Tawila, Ahmed M.Omar, Ashraf M.Phan, Nguyen DuyTakahashi, Ikue...
7页
查看更多>>摘要：Phytochemical investigation of Callistemon citrinus leaves resulted in the isolation of two new structurally unique callistrilone epimers named callistrilone Q(1) and epicallistrilone Q(2). Both epimers were found to exist in the form of equilibrium conformational isomers. The structural elucidation of the new compounds was achieved by HREIMS in addition to extensive 1D and 2D NMR spectroscopic analyses. The absolute configuration was determined using computational ECD and optical rotation calculations. Both isolated compounds displayed unprecedented preferential cytotoxic activities against PANC-1 human pancreatic cancer cells at the nanomolar level. These compounds also were found to inhibit PANC-1 cell migration under normal nutrient-rich conditions. Both compounds downregulated key proteins involved in the PI3K/Akt/mTOR signaling pathway. (C) 2022 Elsevier Ltd. All rights reserved.
Meguro, YasuhiroTaguchi, YukaEnomoto, MasaruKuwahara, Shigefumi...
4页
查看更多>>摘要：The first synthesis of amykitanose, an O-carbamoyl pyranose component of the potent broad-spectrum antibiotic amycolamicin, has been accomplished from L-fucose in eight steps. The key transformations involve a stereochemical inversion at the C2 asymmetric center of an L-fucose derivative via an oxidation/reduction sequence, a regioselective installation of the 3-acetoxy functionality by acid-promoted hydrolysis of a cyclic orthoester, and a titanium tetrabromide-mediated hydrolysis of a penultimate glycoside intermediate. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Phytochemical investigation into the Diaphragma juglandis Fructus led to the isolation of four new tarax-asterane-type triterpenes (1-4). The structures of 1-4 were elucidated by extensive analyses through HRESIMS, NMR and X-ray single-crystal diffraction analysis. In addition, the alpha-glycosidase inhibitory activities of 1-4 were evaluated and further analysis by molecular docking experiments were adopted to reveal the structure-activity relationship. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A simple and efficient method for the synthesis of flavones was achieved by selective sulfide LiebeskindSrogl cross-coupling reaction of 2-(methylthio)-4H-chromen-4-ones and 3-halo-2-(methylthio)-4H-chromen-4-ones with arylboronic acids. This method is the first example of employing Liebeskind-Srogl coupling for the synthesis of flavones. Various aryl groups can be directly installed to the chromone ring. The structure of all the synthesized compounds were assigned by spectroscopic analysis. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Ancepsone A, a new sesterterpene with 13,19-epoxycheilanthane skeleton, i.e (17Z)-13,19-epoxy-cheilanth-1,17-diene-2-ol-3-one (1), together with eight known natural products (2 similar to 9) were isolated from Aleuritopteris anceps. The structure of the new compound was established by means of 1D and 2D NMR, MS, and single-crystal X-ray diffraction methods. All compounds were isolated from A. anceps for the first time. Ancepsone A and the isolated flavonoids can moderately inhibit the proliferation of cancer cells. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We report the first total synthesis of the biologically active fungal natural product daldiquinone (5), which was accomplished with a longest linear sequence of 8 steps in 41% overall yield. The construction of the unsymmetrical binaphthalene core was realized by a Suzuki-Miyaura cross-coupling in 88% yield on gram scale. Oxidation of naphthol 17 with IBX afforded the key naphthoquinone intermediate 18 in high yield (92%). (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We report here the efficient synthesis of prenyl-containing i(6)A-RNA bearing the representative ACGCUAAAAA sequence through phosphoramidite chemistry. To determine proof-of-concept, we have developed two approaches for selectively fluorescent labeling of this i(6)A-RNA, one relied on direct use of probe PTAD-DBCO-Cy5 via Ene-ligation in 37% yield, another one constituted two sequential processes including azidation by use of TMSN3/Selectfluor and subsequent click reaction with DBCO-Cy5 in total 89% yield. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A quinolinium-based probe (QLS) was designed and successfully applied to detect fluoride based on F--triggered cascade reaction followed by formation of a non-fluorescent the neutral quinolone. The probe displayed significant changes in UV-visible absorption (red-shift 150 nm) and fluorescence emission intensities turn-off selectively for recognition of F-. Compared to the nonquaternary salt forms (QL), NMR titration and MS analysis were performed to confirm the sensing mechanism. Accordingly, the fluorescent test paper was prepared and conveniently used to detect fluoride in aqueous solution. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Due to its complex biological toxicity, mercury ions can cause various neurological diseases and even death. Therefore, developing a rapid and efficient mercury ions analysis method is of great significance. In this study, we designed a new water-soluble fluorescent chemical sensor, Hg535, which can sensitively detect mercury ions in an aqueous solution. Based on the specific mercury-mediated desulfurization reaction, the probe exhibits high selectivity for mercury ions, excellent sensitivity, significant Stokes shift (108 nm), and fast kinetics (within 15 s), with a low detection limit (1.66 ppb). Finally, agar gels based on the probe Hg535 were fabricated, which could act as a solid optical sensor to conveniently and efficiently detect He2+. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A new neo-clerodane diterpenoid, teuchamaedol A (1) was isolated from the EtOAc-soluble materials of the aerial parts of Teucrium chamaedrys. The structure of 1 was elucidated on the basis of spectral data. The absolute configuration of 1 was determined by modified Mosher's method. Teuchamaedol A (1) is the first neo-clerodane diterpenoid possessing a tetrahydrofuran moiety without additional oxygen function. (C) 2022 Elsevier Ltd. All rights reserved.
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