Oxygen radical scavenging property

Low bone density is also associated with oxidative stress in lower species. Thus, in ovariectomized rats melatonin has a bone-protective effect, which depends in part on its free radical-scavenging properties (Cardinali et al., 2003). A mouse model that has been used to study the role of ROS in age-related disorders including osteoporosis is the accelerated mouse-senescence-prone P/2 (SAM-P/2) that generates increased oxygen radicals (Hosokawa, 2002 Udagawa, 2002). This model could be very useful in studying the role of lycopene in osteoporosis. 

The presence of dissolved oxygen alters the nature of the redox properties of irradiated water. This is a consequence of the radical scavenging property of oxygen. Molecular oxygen has two unpaired electrons. One of these can form a covalent bond with a hydrogen atom, forming the hydroperoxy radical... 

There are many studies about the relation between the free oxygen radical scavenging activities of many flavonoids and their effects on the enzymes which take part in the metabolism of arachidonic acid, cyclooxygenase (COX) and lipoxygenase (LOX). Duneic [182] shows that the antiradical action affects the COX activity in several ways. In most of the cases, at high substrate concentrations the enzymatic activity was intensified and at low concentrations it was inhibited. Apparently, the influence of the antiradical properties on the activity of enzymatic metabolism of the arachidonic acid in vitro might also be due to the effect of these agents on the active center of the enzymes. 

The physiological activity of the T. is based on their radical scavenging properties, they are of major importance in cell membranes and lipoproteins as antioxidants. Long-term supplementation with a-T. can reduce the incidence of certain forms of cancer. T. are pale yellow, viscous oils. They are oxidized by atmospheric oxygen in the presence of metal ions or under the action of light. T. occur in plant oils seed oils of soya, wheat, com, rice, cotton, alfalfa, and nuts are particularly rich in T. Fruits and vegetables such as raspberries, legumes, fennel, paprika and celery also con-... 

In addition to their broncho dilatory action in asthma, P-agonistically active substances of diphe-nolic structure offer radical scavenging properties toward reactive oxygen species as shown in a model system by electron paramagnetic resonance spectroscopy and photometric approaches (Zwicker et al. 1998). The substances under study showed activity in superoxide radical scavenging under aprotic and protic conditions as well. The efficiency of the reaction decreased in the order fenoterol > salbuta-mol > reproterol > terbutaline > oxyfedrine when 5,5-dimethyl-l-pyrroline-N-oxide (DMSO) was used as an aprotic solvent. In an aqueous system, the rate constants decreased in the order fenoterol > reproterol > salbutamol. 

Chemical, biological, and pharmacological properties of lipoic acid as well as its therapeutic effects in several diseases (diabetes mellitus, liver cirrhosis, polyneuritis, etc.) are reviewed [198,199], It is evident from the chemical structures of LA and DHLA that only DHLA may be an efficient scavenger of all oxygen radicals, while LA should be active only in the reactions with highly reactive hydroxyl radicals. On the other hand, DHLA must be easily... 

The production of superoxide anions is one of the major factors involved in NO toxicity because superoxide anions can react with NO to form the highly toxic free-radical peroxynitrite. A pivotal role for superoxide anions in NO-related insults is emphasized by results showing that transgenic mice overexpressing superoxide dismutase (SOD) are resistant to brain ischemia. Superoxide can protect against SNP-induced toxicity. Thus, the superoxide-scavenging properties of EGb 761 are likely to explain, at least in part, its ability to block cell death and the increase in reactive oxygen species accumulation induced by the two NO donors used here, SNP and SIN-1. 

B. Cammerer, I. J. Fuchs, and L. W. Kroh, Antioxidative activity of melanoidins — radical and oxygen scavenging properties, in Melanoidins in Food and Health, Vol. 2, J. M. Ames (ed), European Communities, Luxembourg, 2001, 159-164. 

---