Antioxidant Properties of Quercetin Zhang, Mei; Swarts, Steven G.; Yin, Liangjie ...
Advances in experimental medicine and biology,
2011, Letnik:
701
Book Chapter, Journal Article
Recenzirano
Quercetin, a plant-derived aglycone form of flavonoid glycosides, has been used as a nutritional supplement and may be beneficial against a variety of diseases, including cancer. We examined the ...antioxidant properties of quercetin. The reduction potential of quercetin was measured at various pH values using voltammetric methods, and its total antioxidant capacity (TAC) was measured using the phosphomolybdenum method. The effect of quercetin on production of reactive oxygen species (ROS) and nitric oxide (NO) in LPS-stimulated human THP-1 acute monocytic leukemia cells was determined by flow cytometry using CM-H2DCFDA dye. The results were compared with curcumin, a natural product exhibiting a similar range of reported health benefits. Results: 1) Quercetin has a higher reduction potential compared with curcumin at three different pH settings and is comparable to Trolox at pH 7-9.5; 2) its TAC is 3.5 fold higher than curcumin; 3) it reduced LPS-induced ROS to near normal levels; 4) it reduced LPS-induced NO production. These data provide a physico-chemical basis for comparing antioxidants, with potential benefits individually or in combination.
Abstract Spintronics offers promising routes for efficient memory, logic, and computing technologies. The central challenge in spintronics is electrically manipulating and detecting magnetic states ...in devices. The electrical control of magnetization via spin-orbit torques is effective in both conducting and insulating magnetic layers. However, the electrical readout of magnetization in the latter is inherently difficult, limiting their use in practical applications. Here, we show magnetoresistive detection of perpendicular magnetization reversal in an electrically insulating ferrimagnet, terbium iron garnet (TbIG). To do so, we use TbIG|Cu|TbCo, where TbCo is the reference conducting ferrimagnet and Cu is a nonmagnetic spacer. Current injection through Cu|TbCo allows us to detect the magnetization reversal of TbIG with a simple resistance readout during an external magnetic field sweep. By examining the effect of measurement temperature, TbCo composition, and Cu thickness on the sign and amplitude of the magnetoresistance, we conclude that the spin-dependent electron scattering at the TbIG|Cu interface is the underlying cause. Magnetoresistive detection of perpendicular switching in a ferrimagnetic garnet may enable alternative insulating spintronic device concepts.
We theoretically demonstrate that class-I topological Dirac semimetals (TDSMs) can provide a platform for realizing both electrically and magnetically tunable spin–charge conversion. With ...time-reversal symmetry, the spin component along the uniaxial rotation axis (z axis) is approximately conserved, which leads to an anisotropic spin Hall effect; the resulting spin Hall current relies on the relative orientation between the external electric field and the z axis. The application of a magnetic field, on the other hand, breaks time-reversal symmetry, driving the TDSM into a Weyl semimetal phase and, consequently, partially converting the spin current to a charge Hall current. Using the Kubo formulas, we numerically evaluate the spin and charge Hall conductivities based on a low-energy TDSM Hamiltonian together with the Zeeman coupling. Besides the conventional tensor element of the spin Hall conductivity σxyz, we find that unconventional components, such as σxyx and σxyy, also exist and vary as the magnetic field is rotated. Likewise, the charge Hall conductivity also exhibits appreciable tunability upon variation of the magnetic field. We show that such tunability—as well as large spin–charge conversion efficiency—arises from the interplay of symmetry and band topology of the TDSMs.
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In an effort to develop new drug candidates with enhanced anticancer activity, our team synthesized and assessed the cytotoxicity of a series of novel xanthone derivatives with two ...longer 3,6-disubstituted amine carbonyl methoxy side chains on either benzene ring in selected human cancer cell lines. An MTT assay revealed that a set of compounds with lower IC50 values than the positive control, 5-FU, exhibited greater anticancer effects. The most potent derivative (XD8) exhibited anticancer activity in MDA-MB-231, PC-3, A549, AsPC-1, and HCT116 cells lines with IC50 values of 8.06, 6.18, 4.59, 4.76, and 6.09μM, respectively. Cell cycle analysis and apoptosis activation suggested that the mechanism of action of these derivatives includes cell cycle regulation and apoptosis induction.
The spin-momentum locking of surface states in topological materials can produce a resistance that scales linearly with magnetic and electric fields. Such a bilinear magnetoelectric resistance (BMER) ...effect offers a new approach for information reading and field sensing applications, but the effects demonstrated so far are too weak or for low temperatures. This article reports the first observation of BMER effects in topological Dirac semimetals; the BMER responses were measured at room temperature and were substantially stronger than those reported previously. The experiments used topological Dirac semimetal α-Sn thin films grown on silicon substrates. The films showed BMER responses that are 10
times larger than previously measured at room temperature and are also larger than those previously obtained at low temperatures. These results represent a major advance toward realistic BMER applications. Significantly, the data also yield the first characterization of three-dimensional Fermi-level spin texture of topological surface states in α-Sn.
Silicon photonics is now widely accepted as a key technology in a variety of systems. But owing to material limitations, now it is challenging to greatly improve the performance after decades of ...development. Here, we show a high-performance broadband photodetector with significantly enhanced sensitivity and responsivity operating over a wide wavelength range of light from near-ultraviolet to near-infrared at low power consumption. The specially designed textured top ceiling electrode works effectively as an antireflection layer to greatly improve the absorption of near-infrared light, thereby overcoming the absorption limitation of near-infrared light. Instead of the conventional p–n junction and p–intrinsic–n junction, we introduce a ∼15 nm thick alumina insulator layer between a p-type Si substrate and n-type ZnO nanowire (NW) arrays, which significantly enhances the charge carrier separation and collection efficiency. The photosensing responsivity and sensitivity are found to be nearly 1 order of magnitude higher than that of a reference device of p-Si/n-ZnO NW arrays, significantly higher than the commercial silicon photodiodes as well. The light-induced charge carriers flow across the appropriate thickness of insulator layer via the quantum mechanical Fowler–Nordheim tunneling mechanism. By virtue of the piezo-phototronic effect, the charge density at the interfaces can be tuned to alter the energy bands and the potential barrier distance for tunneling. Additionally, along with the use of incident light of different wavelengths, the influence of the insulator layer on the transport of electrons and holes separately is further investigated. The demonstrated concepts and study would lead to sensitivity improvement, quality enhancement of data transfer, decrease of power consumption, and cost reduction of silicon photonics.
We predict a nonlinear Hall effect in certain Weyl semimetals with broken inversion symmetry. When the energy dispersions about pairs of Weyl nodes are skewed-the Weyl cones are "tilted"-the ...concerted actions of the anomalous velocity and the chiral anomaly give rise to the nonlinear Hall effect. This Hall conductivity is linear in both electric and magnetic fields and depends critically on the tilting of the Weyl cones. We also show that this effect does not rely on a finite Berry curvature dipole, in contrast with the intrinsic quantum nonlinear Hall effect that was recently observed in type-II Weyl semimetals.
Recent advances in the Internet of Things (IoTs) technology have accelerated the realization of micro or nano systems that necessitate not only the development of a self‐powered sensing system, but ...also devices that are able to protect personal security. Here, a direct ink write (DIW) 3D‐printed ultrathin fuse is fabricated and coupled with a high performance triboelectric nanogenerator (TENG). By triggering the high‐AC voltage TENG with a low‐frequency sliding motion, the fuse, which initially has low resistance, can instantly transition from a short‐circuit state to an open circuit state. Utilizing this method, a variety of self‐powered applications can be realized. Here, the first triboelectric, fully self‐powered system is demonstrated, which can accurately detect package drops without the use of a computing element or an external power source. In addition, by coupling the TENG, 3D printed fuse, and logic circuit elements, a self‐powered security device is developed, in which users are able to quickly change sensitive information if it is at risk of exposure by a single sliding motion on the TENG.
An electromagnetic pulse triboelectric nanogenerator (TENG) system, consisting of a high voltage TENG and DIW 3D‐Printed Electrical Fuse, is designed. By performing a single sliding motion on the TENG, the 3D‐printed fuse would break, causing a large change in resistance. This system is used in various applications, such as a self‐powered drop detection system and a personal security device.
Purpose: IR-induced pulmonary fibrosis is one of the most severe late complications of radiotherapy for lung cancer. It is urgently needed to discover a new drug for anti-IR lung fibrosis. Our ...previous studies have indicated that TPL exhibits both anti-IR lung fibrosis and anti-tumor activities. To reveal the mechanism of TPL on anti-IR lung fibrosis, alveolar macrophages (AMs) were examined for TPL effect on their axis of Nicotinamide adenine dinucleotide phosphate oxidase-reactive oxygen species (NOXes-ROS) and myofibroblast activation. Methods and Materials: The fibrosis-prone C57BL/6 mice were irradiated with 15 Gy on whole chest, then one day later, mice were treated without or with TPL (i.v. 0.25 mg/kg, qod for 1 month). The AMs were collected from bronchoalveolar lavage fluids and studied for the production of ROS and the levels of NOXes. The effect of AMs on myofibroblast activation as labeled with F4/80 or α-SMA (α-smooth muscle actin) were examined using flow cytometry, Western blotting, or immunohistochemical staining. Results: TPL effectively reduced the IR-induced lung fibrosis as evidenced by the less myofibroblasts, less collagen deposit and less ROS in the IR-lung tissues. We found that ROS which responsible for myofibroblasts activation was mainly from AMs and was NOX2 and NOX4 dependent. TPL significantly reduced the infiltrated AMs in IR-lung tissues, and in addition, down regulated the level of NOX2 and NOX4 in AMs both in vitro and in vivo. Furthermore, by inhibiting NOXes dependent ROS in AMs, TPL deprived AMs' paracrine activation of myofibroblasts. Conclusions: Our work demonstrated that the anti-fibrotic effect of TPL on IR-induced pulmonary fibrosis was related to its inhibition on the axis of alveolar macrophages-NOXes-ROS-myofibroblasts.
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