Low-energy electron interaction with retusin extracted from Maackia amurensis: towards a molecular mechanism of the biological activity of flavonoids

Abstract

The antioxidant isoflavone retusin efficiently attaches low-energy electrons in vacuo, generating fragment species via dissociative electron attachment (DEA), as has been shown by DEA spectroscopy. According to in silico results obtained by means of density functional theory, retusin is able to attach solvated electrons and could be decomposed under reductive conditions in vivo, for instance, near the mitochondrial electron transport chain, analogous to gas-phase DEA. The most intense decay channels of retusin temporary negative ions were found to be associated with the elimination of H atoms and H2 molecules. Doubly dehydrogenated fragment anions were predicted to possess a quinone structure. It is thought that molecular hydrogen, known for its selective antioxidant properties, can be efficiently generated via electron attachment to retusin in mitochondria and may be responsible for its antioxidant activity. The second abundant species, i.e., quinone bearing an excess negative charge, can serve as an electron carrier and can return the captured electron back to the respiration cycle. The number of OH substituents and their relative positions are crucial for the present molecular mechanism, which can explain the radical scavenging activity of polyphenolic compounds.

Hypothesis for the Mechanism of Ascorbic Acid Activity in Living Cells Related to Its Electron-Accepting Properties

“…So we envisage that H atom donation from cellular AA can be stimulated by electron addition, similarly to other polyphenolic compounds. 25,28,29,46 According to the present data, the linear forms of AA are able to abstract an electron from the superoxide anion (or to capture a solvated electron) due to their high electron affinities. However, the energy release for the above reaction in water is predicted to be only slightly different (0.31 and 0.39 eV, respectively) for AA and AA 2 .…”

“…Cleavage of O−H bonds in polyphenolic compounds is usually associated with antioxidant effect 60 giving rise to deactivation of reactive free radicals by H atom transfer, so that formation of the m/e = 175 fragment could be responsible for (or contribute to) the antioxidant activity of AA. Another mechanism for the free radical scavenging activity of OH-substituted compounds, based on their DEA properties, has been proposed 46 to be associated with double dehydrogenation of molecular anions to produce quinone species and the therapeutic antioxidant H 2 61 near the main site of ROS production in mitochondria.…”

Resonance electron attachment to natural polyphenolic compounds and their biological activity

“…Насколько известно авторам, выброс двух атомов водорода из ОМИ наблюдается (при низких энергиях электронов) лишь в тех случаях, когда молекула-мишень имеет определённую структуру: либо содержит несколько гидроксильных групп (полифенол) [11,12,33], либо существует возможность внутренних вращений одних частей молекулы по отношению к дру-гим, при которых происходит сближение атомов водо-рода [34]. В обоих случаях необходимо, чтобы в качестве нейтрального фрагмента образовалась молекула водо-рода: только при таком условии удаётся объяснить факт наблюдения анионов [M -2H] -при низких (вплоть до тепловых) энергиях электронов.…”

Атомный Состав И Морфология Тонких Пленок Ресвератрола На Поверхности Окисленного Кремния И Поликристаллического Золота

“…Натуральные полифенольные соединения, такие как пицеатаннол, кверцетин и ресвератрол, широко известны вследствие своих и антиоксидантных свойств [1,2]. Один из механизмов воздействия антиоксидантов, приводящий к снижению концентрации свободных радикалов, обусловлен захватом молекулой антиоксиданта электрона, конкурирующим с захватом электрона молекулой кислорода [3][4][5][6][7]. Важную роль в реализации этого механизма играет энергетическое положение вакантных электронных орбиталей, то есть резонансных значений энергий отрицательных ионов полифенольных соединений в энергетическом диапазоне 0−5 eV выше уровня вакуума [6,7].…”