Antioxidant properties of natural flavonoids: quenching and generation of singlet molecular oxygen

Abstract

This paper describes the interaction between photochemically generated singlet molecular oxygen [O 2 ( 1 D g )] and a series of naturally occurring flavonoids (FL) (29,49-dihydroxychalcone (I), 29,49-dihydroxy, 39-methoxy chalcone (II), 7-hydroxyflavanone (III) and 7-hydroxy-8methoxyflavanone (IV) all obtained from Zuccagnia punctata Cav. The properties of these compounds as generators and quenchers of the known oxidative species O 2 ( 1 D g ), upon direct and dye-sensitized photoirradiation, were investigated. Time-resolved phosphorescence detection, and conventional spectroscopic measurements demonstrate that compounds I-IV are fairly good O 2 ( 1 D g ) deactivators with overall rate constant for the process of quenching in the range of 3.7 x10 6 (IV) to 2.8 310 8 M 21 s 21 (I). Because the O 2 ( 1 D g ) quenching possesses an exclusively physical component, O 2 ( 1 D g ) scavenging is not accompanied by consumption of the flavonoid. Compounds I, III and IV are poor O 2 ( 1 D g ) generators upon direct (near UV) photoirradiation, whereas compound II does not generate any of the oxidative species. Experiments measuring inhibition by flavonoids I-IVof the photosensitized lipid peroxidation employed linoleic acid as a photoxidizable substrate and Rose Bengal and Methylene Blue as photosenstizers. Results demonstrate that the interesting properties of flavonoids I-IV as O 2 ( 1 D g ) scavengers cannot be straightforwardly extrapolated to their potential activity as photoprotectors for lipid peroxidation.

The Profile in Polyphenols and Volatile Compounds in Alcoholic Beverages from Different Cultivars of Mulberry

“…The main flavonols in mulberry fruit are morin, quercetin, rutin, and myricetin (Yang and others 2010). Pharmacological and biochemical activities of flavonoids have been reported (Bravo 1998; Ávila and others 2001). Anthocyanins are a group of natural phenolic compounds responsible for the coloring of fruit and fruit products, cyanidin 3‐rutinoside, and cyanidin 3‐glucoside being the major ones of mulberry (Liu and others 2004; Bae and Suh 2007).…”

Theoretical study of the hydrogen bond interaction between methylene blue and water and possible role on energy transfer for photodynamics

“…MB has been implicated also as an emergency aid in underwater diving‐related accidents 11. There is an intense research related to the activity of MB in photodynamic therapy 12–16 and singlet‐oxygen reactions 17–20. MB is also a photodynamic antimicrobial agent 21 for the inactivation or destruction of pathogens contained in blood products.…”

Influence of total solids concentration and temperature on the changes in redox potential of tomato pastes

“…In fact, because of their widespread use, tomato and tomato-based products represent a good source of certain vitamins, minerals and anti-oxidants. The health benefits of diets rich in a variety of fruits and vegetables, including tomato and tomatobased products, have been recently reviewed (Giovannucci, 1999;Avila et al 2001;Kaur & Kapoor, 2001, 2002Landbo & Meyer, 2001). Many epidemiological studies suggest that a high intake of tomato and tomato derivatives is associated with a reduced risk of cancer and cardiovascular diseases (Franceschi et al, 1994;Levy et al, 1995;Giovannucci, 1999).…”