Suppression of Lipid Photoperoxidation by Quercetin and Its Glycosides in Spinach Chloroplasts

Abstract

Quercetin. quercitrin and rutin suppressed lipid photoperoxidation in spinach chloroplasts in the presence of 100 )*M carbonylcyanide m-chlorophenylhydrazone (CCCP) or 100 )*M methyl viologen (MV). Fifty percent inhibition of lipid peroxidation by quercetin was observed between 30 and 50 pM.Concentrations of quercetin and rutin higher than 100 FM were required to obtain 50% inhibition. Quercitrin was more effective than rutin in the suppression of lipid photoperoxidation.Photooxidation of the flavonols by chloroplasts in the presence of MV was suppressed by superoxide dismutase (SOD) more than 90%. and the rates of the oxidation decreased in order of quercetin, quercitrin and rutin suggesting that the reactivity of the flavonols with 02decreased in that order. The photooxidation of the flavonols by CCCP-poisoned chloroplasts was partially suppressed by SOD. Radicals generated in the course of lauroyl peroxide degradation also oxidized the flavonols and the oxidation was insensitive to SOD. In these experiments, oxidation rate of quercetin was faster than those of its glycosides. The results obtained suggest that flavonols can function as antioxidants in chloroplasts by scavenging both 02and the radicals formed during lipid peroxidation.

A Parallel Study of Pigment Bleaching and Cytochrome Breakdown during Aging of Thylakoid Membranes

“…This proposal is in agreement with reports by Yang (1977, 1978), Takahama (1983) and Kato and Shimizu (1985). In that respect, it is noteworthy that allomerization of chlorophylls a and b proceeds via a free radical mechanism (Hynninen 1981, Merzliak andKoorighnih 1984).…”

Effect of extracts from araticum (Annona crassiflora) on CCl4-induced liver damage in rats

“…Thus, the maintenance of normal levels of hepatic MDA is of great interest since MDA is a major aldehyde resulting from the peroxidation of biological tissue and it is an indicator of tissue damage. Lipid peroxidation may be prevented at the initiation stage by free radical scavengers, whereas the chain propagation reaction can be intercepted by peroxy-radical scavengers such as phenolic antioxidants (TAKAHAMA, 1983). The investigation by direct infusion electrospray ionization mass spectrometry (ESI-MS) provided important information of biactive components of araticum extracts mainly phenolic antioxidants such as caffeic acid, quinic acid, ferulic acid, xanthoxylin, caffeoyltartaric acid, caffeoyl glucose, [quercetin + hexose + pentose -H]-, and rutin (ROESLER et al, 2007).The phenolic compounds act by scavenging free radicals and quenching the lipid peroxides.…”

The Generation of Singlet Oxygen (1O2) by the Nitrodiphenyl Ether Herbicide Oxyfluorfen Is Independent of Photosynthesis

“…No inhibition of RNO bleaching was observed when paraquat (0.25 mM) was included with cercosporin in the absence of thylakoid membranes. More importantly the bleaching of RNO observed in the presence of either cercosporin or oxyfluorfen is inhibited by known singlet oxygen quenchers, quercetin and azide (25,27) see Figure 5. The degree to which quercetin and azide inhibit this bleaching is consistent with their previously reported 'O.…”