Abstract
The photostability of quercetin in alcoholic solutions was studied. Both UVA and UVB light induced degradation of quercetin, yielding a single product 1 deriving from oxidation and addition of an alcohol molecule to the 2,3 double bond. The same mechanism operated when quercetin was dissolved in alkaline solutions, and again a product 2 due to oxidation and addition of water was characterized. Comparison with quercetin analogs confirmed that, despite the presence of five hydroxy groups in quercetin, those in positions 3, 3′, and 4′ are mainly involved in the antioxidant activity of the compound , as well as in its photolability.
Highlights
Quercetin (3,5,7,3′,4′-pentahydroxyflavone, Figure 1) is one of the most widespread compounds of the natural flavonoids class
The mechanism mainly involves the capacity of flavonoids to scavenge free radicals and reactive oxygen species
Addition may precede oxidation or vice versa. In the former hypothesis the structure of the possible quercetin-ethanol adduct closely resembles that of ascorbic acid: if addition occurs first, oxidation should be easy
Summary
Quercetin (3,5,7,3′,4′-pentahydroxyflavone, Figure 1) is one of the most widespread compounds of the natural flavonoids class. Such compounds are known for their ultraviolet (UV) B photoprotective properties in plants. In different cell compartments and tissue structures, plants accumulate pigments, such as flavonoids, which can attenuate radiation in the UV and visible parts of the spectrum [1]. The mechanism mainly involves the capacity of flavonoids to scavenge free radicals and reactive oxygen species. Due to the presence of many phenolic hydroxy groups, flavonoids can donate hydrogen atoms to radicals, acting as radical chain terminators [2]. Formed flavonoid radicals are delocalized on the whole molecule, making them far less aggressive
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
