Free Radicals in Biochemistry and Medicine

Halliwell, Barry

doi:10.1002/3527600906.mcb.200300036

Cited by 21 publications

(7 citation statements)

References 45 publications

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“…The qualitative conclusions drawn here are equally applicable to atmospheric jets or streamer systems in which the ionic wind plays a key role in momentum transport. Moreover, we postulate that the steep gradients in highly reactive neutral species concentrations at the gas-liquid interface shown in the proceeding section are a universal phenomena of atmospheric plasma-liquid systems, regardless of whether they are convective or diffusive; this is consistent with the recent research by [18] as well as the greater reservoir of biochemistry literature [21]. Morever, these gradients have important implications for plasma medicine, mainly that cellular responses must be induced through secondary as opposed to directly generated plasma reactivity.…”

Section: Introductionsupporting

confidence: 84%

“…Perhaps the most interesting result of the study is the sharp distinction between reactivity at the surface and in the liquid bulk. Though the limited penetration (tens of µm or less) of reactive neutral radicals is well publicized in prominent biochemistry texts like [21], this phenomena has yet to receive significant attention in the plasma-liquid literature with the exception of [18]. Concentrations of species of interest for plasma-medicine and other applications (e.g.…”

Section: Resultsmentioning

confidence: 99%

“…In the liquid near the interface, OH concentrations fall by as many as 9 orders of magnitude over tens of microns. Though the existence of strong gradients in aqueous radical concentrations is well known in the biochemistry literature, [20,21], it has yet to receive significant attention in the plasma-liquid and plasma-medicine communities. Reference [18] explicitly models the limited penetration of primary plasma-generated species into aqueous solutions.…”

Section: Introductionmentioning

confidence: 99%

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Momentum, heat, and neutral mass transport in convective atmospheric pressure plasma-liquid systems and implications for aqueous targets

Lindsay

Anderson

Slikboer

et al. 2015

J. Phys. D: Appl. Phys.

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There is a growing interest in the study of plasma-liquid interactions with application to biomedicine, chemical disinfection, agriculture, and other fields. This work models the momentum, heat, and neutral species mass transfer between gas and aqueous phases in the context of a streamer discharge; the qualitative conclusions are generally applicable to plasma-liquid systems. The problem domain is discretized using the finite element method. The most interesting and relevant model result for application purposes is the steep gradients in reactive species at the interface. At the center of where the reactive gas stream impinges on the water surface, the aqueous concentrations of OH and ONOOH decrease by roughly 9 and 4 orders of magnitude respectively within 50 µm of the interface. Recognizing the limited penetration of reactive plasma species into the aqueous phase is critical to discussions about the therapeutic mechanisms for direct plasma treatment of biological solutions. Other interesting results from this study include the presence of a 10 K temperature drop in the gas boundary layer adjacent to the interface that arises from convective cooling and water evaporation. Accounting for the resulting difference between gas and liquid bulk temperatures has a significant impact on reaction kinetics; factor of two changes in terminal aqueous species concentrations like H 2 O 2 , NO − 2 , and NO − 3 are observed if the effect of evaporative cooling is not included.The convective system chosen for modelling is shown in fig. 1. It is essentially a point-to-plane pulsed-streamer in which the liquid surface serves as the gas discharge cathode. The streamer is self-pulsed because of a ballasting resistor; typical discharge voltages are between 6 and 8 kV and pulse frequencies are generally 10 to 30 kHz. The sharp anode tip can be stationed anywhere between 3 and 15 mm above the water surface. The water is contained within a glass petri dish of radius 3 cm; water treatment volumes are generally between 10 and 20 mL.

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Section: Introductionsupporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Momentum, heat, and neutral mass transport in convective atmospheric pressure plasma-liquid systems and implications for aqueous targets

Lindsay

Anderson

Slikboer

et al. 2015

J. Phys. D: Appl. Phys.

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“…The similarity in the results between FTC and TBA suggests the reliability of the results. In the context of toxicity, despite the fact that hydrogen peroxide is unreactive in the body systems, it may be toxic to cells, inhibiting cell functioning abilities by yielding hydroxyl radicals [ 32 ]. In this regard, elimination of hydrogen peroxide is considered a crucial antidetoxification process [ 33 ].…”

Section: Discussionmentioning

confidence: 99%

Anti‐HMG‐CoA Reductase, Antioxidant, and Anti‐Inflammatory Activities of Amaranthus viridis Leaf Extract as a Potential Treatment for Hypercholesterolemia

Salvamani

Gunasekaran

Shukor

et al. 2016

Evidence-Based Complementary and Alternative Medicine

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Inflammation and oxidative stress are believed to contribute to the pathology of several chronic diseases including hypercholesterolemia (elevated levels of cholesterol in blood) and atherosclerosis. HMG-CoA reductase inhibitors of plant origin are needed as synthetic drugs, such as statins, which are known to cause adverse effects on the liver and muscles. Amaranthus viridis (A. viridis) has been used from ancient times for its supposedly medically beneficial properties. In the current study, different parts of A. viridis (leaf, stem, and seed) were evaluated for potential anti-HMG-CoA reductase, antioxidant, and anti-inflammatory activities. The putative HMG-CoA reductase inhibitory activity of A. viridis extracts at different concentrations was determined spectrophotometrically by NADPH oxidation, using HMG-CoA as substrate. A. viridis leaf extract revealed the highest HMG-CoA reductase inhibitory effect at about 71%, with noncompetitive inhibition in Lineweaver-Burk plot analysis. The leaf extract showed good inhibition of hydroperoxides, 2,2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO), and ferric ion radicals in various concentrations. A. viridis leaf extract was proven to be an effective inhibitor of hyaluronidase, lipoxygenase, and xanthine oxidase enzymes. The experimental data suggest that A. viridis leaf extract is a source of potent antioxidant and anti-inflammatory agent and may modulate cholesterol metabolism by inhibition of HMG-CoA reductase.

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“…In higher plants, this energy is readily obtained from light quanta via such transfer molecules as chlorophyll. Unless abated, all of these intermediate oxygen species are extremely reactive and cytotoxic in all organisms (9,13). ROS can interact with proteins, lipids, and nucleic acids to cause severe molecular damage (Table 2).…”

Section: O 2 Ros and Oxygen Toxicitymentioning

confidence: 99%

Oxidative stress: molecular perception and transduction of signals triggering antioxidant gene defenses

2005

Braz J Med Biol Res

974

470

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Molecular oxygen (O 2 ) is the premier biological electron acceptor that serves vital roles in fundamental cellular functions. However, with the beneficial properties of O 2 comes the inadvertent formation of reactive oxygen species (ROS) such as superoxide (O 2 •-), hydrogen peroxide, and hydroxyl radical (OH • ). If unabated, ROS pose a serious threat to or cause the death of aerobic cells. To minimize the damaging effects of ROS, aerobic organisms evolved non-enzymatic and enzymatic antioxidant defenses. The latter include catalases, peroxidases, superoxide dismutases, and glutathione S-transferases (GST). Cellular ROS-sensing mechanisms are not well understood, but a number of transcription factors that regulate the expression of antioxidant genes are well characterized in prokaryotes and in yeast. In higher eukaryotes, oxidative stress responses are more complex and modulated by several regulators. In mammalian systems, two classes of transcription factors, nuclear factor κB and activator protein-1, are involved in the oxidative stress response. Antioxidant-specific gene induction, involved in xenobiotic metabolism, is mediated by the "antioxidant responsive element" (ARE) commonly found in the promoter region of such genes. ARE is present in mammalian GST, metallothioneine-I and MnSod genes, but has not been found in plant Gst genes. However, ARE is present in the promoter region of the three maize catalase (Cat) genes. In plants, ROS have been implicated in the damaging effects of various environmental stress conditions. Many plant defense genes are activated in response to these conditions, including the three maize Cat and some of the superoxide dismutase (Sod) genes. Correspondence

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Free Radicals in Biochemistry and Medicine

Cited by 21 publications

References 45 publications

Momentum, heat, and neutral mass transport in convective atmospheric pressure plasma-liquid systems and implications for aqueous targets

Momentum, heat, and neutral mass transport in convective atmospheric pressure plasma-liquid systems and implications for aqueous targets

Anti‐HMG‐CoA Reductase, Antioxidant, and Anti‐Inflammatory Activities of Amaranthus viridis Leaf Extract as a Potential Treatment for Hypercholesterolemia

Oxidative stress: molecular perception and transduction of signals triggering antioxidant gene defenses

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