Beckman, Kenneth B., and Bruce N. Ames. The Free Radical Theory of Aging Matures. Physiol. Rev. 78: 547–581, 1998. — The free radical theory of aging, conceived in 1956, has turned 40 and is rapidl...

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The Free Radical Theory of Aging Matures

A good number of abstracts and research articles (in total 74) published, so far, for evaluating antioxidant activity of various samples of research interest were gone through where 407 methods were come across, which were repeated from 29 different methods. These were classified as in vitro and in vivo methods. And those are described and discussed below in this review article. In the later part of this review article, frequency of in vitro as well as in vivo methods is analyzed with a bar diagram. Solvents are important for extracting antioxidants from natural sources. Frequency of solvents used for extraction is also portrayed and the results are discussed in this article. As per this review there are 19 in vitro methods and 10 in vivo methods that are being used for the evaluation of antioxidant activity of the sample of interest. DPPH method was found to be used mostly for the in vitro antioxidant activity evaluation purpose while LPO was found as mostly used in vivo antioxidant assay. Ethanol was with the highest frequency as solvent for extraction purpose.

Review on in vivo and in vitro methods evaluation of antioxidant activity.

A vast amount of circumstantial evidence implicates oxygen-derived free radicals (especially superoxide and hydroxyl radical) and high-energy oxidants (such as peroxynitrite) as mediators of inflammation, shock, and ischemia/reperfusion injury. The aim of this review is to describe recent developments in the field of oxidative stress research. The first part of the review focuses on the roles of reactive oxygen species (ROS) in shock, inflammation, and ischemia/reperfusion injury. The second part of the review deals with the novel findings using recently identified pharmacological tools (e.g., peroxynitrite decomposition catalysts and selective superoxide dismutase mimetics (SODm) in shock, ischemia/reperfusion, and inflammation. 1) The role of ROS consists of immunohistochemical and biochemical evidence that demonstrates the production of ROS in shock, inflammation, and ischemia/reperfusion injury. ROS can initiate a wide range of toxic oxidative reactions. These include initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3-phosphate dehydrogenase, inhibition of membrane sodium/potassium ATPase activity, inactivation of membrane sodium channels, and other oxidative modifications of proteins. All these toxicities are likely to play a role in the pathophysiology of shock, inflammation, and ischemia/reperfusion. 2) Treatment with either peroxynitrite decomposition catalysts, which selectively inhibit peroxynitrite, or with SODm, which selectively mimic the catalytic activity of the human superoxide dismutase enzymes, have been shown to prevent in vivo the delayed vascular decompensation and the cellular energetic failure associated with shock, inflammation, and ischemia/reperfusion injury. ROS (e.g., superoxide, peroxynitrite, hydroxyl radical, and hydrogen peroxide) are all potential reactants capable of initiating DNA single-strand breakage, with subsequent activation of the nuclear enzyme poly(ADP-ribose) synthetase, leading to eventual severe energy depletion of the cells and necrotic-type cell death. Antioxidant treatment inhibits the activation of poly(ADP-ribose) synthetase and prevents the organ injury associated with shock, inflammation, and ischemia/reperfusion.

Antioxidant Therapy: A New Pharmacological Approach in Shock, Inflammation, and Ischemia/Reperfusion Injury

The generation of reactive oxygen species (ROS) and other free radicals (R) during metabolism is a necessary and normal process that ideally is compensated for by an elaborate endogenous antioxidant system. However, due to many environmental, lifestyle, and pathological situations, excess radicals can accumulate, resulting in oxidative stress. Oxidative stress has been related to cardiovascular disease, cancer, and other chronic diseases that account for a major portion of deaths today. Antioxidants are compounds that hinder the oxidative processes and thereby delay or prevent oxidative stress. This article examines the process of oxidative stress and the pathways by which it relates to many chronic diseases. We also discuss the role that endogenous and exogenous antioxidants may play in controlling oxidation and review the evidence of their roles in preventing disease.

Antioxidants and Prevention of Chronic Disease

Because curcumin, a compound with anti-inflammatory and anticancer activity, inhibits induction of nitric oxide synthase in activated macrophages and has been shown to be a potent scavenger of free radicals we have investigated whether it can scavenge nitric oxide directly. Curcumin reduced the amount of nitrite formed by the reaction between oxygen and nitric oxide generated from sodium nitroprusside. Other related compounds, e.g. demethoxycurcumin, bisdemethoxycurcumin and diacetylcurcumin were as active as curcumin, indicating that the methoxy and the phenolic groups are not essential for the scavenging activity. The results indicate curcumin to be a scavenger of nitric oxide. Because this compound is implicated in inflammation and cancer, the therapeutic properties of curcumin against these conditions might be at least partly explained by its free-radical scavenging properties, including those toward nitric oxide.

Nitric Oxide Scavenging by Curcuminoids

The nitric oxide-scavenging properties of Ginkgo biloba extract EGb 761.

Extracts from the leaves of Ginkgo biloba trees have been used therapeutically for centuries in traditional Chinese medicine, and in modern Chinese pharmacopoeias both the leaves and fruits are recommended for treating problems of heart and lungs. EGb 761 is a dry, powdered extract prepared from Ginkgo biloba leaves. It is a standardized mixture of several different chemical constituents; its two major classes of compounds are flavonoid glycosides and terpenoids (Drieu 1986; DeFeudis 1991). The flavonoid fraction is mainly composed of three flavonols: quercetin, kaempferol, and isorhamnetin, which are linked to a sugar(DeFeudis 1991). The terpenoid fraction is composed of ginkgolides and bilobalides(Drieu 1988). It also contains some organic acids, which help make it water-soluble(Drieu 1986).

Antioxidant action of Ginkgo biloba extract EGb 761.

Publisher Summary Extracts of Ginkgo biloba leaves (EGb 761) are complex titrated, standardized mixtures of active ingredients introduced into medical practice as polyvalent therapeutic agents. This chapter discusses the radical scavenging properties of EGb 761, in several in vitro systems. The interaction of EGb 761 with superoxide and hydroxyl radicals generated by using the water radiolysis method is presented in the chapter. The method of radiolysis is useful because it specifically generates superoxide and hydroxyl radicals in known quantities, thus reducing the risk of possible interferences. To evaluate the role of terpenes contained in EGb 761, a comparative study is described using CP 202, a similar mixture lacking the terpene fraction. The interaction of EGb 761 with peroxyl radicals is assayed by a chemiluminescent method. The interaction of EGb 761 with nitric oxide is assessed by two different spectrophotometric methods. Finally, the effect of EGb 761 on xanthine oxidase activity is described.

Marie-Thérèse Droy-Lefaix

Papers

The nitric oxide-scavenging properties of Ginkgo biloba extract EGb 761.

Antioxidant action of Ginkgo biloba extract EGb 761.

[46] Antioxidant action of Ginkgo biloba extract EGb 761

A Ginkgo Biloba Extract (EGb 761) Prevents Mitochondrial Aging by Protecting Against Oxidative Stress

Effects of natural antioxidant ginkgo biloba extract (EGB 761) on myocardial ischemia-reperfusion injury.