Insights into Molecular Structure of Pterins Suitable for Biomedical Applications

Abstract

Pterins are an inseparable part of living organisms. Pterins participate in metabolic reactions mostly as tetrahydropterins. Dihydropterins are usually intermediates of these reactions, whereas oxidized pterins can be biomarkers of diseases. In this review, we analyze the available data on the quantum chemistry of unconjugated pterins as well as their photonics. This gives a comprehensive overview about the electronic structure of pterins and offers some benefits for biomedicine applications: (1) one can affect the enzymatic reactions of aromatic amino acid hydroxylases, NO synthases, and alkylglycerol monooxygenase through UV irradiation of H4pterins since UV provokes electron donor reactions of H4pterins; (2) the emission properties of H2pterins and oxidized pterins can be used in fluorescence diagnostics; (3) two-photon absorption (TPA) should be used in such pterin-related infrared therapy because single-photon absorption in the UV range is inefficient and scatters in vivo; (4) one can affect pathogen organisms through TPA excitation of H4pterin cofactors, such as the molybdenum cofactor, leading to its detachment from proteins and subsequent oxidation; (5) metal nanostructures can be used for the UV-vis, fluorescence, and Raman spectroscopy detection of pterin biomarkers. Therefore, we investigated both the biochemistry and physical chemistry of pterins and suggested some potential prospects for pterin-related biomedicine.

Photosensitive Dye as an Ideal Peroxymonosulfate Activator for Efficient Self-Degradation: A Novel Idea of Using Waste to Treat Waste

“…According to the obtained results, the possible mechanism of AG self-activating PMS is proposed ( Figure 9 ). In general, the photooxidation process of photosensitive substances occurs through two mechanisms: (1) electron transfer (type I photooxidation); (2) energy transfer (type II photooxidation) [ 60 , 61 ]. In the type I photooxidation, AG transforms from the ground state to the excited state (AG*) when irradiated by visible light within its light absorption range (Equation (3)) [ 18 , 62 ], and the outer electrons in its HOMO jump into the LUMO.…”

“…Except for the inevitable recombination of electron–hole pairs, part of photo-induced electrons are captured by HSO 5 − to produce SO 4 •− (Equation (4)) [ 43 , 63 ]. The remaining electrons are captured by O 2 to generate O 2 •− (Equation (5)) [ 61 ], but they rapidly react with H 2 O to produce 1 O 2 (Equation (6)). Meanwhile, the other HSO 5 − reacts with HO 2 − to produce 1 O 2 and SO 4 •− (Equation (7)), and most of the SO 4 •− produced via Equations (4) and (7) reacts with OH − or H 2 O to form •OH (Equation (8) or (9)), depending on the pH of the reaction solution, which accounts for the small amount of SO 4 •− in the system.…”

“…•− (Equation ( 5)) [61], but they rapidly react with H 2 O to produce 1 O 2 (Equation ( 6)). Meanwhile, the other HSO 5 − reacts with HO 2 − to produce 1 O 2 and SO 4…”

Harnessing visible light: enhancing TiO2 photocatalysis with photosensitizers for sustainable and efficient environmental solutions

“…Frontiers in Chemical Engineering frontiersin.org photophysical and photochemical reactions, such as fluorescence quenching and charge separation in photovoltaic devices (Speirs et al, 2023;Buglak et al, 2022;El-Khouly et al, 2004). The photosensitization mechanism and the role of electron energy transfer in photosensitizers, including the generation of ROS and the potential for tuning ROS generation through anionization are shown in Figure 7.…”