Photophysical and photochemical properties of resveratrol and its reactions with biologically relevant free radicals

Abstract

Poznato je da prirodni spoj trans-resveratrol (trans-3,5,4'-trihidroksistilben, ArOH) posjeduje izrazitu biološku aktivnost. Unatoč poznavanju mogućih mehanizama antioksidacijskog djelovanja kojima se pridjeljuje protektivna uloga ArOH u živim organizmima, o njegovim kemijskim svojstvima se malo zna. Cilj ove disertacije je istražiti kinetike i mehanizme reakcija ArOH s do sada neistraženim radikalima koji nastaju u uvjetima stanja oksidacijskog stresa. Ovi radikali i pobuđena stanja ArOH generirani su svjetlosnim pulsom koristeći rubinski i Nd:YAG laserski uređaj odnosno pulsom ubrzanih elektrona. Tranzijentnom apsorpcijskom spektroskopijom detektirane su intermedijerne vrste te određene konstante brzina reakcija ArOH s radikalima lokaliziranim na kisiku, ugljiku i sumporu odnosno s aril-ketonima u tripletnim stanjima. Reakcije su praćene na vremenskim skalama reda veličine 1061012 s u acetonitrilu i otopinama alkohol/voda. Budući da je poznato da su istraživani radikali odgovorni za poremećaje u odvijanju normalnih procesa u stanicama živih organizama, rezultati ovih istraživanja su originalan doprinos razumijevanju mehanizama i kinetike reakcija ArOH s biološki značajnim radikalima.It is well known that natural compound trans-resveratrol (trans-3,5,4'-trihydroxystilbene) possesses significant biological activity. However, despite the knowledge of its possible antioxidant mechanisms which have a protective role in the living organisms, chemical properties of ArOH are less known. The main goal of this thesis is to investigate reaction kinetics and mechanisms of ArOH with so far unresearched free bioradicals which occur in the conditions of oxidative stress. These free radicals and ArOH excited states were generated with ruby or Nd:YAG laser flash or electron accelerator pulse. Short-lived intermediate species of ArOH and its reaction kinetics with oxygen, sulphur and carbon-centered radicals and aromatic carbonyl triplets were determined with transient absorption spectroscopy. Measurements were conducted at the 1061012 sec time scales in acetonitrile and solutions of water/alcohol. This research is original contribution to the understanding of the mechanism and reaction kinetics of ArOH antioxidant activity with biologically relevant free radicals under investigation which are known to be responsible for the malfunction of the normal processes in living cells