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Journal of Antibiotics

Huijing Wang, Tina Chang, Srihari Konduri, Jianbo Huang, Alan Saghatelian, Dionicio Siegel
Fatty acid esters of hydroxy fatty acids (FAHFAs) are a growing class of natural products found in organisms ranging from plants to humans. The roles these endogenous derivatives of fatty acids play in biology and their novel pathways for controlling inflammation have increased our understanding of basic human physiology. FAHFAs incorporate diverse fatty acids into their structures, however, given their recent discovery non-natural derivatives have not been a focus and as a result structure-activity relationships remain unknown...
April 15, 2019: Journal of Antibiotics
Michaelyn C Lux, Lisa C Standke, Derek S Tan
Adenylate-forming enzymes are a mechanistic superfamily that are involved in diverse biochemical pathways. They catalyze ATP-dependent activation of carboxylic acid substrates as reactive acyl adenylate (acyl-AMP) intermediates and subsequent coupling to various nucleophiles to generate ester, thioester, and amide products. Inspired by natural products, acyl sulfonyladenosines (acyl-AMS) that mimic the tightly bound acyl-AMP reaction intermediates have been developed as potent inhibitors of adenylate-forming enzymes...
April 15, 2019: Journal of Antibiotics
Nils Winter, Zeljka Rupcic, Marc Stadler, Dirk Trauner
Due its unique structure and its reported potent antifungal activity, the marine polyketide hippolachnin A (1) has attracted much attention in the synthetic community. Herein, we describe the development of a concise, diversifiable and scalable synthesis of the racemic natural product, which serves as a platform for the generation of bioactive analogues. Biological testing of our synthetic material did not confirm the reported antifungal activity of hippolachnin A but unraveled moderate activity against nematodes and microbes...
April 12, 2019: Journal of Antibiotics
Jia-Hui Tay, Valentin Dorokhov, Sibin Wang, Pavel Nagorny
This manuscript describes a single pot protocol for the selective introduction of unprotected sugars to the C3 position of the cardiotonic steroid strophanthidol. These reactions proceed with high levels of regiocontrol (>20:1 rr) in the presence of three other hydroxyl functionalities including the C19 primary hydroxyl group and could be applied to different sugars to provide the deprotected cardiac glycosides upon work up (5 examples, 77-69% yield per single operation). The selective glycosylation of the less reactive C3 position is accomplished by the use of traceless protection with methylboronic acid that blocks the C5 and C19 hydroxyls by forming a cyclic boronic ester, followed by in situ glycosylation and a work up with ammonia in methanol to remove the boronic ester and the carbohydrate ester protecting groups...
April 4, 2019: Journal of Antibiotics
San N Khong, Changmin Xie, Xinyi Wang, Hao Tan, Ohyun Kwon
A robust synthetic route from L-hydroxyproline (L-Hyp) to phosphines has established an expandable library of six chiral aminophosphines, which were then applied to the phosphine-catalyzed [4 + 2] allene-imine annulation. The enantioinduction in the annulations-induced by a purely steric effect-were moderate (up to 57% ee). A switch of the reaction site from the γ- to the β'-carbon atom of the allenoate was observed during the annulations performed using sterically demanding chiral phosphines.
April 2, 2019: Journal of Antibiotics
Yao Chen, Yuan Ju, Chungen Li, Tao Yang, Yong Deng, Youfu Luo
Methicillin-resistant Staphylococcus aureus (MRSA) infections are a significant global health challenge due to the emergence of strains exhibiting resistance to nearly all classes of antibiotics. This necessitates the rapid development of novel antimicrobials to circumvent this critical problem. Screening of compounds based on phenotypes is one of the major strategies for finding new antibiotics at present. Hence, we here performed a phenotypic screening against MRSA and identified NPS-2143 exhibiting activity against MRSA with an MIC value of 16 μg ml-1 ...
April 2, 2019: Journal of Antibiotics
You-Ping Luo, Cai-Juan Zheng, Guang-Ying Chen, Xiao-Ping Song, Zhe Wang
Three new polyketides, (2S)-2,3-dihydro-5,6-dihydroxy-2-methyl-4H-1-benzopyran-4-one (1), (2'R)-2-(2'-hydroxypropyl)-4-methoxyl-1,3-benzenediol (2), and 4-ethyl-3-hydroxy-6-propenyl-2H-pyran-2-one (3) were isolated from the culture broth of Colletotrichum gloeosporioides, an endophytic fungus derived from the mangrove Ceriops tagal. The structures of 1-3 were elucidated on the basis of NMR spectra and HR-ESI-MS data. Their absolute configurations were determined by comparing with the experimental and calculated ECD spectrum...
April 1, 2019: Journal of Antibiotics
Loïc Deblais, Yosra A Helmy, Anand Kumar, Janet Antwi, Dipak Kathayat, Ulyana Munoz Acuna, Huang-Chi Huang, Esperanza Carcache de Blanco, James R Fuchs, Gireesh Rajashekara
Campylobacter is a leading cause of bacterial foodborne gastroenteritis worldwide, and poultry are a major source of human campylobacteriosis. The control of Campylobacter from farm to fork is challenging due to emergence of microbial resistance and lack of effective control methods. We identified a benzyl thiophene sulfonamide based small molecule (compound 1) with a minimal inhibitory concentration (MIC) of 100 μM against Campylobacter jejuni 81-176 and Campylobacter coli ATCC33559, good drug-like properties, and low toxicity on eukaryotic cells...
March 27, 2019: Journal of Antibiotics
Martin J Lear, Keiichiro Hirai, Kouki Ogawa, Shuji Yamashita, Masahiro Hirama
The kedarcidin chromophore is a formidible target for total synthesis. Herein, we describe a viable synthesis of this highly unstable natural product. This entailed the early introduction and gram-scale synthesis of 2-deoxysugar conjugates of both L-mycarose and L-kedarosamine. Key advances include: (1) stereoselective allenylzinc keto-addition to form an epoxyalkyne; (2) α-selective glycosylations with 2-deoxy thioglycosides (AgPF6 /DTBMP) and Schmidt donors (TiCl4 ); (3) Mitsunobu aryl etherification to install a hindered 1,2-cis-configuration; (4) atropselective and convergent Sonogashira-Shiina cyclization sequence; (5) Ohfune-based amidation protocol for naphthoic acid; (6) Ce(III)-mediated nine-membered enediyne cyclization and ester/mesylate derivatisation; (7) SmI2 -based reductive olefination and global HF-deprotection end-game...
March 25, 2019: Journal of Antibiotics
Matthew Zimmerman, Stacey L McDonald, Hsin-Pin Ho-Liang, Patrick Porubsky, Quyen Nguyen, Cameron W Pharr, Andrew J Perkowski, Robert Smith, Frank J Schoenen, Ben S Gold, David Zhang, Carl F Nathan, Véronique Dartois, Jeffrey Aubé
A systematic study of the stability of a set of cephalosporins in mouse plasma reveals that cephalosporins lacking an acidic moiety at C-2 may be vulnerable to β-lactam cleavage in mouse plasma.
March 22, 2019: Journal of Antibiotics
Ruohan Wei, Han Liu, Xuechen Li
Fusobacterium nucleatum is an oral bacteria related to various types of diseases. As Gram-negative bacteria, lipopolysaccharide (LPS) of Fusobacterium nucleatum could be a potential virulence factor. Recently, the structure of O-antigen in LPS of Fusobacterium nucleatum strain 25586 was elucidated to contain a trisaccharide repeating unit -(4-β-Nonp5Am-4-α-L-6dAltpNAc3PCho-3-β-D-QuipNAc)-. The nonulosonic acid characterized as 5-acetamidino-3,5,9-trideoxy-L-glycero-L-gluco-non-2-ulosonic acid (named as fusaminic acid), and 2-acetamido-2,6-dideoxy-L-altrose are the novel monosaccharides isolated...
March 22, 2019: Journal of Antibiotics
Yu-Fu Liang, Chuang-Chung Chung, Meng-Wen Huang, Biing-Jiun Uang
The synthesis of functionalized pyroglutamates 15 and 16 could be achieved by the application of recently developed diastereodivergent asymmetric Michael addition reaction of iminoglycinate 7 to ethyl γ-silyloxycrotonate with >98:<2 diastereoselectivity followed by hydrolysis and lactamization. Formal syntheses of (-)-isoretronecanol and (+)-laburnine as well as a concise enantioselective synthesis of (+)-turneforcidine could be achieved from functionalized pyroglutamates 15 or 16.
March 20, 2019: Journal of Antibiotics
Tianhu Zhao, Jian Zhang, Maomao Tang, Luyan Z Ma, Xiaoguang Lei
The human pathogen Pseudomonas aeruginosa can easily form biofilms. The extracellular matrix produced by the bacterial cells acts as a physical barrier to hinder the antibiotics treatment. It is necessary to destroy the biofilm in order to improve the efficacy of antibiotics. However, it has been a significant challenge to develop effective small molecules targeting the components of biofilm matrix. In this study, we report the development of a new effective fluorescence probe that could be used in the high throughput screening to identify novel small molecule inhibitors targeting the most abundant component in the biofilm formation: P...
March 20, 2019: Journal of Antibiotics
Simon S Park, Jacquelyn Gervay-Hague
Steryl glycosides are prevalent in nature and have unique biological activities dictated by sterol structure, sugar composition, and the stereochemical attachment of the aglycone. A single configurational switch can have profound biological consequences meriting the systematic study of structure and function relationships. Steryl congeners of N-acetyl neuraminic acid (NANA) impact neurobiological processes and may also mediate host/microbe interactions. In order to study these processes, a platform for the synthesis of β-steryl sialosides has been established...
March 19, 2019: Journal of Antibiotics
Zsolt Szűcs, Eszter Ostorházi, Máté Kicsák, Lajos Nagy, Anikó Borbás, Pál Herczegh
Ten analogues of a teicoplanin pseudoaglycon derivative have been synthesized with the aim of optimizing the in vitro activity of the compound against VanA type vancomycin resistant enterococci (VRE) isolated from hospitalized patients. Teicoplanin, vancomycin, and oritavancin were used as reference antibiotics for the antibacterial evaluations. One of the new derivatives exhibited far superior activity than the original compound. The in vitro MICs measured were comparable to that of oritavancin against the investigated VRE strains...
March 15, 2019: Journal of Antibiotics
Linfang Hu, Xiao Chen, Li Han, Lixing Zhao, Cuiping Miao, Xueshi Huang, Youwei Chen, Ping Li, Yiqing Li
Two new phenazine metabolites, 6-hydroxyphenazine-1-carboxamide (1) and methyl 6-carbamoylphenazine-1-carboxylate (2), were isolated from a soil-derived Streptomyces diastaticus subsp. ardesiacus strain YIM PH20246, and their structures were elucidated by extensive spectroscopic data analysis. The antimicrobial activities of the isolates were assayed. Compound 1 showed moderate antifungal and antibacterial activities against Fusarium oxysporum (ATCC 7808), Fusarium solani (ATCC 36031) and Plectosphaerella cucumerina (local isolate), Staphylococcus aureus (ATCC 25923) and Staphylococcus albus (ATCC 10231), respectively...
March 11, 2019: Journal of Antibiotics
Shoya Watanabe, Akane Ario, Nobuharu Iwasawa
Hydropropargylation of enamides was achieved in good yields through the 1,4-addition of enamides to the α,β-unsaturated carbene complex intermediate, followed by intramolecular hydrogen transfer to the iminium carbon. This method is useful for the synthesis of 4-pentynylamine derivatives from enamides and easily available propargyl ether. Moreover, tandem cyclization reaction was achieved to afford a pyrrolidine derivative in a single operation by using a secondary enamide.
March 7, 2019: Journal of Antibiotics
Chunshuai Huang, Chunfang Yang, Wenjun Zhang, Yiguang Zhu, Liang Ma, Zhuangjie Fang, Changsheng Zhang
Heterologous expression of the fluostatin biosynthetic gene cluster from the marine-derived Micromonospora rosaria SCSIO N160 in Streptomyces albus J1074 led to the isolation of a novel isoindolequinone albumycin (1) and a known isoquinolinequinone mansouramycin A (2). The structure of 1 was elucidated on the basis of detailed 1D and 2D NMR spectroscopic analysis. Mansouramycin A (2) is active against methicillin-resistant Staphylococcus aureus ATCC 43300, with a MIC of 8 μg ml-1 , while albumycin (1) displayed negligible antibacterial activities...
February 28, 2019: Journal of Antibiotics
Libing Yu, Huan Wang, Novruz Akhmedov, Lawrence J Williams
A concise route to a glycosylated allenic erythronolide was achieved. Key findings include the preparation of a desosamine sulfoxide donor and the use of the donor to glycosylate bulky acceptors. Additionally, the new reagent was used to prepare allene-containing macrocycles and to realize a four-step synthesis of macrolide 6 from bis[allene] 5. The longest linear sequence required to prepare 6 from commercial reagents was 15 steps.
February 28, 2019: Journal of Antibiotics
Masanori Nagatomo, Yuki Fujimoto, Keisuke Masuda, Masayuki Inoue
A three-component coupling reaction of structurally simple 6-8 was successfully applied for expeditious synthesis of the 6/5/9-membered tricyclic structure 3 of cladieunicellin D (1) and klysimplexin U (2). Upon treatment with the Et3 B/O2 reagent system, α-alkoxyacyl telluride 6, six-membered enone 7, and (Z)-4-hexenal (8) were linked in one pot to provide the densely functionalized 5 via sequential decarbonylative radical generation, radical addition, boron enolate formation, and intermolecular aldol reaction...
February 25, 2019: Journal of Antibiotics
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