Antioxidants, therapeutic applications

In the context of the theoretically existing problems, a need exists to investigate the antiradical efficacy of compounds independent of pH value or polarity of the solvent, respectively. These problems are particularly relevant in the design of new pharmaceutical antioxidant preparations for specialized therapeutic applications. 

Another possibility for therapeutic application of polymer vesicles has been presented recently [242], Superoxide dismutase, an antioxidant enzyme, was encapsulated in the vesicular cavity and shown to remain functional in neutralizing superoxide radicals in situ. The polymer membranes were proven permeable to superoxide radicals by pulse radiolysis, and the encapsulation of the enzyme prolongs its lifetime (which is only minutes in the bloodstream, when non-shielded). 

It has frequently been reported that the antimicrobial activities of many naturally occurring phenolic compounds in fruits play an important role in their protection against pathogenic microorganisms. It has been suggested that the hy-products of tropical fruit production contain high levels of essential healthy compounds which can be extracted and used for many therapeutic applications of these by-products, phenolic compounds have shown both antimicrobial and antioxidant activities. 

Large quantities of polysaccharides are available in nature and many of them display a variety of biological functions [1 ]. There is an abundance of literature on the isolation of bioactive polysaccharides from botanical sources [1-5]. This area of research has attracted a lot of interest due to the fact that most of the bioactive polysaccharides are nontoxic with minimal side effects [4,5]. Hence, this class of biopolymers forms ideal candidates for therapeutic applications. Some of the notable bioactivities of botanical polysaccharides include antioxidant, immunomodulatory, and antitumor properties [4-10]. However, the mechanism of action of these biopolymers is not well understood. In general, one of the primary mechanisms of action of polysaccharides is nonspecific immunomodulation [8]. The key mechanism behind the immunomodulatory, anticancer, antibacterial, and other pharmacological activities of plant polysaccharides is to activate macrophages, which then leads to modulation of the complement system that activates the cells involved in innate immunity and improves host defense [1—4,11,12]. 

From their results one can see that the cultivar with the highest amounts of total anthocyanins is Rubini which also contains high amounts of quercetins, especially quercetin 3-rutinoside, a compound with important antioxidant activity and therapeutic applications. 

Bonavida, B., Baritaki, S., Huerta-Yepez, S., Vega, M.I., Chatterjee, D., and Yeung, K. (2008). Novel therapeutic applications of nitric oxide donors in cancer roles in chemo- and immunosensitization to apoptosis and inhibition of metastases. Nitric Oxide 19, 152-157. Bracht, K., Liebeke, M., Ritter, C.A., Griinert, R., and Bednarski, P.J. (2007). Correlations between the activities of 19 standard anticancer agents, antioxidative enzyme activities and the expression of ATP-binding cassette transporters comparison with the National Cancer Institute data. Anticancer Drugs 18, 389 04. 

Free-radical generation occurs normally in the human body, and rates of free-radical generation are probably increased in most diseases (see Table 13.1). Their importance as a mechanism of tissue injury is still uncertain, largely because the assays used to measure them have, until recently, been primitive. The development of new assays applicable to humans (such as the assays of oxidative DNA damage described above) should allow rapid evaluation of the role of free radicals in disease pathology and provide a logical basis for the therapeutic use of antioxidants. A rationale is presented in Fig. 13.3. Attempts to use antioxidants in the treatment of human disease can be divided into three main areas ... 

At present, many natural and synthetic chelators have been studied as potential pharmacological agents for the treatment of iron or copper overload under various pathophysiological conditions. (The chelating activity of flavonoids was already discussed above and the application of chelators in thalassemia and some other pathologies is considered in Chapter 31.) There are specific thermodynamic demands to chelators to be efficient antioxidants [369], We will consider just several chelators of potential therapeutic importance. 

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