- A structure activity-relationship study of the bacterial signal molecule HHQ reveals swarming motility inhibition in Bacillus atrophaeus
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The sharp rise in antimicrobial resistance has been matched by a decline in the identification and clinical introduction of new classes of drugs to target microbial infections. Thus new approaches are being sought to counter the pending threat of a post-antibiotic era. In that context, the use of non-growth limiting small molecules, that target virulence behaviour in pathogens, has emerged as a solution with real clinical potential. We have previously shown that two signal molecules (HHQ and PQS) from the nosocomial pathogen Pseudomonas aeruginosa have modulatory activity towards other microorganisms. This current study involves the synthesis and evaluation of analogues of HHQ towards swarming and biofilm virulence behaviour in Bacillus atrophaeus, a soil bacterium and co-inhibitor with P. aeruginosa. Compounds with altered C6-C8 positions on the anthranilate-derived ring of HHQ, display a surprising degree of biological specificity, with certain candidates displaying complete motility inhibition. In contrast, anti-biofilm activity of the parent molecule was completely lost upon alteration at any position indicating a remarkable degree of specificity and delineation of phenotype.
- Reen, F. Jerry,Shanahan, Rachel,Cano, Rafael,O'Gara, Fergal,McGlacken, Gerard P.
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- A new approach to the synthesis of 3,6- and 5,6-dialkyl derivatives of 4-hydroxy-2-pyrone. Synthesis of rac-germicidin
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A new approach to the synthesis of 3,6- and 5,6-dialkyl-4-hydroxy-2- pyrones has been developed. The method includes the formation of acylated Meldrum's acids (5-(2-alkyl-3-oxoacyl)-2,2-dimethyl-1,3-dioxane-4,6-diones) followed by their thermal transformation. Introduction of 3-alkyl substituents was accomplished by acylation of 4-hydroxy-2-pyrones and ionic hydrogenation of the 3-acyl derivatives obtained. The effectiveness of this new approach has been demonstrated in the synthesis of rac-germicidin, an autoregulative germination inhibitor of Streptomyces viridochromogenes NRRL B-1551.
- Lokot, Igor P.,Pashkovsky, Felix S.,Lakhvich, Fedor A.
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- Insights into the programmed ketoreduction of partially reducing polyketide synthases: Stereo- and substrate-specificity of the ketoreductase domain
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One of the hallmarks of iterative polyketide synthases (PKSs) is the programming mechanism which is essential for the generation of structurally diverse polyketide products. In partially reducing iterative PKSs (PR-PKSs), the programming mechanism is mainly dictated by the ketoreductase (KR) domain. The KR domain contributes to the programming of PR-PKSs through selective reduction of polyketide intermediates. How the KR domain achieves the selective ketoreduction remains to be fully understood. In this study, we found that the KR domain of the (R)-mellein-synthesizing PR-PKS SACE5532 functions as a B-type KR domain to generate (R)-hydroxyl functionalities. Comparative studies of the KR domains of SACE5532 and NcsB suggested that the two KR domains have distinct substrate preferences towards simple N-acetylcysteamine thioester (SNAC) substrates. We further found that the substrate preference of KRSACE5532 can be switched by swapping several motifs with KRNcsB, and that swapping of the same motifs in the full length SACE5532 resulted in a reprogramming of the PKS. Together, the results advance our understanding of the programming of iterative PR-PKSs by providing new support to the hypothesis that the programmed ketoreduction is accomplished by differential recognition of polyketide intermediates. This journal is
- Soehano, Ishin,Yang, Lifeng,Ding, Feiqing,Sun, Huihua,Low, Zhen Jie,Liu, Xuewei,Liang, Zhao-Xun
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- Quinolones modulate ghrelin receptor signaling: Potential for a novel small molecule scaffold in the treatment of cachexia
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Cachexia is a metabolic wasting disorder characterized by progressive weight loss, muscle atrophy, fatigue, weakness, and appetite loss. Cachexia is associated with almost all major chronic illnesses including cancer, heart failure, obstructive pulmonary disease, and kidney disease and significantly impedes treatment outcome and therapy tolerance, reducing physical function and increasing mortality. Current cachexia treatments are limited and new pharmacological strategies are needed. Agonists for the growth hormone secretagogue (GHS-R1a), or ghrelin receptor, prospectively regulate the central regulation of appetite and growth hormone secretion, and therefore have tremendous potential as cachexia therapeutics. Non-peptide GHS-R1a agonists are of particular interest, especially given the high gastrointestinal degradation of peptide-based structures, including that of the endogenous ligand, ghrelin, which has a half-life of only 30 min. However, few compounds have been reported in the literature as non-peptide GHS-R1a agonists. In this paper, we investigate the in vitro potential of quinolone compounds to modulate the GHS-R1a in both transfected human cells and mouse hypothalamic cells. These chemically synthesized compounds demonstrate a promising potential as GHS-R1a agonists, shown by an increased intracellular calcium influx. Further studies are now warranted to substantiate and exploit the potential of these novel quinolone-based compounds as orexigenic therapeutics in conditions of cachexia and other metabolic and eating disorders.
- Torres-Fuentes, Cristina,Pastor-Cavada, Elena,Cano, Rafael,Kandil, Dalia,Shanahan, Rachel,Juan, Rocio,Shaban, Hamdy,McGlacken, Gerard P.,Schellekens, Harri?t
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- Structure-activity relationships of rationally designed AMACR 1A inhibitors
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α-Methylacyl-CoA racemase (AMACR; P504S) is a promising novel drug target for prostate and other cancers. Assaying enzyme activity is difficult due to the reversibility of the ‘racemisation’ reaction and the difficulties in the separation of epimeric prod
- Yevglevskis, Maksims,Lee, Guat L.,Nathubhai, Amit,Petrova, Yoana D.,James, Tony D.,Threadgill, Michael D.,Woodman, Timothy J.,Lloyd, Matthew D.
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- The requirements at the C-3 position of alkylquinolones for signalling in Pseudomonas aeruginosa
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The 'perfect storm' of increasing bacterial antibiotic resistance and a decline in the discovery of new antibiotics, has made it necessary to search for new and innovative strategies to treat bacterial infections. Interruption of bacterial cell-to-cell communication signalling (Quorum Sensing), thus neutralizing virulence in pathogenic bacteria, is a growing area. 2-Alkyl-4-quinolones, HHQ and PQS, play a key role in the quorum sensing circuitry of P. aeruginosa. We report a new set of isosteres of 2-heptyl-6-nitroquinolin-4-one, with alterations at C-3, and evaluate the key structural requirements for agonistic and antagonistic activity in Pseudomonas aeruginosa.
- Shanahan, Rachel,Reen, F. Jerry,Cano, Rafael,O'Gara, Fergal,McGlacken, Gerard P.
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- Structure-Activity Relationship Study of Majusculamides A and B and Their Analogues on Osteogenic Activity
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We discovered that majusculamide A (1) and majusculamide B (2), isolated from a marine cyanobacterium collected in Okinawa, induced osteoblast differentiation in MC3T3-E1 cells. Although majusculamide A (1) has a different configuration only at the C-19 stereocenter, bearing a methyl group, compared to majusculamide B (2), the effect of 1 was stronger than that of 2. We synthesized some analogues of the majusculamides (3-15) and evaluated osteogenic activities of these analogues. The structure-activity relationship study of majusculamide analogues suggested that the number of methyls and configuration at C-19 and the nature of the substituent at C-20 of majusculamide A (1) may be important for the osteoblast differentiation-inducing effect of 1.
- Nakajima, Daisuke,Natsume, Noriyuki,Ozaki, Kaori,Teruya, Toshiaki,Yokoshima, Satoshi
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p. 2477 - 2482
(2020/10/02)
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- Screening, synthesis, crystal structure, and molecular basis of 6-amino-4-phenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles as novel AKR1C3 inhibitors
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AKR1C3 is a promising therapeutic target for castration-resistant prostate cancer. Herein, an evaluation of in-house library discovered substituted pyranopyrazole as a novel scaffold for AKR1C3 inhibitors. Preliminary SAR exploration identified its derivative 19d as the most promising compound with an IC50 of 0.160 μM among the 23 synthesized molecules. Crystal structure studies revealed that the binding mode of the pyranopyrazole scaffold is different from the current inhibitors. Hydroxyl, methoxy and nitro group at the C4-phenyl substituent together anchor the inhibitor to the oxyanion site, while the core of the scaffold dramatically enlarges but partially occupies the SP pockets with abundant hydrogen bond interactions. Strikingly, the inhibitor undergoes a conformational change to fit AKR1C3 and its homologous protein AKR1C1. Our results suggested that conformational changes of the receptor and the inhibitor should both be considered during the rational design of selective AKR1C3 inhibitors. Detailed binding features obtained from molecular dynamics simulations helped to finally elucidate the molecular basis of 6-amino-4-phenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles as AKR1C3 inhibitors, which would facilitate the future rational inhibitor design and structural optimization.
- Zheng, Xuehua,Jiang, Zan,Li, Xiaolin,Zhang, Chen,Li, Zhe,Wu, Yinuo,Wang, Xinhua,Zhang, Chao,Luo, Hai-bin,Xu, Jun,Wu, Deyan
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supporting information
p. 5934 - 5943
(2018/11/23)
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- Identification and Quantification of N-Acyl Homoserine Lactones Involved in Bacterial Communication by Small-Scale Synthesis of Internal Standards and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry
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N-acyl homoserine lactones (AHL) are small signal molecules involved in the quorum sensing of many gram-negative bacteria, and play an important role in biofilm formation and pathogenesis. Present analytical methods for identification and quantification of AHL require time-consuming sample preparation steps and are hampered by the lack of appropriate standards. By aiming at a fast and straightforward method for AHL analytics, we investigated the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Suitable MALDI matrices, including crystalline and ionic liquid matrices, were tested and the fragmentation of different AHL in collision-induced dissociation MS/MS was studied, providing information about characteristic marker fragments ions. Employing small-scale synthesis protocols, we established a versatile and cost-efficient procedure for fast generation of isotope-labeled AHL standards, which can be used without extensive purification and yielded accurate standard curves. Quantitative analysis was possible in the low pico-molar range, with lower limits of quantification reaching from 1 to 5 pmol for different AHL. The developed methodology was successfully applied in a quantitative MALDI MS analysis of low-volume culture supernatants of Pseudomonas aeruginosa. [Figure not available: see fulltext.].
- Leipert, Jan,Treitz, Christian,Leippe, Matthias,Tholey, Andreas
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p. 2538 - 2547
(2017/12/12)
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- AMIDE COMPOUND AND BACTERIAL DISEASE CONTROL AGENT FOR AGRICULTURAL AND HORTICULTURAL USE
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The present invention provides an amide compound having antibacterial activity, and a bacterial infection control agent for agricultural and horticultural use that contains the amide compound. The novel amide compound of the present invention is represented by General Formula (1): wherein R is a -CH(R1)(R2) or a -CO(R2) group, R1 is a hydrogen atom or a hydroxyl group, and R2 is a C1-12 alkyl group.
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Page/Page column 10
(2010/09/05)
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- Asymmetric syntheses of panclicins A-E via [2+2] cycloaddition of alkyl(trimethylsilyl)ketenes to a β-silyloxyaldehyde
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Panclicins A-E, pancreatic lipase inhibitors from Streptomyces, were synthesised in a modular fashion starting with three alkyl(trimethylsilyl)ketenes, two amino acids and a single aldehyde component, (3R)-3-(tert-butyldimethylsilyloxy)decanal 11. The lone stereocentre in 11 which governs the stereochemistry in subsequent steps was generated by Noyori asymmetric hydrogenation. The key step, a Lewis acid catalysed [2+2] cycloaddition of alkyl(trimethylsilyl)ketenes 13a-c to 11, gave three 3-trimethylsilyloxetan-2-ones with good 1,3-asymmetric induction. After C- and O-desilylation the amino acid side chains were introduced using a Mitsunobu inversion.
- Kocienski, Philip J.,Pelotier, Beatrice,Pons, Jean-Marc,Prideaux, Heather
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p. 1373 - 1382
(2007/10/03)
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- BIOMIMETIC SYNTHESIS OF LONG-CHAIN ALIPHATIC β-DIKETONES
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Long-chain aliphatic β-diketones found in epicuticular waxes are synthesized according to a "biological Claisen reaction scheme" producing precursor diacyl acetates.
- Bianchi, Giorgio,Grugni, Mario
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p. 633 - 636
(2007/10/02)
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- The Preparation of Optically Pure 3-Hydroxyalkanoic Acid. The Enantioface-differentiating Hydrogenation of the C=O Double Bond with Modified Raney Nickel. XXXVII
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The enantioface-differentiating hydrogenation of methyl 3-oxoalkanoate (CH3(CH2)nCOCH2COOCH3, n=0, 6, 8, 10, 12) over the (R,R)-tartaric acid-NaBr-modified Raney nickel catalyst ((R,R)-TA-NaBr-MRNi) gave methyl (R)-3-hydroxyalkanoate (CH3(CH2)nCH(OH)CH2COOCH3, n=0, 6, 8, 10, 12) in an average optical yield of 85percent.After the methyl ester had been converted to dicyclohexylammonium salt of 3-hydroxyalkanoic acid, the salt was recrystallized three times from acetonitrile and then treated with acid to give optically pure (R)-3-hydroxyalkanoic acid (CH3(CH2)nCH(OH)CH2COOH, n=0, 6, 8, 10, 12) in a reasonable yield.From the hydrogenation product with (S,S)-TA-NaBr-MRNi, optically pure (S)-3-hydroxyalkanoic acid was obtained by the same process as above.
- Nakahata, Masaaki,Imaida, Motomasa,Ozaki, Hiroshi,Harada, Tadao,Tai, Akira
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p. 2186 - 2189
(2007/10/02)
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