Репозиторий Университета

© 2019, Springer Science+Business Media, LLC, part of Springer Nature. Here, I present the data testifying that the conversion of free radical NO molecules to nitrosonium ions (NO+), which are necessary for the realization of one of NO biological effects (S-nitrosation), may occur in living organisms after binding NO molecules to loosely bound iron (Fe2+ ions) with the subsequent mutual one-electron oxidation–reduction of NO molecules (their disproportionation). Inclusion of thiol-containing substances as iron ligands into this process prevents hydrolysis of NO+ ions bound to iron thus providing the formation of stable dinitrosyl iron complexes (DNIC) with thiol ligands. Such complexes act in living organisms as donors of NO and NO+, providing stabilization and transfer of these agents via the autocrine and paracrine pathways. Without loosely bound iron (labile iron pool) and thiols participating in the DNIC formation, NO functioning as one of universal regulators of diverse metabolic processes would be impossible.

© 2018 Journal of Pharmaceutical Negative Results. Objective: The objective was to compare the complex formation of flavones (luteolin, apigenin), flavonols (morin, quercetin, and rutin), flavanones (naringenin), flavanonols (dihydroquercetin), caffeic, and ferulic acids with aluminum ion using two spectrophotometric methods and the application of these methods to estimate the flavonoid content in the angionorm herbal product. Materials and Methods: Method 1 included direct complex formation with aluminum chloride, and Method 2 involved preliminary nitrozation and subsequent complex formation of nitroso-derivatives with aluminum chloride. 2,4-dinitrophenylhydrazine method was also tested. Results: The conjugation system increase in the chromophore structure of nitroso derivatives is reflected by the hyperchromic effect of all substances (from 1.4 to 4-fold). The largest bathochromic shift of nitroso derivatives was seen for rutin, luteolin, and dihydroquercetin (to 510-530 nm). The total flavonoids estimation in the extract of the four herbs mixture, which constitute angionorm preparation active ingredient, depends on the chosen reference substance (3.49% calculated as luteolin when measured by Method 1 or 8.71% by Method 2; 7.97% calculated as dihydroquercetin when measured by Method 1 and 4.14% by Method 2. Conclusion: The complex formation according to Methods 1 and 2 does not allow the identification of the selective spectral regions typical for the certain flavonoids subgroups and hydroxycinnamic acids. Neither method of complex formation is suitable for the assay of total flavonoids in unknown samples or for the flavonoid content comparison in the different herbal material.