PURPOSE: To investigate the potential antioxidative role of carnosine (beta-alanyl-L-histidine) through its interaction with radiation induced radicals. MATERIALS AND METHODS: Pulse radiolysis experiments were performed by a 12 MeV electron linear accelerator (LINAC) on carnosine aqueous solutions at different pHs. The Raman spectra of solid samples were obtained by a Bruker IFS 66 spectrometer. RESULTS: The protonation state of the imidazole ring was observed to affect the site(s) of .OH attack on carnosine as well as the decay rates of the resulting adducts. Reasonably, a base catalysed water elimination from the adducts leading to a resonance-stabilized radical, which absorbs at lambda = 270 nm, takes place. Raman spectra in slightly alkaline medium have indicated that carnosine is mainly present as tautomer I and, of consequence, positions C(2) and C(4) of the imidazole ring are the preferential sites for .OH attack. CONCLUSIONS: These studies have shown that carnosine is a good scavenger of .OH radicals giving rise to a quite stable intermediate which should be less reactive towards other biological components than .OH itself. Raman data have been helpful in predicting the preferential sites for the .OH attack.
A pulse radiolysis study of carnosine in aqueous solution
M Tamba;A Torreggiani
1998
Abstract
PURPOSE: To investigate the potential antioxidative role of carnosine (beta-alanyl-L-histidine) through its interaction with radiation induced radicals. MATERIALS AND METHODS: Pulse radiolysis experiments were performed by a 12 MeV electron linear accelerator (LINAC) on carnosine aqueous solutions at different pHs. The Raman spectra of solid samples were obtained by a Bruker IFS 66 spectrometer. RESULTS: The protonation state of the imidazole ring was observed to affect the site(s) of .OH attack on carnosine as well as the decay rates of the resulting adducts. Reasonably, a base catalysed water elimination from the adducts leading to a resonance-stabilized radical, which absorbs at lambda = 270 nm, takes place. Raman spectra in slightly alkaline medium have indicated that carnosine is mainly present as tautomer I and, of consequence, positions C(2) and C(4) of the imidazole ring are the preferential sites for .OH attack. CONCLUSIONS: These studies have shown that carnosine is a good scavenger of .OH radicals giving rise to a quite stable intermediate which should be less reactive towards other biological components than .OH itself. Raman data have been helpful in predicting the preferential sites for the .OH attack.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
