Dissociative electron attachment to some spinochromes: Fragment anion formation

- Spinochromes are natural extracts from sea urchins possessing antioxidant activity.
- A variety of fragments is formed by dissociative electron attachment to spinochromes.
- H atoms elimination is observed at very low (thermal) energy of incident electrons.
- Deprotonated species can be responsible for biological activity of spinochromes.

Resonance attachment of low-energy (0-14 eV) electrons to a series of natural polyphenolic naphthoquinones (so-called spinochromes) derived from sea urchins is studied by means of dissociative electron attachment (DEA) spectroscopy. The experimental findings are interpreted using quantum-chemical calculations of the empty level structure to predict the energies of negative ion resonant states as well as the thermodynamic energy thresholds for formation of fragments by DEA. A variety of fragment species is found to be formed at very low energies of incident electrons, thus modeling reductive conditions in living cells near the pathways of cellular electron transfer. In particular, the temporary molecular anions of the compounds under investigation dissociate efficiently through elimination of neutral H atoms or diatomic hydrogen molecules (in analogy with previous findings in flavonoids), this process being energetically possible owing to the presence of multiple hydroxyl groups usually associated with radical scavenging activity. A likely correlation between dehydrogenation of spinochromes stimulated by electron attachment and their well-documented antioxidant protective properties is briefly discussed.

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