Showing papers by "Pusan National University published in 2002"
TL;DR: In this article, the authors investigated the p-type doping difficulty in ZnO by first-principles total energy calculations and found that the most likely cause for doping difficulty is the formation of interstitials for group-I elements and antisites for groupV elements.
Abstract: We investigate the p-type doping difficulty in ZnO by first-principles total-energy calculations. The dopants being considered are group-I elements Li, Na, and K and group-V elements N, P, and As. We find that substitutional group-I elements are shallow acceptors, while substitutional group-V elements such as P and As are deep acceptors. The AX centers that convert acceptors into deep donors are found to be unstable except for P and As. Without compensation by intrinsic defects, the most likely cause for doping difficulty is the formation of interstitials for group-I elements and antisites for group-V elements. Among all the dopants studied here, N is a relatively better candidate for p-type ZnO.
1,116 citations
TL;DR: It is concluded that the role of ARD1 in the acetylation of Hif-1α provides a key regulatory mechanism underlying HIF-1 α stability, and is critical to proteasomal degradation.
672 citations
TL;DR: The findings suggest that clinical trials to further assess chemopreventive and adjuvant therapeutic applications of pomegranate in human breast cancer may be warranted.
Abstract: Fresh organically grown pomegranates (Punica granatum L.) of the Wonderful cultivar were processed into three components: fermented juice, aqueous pericarp extract and cold-pressed or supercritical CO2-extracted seed oil. Exposure to additional solvents yielded polyphenol-rich fractions ('polyphenols') from each of the three components. Their actions, and of the crude whole oil and crude fermented and unfermented juice concentrate, were assessed in vitro for possible chemopreventive or adjuvant therapeutic potential in human breast cancer. The ability to effect a blockade of endogenous active estrogen biosynthesis was shown by polyphenols from fermented juice, pericarp, and oil, which inhibited aromatase activity by 60-80%. Fermented juice and pericarp polyphenols, and whole seed oil, inhibited 17-beta-hydroxysteroid dehydrogenase Type 1 from 34 to 79%, at concentrations ranging from 100 to 1,000 microg/ml according to seed oil >> fermented juice polyphenols > pericarp polyphenols. In a yeast estrogen screen (YES) lyophilized fresh pomegranate juice effected a 55% inhibition of the estrogenic activity of 17-beta-estradiol; whereas the lyophilized juice by itself displayed only minimal estrogenic action. Inhibition of cell lines by fermented juice and pericarp polyphenols was according to estrogen-dependent (MCF-7) >> estrogen-independent (MB-MDA-231) > normal human breast epithelial cells (MCF-10A). In both MCF-7 and MB-MDA-231 cells, fermented pomegranate juice polyphenols consistently showed about twice the anti-proliferative effect as fresh pomegranate juice polyphenols. Pomegranate seed oil effected 90% inhibition of proliferation of MCF-7 at 100 microg/ml medium, 75% inhibition of invasion of MCF-7 across a Matrigel membrane at 10 microg/ml, and 54% apoptosis in MDA-MB-435 estrogen receptor negative metastatic human breast cancer cells at 50 microg/ml. In a murine mammary gland organ culture, fermented juice polyphenols effected 47% inhibition of cancerous lesion formation induced by the carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). The findings suggest that clinical trials to further assess chemopreventive and adjuvant therapeutic applications of pomegranate in human breast cancer may be warranted.
438 citations
TL;DR: In this article, thermoplastic starch (TPS)/clay hybrids were prepared by melt intercalation and three organically modified montmorillonite (MMT) with different ammonium cations and one unmodified Na+ MMT (Cloisite Na+) were used.
Abstract: Biodegradable thermoplastic starch (TPS)/clay hybrids were prepared by melt intercalation. Three organically modified montmorillonite (MMT) with different ammonium cations and one unmodified Na+ MMT (Cloisite Na+) were used. Cloisite Na+ showed the best dispersion in the TPS matrix. It was observed that the TPS/Cloisite Na+ hybrid showed an intercalation of TPS in the silicate layer due to the matching of the surface polarity and interactions of the Cloisite Na+ and the TPS, which gives higher tensile strength and better barrier properties to water vapor as compared to the other TPS/organoclay hybrids as well as the pristine TPS. It was found that the dynamic mechanical properties of the TPS/clay hybrids were also affected by the polar interactions.
369 citations
TL;DR: The biochemical and genetic characterization of a Drosophila serine protease inhibitor protein, Serpin-27A, is reported, which regulates the melanization cascade through the specific inhibition of the terminal protease prophenoloxidase-activating enzyme.
335 citations
TL;DR: In this paper, the dispersion of the silicate layers in the APES hybrids was characterized by using X-ray diffraction (XRD) and transmission electron microscopy (TEM).
307 citations
TL;DR: The biochemical and molecular bases of the inflammatory process in the aging process are analyzed and it is proposed that CR's major force of the regulation of redox‐sensitive inflammation may well be its life‐prolonging action.
Abstract: Accumulating evidence strongly suggests that oxidative stress underlies aging processes. Research provides consistent evidence that calorie restriction (CR) reduces age-related oxidative stress and has anti-inflammatory properties. However, information is lacking on the molecular mechanism that would better define the interrelation of reactive oxygen species and nitrogen species and the pro-inflammatory states of the aging process. In this review, the biochemical and molecular bases of the inflammatory process in the aging process are analyzed to delineate the molecular inflammation hypothesis of aging. The key players involved in the proposed hypothesis are the age-related upregulation of NF-kappa B, IL-1 beta, IL-6, TNFalpha, cyclooxygenase-2, and inducible NO synthase, all of which are attenuated by CR. Furthermore, age-related NF kappa B activation is associated with phosphorylation by I kappa B kinase/NIK and MAPKs, while CR blocked these activation processes. The modulation of these factors provides molecular insights of the anti-inflammatory action of CR in relation to the aging process. Based on available finding and our recent supporting evidence, we prefer to use "molecular inflammation" to emphasize the importance of the molecular reaction mechanisms and their aberrance, predisposing to fully expressed chronic inflammatory phenomena. It was further proposed that CR's major force of the regulation of redox-sensitive inflammation may well be its life-prolonging action.
284 citations
TL;DR: In this paper, the lattice constant increases linearly with Mn concentration due to the larger Mn atomic radius compared with Ge, strongly indicating that Mn ions are being incorporated into the host Ge lattice.
Abstract: We have successfully fabricated highly (up to 6%) Mn-doped bulk Ge single crystals. The lattice constant increases linearly with Mn concentration due to the larger Mn atomic radius compared with Ge, strongly indicating that Mn ions are being incorporated into the host Ge lattice. Alloys with lower Mn concentrations showed paramagnetism due to localized magnetic ions. ${\mathrm{Ge}}_{0.94}{\mathrm{Mn}}_{0.06}$ showed ferromagnetic ordering at \ensuremath{\sim}285 K, as determined from temperature-dependent magnetization and resistance measurements. The coersive field was 1260 Oe at 250 K.
253 citations
TL;DR: In this paper, a road adaptive modified skyhook control for the semi-active Macpherson strut suspension system of hydraulic type is investigated, which incorporates the rotational motion of the unsprung mass.
Abstract: In this paper, a road adaptive modified skyhook control for the semi-active Macpherson strut suspension system of hydraulic type is investigated. A new control-oriented model, which incorporates the rotational motion of the unsprung mass, is introduced. The control law extends the conventional skyhook-groundhook control scheme and schedules its gains for various road conditions. Using the vertical acceleration data measured, the road conditions are estimated by using the linearized new model developed. Two filters for estimating the absolute velocity of the sprung mass and the relative velocity in the rattle space are also designed. The hydraulic semi-active actuator dynamics are incorporated in the hardware-in-the-loop tuning stage of the control algorithm developed. The optimal gains for the ISO road classes are discussed. Experimental results are included. @DOI: 10.1115/1.1434265#
245 citations
TL;DR: In this paper, the structures of Armendariz rings and semicommutative rings were studied, which are generalizations of reduced rings, and the classical right quotient rings of Armenderiz rings, the polynomi...
Abstract: In this note we concern the structures of Armendariz rings and semicommutative rings which are generalizations of reduced rings, the classical right quotient rings of Armendariz rings, the polynomi...
242 citations
TL;DR: In this article, a critic review on the recent progress of the polymer blends based on the microbial polyesters is presented, where the authors have analyzed the physicochemical properties of microbial polyester containing blends.
TL;DR: Jab1 should be considered as a novel regulator of HIF-1α stability via direct interaction, as it led to increase the expression of VEGF, a major Hif-1 target gene.
TL;DR: In this article, a cost model consisting of the space cost, the investment cost of transfer cranes, and the operating cost of both the terminal operator and the customers is developed for the decision making.
Abstract: This paper discusses a method of determining the optimal amount of storage space and the optimal number of transfer cranes for handling import containers. A cost model is developed for the decision making. The cost model consists of the space cost, the investment cost of transfer cranes, and the operating cost of transfer cranes and trucks. Two different cases are treated, one where the cost of only the terminal operator is minimized, and another where the total cost of both the terminal operator and the customers is minimized. For the former case, a deterministic model is developed, while for the latter case, a stochastic model is developed. Simple solution procedures for the models are provided. The solution procedures are illustrated using numerical examples.
TL;DR: Results indicate that FK228 is a novel antiangiogenic agent and may suppress tumor expansion, at least in part, by the inhibition of neovascularization.
Abstract: FK228 (formerly FR901228) was recently isolated from Chromobacterium violaceum as a potent antitumor agent and its biologic target protein was identified as histone deacetylase (HDAC). Because of its unique chemical structure (i.e., bicyclic depsipeptide) and activity profile in the National Cancer Institute's developmental therapeutics program, FK228 is currently in a phase I clinical trial for cancer therapy. In the present study, we investigated the antiangiogenic activity of FK228 in vivo and in vitro. FK228 potently blocked the hypoxia-stimulated proliferation, invasion, migration, adhesion and tube formation of bovine aortic endothelial cells at the same concentration at which the agent inhibited the HDAC activity of cells. In addition, FK228 inhibited the neovascularization of chick embryo and that of adult mice in the Matrigel plug assay. Interestingly, the expression of angiogenic-stimulating factors such as vascular endothelial growth factor or kinase insert domain receptor were suppressed by FK228, whereas that of angiogenic-inhibiting factors such as von Hippel Lindau and neurofibromin2 were induced, suggesting that a gene-transcription effect was involved in the inhibition of angiogenesis by FK228. These results indicate that FK228 is a novel antiangiogenic agent and may suppress tumor expansion, at least in part, by the inhibition of neovascularization.
TL;DR: Age-related increases in redox-sensitive NF-kappaB, AP-1, and HIF-1 binding activities are concluded to be associated with increased ROS and CR to modulate their activations by suppressing oxidative stress.
TL;DR: The findings suggest that upregulated expression of p22phox mRNA and enhanced NADH oxidase activity contribute to the impaired endothelium-dependent vasodilation in OLETF rats.
Abstract: Superoxide anion can modulate vascular smooth muscle tone and is potentially involved in diabetic vascular complications. The present study was undertaken to characterize both vascular production and the enzymatic source of superoxide anion in type 2 diabetic rats. In the thoracic aorta of OLETF rats, endothelium-dependent relaxation was markedly attenuated compared with that of control (LETO) rats in association with a significant increase in superoxide production (2,421.39 +/- 407.01 nmol x min(-1) x mg(-1)). The increased production of superoxide anion was significantly attenuated by diphenyleneiodonium (DPI; 10 micromol/l), an inhibitor of NAD(P)H oxidase. The production of superoxide anion in response to NADH as a substrate was markedly increased in the vascular homogenates, but NADPH, arachidonic acid, xanthine, and succinate produced only small increases in chemiluminescence. In line with these results, studies using various enzyme inhibitors, such as DPI, allopurinol, rotenone, N(G)-monomethyl-L-arginine, and indomethacin, suggest that the predominant source of superoxide anion in vascular particulate fraction is NADH-dependent membrane-bound oxidase. Furthermore, the expression of p22phox, a major component of vascular NAD(P)H oxidase, was markedly increased in the aorta from OLETF rats compared with that of LETO rats. These findings suggest that upregulated expression of p22phox mRNA and enhanced NADH oxidase activity contribute to the impaired endothelium-dependent vasodilation in OLETF rats.
TL;DR: In this article, the authors describe the pharmacological inhibition by cilostazol and its metabolites, OPC-13015 and OP-13213, of the apoptosis in the human umbilical vein endothelial cells (HUVECs) damaged by lipopolysaccharide (LPS) in comparison with its analog, Cilostamide, and show that these compounds potently inhibited the 5,5-dimethyl-1 pyrroline-1-oxide (DMPO)/ ⋅ OH adduct formation and significantly reduced the
Abstract: This work describes the pharmacological inhibition by cilostazol and its metabolites, OPC-13015 and OPC-13213, of the apoptosis in the human umbilical vein endothelial cells (HUVECs) damaged by lipopolysaccharide (LPS) in comparison with its analog, cilostamide. Cilostazol and OPC-31213 caused a significant suppression of cell death induced by LPS (1 μg/ml) in a concentration-dependent manner but a modest suppression by cilostamide and OPC-13015. These compounds potently inhibited the 5,5-dimethyl-1-pyrroline-1-oxide (DMPO)/ ⋅ OH adduct formation and significantly reduced the increased intracellular reactive oxygen species (ROS) and tumor necrosis factor-α (TNF-α) production induced by LPS (1 μg/ml). An apoptotic death of HUVECs by 1 μg/ml LPS (DNA ladders on electrophoresis) was strongly suppressed by all these compounds. Incubation with LPS caused a marked decrease in Bcl-2 protein, which was significantly reversed by cilostazol and its analogs. The greatly increased Bax protein expression and cytochrome c release by LPS were, in contrast, suppressed by cilostazol and, to a lesser degree, by others. In conclusion, cilostazol and its analogs exert a strong protection against apoptotic cell death by scavenging hydroxyl radicals and intracellular ROS with reduction in TNF-α formation and by increasing Bcl-2 protein expression and decreasing Bax protein and cytochrome c release.
TL;DR: The performance evaluation of the switched Ethernet on an experimental network testbed along with an implementation method for using the switch for industrial automation and the elimination of uncertainties in the network operation leads to the dramatically improved performance.
TL;DR: Results indicate that, although isolated for CO-dependent H2 production, R. palustris P4 has a high potential as a fermentative H2 producer.
TL;DR: In this paper, a thermal leakage injection model was proposed to incorporate a combined gasdynamics and cosmic-ray (CR) diffusion-convection code for planar quasi-parallel shocks.
Abstract: A numerical scheme that incorporates a thermal leakage injection model into a combined gasdynamics and cosmic-ray (CR) diffusion-convection code has been developed. The hydro/CR code can follow in a very cost-effective way the evolution of CR-modified planar quasi-parallel shocks by adopting subzone shock tracking and multilevel adaptive mesh refinement techniques. An additional conservative quantity, S = Pg/ργg−1, is introduced to follow the adiabatic compression accurately in the precursor region, especially in front of strong, highly modified shocks. The "thermal leakage" injection model is based on the nonlinear interactions of the suprathermal particles with self-generated MHD waves in quasi-parallel shocks. The particle injection is followed numerically by filtering the diffusive flux of suprathermal particles across the shock to the upstream region according to a velocity-dependent transparency function that controls the fraction of leaking particles. This function is determined by a single parameter, , which should depend on the strength of postshock wave turbulence but is modeled as a constant parameter in our simulations. We have studied CR injection and acceleration efficiencies during the evolution of CR-modified planar shocks for a wide range of initial shock Mach numbers, M0, assuming a Bohm-like diffusion coefficient. For expected values of the injection process is very efficient when the subshock is strong, leading to fast and significant modification of the shock structure. As the CR pressure increases, the subshock weakens and the injection rate decreases accordingly so that the subshock does not disappear. Although some fraction of the particles injected early in the evolution continue to be accelerated to ever higher energies, the postshock CR pressure reaches an approximate time-asymptotic value because of a balance between fresh injection/acceleration and advection/diffusion of the CR particles away from the shock. In the strong shock limit of M0 30, the injection and acceleration processes are largely independent of the initial shock Mach number for a given , while they are sensitively dependent on M0 for M0 < 30. We conclude that the injection rates in strong parallel shocks are sufficient to lead to rapid nonlinear modifications to the shock structures and that self-consistent injection and time-dependent simulations are crucial to understanding the nonlinear evolution of CR-modified shocks.
TL;DR: Results suggest that AC5 is the principal AC integrating signals from multiple receptors including D1, D2, and A2A in striatum and the cascade involving AC5 among diverse D2 signaling pathways is essential for neuroleptic effects of antipsychotic drugs.
Abstract: Dopamine receptor subtypes D1 and D2, and many other seven-transmembrane receptors including adenosine receptor A2A, are colocalized in striatum of brain. These receptors stimulate or inhibit adenylyl cyclases (ACs) to produce distinct physiological and pharmacological responses and interact with each other synergistically or antagonistically at various levels. The identity of the AC isoform that is coupled to each of these receptors, however, remains unknown. To investigate the in vivo role of the type 5 adenylyl cyclase (AC5), which is preferentially expressed in striatum, mice deficient for the AC5 gene were generated. The genetic ablation of the AC5 gene eliminated 80% of forskolin-induced AC activity and 85‐90% of AC activity stimulated by either D1 or A2A receptor agonists in striatum. However, D1 -o r A 2A-specific pharmaco-behaviors were basically preserved, whereas the signal cascade from D2 to AC was completely abolished in AC5 / , and motor activity of AC5 / was not suppressed by treatment of cataleptic doses of the antipsychotic drugs haloperidol and sulpiride. Interestingly, both haloperidol and clozapine at low doses remarkably increased the locomotion of AC5 / in the open field test that was produced in part by a common mechanism that involved the increased activation of D1 dopamine receptors. Together, these results suggest that AC5 is the principal AC integrating signals from multiple receptors including D1 ,D 2, and A2A in striatum and the cascade involving AC5 among diverse D2 signaling pathways is essential for neuroleptic effects of antipsychotic drugs.
TL;DR: In this article, the discovery of a room-temperature ferromagnetic semiconductor in chalcopyrite was reported, which is consistent with the predictions of full-potential linearized augmented plane wave total energy calculations.
Abstract: We report on the discovery of a room-temperature ferromagnetic semiconductor in chalcopyrite $({\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}){\mathrm{GeP}}_{2}$ with ${T}_{c}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}312\mathrm{K}$. We have also observed that, at temperatures below 47 K, samples for $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.056$ and 0.2 show a transition to the antiferromagnetic (AFM) state, so that ferromagnetism is well defined to be present between 47 and 312 K. The observation that the AFM phase is most stable at low temperatures is consistent with the predictions of full-potential linearized augmented plane wave total energy calculations and has consequences for other chalcopyrite materials.
TL;DR: Cilostazol treatment decreases ischemic brain infarction in association with inhibition of apoptotic and oxidative cell death and reduces the size of infarcts produced by subjecting rats to 2-h occlusion of the left middle cerebral artery followed by 24-h reperfusion.
Abstract: This study examined the protective effects of cilostazol on cerebral infarcts produced by subjecting rats to 2-h occlusion of the left middle cerebral artery followed by 24-h reperfusion. The ischemic cerebral infarct consistently involved the cortex and striatum. The infarct size was significantly reduced, when rats received 10 mg/kg cilostazol intravenously 5 min or 1 h after the completion of 2-h ischemia. Cyclic AMP level was significantly elevated in the cortex of 4- and 12-h reperfusion (P < 0.01) following treatment with cilostazol (10 mg/kg, 5 min after 2-h ischemia) accompanied by decreased tumor necrosis factor-alpha level. Samples from the regions corresponding to the penumbra showed markedly reduced Bcl-2 protein level and, in contrast, high levels of Bax protein and cytochrome c release. Cilostazol decreased Bax protein and cytochrome c release and increased the levels of Bcl-2 protein. Cilostazol (10(-7)-10(-5) M) potently and concentration dependently scavenged hydroxyl and peroxyl radicals. In conclusion, cilostazol treatment decreases ischemic brain infarction in association with inhibition of apoptotic and oxidative cell death.
TL;DR: Results indicate that the conversion of Holotrichia proPOs to enzymatically active phenoloxidase is accomplished by PPAF-I, PAF-II, and PPAf-III through a two-step limited proteolysis in the presence of Ca2+.
TL;DR: A method for establishing a berth schedule consisting of berthing times and berthing positions of containerships in port container terminals is addressed and a Lagrangean relaxation model of the discretized model is solved using a sub-gradient optimization technique.
Abstract: A method for establishing a berth schedule consisting of berthing times and berthing positions of containerships in port container terminals is addressed in this paper. Each vessel requires a specific amount of space on the berth during a predetermined length of time for unloading and loading containers. The berth schedule must be constructed in a way to satisfy requests from carriers on berthing times and minimize handling efforts during ship operation. A mixed integer program is formulated for the berth-scheduling problem, which can be solved using a commercial package. In order to overcome the computational load of the mixed integer program, the formulation is converted into another integer linear program in which the solution space of the berth and the time is discretized. A Lagrangean relaxation model of the discretized model is solved using a sub-gradient optimization technique. Results of a numerical experiment are provided and discussed.
TL;DR: A novel scheme for broadband second-harmonic generation was developed with type I quasi phase matching by use of an off-digital nonlinear optical coefficient d(31) and the desired group-velocity dispersion could be obtained with LiNbO(3) doped with 5 mol.
Abstract: A novel scheme for broadband second-harmonic generation was developed with type I quasi phase matching by use of an off-digital nonlinear optical coefficient d31. This was achieved by matching of the group velocities of the second harmonic and the fundamental, while the phase velocities were quasi phase matched. The desired group-velocity dispersion could be obtained with LiNbO3 doped with 5 mol. % of MgO. Efficient second-harmonic generation with a bandwidth of 52 nm was obtained for the fundamental wavelength centered at 1566 nm in MgO-doped periodically poled LiNbO3, compared with a bandwidth of 1.3 nm for the conventional scheme using d33. Efficient frequency doubling of an ultrafast pulse is expected without group-velocity walk-off or pulse distortion.
TL;DR: This is the first demonstration that syntenin, a PDZ motif-containing protein, can be overexpressed during the metastatic progression of human breast and gastric cancer cells and that it can function as a metastasis-inducing gene.
Abstract: Two human breast cancer cell lines of differing invasive and metastatic potential, MDA-MB-435 and MCF7, were examined using subtractive suppression hybridization in a search for any genes associated with metastasis. Of the 17 cDNAs identified as being differentially expressed genes, it was determined that syntenin was overexpressed in metastatic MDA-MB-435 cells. Expression analysis showed that the expression level of syntenin was well correlated with invasive and metastatic potential in various human breast and gastric cancer cell lines. Moreover, gastric tumor tissues exhibited a much higher syntenin mRNA expression than their normal counterparts. Syntenin-transfected MCF7 cells migrated more actively, and showed an increased invasion rate relative to vector-transfectants or parental MCF7 in vitro, without evidencing any effect on the adhesion to fibronectin, type I collagen and laminin. Similarly, the forced expression of syntenin to human gastric cancer cell line Az521 increased its migratory and invasive potential in vitro. Syntenin-expressing MCF7 cells were associated with the appearance of numerous cell surface extensions and with pseudopodia formation on collagen I, suggesting that syntenin may be involved in the signaling cascade to actin-reorganization. Mutation study suggested that PDZ2 domain of syntenin could be an essential role in its stimulatory effect on the cell migration. This is the first demonstration that syntenin, a PDZ motif-containing protein, can be overexpressed during the metastatic progression of human breast and gastric cancer cells and that it can function as a metastasis-inducing gene.
TL;DR: It was found that witch hazel (Hamamelis virginiana L.) bark showed the strongest effect for scavenging ONOO− of the 28 herbs, and it is suggested that hamamelitannin might be developed as an effective peroxynitrite scavenger for the prevention of ONOO − involved diseases.
Abstract: Peroxynitrite (ONOO(-)) is a cytotoxicant with strong oxidizing properties toward various cellular constituents, including sulphydryls, lipids, amino acids and nucleotides and can cause cell death, lipid peroxidation, carcinogenesis and aging. The aim of this study was to characterize ONOO(-) scavenging constituents from herbs. Twenty-eight herbs were screened for their ONOO(-) scavenging activities with the use of a fluorometric method. The potency of scavenging activity following the addition of authentic ONOO(-) was in the following order: witch hazel bark > rosemary > jasmine tea > sage > slippery elm > black walnut leaf > Queen Anne's lace > Linden flower. The extracts exhibited dose-dependent ONOO(-) scavenging activities. We found that witch hazel (Hamamelis virginiana L.) bark showed the strongest effect for scavenging ONOO(-) of the 28 herbs. Hamamelitannin, the major active component of witch hazel bark, was shown to have a strong ability to scavenge ONOO(-). It is suggested that hamamelitannin might be developed as an effective peroxynitrite scavenger for the prevention of ONOO(-) involved diseases.