Clostridium zeae sp. nov., isolated from corn silage

A rod-shaped, Gram-stain-negative, strictly anaerobic, catalase-negative and endospore-forming bacterial strain CSC2T was isolated from corn silage preserved in Tochigi, Japan. The strain CSC2T grew at 15–40 °C, at pH 5.0–7.7 and with up to 0.5 % (w/v) NaCl. The main cellular fatty acids were C14 : 0, C16 : 0 and C16 : 0 dimethyl acetal. The cellular polar lipids detected were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidic acid, lysophosphatidylethanolamine, phosphatidylserine, lysophosphatidylcholine and two unidentified polar lipids. Phylogenetic analysis of the 16S rRNA gene showed that strain CSC2T was a member of the genus Clostridium and closely related to Clostridium polyendosporum DSM 57272T (95.6 % gene sequence similarity) and Clostridium fallax ATCC 19400T (95.3 %). The genomic DNA G+C content of strain CSC2T was 31.1 mol% (whole genome analysis). The average nucleotide identity based on blast and digital DNA–DNA hybridization values between strain CSC2T and the type strains of phylogenetically related species were below 71 and 24 %, respectively. On the basis of the genotypic, phenotypic and chemotaxonomic characteristics, it is proposed to designate strain CSC2T as representing Clostridium zeae sp. nov. The type strain is CSC2T (=MAFF212476T=JCM 33766T=DSM 111242T).

Anaerosporobacter faecicola sp. nov. isolated from faeces of Korean cow

A novel bacterial isolate designated as strain AGMB01083T was isolated from Korean cow faeces deposited in the National Institute of Animal Science (Wanju, Republic of Korea). The bacterium is obligate anaerobic, Gram-strain-positive, and motile. Cells are straight or curved rod-shaped, flagella and spores are observed. Growth occurs between 20–40 °C (temperature optimum of 35 °C), at pH 7–9 (pH optimum of 7), and in the presence of 0.5–1.0 % (w/v) NaCl. Based on the 16S rRNA gene sequence analysis, the strain belongs to the genus Anaerosporobacter and is most closely related to A. mobilis HY-37-4T (=KCTC5027T, similarity, 95.7 %). The DNA G+C content is 36.2 mol%, determined by the whole-genome sequence. The average nucleotide identity value between strain AGMB01083T and strain A. mobilis HY-37-4T is 75.5 %, below the interspecies identity threshold value. The major cellular fatty acids (>10 %) of strain AGMB01083T are C16 : 0, C16 : 0 dimethyl acetal (DMA), and C16 : 0 3-OH. Based on the phylogenetic, phenotypic, biochemical, chemotaxonomic, and genomic characterization, strain AGMB01083T is proposed to be a novel species, named Anaerosporobacter faecicola, in the genus Anaerosporobacter . The type strain is AGMB01083T (=KCTC 15857T=NBRC 114517T).

Synthesis and Characterization of Novel Methyl (3)5-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates

Series of methyl 3- and 5-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates were developed and regioselectively synthesized as novel heterocyclic amino acids in their N-Boc protected ester form for achiral and chiral building blocks. In the first stage of the synthesis, piperidine-4-carboxylic and (R)- and (S)-piperidine-3-carboxylic acids were converted to the corresponding β-keto esters, which were then treated with N,N-dimethylformamide dimethyl acetal. The subsequent reaction of β-enamine diketones with various N-mono-substituted hydrazines afforded the target 5-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates as major products, and tautomeric NH-pyrazoles prepared from hydrazine hydrate were further N-alkylated with alkyl halides to give 3-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates. The structures of the novel heterocyclic compounds were confirmed by 1H-, 13C-, and 15N-NMR spectroscopy and HRMS investigation.

New Cardenolides from Biotransformation of Gitoxigenin by the Endophytic Fungus Alternaria eureka 1E1BL1: Characterization and Cytotoxic Activities

Microbial biotransformation is an important tool in drug discovery and for metabolism studies. To expand our bioactive natural product library via modification and to identify possible mammalian metabolites, a cytotoxic cardenolide (gitoxigenin) was biotransformed using the endophytic fungus Alternaria eureka 1E1BL1. Initially, oleandrin was isolated from the dried leaves of Nerium oleander L. and subjected to an acid-catalysed hydrolysis to obtain the substrate gitoxigenin (yield; ~25%). After 21 days of incubation, five new cardenolides 1, 3, 4, 6, and 8 and three previously- identified compounds 2, 5 and 7 were isolated using chromatographic methods. Structural elucidations were accomplished through 1D/2D NMR, HR-ESI-MS and FT-IR analysis. A. eureka catalyzed oxygenation, oxidation, epimerization and dimethyl acetal formation reactions on the substrate. Cytotoxicity of the metabolites were evaluated using MTT cell viability method, whereas doxorubicin and oleandrin were used as positive controls. Biotransformation products displayed less cytotoxicity than the substrate. The new metabolite 8 exhibited the highest activity with IC50 values of 8.25, 1.95 and 3.4 µM against A549, PANC-1 and MIA PaCa-2 cells, respectively, without causing toxicity on healthy cell lines (MRC-5 and HEK-293) up to concentration of 10 µM. Our results suggest that A. eureka is an effective biocatalyst for modifying cardenolide-type secondary metabolites.

Preparation of the Key Dolutegravir Intermediate via MgBr2-Promoted Cyclization

A novel approach for synthesizing the key dolutegravir intermediate is described via MgBr2-promoted intramolecular cyclization. Condensation of commercially available methyl oxalyl chloride and ethyl 3-(N,N-dimethylamino)acrylate afforded the vinylogous amide in an excellent yield. Subsequent substitution by aminoacetaldehyde dimethyl acetal and methyl bromoacetate gave rise to the expected precursor for cyclization, which was promoted by MgBr2 to highly selectively convert into pyridinone diester. The key dolutegravir intermediate was finally prepared by the selective hydrolysis of the corresponding diester via LiOH.

Multicomponent Stereoselective Polymerizations toward Multifunctional AIE Polymers with α,β-Unsaturated Amidines

<p>Heterochain polymers play an essential role in our daily lives due to their distinctive properties. Among various heteroatom-rich structures, amidine derivatives serve as a synthetically important and pharmacologically useful structural branch and have found wide applications in synthetic chemistry and biomedicine field. In this work, we developed a straightforward and powerful polymerization tool to access diverse heterochain polymers with <i>α</i>,<i>β</i>-unsaturated amidine units. The multicomponent electrophilic polymerizations of readily accessible diynes, disulfonyl azides, and <i>N</i>,<i>N</i>-dimethylformamide dimethyl acetal proceed efficiently at room temperature, producing amidine-containing polymers with high molecular weights (<i>M</i>_w up to 74500) in high yields within merely 1 h. Nuclear magnetic resonance spectra analysis revealed that all the obtained polymers are formed with excellent stereoselectiviy. The introduction of aggregation-induced emission (AIE) luminogen together with the inherent heteroatom-rich structure feature endow these polymers with multiple functionalities. The nanoaggregates of the diethylamino-substituted polymer show remarkable and reversible fluorescence response to acid and base, and the acid-fumed polymer thin film can be used as a sensitive and reusable fluorescent probe for detecting seafood spoilage. This polymer system can also be employed as a highly selective and sensitive Au³⁺ sensor, and efficient gold recovery can be achieved based on the excellent gold enrichment capability of the polymer. In addition, the AIE polymers can also be applied in lysosome-specific cell imaging with low cytotoxicity and excellent photostability.</p>

Multicomponent Stereoselective Polymerizations toward Multifunctional AIE Polymers with α,β-Unsaturated Amidines

<p>Heterochain polymers play an essential role in our daily lives due to their distinctive properties. Among various heteroatom-rich structures, amidine derivatives serve as a synthetically important and pharmacologically useful structural branch and have found wide applications in synthetic chemistry and biomedicine field. In this work, we developed a straightforward and powerful polymerization tool to access diverse heterochain polymers with <i>α</i>,<i>β</i>-unsaturated amidine units. The multicomponent electrophilic polymerizations of readily accessible diynes, disulfonyl azides, and <i>N</i>,<i>N</i>-dimethylformamide dimethyl acetal proceed efficiently at room temperature, producing amidine-containing polymers with high molecular weights (<i>M</i>_w up to 74500) in high yields within merely 1 h. Nuclear magnetic resonance spectra analysis revealed that all the obtained polymers are formed with excellent stereoselectiviy. The introduction of aggregation-induced emission (AIE) luminogen together with the inherent heteroatom-rich structure feature endow these polymers with multiple functionalities. The nanoaggregates of the diethylamino-substituted polymer show remarkable and reversible fluorescence response to acid and base, and the acid-fumed polymer thin film can be used as a sensitive and reusable fluorescent probe for detecting seafood spoilage. This polymer system can also be employed as a highly selective and sensitive Au³⁺ sensor, and efficient gold recovery can be achieved based on the excellent gold enrichment capability of the polymer. In addition, the AIE polymers can also be applied in lysosome-specific cell imaging with low cytotoxicity and excellent photostability.</p>

Mediterraneibacter catenae SW178 sp. nov., an intestinal bacterium of feral chicken

A Gram-positive, coccobacillus, white raised and circular with an entire edge colony, and obligately anaerobic bacterium, strain SW178 was isolated from the cecum content of feral chickens in Brookings, South Dakota, USA. The most closely related strain based on 16S rRNA gene sequence analysis of strain SW178 was Mediterraneibacter torques ATCC 27756T (Ruminococcus torques ATCC 27756T) with 96.94% similarity. The genome of strain SW178 is 3.18 Mbp with G+C content of 46.9 mol%. The optimal temperature and pH for growth in modified brain heart infusion (BHI-M) medium were 45 °C and pH 7.5, respectively. The sole carbon sources of the strain were dextrin, L-fucose, D-galacturonic, α-D-glucose, L-rhamnose and D-sorbitol. The primary cellular fatty acids were C14 : 0, C16 : 0 and C16 : 0 dimethyl acetal (DMA). Based on the genotypic and phenotypic comparison, we proposed that strain SW178 belong to the genus Mediterraneibacter in the family Lachnospiraceae as a novel species, in which the name Mediterraneibacter catenae is proposed. The type strain is SW178 (= DSM 109242T = CCOS 1886T).