ИСТИНА

It is considered that oxidative stress leads to damage of the intracellular and extracellular components, proteins, lipids, and nucleic acids, promoting the development of various diseases and accelerating the aging process. The potential of antioxidants to prevent oxidative processes in the living organism has therefore attracted much attention. The detection and measurement of lipid peroxidation (LP) level is most frequently used as a marker of oxidative stress degree. Usually only one or two methods of antioxidant activity determination are applied for each compound under investigation. The aim of our study is the all-round evaluation of antioxidant activity of physiologically active compounds. The comparative analysis of various organic, organometallic and coordination compounds has been performed using following methods: DPPH-test, CUPRAC, scavenging activity of superoxide radical-anion generated by xanthine/xanthine oxidase, in vitro LP in liver homogenates and ex vivo LP in rat brain and rat liver mitochondria. A special attention has been paid to lipoxygenase inhibition activity of tested compounds. The following antioxidant candidates were studied: ferrocenes and dipicolylamine (DPA) complexes of biometals (Fe, Co, Cu, Mn, Ni, Zn) bearing antioxidative 2,6-di-tert-butylphenol and 2,6-di-isobornylphenol fragments; and antimony(III) iodide complexes of the heterocyclic thioamides. Antioxidant capasity assays may be broadly classified as electron transfer (ET) and hydrogen atom transfer assays according to the mechanism of antioxidant effect. DPPH-test is a model reaction of hydrogen atom transfer. Superoxide radical-anion scavenging activity and CUPRAC method show the capasity of an antioxidant to be involved in ET mechanism. In vitro LP inhibition includes hydrogen transfer to peroxyl radicals of fatty acids. Conversion of arachidonic acid via the lipoxygenase pathway is associated with a production of ROS. Antioxidants may interact non-specifically with lipoxygenase by scavenging radical intermediates and/or reducing the active site. Thus, the impact of antioxidant on the lypoxygenase activity might be considered as a more sophisticated biotest. Therefore, there is a strong necessity to consider all the mechanistic pathways responsible for the antioxidant effect.The most promising candidates were choosen according to the activity in all processes studied.