacteria were consistent with 22, inhibiting the NusB–NusE PPI as proposed.]]> Wed 04 Sep 2019 09:54:32 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20055 70/σ^A for the development of lead molecules exhibiting a novel mechanism of antibacterial activity. Several classes of structurally related bis-indole inhibitors of bacterial transcription initiation complex formation were synthesized and their antimicrobial activities were evaluated. Condensation of indole-7- and indole-2-carbohydrazides with 7- and 2-trichloroacetylindoles or indole-7- and indole-2-glyoxyloyl chlorides resulted in the successful synthesis of 7,7′-, 2,2′-, 2,7′- and 3,2′-linked bis-indole derivatives with –CO–NH–NH–CO– and –CO–CO–NH–NH–CO– linkers. Indole-7-glyoxyloyl chlorides were reacted with hydrazine hydrate in different ratios to afford respective –CO–CO–NH–NH–CO–CO– bis-indole or hydrazide derivatives. The resulting compounds were found to be active against the β′-CHσ⁷⁰/σ^A_2.2 interaction in ELISA assays and inhibited the growth of both Gram-positive and Gram-negative bacteria. Structure–activity relationship (SAR) studies were performed in order to identify the structural features of the synthesized inhibitors required for biological activity.]]> Sat 24 Mar 2018 08:00:13 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:19931 Sat 24 Mar 2018 07:58:36 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20873 Sat 24 Mar 2018 07:57:58 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20628 Sat 24 Mar 2018 07:55:47 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20965 Sat 24 Mar 2018 07:54:22 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:19179 Sat 24 Mar 2018 07:52:17 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:19340 in vitro antibacterial activity against several representative pathogenic bacterial strains. Compounds 20(S)-protopanaxadiol (PPD), 3, 5, 16 and 24 exhibited potent antibacterial activity against Gram-positive bacteria. Compounds 3 and 5 also displayed promising antibacterial activity against a community associated methicillin-resistant Staphylococcus aureus (CA-MRSA; strain USA300). Furthermore, compounds PPD, 3 and 16 combined with two commercially available antibiotics kanamycin and chloramphenicol showed strong synergistic inhibitory effects at their sub-MIC concentrations against S. aureus USA300 and Bacillus subtilis 168. Additionally, cytotoxic activity assay showed that the compounds tested did not affect cell viability of the human epithelial kidney (HEK-293) and human cervical (HeLa) cells at their MICs.]]> Sat 24 Mar 2018 07:52:12 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29829 Sat 24 Mar 2018 07:40:53 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:27697 70/σ^A factors in bacteria. In this study, the reaction of indole-2-, indole-3-, indole-7- and benzofuran-2-glyoxyloyl chlorides with amines and hydrazines afforded a variety of glyoxyloylamides and glyoxyloylhydrazides. Similarly, condensation of 2- and 7-trichloroacetylindoles with amines and hydrazines delivered amides and hydrazides. The novel molecules were found to inhibit the RNA polymerase-σ⁷⁰/σ^A interaction as measured by ELISA, and also inhibited the growth of both Gram-positive and Gram-negative bacteria in culture. Structure-activity relationship (SAR) studies of the mono-indole and mono-benzofuran inhibitors suggested that the hydrophilic-hydrophobic balance is an important determinant of biological activity.]]> Sat 24 Mar 2018 07:40:09 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28658 In vitro transcription assays have been developed and widely used for many years to study the molecular mechanisms involved in transcription. This process requires multi-subunit DNA-dependent RNA polymerase (RNAP) and a series of transcription factors that act to modulate the activity of RNAP during gene expression. Sequencing gel electrophoresis of radiolabeled transcripts is used to provide detailed mechanistic information on how transcription proceeds and what parameters can affect it. In this paper we describe the protocol to study how the essential elongation factor NusA regulates transcriptional pausing, as well as a method to identify an antibacterial agent targeting transcription initiation through inhibition of RNAP holoenzyme formation. These methods can be used a as platform for the development of additional approaches to explore the mechanism of action of the transcription factors which still remain unclear, as well as new antibacterial agents targeting transcription which is an underutilized drug target in antibiotic research and development.]]> Sat 24 Mar 2018 07:37:12 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:26825 in silico screening of novel transcription inhibitors. Here, we describe our approach for the design and testing of small molecule transcription inhibitors that work by preventing the interaction between the essential transcription initiation factor σ and RNAP. With the appropriate structural information this approach can be easily modified to other essential protein-protein interactions.]]> Sat 24 Mar 2018 07:36:25 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28373 Escherichia coli sliding clamp occurs via a sequential mechanism that involves two subsites (I and II). Here, we report the development of small-molecule inhibitors that mimic this mechanism. The compounds contain tetrahydrocarbazole moieties as "anchors" to occupy subsite I. Functional groups appended at the tetrahydrocarbazole nitrogen bind to a channel gated by the side chain of M362 and lie at the edge of subsite II. One derivative induced the formation of a new binding pocket, termed subsite III, by rearrangement of a loop adjacent to subsite I. Discovery of the extended binding area will guide further inhibitor development.]]> Sat 24 Mar 2018 07:35:58 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28246 1, II₃, II₄, III₂ displayed higher potency in releasing NO at this concentration. Analysis of the in vitro data showed that the derivatives bearing the same furoxan group on different ocotillol cores possessed various NO releasing capacity, suggesting that the structure of carrier of NO releasing groups may affect the NO release. Indeed, except compound II₂, 24(S)-6-deoxy ocotillol derivatives from compound 6 with different furoxan substitutions at 3-OH and III₂ displayed enhanced NO releasing capacity, compared to other compounds derived from compounds 5 and 9. The results illustrated that the functional group and the stereochemistry on the ocotillol structure may affect the NO release of furoxans.]]> Sat 24 Mar 2018 07:28:32 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28338 Sat 24 Mar 2018 07:25:14 AEDT ]]>