Background/aim: Melatonin not only regulates circadian rhythm, but also induces apoptosis in tumor cells. Hence, elucidation of the basic reaction mechanisms of melatonin and its metabolites is a matter of interest.
Material and methods: Melatonin dissolved in a mixture of water/ethanol=40/60 form associates (unstable complexes). For simulation of biological processes, melatonin was excited by UV light into the singlet state.
Results: By using monochromatic UV light (λ=254 nm) melatonin ejects solvated electrons (eaq (-)), a part of which is scavenged by melatonin in ground state contained in the associates. Consequently, with increase of melatonin concentration a decrease of the determined quantum yield of emitted eaq (-), Q(eaq (-)), is obtained. The complex molecular structure of melatonin contains functional groups which can emit eaq (-), as well such consuming eaq (-). As a succession of these processes various types of metabolites are generated, as well as degradation products, with lower molecular weight, are formed.
Conclusion: Not melatonin per se, but the ejected eaq (-) and thereby resulting various metabolites are responsible for different biological properties of melatonin.
Keywords: Melatonin; free radicals; metabolites; solvated electrons.
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