Five biflavonoids from Calycopteris floribunda (Combretaceae).
ABSTRACT The structures of five biflavonoids, 6"-demethoxyneocalycopterone (1), calyflorenone C (2), 6"-epi-calyflorenone B (3), 6"-epi-calyflorenone C (4) and calyflorenone D (5) from the green parts of Calycopteris floribunda were established by NMR and MS. Their NMR and chiroptical properties (CD, [alpha]20D ) were compared with those of the known C. f. biflavonoids 6-11. Compound 1 represents a calycopterone derivative, 2-5 have a calyflorenone skeleton. With regard to one chiral center (C-6"), 4 and 3 are the respective epimers of 2 and 11.
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ABSTRACT: The aim of this study was to obtain flavonoids extracts from Calycopteris floribunda leaves using supercritical fluid extraction (SFE) with CO2 and a co-solvent. Pachypodol, a potential anticancer drug lead compound separated from the extracts, was examined. Classical organic solvent extraction (CE) with ethanol was performed to evaluate the high pressure method. HPLC analysis was introduced to interpret the differences between SFE and CE extracts in terms of antioxidant activity and the concentration of pachypodol. SFE kinetics and mathematical modeling of the overall extraction curves (OEC) were investigated. Evaluation of the models against experimental data showed that the Sovová model performs the best. The supercritical fluid extraction process was optimized using a central composite design (CCD), where temperature and pressure were adjusted. The optimal conditions of SFE were: pressure of 30 MPa and temperature of 35°C.Chemical Papers- Slovak Academy of Sciences 03/2014; · 1.19 Impact Factor
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ABSTRACT: Metallic oxynitrides have attracted the attention of several researchers in the last decade due to their versatile properties. Through the addition of a small amount of oxygen into a transition metal nitride film, the material's bonding states between ionic and covalent types can be tailored, thus opening a wide range of electrical, optical, mechanical and tribological responses. Among the oxynitrides, chromium oxynitride (CrNxOy) has many interesting applications in different technological fields. In the present work the electrical behavior of CrNxOy thin films, deposited by DC reactive magnetron sputtering, were investigated and correlated with their compositional and structural properties. The reactive gas flow, gas pressure, and target potential were monitored during the deposition in order to control the chemical composition, which depend strongly on reactive sputtering process. Depending on the particular deposition parameters that were selected, it was possible to identify three types of films with different growth conditions and physical properties. The electrical resistivity of the films, measured at room temperature, was found to depend strongly on the chemical composition of the samples.Highlights► CrNxOy thin films were deposited by DC reactive magnetron sputtering. ► The thin films structural and electrical properties were investigated. ► Three different types of films were found depending on deposition parameters. ► The electrical resistivity depends strongly on thin film chemical composition.Applied Surface Science 08/2011; 257(21):9120-9124. · 2.54 Impact Factor
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ABSTRACT: Protein tyrosine phosphatase (PTP) 1B is the superfamily of PTPs and a negative regulator of multiple receptor tyrosine kinases (RTKs). Inhibition of protein tyrosine phosphatase 1B (PTP1B) has been proposed as a strategy for the treatment of type 2 diabetes and obesity. Recently, it has been reported that amentoflavone, a biflavonoid extracted from Selaginella tamariscina, inhibited PTP1B. In the present study, docking model between amentoflavone and PTP1B was determined using automated docking study. Based on this docking model and the interactions between the known inhibitors and PTP1B, we determined multiple pharmacophore maps which consisted of five features, two hydrogen bonding acceptors, two hydrogen bonding donors, and one lipophilic. Using receptor-oriented pharmacophore-based in silico screening, we searched the biflavonoid database including 40 naturally occurring biflavonoids. From these results, it can be proposed that two biflavonoids, sumaflavone and tetrahydroamentoflavone can be potent allosteric inhibitors, and the linkage at 5',8''-position of two flavones and a hydroxyl group at 4'-position are the critical factors for their allosteric inhibition. This study will be helpful to understand the mechanism of allosteric inhibition of PTP1B by biflavonoids and give insights to develop potent inhibitors of PTP1B.Bulletin- Korean Chemical Society 01/2008; 29(8). · 0.84 Impact Factor