Effects of quercetin on magnesium-dependent adenosine triphosphatase and the metabolism of human polymorphonuclear leukocytes

Abstract

The bioflavinoid quercetin was found to exert at least three separate effects on human polymorphonuclear leukocytes. (1) Concentrations of approximately 100 microM inhibited the membrane-associated magnesium adenosine triphosphatase by 60%-80% in either broken cell preparations or intact cells. Lineweaver-Burk plots showed the inhibition to be uncompetitive in nature. (2) Similar concentrations of quercetin inhibited respiratory burst activity of the cells as measured by oxygen consumption, glucose oxidation, or iodination of protein. All inhibitions were dose-dependent and were observed with either opsonized zymosan or phorbol myristate acetate as stimulus. (3) Quercetin likewise inhibited the transport of the nonmetabolizable hexose, 3H-2- deoxyglucose. These observations are most consistent with the hypothesis that quercetin exerts a generalized effect at the level of the cell membrane of the neutrophi.

Polyphenols from Silybum marianum inhibit in vitro the oxidant response of equine neutrophils and myeloperoxidase activity

“…MPO is considered an inflammatory marker and the release of its active form, as evidenced in laminar tissues of horse with laminitis (Riggs et al, 2007), could involve the formation of strong oxidant species such as HOCl and NO 2 Á produced, respectively, by the chlorination and peroxidase activity of MPO, hence the interest in finding reversible inhibitors of MPO. While the inhibition of human MPO by taxifolin and quercetin is well characterized, there have been no previous studies into the inhibition of the enzyme by silybin and DHSB (Momi c et al, 2008;Kostyuk et al, 2003;Long et al, 1981). Likewise, the effects of these compounds on equine MPO remained to be explored.…”

“…As early as the 80s, it was already shown that quercetin, one of silymarin's components, inhibited the oxidative burst in neutrophils (Berton et al ., ; Long et al ., ). Pincemail et al .…”

“…As early as the 80s, it was already shown that quercetin, one of silymarin's components, inhibited the oxidative burst in neutrophils (Berton et al, 1980;Long et al, 1981). Pincemail et al (1988) showed that quercetin inhibits human MPO with a Ki of 3.5 lM and Momi c et al (2008,2009) unravelled the mechanism by which quercetin interacts and inhibits human MPO.…”

The Bioavailability, Transport, and Bioactivity of Dietary Flavonoids: A Review from a Historical Perspective

“…There was an accumulation of studies reporting the ability of flavonols and flavanones to act as anti‐inflammatory agents (Brasseur, ; Middleton & Kandaswami, ), including interfering with leukocyte migration, basophil histamine release (Middleton, ), arachidonic acid metabolism, and prostaglandin biosynthesis (Moore, Griffiths, & Lofts, ; Panthong, Tassaneeyakul, Kanjanapothi, Tantiwachwuttikul, & Reutrakul, ; Welton, Hurley, & Will, ). Other studies reported various actions on enzyme function (Nagai, Miyaichi, Tomimori, & Yamada, ) including: activity of flavonols on protein kinase inhibition (Cochet, Feige, Pirollet, Keramidas, & Chambaz, ; Ferriola, Cody, & Middleton, ; Rogers & Williams, ); flavone‐induced liver monooxygenase activity (Siess, Guillermic, Le Bon, & Suschetet, ); the impact of flavonoids on xenobiotic metabolizing enzymes such as cyclooxygenase (COX) and lipoyxgenase (LOX; Roger, ; Wood, Smith, Chang, Huang, & Conney, ); the effects of quercetin on enzyme secretory mechanisms, including interference of neutrophil enzyme transport (Long et al.,); and effects of quercetin and quercetin‐3‐ O ‐rutinoside on lysosomal enzymes in fibroblasts (Vladutiu & Middleton, ). Flavonoids were also reported to have high affinities for membrane transport proteins (Kohrle, Spanka, Irmscher, & Hesch, ).…”

Tobacco components induce alterations in keratinocyte lipid membrane fluidity and inhibit cell proliferation in culture

“…A possible explanation for these findings may be that these compounds alter other metabolic pathways. For example, quercetin and related com-pounds have been shown to inhibit Na-I-, K-l-adenosine triphosphatase (23) and to inhibit the hexose monophosphate pathway and the uptake of a-deoxyglucose (24).…”