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تعداد نتایج: 16829797 فیلتر نتایج به سال:
The present article describes the isolation of a new natural product of the lobophorin family, designated as lobophorin K (1), from cultures of the marine actinobacteria Streptomyces sp. M-207, previously isolated from the cold-water coral Lophelia pertusa collected at 1800 m depth during an expedition to the submarine Avilés Canyon. Its structure was determined using a combination of spectrosc...
Neuropeptides of the capa-gene are typical of the abdominal neurosecretory system of insects. In this study, we investigated these peptides in two widely distributed and large pest flies, namely Musca domestica and Neobellieria bullata. Using a combination of MALDI-TOF and ESI-QTOF mass spectrometry, periviscerokinins and a pyrokinin were analyzed from single perisympathetic organ preparations....
Cauxin is a carboxylesterase-like glycoprotein excreted as a major component of cat urine. Cauxin contains four putative N-glycosylation sites. We characterized the structure of an N-linked oligosaccharide of cauxin using nano liquid chromatography (LC)-electrospray ionization (ESI) and matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-T...
The reaction of 3-aminopropylamide of cholic acid with CS₂ produced a bile acid derivative of dithiocarbamic acid which further formed an ammonium salt with another molecule of 3-aminopropylamide of cholic acid. The cationic 3-ammonium propylamide of cholic acid did not react further with CS₂ and the formed salt was stable in the reaction mixture, even when excess CS₂ was used. When the reactio...
We present direct ESI Q-TOF MS and X-ray evidence for remarkable structural and metal ion size effects on the formation of thymidine-based T-tetramers. The conventional H-bond acceptors on the ribose and deoxyribose may disfavor the formation of T-tetramers, and in the series of alkali metal ions, lithium did not induce T-tetramer due to its small ion size. Sodium, potassium, rubidium and caesi...
A bioassay guided fractionation of the ethyl acetate extract from culture broths of the strain Streptomyces zhaozhouensis CA-185989 led to the isolation of three new polycyclic tetramic acid macrolactams (1-3) and four known compounds. All the new compounds were structurally related to the known Streptomyces metabolite ikarugamycin (4). Their structural elucidation was accomplished using a comb...
Phytochemical studies on Viscum coloratum have resulted in the isolation of nineteen compounds. The structures of the isolated compounds were identified on the basis of 1D, 2D NMR and HR-ESI-Q-TOF-MS. Pachypodol (4) and ombuine (6) were characterized in the family Loranthaceae for the first time. 1,7-Bis(4-hydroxyphenyl)-1,4-heptadien-3-one (8) and 5-hydroxy-3,7,3'-trimethoxyflavone-4'-O-beta-D...
Protopanaxatriol saponins obtained with AB-8 macroporous resin mainly consisted of ginsenosides Rg(1) and Re. A novel mono-ester of ginsenoside-Rh(1) (ginsenoside-ORh(1)) was synthesized through further enzymatic hydrolysis and octanoyl chloride modifications. A 53% yield was obtained by a facile synthetic method. The structures were identified on the basis of 1D-NMR and 2D-NMR, as well as ESI-...
Abstract Three molecular catalysts based on mononuclear nickel(II) complexes with square planar geometries, [BzPy] 2 [Ni(mnt) ] ( 1 ), [Ni(i-mnt) and [Ni(tdas) 3 ) (BzPy = benzyl pyridinium) are synthesized by the reaction of NiCl ?6H O, [BzPy]Br, Na (mnt)/Na (i-mnt)/Na (tdas) (mnt 1,2-dicyanoethylene-1,2-dithiolate for i-mnt 2,2-dicyanoethylene-1,1-dithiolate tdas 1,2,5-thiadiazole-3,4-dithiol...
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