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101.
Takamasa Ohno Munehiro Nakagawa Yun-Mo Li Hajime Mizukami 《Tetrahedron letters》2005,46(50):8657-8660
In the present study, new sesquiterpene lactones (1) and (2) were isolated from the EtOAc soluble fraction of the water extract of Linderae Radix through bioassay-guided fractionation and isolation methods. The structure of these compounds was elucidated by spectroscopic analysis of their 2D NMR spectra, including COSY, HMBC, and HMQC techniques. Two isolates showed significant cytotoxicity against the human small cell lung cancer cell SBC-3, and lesser cytotoxicity against mouse fibroblast cell 3T3-L1. 相似文献
102.
The products of the reactions of polymethylalumoxane (MAO) with triisobutylaluminum (TIBA), rac-Me2Si(2-Me,4-PhInd)2ZrCl2 (1) with MAO (1 + MAO), and (1 + MAO) + TIBA were studied by 1H NMR at different molar ratios of the components. When the ratio AlTIBA/AlMAO is ∼6, the reaction between MAO and TIBA involves the replacement of the methyl group of MAO by isobutyl groups and the formation
of isobutylmethylalumoxane or mixed isobutylmethylalumoxane structures. When the TIBA content in the system increases to 30
mol.%, these structures are rearranged to form products with a low degree of association. With the equimolar ratio of the
reactants, the main reaction products are tetraisobutylalumoxane and polyisobutylalumoxane. The 1 + MAO system with the molar ratio AlMAO/Zr = 50 affords a MAO-bonded monomethyl monochloride derivative [L2ZrCl-μ-Me]δ+[MAO]δ−. An increase in this ratio to 150 produces intermediate binuclear complexes [L2ZrCl-μ-Me-MeZrL2]+[MAO]− and [Me2Al-(μ-Me)2-ZrL2]+[MAO]−. The addition of TIBA induces the replacement of the ZrMe groups by isobutyl groups at the first step of the interaction
and formation of nonidentified reaction products at the subsequent steps.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 934–940, April, 2005. 相似文献
103.
Yoichi Hayakawa Hisashi Adachi Jin Woo Kim Kazuo Shin-ya Haruo Seto 《Tetrahedron》1998,54(52):1817-15878
A new antitumor antibiotic, adenopeptin (1), was isolated from the culture broth of Chrysosporium sp. PF1201. The planar structure, which includes a tridecapeptide and a hexahydropyrrolo[1,2-a]pyrimidinium, was elucidated by mass spectrometric and NMR experiments. Adenopeptin (1) induced apoptotic cell death in cells transformed with the adenovirus oncogenes. 相似文献
104.
Summary: Silica nanotube reactor (SNTR) has been designed and used as a novel catalytic polymerization reactor device to synthesize syndiotactic polystyrene (sPS), and polyethylene with Cp*Ti(OCH3)3 and rac-Et(indenyl)2ZrCl2 metallocene catalysts in conjunction with methylaluminoxane (MAO). The highly crystalline sPS molecules polymerized within the SNTR form nano-scale polymeric fibrils of 30–50 nm in diameter that further intertwine to fill the nanopore. The polymer molecular weight of sPS has been found to increase significantly in the SNTR. A simplified mathematical reaction model for the SNTR suggests that hindered chain transfer reactions in the nanopores filled with rigid polymeric nanofibrils might have caused the extended polymer chain length. The morphological characteristics of polymeric nanofibrils and the effect of SNTR's geometric confinement on the polymer properties are also discussed. It is also demonstrated that the liberated SNTR can be a novel ‘See-Through’ tool for visual observation when it is analyzed by transmission electron microscopy. 相似文献
105.
《Arabian Journal of Chemistry》2022,15(10):104145
In the present study, novel representatives of the important group of biologically-active, dehydroabietic acid-bearing dithiocarbamate moiety, were synthesized and characterized by 1H NMR, 13C NMR, HR-MS. The in vitro antiproliferative activity evaluation (MTT) indicated that these compounds exhibited potent inhibitory activities in various cancer cell lines (HepG-2, MCF-7, HeLa, T-24, MGC-803). Particularly, compound III-b possessed extraordinary cytotoxicity with low micromolar IC50 values ranging from 4.07 to 38.84 µM against tested cancer cell lines, while displayed weak cytotoxicity on two normal cell lines (LO-2 and HEK 293 T). Subsequently, the potential mechanisms of representative compound III-b were elementarily investigated by Transwell experiment, which showed III-b can inhibit cancer cells migration. Annexin-V/PI dual staining showed that the compound can induce HepG-2 cells apoptosis in a dose-dependent manner. Meanwhile this apoptosis may be related to the upregulated protein expression of cleaved-caspase 3, cleaved-caspase 9, Bax and downregulated of Bcl-2 indicated by Western Blot. Later study further confirmed that ROS levels in HepG-2 cells increased significantly with the rise of concentrations. In addition, through the network pharmacology data analyzing, the core targets and signaling pathways of compound III-b for treatment of liver neoplasms were forecasted. Molecular docking model showed that compound III-b had high affinity with hub targets (CASP3, EGFR, HSP90AA1, MAPK1, ERBB2, MDM2), suggesting that compound III-b might target the hub protein to modulate signaling activity. Taken together, these data indicated that dehydroabietic acid structural modification following the “Molecular hybridization” principle is a feasible way to discover the potential multi-targeted antitumor compounds. 相似文献
106.
Dr. Motoki Toganoh Hideaki Matsuo Ayumi Sato Prof. Hiroyuki Furuta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8316-8322
Ruthenocene‐type hybrid complexes with N‐fused porphyrinato ligands, [Ru(NFp)Cp] (NFp=N‐fused porphyrin, Cp=cyclopentadienyl), have been prepared and characterized by NMR and UV/Vis/NIR spectroscopy, cyclovoltammetry, and X‐ray crystallography. [Ru(NFp)Cp] is a common low‐spin ruthenium(II) complex and shows strong aromaticity. The Ru–Cp distance (1.833 Å) in [Ru(NFp)Cp] is comparable to that in [RuCp2] (1.840 Å). DFT calculations on [Ru(NFp)Cp] showed the unequivocal contribution of the RuCp moiety as well as the NFp moiety to both the HOMO and LUMO, constructing a three‐dimensional d–π conjugated system. The HOMO–LUMO gaps of [Ru(NFp)Cp] are insensitive to the substituents on the NFp ligand, which is illustrated spectroscopically as well as theoretically. This is in sharp contrast to the ligand precursor, the N‐fused porphyrin, in which the HOMO–LUMO gap is affected by substituents in a similar manner to standard porphyrins and related macrocycles. 相似文献
107.
An efficient and practical method to access bioactive 2,3-dehydrosilybin and 19-O-demethyl-2,3-dehydrosilybin using naturally abundant flavonolignan silybin in the presence of metal salt as a chelating agent is described. The procedure presented here has several advantages including one-pot, synthetic ease, and products in high yields with no side reactions, and large-scale feasibility. The dehydrogenation and demethylation proceed smoothly via a one-pot process using the AlCl3/Pyridine system and I2 as the additive. Furthermore, 2,3-dehydrosilybin and 19-O-demethyl-2,3-dehydrosilybin can inhibit the expression of intracellular mature miRNA-21 with IC50 values of 4.46?μM and 8.25?μM, respectively, and show moderate anticancer activities against HeLa cell lines. 相似文献
108.
Stefano Federico Tuhina Khan Nicola Relitti Giulia Chemi Margherita Brindisi Simone Brogi Ettore Novellino Daniela M. Zisterer Giuseppe Campiani Sandra Gemma Stefania Butini 《Tetrahedron letters》2018,59(51):4466-4470
We developed a Jocic-type protocol for the construction of the pyrrolonaphthoxazepine (PNOX) core. After an initial investigation based on the isolation of a trichloromethyl carbinol derivative, we shifted our attention towards a multicomponent single-step protocol. Screening of a variety of bases and solvents led to the identification of the optimum conditions for the preparation of the key α-aryloxy carboxylic acids to undergo intramolecular cyclization. The novel chemical route significantly improved overall yields for the preparation of PNOX-based compounds and was successfully extended to the preparation of 1,4-benzoxazinone-based templates. 相似文献
109.
Vladimir A. Dyakonov Gulnara N. Kadikova Lilya U. Dzhemileva Guzel F. Gazizullina Milyausha M. Yunusbaeva Usein M. Dzhemilev 《Tetrahedron》2018,74(30):4071-4077
Bicyclo[4.3.1]deca-2,4,8-triene-7,10-diols were synthesized in 76–85% yields by oxidative skeletal isomerization of the substituted bicyclo[4.2.2]deca-2,4,7,9-tetraenes of various structures on treatment with m-chloroperbenzoic acid. The structures of the obtained bicyclic unsaturated diols were reliably proven by modern spectral methods and X-ray diffraction. A high antitumor activity in vitro was found for bicyclo[4.3.1]deca-2,4,8-triene-7,10-diols against the Jurkat, K562, U937 and HL-60 tumor cell lines. 相似文献
110.
Mikihiro Ichikawa Shinya Yamamoto Chisato Ishihara Shuhei Nonobe Yasunao Hattori Koji Umezawa Hiroshi Fujii Hidefumi Makabe 《Tetrahedron》2018,74(27):3534-3542
Syntheses of epigallocatechin trimer, (epigallocatechin)2-epicatechin and (epigallocatechin)2-catechin were achieved. The key condensation to form the proanthocyanidin trimer derivatives was accomplished in a one-pot procedure using a dimeric epigallocatechin electrophile, which was prepared in situ by self-condensation of an epigallocatechin derivative, and an epigallocatechin, epicatechin, or catechin derivative as the nucleophile in the presence of a Lewis acid. The epigallocatechin monomer to trimer compounds containing a pyrogallol group significantly suppressed cell proliferation in PC-3 prostate cancer cells. 相似文献