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Journal of Antibiotics

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https://www.readbyqxmd.com/read/28901329/wakodecalines-a-and-b-new-decaline-metabolites-isolated-from-a-fungus-pyrenochaetopsis-sp-rk10-f058
#1
Toshihiko Nogawa, Naoki Kato, Takeshi Shimizu, Akiko Okano, Yushi Futamura, Shunji Takahashi, Hiroyuki Osada
Two new decaline metabolites, wakodecalines A and B, were isolated from a fungus, Pyrenochaetopsis sp. RK10-F058, by screening for structurally unique metabolites using LC/MS analysis. Their structures were determined on the basis of NMR and mass spectrometric measurements. The absolute structures were confirmed by a combination of chemical methods including chemical degradation, a modified Mosher's method and Marfey's method, and comparison of the experimental electronic CD (ECD) spectrum with calculated one...
September 13, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28901328/autophagy-regulating-protease-atg4-structure-function-regulation-and-inhibition
#2
REVIEW
Tatsuro Maruyama, Nobuo N Noda
Autophagy is an intracellular degradation system that contributes to cellular homeostasis through degradation of various targets such as proteins, organelles and microbes. Since autophagy is related to various diseases such as infection, neurodegenerative diseases and cancer, it is attracting attention as a new therapeutic target. Autophagy is mediated by dozens of autophagy-related (Atg) proteins, among which Atg4 is the sole protease that regulates autophagy through the processing and deconjugating of Atg8...
September 13, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28874851/progress-towards-the-total-synthesis-of-hamigerans-c-and-d-a-direct-approach-to-an-elaborated-6-7-5-carbocyclic-core
#3
Douglas Charles Duquette, Thomas Jensen, Brian Mark Stoltz
The hamigeran family of natural products has been the target of numerous synthetic efforts because of its biological activity and interesting structural properties. Herein, we disclose our efforts toward the synthesis of hamigerans C and D, unique among the initially isolated members because of their 6-7-5 carbocyclic core. Our approach directly targets this tricyclic motif by sequential Negishi and Heck coupling reactions, yielding an advanced intermediate with all necessary carbons and sufficient functionality poised for completion of the synthesis of these two natural products...
September 6, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28874850/structures-and-biological-activities-of-novel-4-acetylated-analogs-of-chrysomycins-a-and-b
#4
Shun-Ichi Wada, Ryuichi Sawa, Fumiki Iwanami, Miho Nagayoshi, Yumiko Kubota, Kiyoko Iijima, Chigusa Hayashi, Yuko Shibuya, Masaki Hatano, Masayuki Igarashi, Manabu Kawada
Two new 4'-acetylated analogs of chrysomycin were discovered during the screening for antitumor agents from the metabolites of actinomycetes. Their structures and physicochemical properties were determined by standard spectrometric analyses. Their cytotoxicities and antimicrobial activities were evaluated against a panel of cancer cell lines and microbes. While acetylation reinforced the cytotoxicity of chrysomycin B, it weakened the activity of chrysomycin A. Chrysomycin A and its acetylated analog showed high cytotoxicity toward most of the cancer cells with IC50s less than 10 ng ml(-1)...
September 6, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28874849/inhibitory-effect-of-obovatol-from-magnolia-obovata-on-the-salmonella-type-iii-secretion-system
#5
Won-Sik Choi, Tae Hun Lee, Se Jin Son, Tae Gyu Kim, Byoung-Mog Kwon, Hyeong-U Son, Sung Uk Kim, Sang-Han Lee
In many pathogenic Gram-negative bacteria, such as Salmonella, Escherichia coli, Yersinia and Chlamydia spp., which cause diseases in humans, the type III secretion system (TTSS) is an important virulence factor that translocates effector proteins into the cytosol of host cells. Thus, the TTSS is a good target for antibacterial agents. Here we used a hemolysis assay to search for TTSS inhibitors and found that a compound from Magnolia obovata called obovatol blocks the TTSS of Salmonella. Obovatol showed potent inhibitory activity (IC50=19...
September 6, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28874848/suppressive-drug-combinations-and-their-potential-to-combat-antibiotic-resistance
#6
REVIEW
Nina Singh, Pamela J Yeh
Antibiotic effectiveness often changes when two or more such drugs are administered simultaneously and unearthing antibiotic combinations with enhanced efficacy (synergy) has been a longstanding clinical goal. However, antibiotic resistance, which undermines individual drugs, threatens such combined treatments. Remarkably, it has emerged that antibiotic combinations whose combined effect is lower than that of at least one of the individual drugs can slow or even reverse the evolution of resistance. We synthesize and review studies of such so-called 'suppressive interactions' in the literature...
September 6, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28874847/a-guanine-derivative-as-a-new-mek-inhibitor-produced-by-streptomyces-sp-mk63-43f2
#7
Masatomi Iijima, Yuji Kubota, Ryuichi Sawa, Yumiko Kubota, Masaki Hatano, Masayuki Igarashi, Manabu Kawada, Isao Momose, Mutsuhiro Takekawa, Masakatsu Shibasaki
Mitogen-activated protein kinase (MAPK) pathways that direct cellular responses are involved in various biological processes; the RAS-RAF-MEK-ERK pathway is one of the most important MAPK pathways. It is frequently activated in human malignant tumors such as melanomas, thyroid tumors and colorectal carcinomas. Therefore, targeting this pathway has been considered an attractive strategy for new anticancer drugs. In particular, MEK is a promising target because it is a kinase that directly phosphorylates ERK...
September 6, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28852179/total-synthesis-of-architecturally-complex-indole-terpenoids-strategic-and-tactical-evolution
#8
REVIEW
Yike Zou, Amos B Smith Iii
Indole terpenes have attracted the interests of synthetic chemists due to their complex architectures and potent biological activities. Examples of total syntheses of several indole terpenes were reviewed in this article to honor Professor KC Nicolaou.The Journal of Antibiotics advance online publication, 30 August 2017; doi:10.1038/ja.2017.94.
August 30, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28852178/novel-approaches-for-identification-of-anti-tumor-drugs-and-new-bioactive-compounds
#9
REVIEW
Manabu Kawada, Sonoko Atsumi, Shun-Ichi Wada, Shuichi Sakamoto
Thanks to the pioneering work done by Professor Hamao Umezawa, bioactive compounds have been used in treatment of several diseases including cancer. In this review, we discuss our work, which focuses on developing new candidates for anti-tumor drugs by screening for bioactive natural compounds in microbial cultures using unique experimental systems. We summarize our recent progress including the following: (1) small-molecule modulators of tumor-stromal cell interactions, (2) inhibitors of three-dimensional spheroid formation of cancer cells, (3) multi-cancer cell panel screening and (4) new experimental animal models for cancer metastasis...
August 30, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28831149/engineered-production-and-evaluation-of-6-deoxy-tallysomycin-h-1-revealing-new-insights-into-the-structure-activity-relationship-of-the-anticancer-drug-bleomycin
#10
Dong Yang, Hindra, Liao-Bin Dong, Ivana Crnovcic, Ben Shen
The bleomycins (BLMs), a family of glycopeptide antibiotics, are currently used clinically in combination with a number of other agents for the treatment of malignant tumors. Other members of the BLM family include tallysomycins (TLMs), phleomycins and zorbamycin (ZBM). We previously cloned and characterized the biosynthetic gene clusters for BLMs, TLMs and ZBM. Applications of combinatorial biosynthesis strategies to the three biosynthetic machineries enabled the engineered production of several BLM analogs with unique structural characteristics and varying DNA cleavage activities, thereby providing an outstanding opportunity to study the structure-activity relationship (SAR) for the BLM family of anticancer drugs...
August 23, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28811620/a-new-anthracycline-type-metabolite-from-streptomyces-sp-neau-l3
#11
Chang Lu, Yue Zhao, Wei-Qi Jia, Hui Zhang, Huan Qi, Wen-Sheng Xiang, Ji-Dong Wang, Xiang-Jing Wang
A new anthracycline-type metabolite, designated as tetracenoquinocin A (1), was isolated from the fermentation broth of Streptomyces sp. NEAU-L3. Its structure was determined on the basis of spectroscopic analysis, including 1D and 2D NMR techniques as well as ESI-MS and comparison with data from the literature. Compound 1 showed potent cytotoxic activity against three cancer cell lines (HepG2, A549, HCT-116) with IC50 values of 5.57, 24.30 and 20.82 μM, respectively.The Journal of Antibiotics advance online publication, 16 August 2017; doi:10...
August 16, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28792011/f-36316-a-and-b-novel-vasoactive-compounds-isolated-from-incrucipulum-sp-sank-10414
#12
Yuki Hirota-Takahata, Yoko Ishimoto, Emi Kurosawa, Yuko Iwadate, Yoshiko Onozawa, Isshin Tanaka, Masahiro Tanaka, Hideki Kobayashi
In the course of our screening program for vasoactive compounds using co-culture assay of endothelial cells and fibroblast cells, potent activity was detected in the cultured broth of Incrucipulum sp. SANK 10414. Two active compounds, F-36316 A and B, and a non-active homolog, F-36316 C, were isolated from the broth. The structures of F-36316 A, B and C were elucidated by physicochemical data and spectral analyses, and found to be new 3-acylated tetronic acid homologs. F-36316 A and B induced morphological changes of endothelial cells different from vascular endothelial growth factor (VEGF) or vestaines in the assay with EC50 values of 1...
August 9, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28765590/formal-synthesis-of-englerin-a-utilizing-regio-and-diastereoselective-4-3-cycloaddition
#13
Shuichi Hagihara, Kengo Hanaya, Takeshi Sugai, Mitsuru Shoji
Englerin A, a guaiane sesquiterpene isolated from Phyllanthus engleri, showed highly potent and selective growth inhibitory activities against renal cancer cell lines. We synthesized the key tricyclic intermediate from commercially available 2,2-dimethyl-1,3-dioxan-5-one via regio- and diastereoselective [4+3] cycloaddition between the formyl enol silyl ether and the disubstituted furan, in 4.8% total yield over 10 steps.The Journal of Antibiotics advance online publication, 2 August 2017; doi:10.1038/ja.2017...
August 2, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28765589/comparing-the-action-of-ht61-and-chlorhexidine-on-natural-and-model-staphylococcus-aureus-membranes
#14
Alasdair Tm Hubbard, Anthony Rm Coates, Richard D Harvey
HT61 and chlorhexidine (CHX) are both putative membrane-active antimicrobials, which non-specifically target the anionic lipids abundant in bacterial membranes. In model systems, the ability of these antimicrobials to partition into lipid monolayers and increase the permeability of lipid bilayers is dependent upon the presence and proportion of anionic lipids such as phosphatidylglycerol. Despite their apparent similarity in membrane affinity, we have found that HT61 and CHX differ in the extent to which they affect membrane integrity...
August 2, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28765588/rakicidin-f-a-new-antibacterial-cyclic-depsipeptide-from-a-marine-sponge-derived-streptomyces-sp
#15
Shigeru Kitani, Tatsuya Ueguchi, Yasuhiro Igarashi, Kantinan Leetanasaksakul, Arinthip Thamchaipenet, Takuya Nihira
A new cyclic depsipeptide, rakicidin F (1), along with the known compound rakicidin C (2), was isolated from the fermentation broth of the marine sponge-derived actinomycete strain Streptomyces sp. GKU 220. Their structures were elucidated by interpreting the HRFABMS and NMR spectroscopic data. Rakicidin F (1) showed growth inhibitory activity against bacteria.The Journal of Antibiotics advance online publication, 2 August 2017; doi:10.1038/ja.2017.92.
August 2, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28743975/synthesis-of-unique-spirocyclic-orthoester-type-derivatives-of-isothiazolo-4-3-d-pyrimidine-nucleosides
#16
Alexander R Rovira, Yitzhak Tor
A set of unique nucleoside analogs, containing 'spirocyclic orthoester-type' scaffolds, were synthesized from a common isothiazolo[4,3-d]pyrimidine-riboside precursor. The key reaction, using 1,2-di-heteroatomic nucleophiles (e.g., 1,2-ethandithiol) and BF3•OEt2, converts an exocyclic imine into the spirocyclic analogs. The novel structural scaffold is confirmed through the use of one- and two-dimensional (1)H and (13)C NMR experiments.The Journal of Antibiotics advance online publication, 26 July 2017; doi:10...
July 26, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28743974/heterocyclyl-tetracyclines-2-7-methoxy-8-pyrrolidinyltetracyclines-discovery-of-tp-2758-a-potent-orally-efficacious-antimicrobial-against-gram-negative-pathogens
#17
Cuixiang Sun, Yonghong Deng, Diana K Hunt, Corey Fyfe, Chi-Li Chen, Roger B Clark, Trudy H Grossman, Joyce A Sutcliffe, Xiao-Yi Xiao
A convergent total synthesis platform led to the discovery of TP-2758 from a series of novel 7-methoxy-8-heterocyclyl tetracycline analogs. TP-2758 demonstrated high in vitro potency against key Gram-negative pathogens including extended spectrum β-lactamases- and carbapenemase-producing Enterobacteriaceae and Acinetobacter spp. strains. This compound was efficacious when administered either intravenously or orally in multiple murine infection models and displayed a favorable preclinical pharmacological profile supporting its advancement into clinical development...
July 26, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28743973/in-vivo-efficacy-of-%C3%AE-lactam-tripropeptin-c-in-a-mouse-septicemia-model-and-the-mechanism-of-reverse-%C3%AE-lactam-resistance-in-methicillin-resistant-staphylococcus-aureus-mediated-by-tripropeptin-c
#18
Hideki Hashizume, Yoshiaki Takahashi, Tohru Masuda, Shun-Ichi Ohba, Tomokazu Ohishi, Manabu Kawada, Masayuki Igarashi
Natural lipopeptide antibiotic tripropeptin C (TPPC) revitalizes and synergistically potentiates the activities of the class of β-lactam antibiotics against methicillin-resistant Staphylococcus aureus (MRSA) but not against methicillin-sensitive S. aureus in vitro; however, the mode of action remains unclear. In the course of the study to reveal its mode of action, we found that TPPC inhibited the β-lactamase production induced by cefotiam. This prompted us to focus on the β-lactam-inducible β-lactam-resistant genes blaZ (β-lactamase) and mecA (foreign penicillin-binding protein), as they are mutually regulated by the blaZ/I/R1 and mecA/I/R1 systems...
July 26, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28698676/new-anti-inflammatory-metabolites-produced-by-streptomyces-violaceoruber-isolated-from-equus-burchelli-feces
#19
Jian Ma, Hui Lei, Xiu Chen, Xiaoxu Bi, Yi Jiang, Li Han, Xueshi Huang
Three new metabolites (2-4), together with one known compound, GTRI-02, (1) were isolated from a fermentation broth of Streptomyces violaceoruber derived from Equus burchelli feces. The structures of the new compounds 2-4 were established using comprehensive NMR spectroscopic data analysis as well as UV, IR and MS data. The anti-inflammatory activity of compounds 1-4 was tested by examining their ability to inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells...
July 12, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28698675/virgisporangium-myanmarense-sp-nov-a-novel-motile-actinomycete-isolated-from-an-anthill-soil-in-myanmar
#20
Hideki Yamamura, Shoya Miyazaki, Kodai Ikoma, Youji Nakagawa, Moriyuki Hamada, Misa Otoguro, Tomohiko Tamura, Katsuhiko Ando, Nyunt Phay, Masayuki Hayakawa
An actinomycete strain, designated MM04-1133(T), was isolated from an anthill soil sample collected in Bagan, Myanmar. To establish the taxonomic status of this strain, the isolate was subjected to a polyphasic approach. Strain MM04-1133(T) was Gram-staining positive, aerobic, motile and formed long and narrow sporangia directly above the surface of the substrate mycelium. Whole-cell hydrolysates of the strain contained 3-OH-diaminopimelic acid, arabinose, glucose, galactose, mannose, rhamnose and xylose. The predominant menaquinones were MK-10(H6) and MK-10(H8)...
July 12, 2017: Journal of Antibiotics
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