Author/Editor		Umek, Nejc
Title		Cyclization step of noradrenaline and adrenaline autoxidation
Type		članek
Vol. and No.		, št. Vol. 10
Publication year		2020
Volume		str. str.16650-16658
ISSN		2046-2069 - RSC advances
Language		eng
Abstract		Catecholamine autoxidation has been recognized as one of the potential trigger factors for catecholaminergic neuron loss characteristics of neurodegenerative diseases. The cyclization step with intramolecular Michael addition of catecholamine o-quinones has been shown to be the irreversible and rate limiting step of the autoxidation reaction across a broad pH range and has a complex pH dependence that has not yet been fully understood. Using quantum chemical calculations, we demonstrated that in the case of noradrenaline and adrenaline two catecholamine o-quinone species, one with an unprotonated and one with a protonated quinone group can participate in the cyclization reaction and that the mechanisms of these reactions significantly differ, emphasizing the importance of quinone group protonation states in the reaction mechanism. With a thorough exploration of the reaction kinetics, we further showed that at acidic pH the cyclization reaction rate is pH independent, while at alkaline pH the pH dependence is marked, explaining the experimentally observed complex pH dependence.
Keywords		kateholamin noradrenalin in adrenalin reakcijska kinetika catecholamine noradrenaline and adrenaline reaction kinetics