Naslov
Bond dissociation free energy as a general parameter for flavonoid radical scavenging activity

Autori
Stepanić, Višnja ; Gall Trošelj, Koraljka ; Lučić, Bono ; Marković, Zoran ; Amić, Dragan

Izvornik
Food chemistry (0308-8146) 141 (2013), 2; 1562-1570

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
flavonoid ; radical scavenging ; bond dissociation free energy ; HAT ; SPLET

Sažetak
Notwithstanding multiple mechanisms of radical scavenging (RS), measured RS activities (RSA) of flavonoids are usually related to O-H bond dissociation enthalpy (BDE) for hydrogen atom transfer (HAT). For 12 flavonoids the reaction free energies were calculated for: (1) HAT, (2) single electron transfer - proton transfer (SET-PT) and (3) sequential proton loss electron transfer (SPLET) in gas and aqueous phases. Aqueous free energies, like bond dissociation (BDFEaq), ionization (IFEaq) and deprotonation (ΔGdeprot, aq) free energies were estimated using thermochemical cycles. While in gas HAT is a RS mechanism (BDFEg < IFEg < ΔGdeprot, g), in water SPLET can be concurrent or dominant mechanism depending upon pH since ΔGdeprot, aq < BDFEaq and ETFEaq ≤ BDFEaq. For 12 flavonoids, BDFEaq has been correlated with ΔGdeprot, aq and ETFEaq with r = 0.74 and 0.87 respectively. This reveals why BD(F)E parameter explains most of variance in variously measured RSA data even if the underlying mechanism is SPLET.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Temeljne medicinske znanosti

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