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排序方式: 共有1031条查询结果,搜索用时 125 毫秒
1.
Kento Nishikibe Keisuke Nishikawa Momochika Kumagai Matsumi Doe Yoshiki Morimoto 《化学:亚洲杂志》2022,17(1):e202101137
There are marine cytotoxic bromotriterpenoids, named the thyrsiferol family that are structurally characterized by some tetrahydropyran (THP) and tetrahydrofuran (THF) rings. The thyrsiferol family belongs to natural products that are often difficult to determine their stereostructures even by the current, highly advanced spectroscopic methods, especially in acyclic systems including stereogenic tetrasubstituted carbon centers. In such cases, it is effective to predict and synthesize the possible stereostructures. Herein, to elucidate ambiguous stereostructures and unassigned absolute configurations of aplysiol B, laurenmariannol, and saiyacenol A, members of the thyrsiferol family, we carried out their asymmetric chemical syntheses featuring 6-exo and 5-exo oxacyclizations of epoxy alcohol precursors and 6-endo bromoetherification of a bishomoallylic alcohol. In this paper, we report total assignments of their stereostructures through their asymmetric chemical syntheses and also their preliminary cytotoxic activities against some tumor cells. These results could not have been achieved without depending on asymmetric total synthesis. 相似文献
2.
HaiHuiXIE XiaoYiWEI JiDongWANG MeiFangLIU RenZhouYANG 《中国化学快报》2003,14(6):588-590
A New Annonaceous acetogenin,squamostolide(1),was isolated from the seeds of Annona squamosa.Its structure was elucidated based on spectroscopic methods and comparison with known compounds.It is the first example of Annonaceous acetogenin with each of the two ends of the aliphatic chain bearing a γ-lactone.Thenew compound exhibited cytotoxic activity in vitro against bel-7402 and CNE2 human tumor cell lines. 相似文献
3.
本文采用家兔肺泡巨噬细胞(AM)存活率和细胞过氧化脂质(LPO)值为测定指标,研究了硅氧的聚合度对其细胞毒性的影响。结果表明:各种聚合度的硅氧都有一定的细胞毒性,聚合度愈大,细胞毒性也愈大。胶体SiO_2的粒径增大,其细胞毒性降低。十硅酸盐及粒径小于5nm的硅溶胶的细胞毒性大于α-石英。聚合度小于6的低聚硅酸及其盐、粒径18nm以上的硅溶胶以及硅胶H的毒性皆小于α-石英。本实验细胞存活率降低和过氧化脂质值升高的趋势基本一致,这表明硅氧可能主要与细胞表面膜作用,膜上磷脂等表面活性物质被氧化和变性,从而导致细胞损伤。 相似文献
4.
A new pentacyclic triterpenoid, urs-12-en-29α-oic acid-3β-ol (1), was obtained from the ethanol extract of Chinese herb Oldenlandia cantonensis How. The structure was elucidated by spectroscopy methods, including nuclear magnetic resonance (NMR) (1D and 2D), infrared
spectroscopy (IR), and mass spectrometry (MS). 1 exhibited significant inhibitory activity against the human DNA topoisomerase
I (hTopo I), the cancer cell lines BEL-7402 and MCG-803, with the IC50 values 12.0, 6.5, and 8.0 μg/mL, respectively. The volatile oil, the fraction of petroleum ether: EtOAc = 20:1 (V/V) on Si gel chromatography, was also quantitatively analyzed by gas chromatography mass spectrometry (GC-MS). As a result,
60 compounds were identified. Among them, the long chain aliphatics, terpenes and steroids, as the representative structure
type, were found with percentages of 36.16%, 6.42% and 9.28%, respectively.
Translated from Chinese Journal of Applied Chemistry, 2006, 23(8): 871–874 [译自: 应用化学] 相似文献
5.
6.
Hyun-Sun Park 《Tetrahedron》2004,60(1):171-177
Six new S-containing norditerpene dilactones, rakanmakilactones A-F (5-10), were isolated from the leaves of Podocarpus macrophyllus D. Don var. maki Endl., along with four known norditerpene dilactones (1-4). Their structures, stereochemistry and absolute configurations were determined by spectroscopic studies (HRMS, IR, 1H, 13C and 2D NMR), and single-crystal X-ray analyses. Rakanmakilactones were found to have a cytotoxic effect against P388 murine leukemia cells. 相似文献
7.
3-Aryl-4-iodoisocoumarins, which were readily and efficiently prepared by regioselective iodolactonization of methyl 2-ynylbenzoates or the corresponding carboxylic acids, were used as precursors either to 3-arylisocoumarins, including naturally-occurring thunberginols A and B, or to unsymmetrical 3,4-disubstituted isocoumarins. On the other hand, (Z)- and (E)-3-iodomethylidenephthalides, which were regioselectively prepared by iodolactonization of methyl 2-ethynylbenzoate, were employed as starting materials for the stereospecific synthesis of (Z)- and (E)-3-ylidenephthalides, respectively. Some 3-arylisocoumarins and unsymmetrical 3,4-disubstituted isocoumarins showed certain cytotoxic activity against human cancer cell lines in vitro. 相似文献
8.
Sumitra Tavornvipas Hidetoshi Arima Fumitoshi Hirayama Kaneto Uekama Toshihiro Ishiguro Masahide Oka Kenichi Hamayasu Hitoshi Hashimoto 《Journal of inclusion phenomena and macrocyclic chemistry》2002,44(1-4):391-394
Some physicochemical and biological properties of a new branched cyclodextrin, 6-O--(4-O--d-glucuronyl)-d-glucosyl--cyclodextrin GUG--CyD) were investigated. Further, theinteraction of GUG--CyD with several drugs was studied by the solubility and spectroscopic methods, and compared with those of parent -CyD and 6-O--maltosyl--CyD(2--CyD).The hemolytic activity of GUG--CyD on rabbit erythrocytes was lower than those of -CyD and 2--CyD. GUG--CyD and 2--CyD showed negligible cytotoxicity on Caco-2 cells up to at least 0.1 M. The inclusion ability of GUG--CyD to neutral and acidic drugs was comparable to or slightly smaller than those of -CyD and 2--CyD, probably because of a steric hindrance of the branched sugar. On the other hand, GUG--CyD showed greater affinity for the basic drugs, compared with -CyD and 2--CyD, owing to the electrostatic interaction of its carboxylate anion with positive charge of basic drugs. Thus GUG--CyD may be useful as a safe solubilizing agent particularly for basic drugs. 相似文献
9.
E. Lukevics L. Ignatovich I. Sleiksha V. Romanov S. Grinberga J. Popelis I. Shestakova 《Chemistry of Heterocyclic Compounds》2007,43(2):143-150
A new method was developed for the synthesis of silicon-and germanium-containing acetylfurans and acetylthiophene by metallation
of 2-acetylfuran or 2-acetylthiophene with n-BuLi at low temperature after protection of the carbonyl group with lithium N-methylpiperazide
and reaction of the lithium derivative with various trialkyl-, alkylphenyl-, and cycloalkylchlorosilanes or trialkylchloro(bromo)germanes.
The cytotoxic activity of the new compounds was studied, and it was established that the silicon-and germanium-containing
acetylfurans and acetylthiophenes are substances with low toxicity (LD50 312->2000 mg/kg) and have low cytotoxicity toward HT-1080 and MG-22A tumor cells.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 192–199, February, 2007. 相似文献
10.
Kozyr AV Kolesnikov AV Aleksandrova ES Sashchenko LP Gnuchev NV Favorov PV Kotelnikov MA Iakhnina EI Astsaturov IA Prokaeva TB Alekberova ZS Suchkov SV Gabibov AG 《Applied biochemistry and biotechnology》1998,75(1):45-61
DNA-hydrolyzing activity of IgG autoantibodies from sera of patients with various types of lymphoproliferative diseases was
investigated. The association of DNA-hydrolyzing activity with the antibody (Ab) fraction has been proved by newly developed
affinity-capture assay. Study of abzyme incidence in blood tumors and systemic lupus erythematosis (SLE) revealed linkage
of anti-DNA Ab catalysts to mature B-cell tumors, and increased probability of DNA-abzymes formation on the background of
autoimmune manifestations. These data suggest possible similarity between mechanisms of abzyme formation in SLE and B-cell
lymphomas. A new mechanism of formation of DNA-specific catalytic Abs has been proposed based on the increased crossreactivity
of polyclonal DNA-abzymes to DNA-depleted nuclear matrix proteins. The possibility of the abzyme production as Ab to the energetically
destabilized ground state of the antigen has been discussed. Preliminary results were obtained that indicate the complement-independent
cytotoxicity of anti-DNA autoantibodies isolated from blood of patients with SLE and chronic lymphocytic leukemia. 相似文献