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排序方式: 共有165条查询结果,搜索用时 31 毫秒
21.
Malek SN Lee GS Hong SL Yaacob H Wahab NA Faizal Weber JF Shah SA 《Molecules (Basel, Switzerland)》2011,16(6):4539-4548
Investigations on the cytotoxic effects of the crude methanol and fractionated extracts (hexane, ethyl acetate) C. mangga against six human cancer cell lines, namely the hormone-dependent breast cell line (MCF-7), nasopharyngeal epidermoid cell line (KB), lung cell line (A549), cervical cell line (Ca Ski), colon cell lines (HCT 116 and HT-29), and one non-cancer human fibroblast cell line (MRC-5) were conducted using an in-vitro neutral red cytotoxicity assay. The crude methanol and fractionated extracts (hexane and ethyl acetate) displayed good cytotoxic effects against MCF-7, KB, A549, Ca Ski and HT-29 cell lines, but exerted no damage on the MRC-5 line. Chemical investigation from the hexane and ethyl acetate fractions resulted in the isolation of seven pure compounds, namely (E)-labda-8(17),12-dien-15,16-dial (1), (E)-15,16-bisnor-labda-8(17),11-dien-13-on (2), zerumin A (3), β-sitosterol, curcumin, demethoxycurcumin and bis-demethoxycurcumin. Compounds 1 and 3 exhibited high cytotoxic effects against all six selected cancer cell lines, while compounds 2 showed no anti-proliferative activity on the tested cell lines. Compound 1 also demonstrated strong cytotoxicity against the normal cell line MRC-5. This paper reports for the first time the cytotoxic activities of C. mangga extracts on KB, A549, Ca Ski, HT-29 and MRC-5, and the occurrence of compound 2 and 3 in C. mangga. 相似文献
22.
Connection between two sequences of orthogonal polynomials, where the associated measures are related to each other by a first degree polynomial multiplication (or division), are looked at. The results are applied to obtain information regarding Sobolev orthogonal polynomials associated with certain pairs of measures. 相似文献
23.
Mediterranean Journal of Mathematics - Let p be a prime number, let G be a finite group, let N be a normal subgroup of G, and let $$\theta $$ be a G-invariant irreducible character of N. In Rizo (J... 相似文献
24.
An efficient, cost-effective and environmentally benign synthesis of novel tetracyclic bis-isoxazolopyrroloquinoline derivatives has been developed via one-pot four-component reaction of 4-amino-3-methyl-5-styrylisoxazoles, dimedone, aryl glyoxal monohydrates and 5-amino-3-methylisoxazole by employing water as a reaction medium and acetic acid (AcOH) as a green promoter. The advantages of this protocol are environmentally friendly, metal-free, less reaction time, operational simplicity, high yields, broad substrate scope and easy purification. Most significant of all, this method is green. 相似文献
25.
Sri Krishna Nimmagadda Mingyu Liu Malkanthi K. Karunananda De‐Wei Gao Omar Apolinar Jason S. Chen Peng Liu Keary M. Engle 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):3963-3967
A palladium(II)‐catalyzed enantioselective α‐alkylation of azlactones with nonconjugated alkenes is described. The reaction employs a chiral BINOL‐derived phosphoric acid as the source of stereoinduction, and a cleavable bidentate directing group appended to the alkene to control the regioselectivity and stabilize the nucleopalladated alkylpalladium(II) intermediate in the catalytic cycle. A wide range of azlactones were found to be compatible under the optimal reaction conditions to afford products bearing α,α‐disubstituted α‐amino‐acid derivatives with high yields and high enantioselectivity. 相似文献
26.
Adsorption of Cr(III) from both synthetic and real samples of tannery wastewater treatment's effluent on chitin-humic acid (chitin-HA) hybrid has been carried out. Rate constant and capacity of adsorption of Cr(III) from the synthetic sample were investigated and removal of Cr(III) from the real sample was tested at optimum medium acidity equivalent to pH 3.5. Characterization using Fourier transform infra red (FT-IR) spectroscopy revealed that both COO− and N-acetyl originated from respectively humic acid (HA) and chitin were involved on the adsorption of Cr(III), and hence the Freundlich's multilayer and multi-energy adsorption model was more applicable to treat the adsorption data than the Langmuir's monolayer and mono-energy model. The quantification of adsorption capacity and rate constant using Freundlich isotherm model and first order adsorption reaching equilibrium yielded values of 6.84 × 10−4 mol g−1 (35.57 mg g−1) and 1.70 × 10−2 min−1, respectively. Removal test for the real wastewater treatment's effluent showed that the maximum amount of Cr(III) could be removed by 1 g of chitin-HA hybrid was 2.08 × 10−4 mol or equivalent to 10.82 mg. 相似文献
27.
Sri N Shekar David L Duffy Tony Frudakis Grant W Montgomery Michael R James Richard A Sturm Nicholas G Martin 《Photochemistry and photobiology》2008,84(3):719-726
Eumelanin (brown/black melanin) and pheomelanin (red/yellow melanin) in human hair can be quantified using chemical methods or approximated using spectrophotometric methods. Chemical methods consume greater resources, making them less attractive for epidemiological studies. This investigation sought to identify the spectrophotometric measures that best explain the light-dark continuum of hair color and the measure that is best able to distinguish red hair from nonred hair. Genetic analysis was performed on these two measures to determine the proportion of genetic and environmental influences on variation in these traits. Reflectance curves along the visible spectrum and subjective ratings of hair color were collected from 1730 adolescent twin individuals. Discriminant class analyses were performed to determine the spectrophotometric measure that could best proxy for eumelanin and pheomelanin quantities. The ratio of light reflected in the green portion of the spectrum to that reflected in the red portion of the spectrum was best able to distinguish red hair from nonred hair. Melanocortin 1 receptor (MC1R) genotype explained some, but not all, variation in this measure. Light absorbed in the red portion of the spectrum was best able to explain the light-dark continuum of hair color. Variance components analysis showed that there were qualitatively different genetic influences between males and females for the light-dark continuum of hair. Our results show that spectrophotometric measures approximating variation in eumelanin and pheomelanin may be considered as an alternative to chemical methods in larger epidemiological studies. 相似文献
28.
Lim TS Vedula SR Kausalya PJ Hunziker W Lim CT 《Langmuir : the ACS journal of surfaces and colloids》2008,24(2):490-495
Claudins are proteins that are selectively expressed at tight junctions (TJs) of epithelial cells where they play a central role in regulating paracellular permeability of solutes across epithelia. However, the role of claudins in intercellular adhesion and the mechanism by which they regulate the diffusion of solutes are poorly understood. Here, using single molecule force spectroscopy, the kinetic properties and adhesion strength of homophilic claudin-1 interactions were probed at the single-molecule level. Within the range of tested loading rates (10(3)-10(5) pN/s), our results showed that homophilic claudin-1 interactions have a reactive compliance of 0.363 +/- 0.061 nm and an unstressed dissociation rate of 1.351 +/- 1.312 s-1. This is more than 100-fold greater than that of E-cadherin. The weak and short-lived interactions between claudin-1 molecules make them highly unstable and dynamic in nature. Such a dynamic interaction is consistent with a model where breaking and resealing of TJ strands regulate the paracellular diffusion of solutes. 相似文献
29.
Lo AY Sudarsan V Sivakumar S van Veggel F Schurko RW 《Journal of the American Chemical Society》2007,129(15):4687-4700
Multinuclear solid-state NMR spectroscopy and powder X-ray diffraction (XRD) experiments are applied to comprehensively characterize a series of pure and lanthanide-doped LaF3 nanoparticles (NPs) that are capped with di-n-octadectyldithiophosphate ligands (Ln3+ = diamagnetic Y3+ and Sc3+ and paramagnetic Yb3+ ions), as well as correlated bulk microcrystalline materials (LaF3, YF3, and ScF3). Solid-state 139La and 19F NMR spectroscopy of bulk LaF3 and the LaF3 NPs reveal that the inorganic core of the NP retains the LaF3 structure at the molecular level; however, inhomogeneous broadening of the NMR powder patterns arises from distributions of 139La and 19F NMR interactions, confirming a gradual change in the La and F site environments from the NP core to the surface. 139La and 19F NMR experiments also indicate that low levels (5 and 10 mol %) of Ln3+ doping do not significantly change the LaF3 structure in the NP core. Similar doping levels of paramagnetic Yb3+ ions severely broaden 19F resonances, but only marginally effect 139La powder patterns, suggesting that the dopant ions are uniformly distributed throughout the NP core and occupy vacant La sites. Measurements of 139La T1 and T2 relaxation constants are seen to vary between the bulk material and NPs and between samples with diamagnetic and paramagnetic dopants. 45Sc NMR experiments confirm that the dopants are integrated into the La sites of the LaF3 core. Solid-state 1H and 31P magic-angle spinning (MAS) NMR spectra aid in probing the nature of the capping ligands and their interactions at the NP surface. 31P cross-polarization (CP)/MAS NMR experiments identify not only the dithiophosphate head groups but also thiophosphate and phosphate species which may form during NP synthesis. Finally, 19F-31P CP/MAS and 1H MAS experiments confirm that ligands are coordinated to the NP surface. 相似文献
30.
Eka Sunarwidhi Prasedya Nur Ardiana Hasriaton Padmi Bq Tri Khairina Ilhami Ni Wayan Riyani Martyasari Anggit Listyacahyani Sunarwidhi Aluh Nikmatullah Sri Widyastuti Haji Sunarpi Andri Frediansyah 《Molecules (Basel, Switzerland)》2021,26(21)
The red macroalga Gelidium latifolium is widely distributed in the coastal areas of Indonesia. However, current knowledge on its potential biological activities is still limited. In this study, we investigated the potential bioactive compounds in Gelidium latifolium ethanol extract (GLE), and its cytotoxic effects against the murine B16-F10 melanoma cell line. GLE shows high total phenolic content (107.06 ± 17.42 mg GAE/g) and total flavonoid content (151.77 ± 3.45 mg QE/g), which potentially contribute to its potential antioxidant activity (DPPH = 650.42 ± 2.01 µg/mL; ABTS = 557.01 ± 1.94 µg/mL). ESI-HR-TOF-MS analysis revealed large absorption in the [M-H]- of 327.2339 m/z, corresponding to the monoisotopic molecular mass of brassicolene. The presence of this compound potentially contributes to GLE’s cytotoxic activity (IC50 = 84.29 ± 1.93 µg/mL). Furthermore, GLE significantly increased the number of apoptotic cells (66.83 ± 3.06%) compared to controls (18.83 ± 3.76%). Apoptosis was also confirmed by changes in the expression levels of apoptosis-related genes (i.e., p53, Bax, Bak, and Bcl2). Downregulated expression of Bcl2 indicates an intrinsic apoptotic pathway. Current results suggest that components of Gelidium latifolium should be further investigated as possible sources of novel antitumor drugs. 相似文献