Anti-free radical activity

This method was used [123] to quantify the anti-free radical activity of 3,4-dihydroxyphenylethyl-4-fonnylmethyl-4-hexenoate (3,4-DHPEA). This product which has been isolated from the leaves of Olea europea is formed from oleuropein during the period of storage of the leaves. Oleuropein derivatives from different extra virgin olive oils (EVOOs), have also been studied as anti-oxidants using the following systems a)... 

Solid microcapsules using maltodextrins or starch as matrices were incorporated into cosmetic, pharmaceutical, dietetic, and food compositions using the interfacial crosslinking of flavonoids. Such microcapsules prevented discoloration while maintaining both the anti-free radical and antioxidant activities of the flavonoids." ... 

G115 extract protects rat heart from iechemia-reperfusion injury G115 extract protects rabbits pulmonary artery from free radical injury G115 extract inhibita dose-dependently lipid peroxidation in rats Activation of the superoxide dismutase gen by Rb2 Scavenging effect of hydroxyl radicals, protection of fatty acids Anti free radical action of Ginsenosides Rb1, Rb2, Rb3, Rc, Rd in rats Antioxidant action in rats (SOD, catalase, glutathionperoxidase)... 

Documented effects A decoction is recommended as a hemostatic for internal uterine bleeding. An acetone-alcohol extract of the herb has been introduced as a hemostatic treatment (Aliev et al. 1972). Zavrazhanov et al. (1977) stated this species has astringent, anti-inflammatory, hemostatic, and sedative properties. The decoction of the herb is used to treat internal and uterine bleeding (Aliev et al. 1972) and also as an anticonvulsant (Fruentov 1972 Akopov 1981). A water extract, as well as a methanol extract and its fractions, were found to have antiviral effect on myxoviruses, herpes virus type 1, vesicular stomatitis and vaccinia virus (Zielinska-Jenczylik et al. 1987). In vivo, a methanol extract injected intravenously induced interferon in mice (Zielinska-Jenczylik et al. 1988). In vitro, low concentrations of a polyphenolic fraction from an extract of the plant stimulated free radical activity of human granulocytes, whereas high concentrations inhibited the activity (Fecka et al. 1997). 

Condensed tannins are flavan dimers or polymers with C-C bonds between different flavan-3-ol units. An example of this is the green tea extract, a vegetable extract frequently used in cosmetics, whose main active compounds are condensed tannins that reach between 17 and 30% of the dry weight of leaves (Katiyar et at, 1999, 2000). The most important ones are flavan-3-ols (catechins) and their condensed forms like (+)-catechin, (—)-epicatechin, (+)-gallocatechin, ( )-epigallocatechin, ( )-epicatechingallate and epi-gallocatechingallate. This extract is used because of the specific actions exerted by active compounds, which include anti-free radical, anti-metalloproteinase, anti-inflammatory and photo-protective actions (Kim et al, 1999 Ahmad and Mukhtar, 2001). 

Diabetic patients have reduced antioxidant defences and suffer from an increased risk of free radical-mediated diseases such as coronary heart disease. EC has a pronounced insulin-like effect on erythrocyte membrane-bound acetylcholinesterase in type II diabetic patients (Rizvi and Zaid, 2001). Tea polyphenols were shown to possess anti-diabetic activity and to be effective both in the prevention and treatment of diabetes (Choi et al, 1998 Yang et al, 1999). The main mechanism by which tea polyphenols appear to lower serum glucose levels is via the inhibition of the activity of the starch digesting enzyme, amylase. Tea inhibits both salivary and intestinal amylase, so that starch is broken down more slowly and the rise in serum glucose is thus reduced. In addition, tea may affect the intestinal absorption of glucose. 

A thrombotic tendency is present in diabetes due to an imbalance between prostacyclin and thromboxane. Lipid peroxides and newly generated free radicals are thought to inhibit the vasodilator and anti-platelet effects of endothelial-derived prostacyclin, but stimulate platelet cyclooxygenase activity, thereby promoting the production of thromboxane A2. This leads to vasoconstriction and platelet aggregation - the concept of peroxide vascular tone (Halliwell and Gutteridge, 1989). 

Yoshikawa, T., Naito, Y., Tanigawa, T. and Kondo, M. (1993). Free radical scavei ng activity of the novel anti-ulcer agent rebamipide studied by electron spin resonance. Arzneim-Forsch. 43, 363-366. 

The major limitation of nitrate therapy is the development of tolerance with continuous use. The loss of anti-anginal effects may occur within the first 24 hours of continuous nitrate therapy. While the cause of tolerance is unclear, several mechanisms have been proposed. These include depletion of the sulfhydryl groups necessary for the conversion of nitrates to nitric oxide, activation of neurohormonal systems, increased intravascular volume, and generation of free radicals that degrade nitric oxide. The most effective method to avoid tolerance and maintain the anti-anginal efficacy of nitrates is to allow a daily nitrate-free interval of at least 8 to 12 hours. Nitrates do not provide protection from ischemia during the nitrate-free period. Therefore, the nitrate-free... 

The second way in which fats deteriorate is oxidative lipolysis. This is an entirely different process in which oxygen free radicals add across double bonds. Oxidative rancidity can be prevented or reduced by several different routes. One way is to ensure that no double bonds are present. Another is to use anti-oxidants that act as free radical traps. Exposure to oxygen and ultraviolet light should be avoided. Reducing the temperature has no effect since free radical processes have a zero activation energy. 

Samuni AM, Barenholz Y. Site-activity relationship of nitroxide radical s anti-oxidative effect. Free Radicals Biol Med 2003 34 177-185. 

By contrast, other compounds in food may decrease cancer risk (Table 21.7). Free radical scavengers such as the antioxidants, vitamins E and C, carotenoids and fla-venoids have anti-cancer activity, while vitamins A and D and other retinoids may encourage a cell to differentiate rather than proliferate (Box 21.4). Plant oestrogens in soya prodncts may be protective since they compete with human oestrogens for the oestrogen receptors in breast and ovary bnt elicit no response. 

Anti-inflammatory activity. Extract of the green seed, administered externally to adult with skin inflammations by free radical inhibition at a concentration of 1%, was active . 

The anti-inflammatory activity of the NSAIDs is mediated chiefly through inhibition of biosynthesis of prostaglandins (Figure 36-2). Various NSAIDs have additional possible mechanisms of action, including inhibition of chemotaxis, down-regulation of interleukin-1 production, decreased production of free radicals and superoxide, and interference with calcium-mediated intracellular events. Aspirin irreversibly acetylates and blocks platelet cyclooxygenase, while most non-COX-selective NSAIDs are reversible inhibitors. 

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