Reactions of salts of 1,3,5 triazine dinitromethyl derivatives with nitrogen dioxide that result mainly in 1,3,5 triazinenitrolic acids are investigated. The behavior of nitrolic acid in electroreduction at a mercury drop electrode at various pH was studied; oxygen was shown to accelerate the process. The promoting effect of nitrolic acids on the activity of soluble guanylate cyclase of human platelets was shown. The studied nitrolic acids are active donors of nitric oxide, a universal and important regulator of cell metabolism functions. NO releasing proper ties of furoxans are investigated.At present it is reliably established that nitric oxide (NO) is an intra and intercellular second messenger (neurotransmitter). It plays a key role in regulation of the major biological processes of cardiovascular, gastroen teric, urinogenital, respiratory, central and peripheral ner vous systems. Chemical, biochemical, and pharmaceuti cal aspects of action of nitric oxide donors are considered in detail in recent reviews. 1-8It is known that the formation of NO in an organism in insufficient quantities leads to a number of serious consequences. In this connection, one of the most actively developing now directions 1-6 is the search for various compounds that can serve as NO generators, i.e., xenobiotics, that are transformed with its formation. At present a number of drugs the activity of which is reason ably connected with their ability to liberate NO in vivo is employed in medical practice.The substances containing S , O , N , and C nitroso and nitro groups, viz., diazeniumdiolates, furoxans, NO metal complexes, etc., 6 are related to the compounds showing properties of nitric oxide donors. Among the found NO donors, high efficiency of some oximes 4,6 is noted.Nitrolic acids, RC(=NOH)NO 2 , containing the oxime and nitro groups at the same carbon atom, are interesting class of potential prodrugs. Antithrombotic and hypoten sive activity 9 was shown for some nitrolic acids. Ophthal mologic effects of imidazolenitrolic acids were recently described. 10,11 On the basis of a structure of the nitrolic acids it is logical to suppose that they are capable to gen erate nitric oxide. It is established, for example, that some nitrolic acids decompose with formation of HNO even at room temperature. 5 The basic analytical methods that allow identifi cation of NO are described in detail in a review. 7 The colorimetric method that quantifies the nitrite ion, a marker of NO formation, is one of the most common methods (see Ref. 8). It is this method that is employed in the present work.A review 12 on development of the synthesis methods and the reactivity of mono , di , and trinitromethyl derivatives of 1,3,5 triazines has recently been published.