Singlet Oxygen (O2(1Dg)) Quenching by Dihydropterins

M. LAURA DÁNTOLA; ANDRÉS H. THOMAS; ANDRÉ M. BRAUN; ESTHER OLIVEROS; CAROLINA LORENTE

JOURNAL OF PHYSICAL CHEMISTRY A

American Chemical Society

Año: 2007 vol. 111 p. 4280 - 4288

1089-5639

Pterins belong to a class of heterocyclic compounds present in a wide range of living systems. They participate in relevant biological functions and are involved in different photobiological processes. Dihydropterins are one of the biologically active forms of pterins. The photoinduced production and quenching of singlet oxygen (1O2) by a series of dihydropterins (7,8-dihydrobiopterin (DHBPT), 7,8-dihydroneopterin (DHNPT), 6-formyl- 7,8-dihydropterin (FDHPT), sepiapterin (SPT), 7,8-dihydrofolic acid (DHFA), and 7,8-dihydroxanthopterin (DHXPT)) in aqueous solution at physiological pH (7) were investigated, and the quantum yields of 1O2 7,8-dihydropterin (FDHPT), sepiapterin (SPT), 7,8-dihydrofolic acid (DHFA), and 7,8-dihydroxanthopterin (DHXPT)) in aqueous solution at physiological pH (7) were investigated, and the quantum yields of 1O2 7,8-dihydropterin (FDHPT), sepiapterin (SPT), 7,8-dihydrofolic acid (DHFA), and 7,8-dihydroxanthopterin (DHXPT)) in aqueous solution at physiological pH (7) were investigated, and the quantum yields of 1O2 1O2) by a series of dihydropterins (7,8-dihydrobiopterin (DHBPT), 7,8-dihydroneopterin (DHNPT), 6-formyl- 7,8-dihydropterin (FDHPT), sepiapterin (SPT), 7,8-dihydrofolic acid (DHFA), and 7,8-dihydroxanthopterin (DHXPT)) in aqueous solution at physiological pH (7) were investigated, and the quantum yields of 1O27) were investigated, and the quantum yields of 1O2 production (¼¢) and rate constants of total quenching (kt) of 1O2 were determined. Studied compounds do not produce 1O2 under UV-A irradiation and are very efficient 1O2 quenchers. The chemical reactions between not produce 1O2 under UV-A irradiation and are very efficient 1O2 quenchers. The chemical reactions between not produce 1O2 under UV-A irradiation and are very efficient 1O2 quenchers. The chemical reactions between ¼¢) and rate constants of total quenching (kt) of 1O2 were determined. Studied compounds do not produce 1O2 under UV-A irradiation and are very efficient 1O2 quenchers. The chemical reactions between1O2 under UV-A irradiation and are very efficient 1O2 quenchers. The chemical reactions between 1O2 and dihydropterin derivatives were investigated, and the corresponding rate constants (kr) were found to be particularly high. The oxidized pterin derivatives, biopterin (BPT), neopterin (NPT), 6-formylpterin (FPT), and folic acid (FA), were identified and quantified during the reaction of 1O2 with DHBPT, DHNPT, FDHPT, and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. be particularly high. The oxidized pterin derivatives, biopterin (BPT), neopterin (NPT), 6-formylpterin (FPT), and folic acid (FA), were identified and quantified during the reaction of 1O2 with DHBPT, DHNPT, FDHPT, and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. be particularly high. The oxidized pterin derivatives, biopterin (BPT), neopterin (NPT), 6-formylpterin (FPT), and folic acid (FA), were identified and quantified during the reaction of 1O2 with DHBPT, DHNPT, FDHPT, and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. O2 and dihydropterin derivatives were investigated, and the corresponding rate constants (kr) were found to be particularly high. The oxidized pterin derivatives, biopterin (BPT), neopterin (NPT), 6-formylpterin (FPT), and folic acid (FA), were identified and quantified during the reaction of 1O2 with DHBPT, DHNPT, FDHPT, and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed. 1O2 with DHBPT, DHNPT, FDHPT, and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of nonpterinic products, was identified. Mechanisms and biological implications are discussed.