A pulse radiolysis study of carnosine in aqueous solution.
OBJECTIVE
To investigate the potential antioxidative role of carnosine (beta-alanyl-L-histidine) through its interaction with radiation induced radicals.


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.
Tamba
M
M
Istituto F.R.A.E., (C.N.R.), Bologna, Italy.
Torreggiani
A
A
D002336:Carnosine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D016877:Oxidants / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D011675:Pulse Radiolysis; D012996:Solutions; D013059:Spectrum Analysis, Raman
D016877:Oxidants; D012996:Solutions; D017665:Hydroxyl Radical; D002336:Carnosine; D010100:Oxygen