Identification of Peracetylated Quercetin as a Selective 12-Lipoxygenase Pathway Inhibitor in Human Platelets

Abstract

The inflammatory response is necessary for the host's defense against pathogens; however, uncontrolled or unregulated production of eicosanoids has been associated with several types of chronic inflammatory diseases. Thus, it is not surprising that enzymes implicated in the production of eicosanoids have been strategically targeted for potential therapeutic approaches. The 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE] lipid mediator is among inflammatory molecules that are abundantly produced in various diseases and is primarily biosynthesized via the 12(S)lipoxygenase pathway. The effects of the abundance of 12(S)-HETE and its contribution to several chronic inflammatory diseases have been well studied over the last few years. While most developed compounds primarily target the 5-lipoxygenase (5-LO) or the cyclooxygenase (COX) pathways, very few compounds selectively inhibiting the 12-lipoxygenase (12-LO) pathway are known. In this study, we examined whether the distribution of hydroxyl groups among flavones could influence their potency as 12-LO inhibitors. Using human platelets, the human embryonic kidney 293 (HEK293) cell line expressing 5-LO, and human polymorphonuclear leukocytes (PMNLs) we investigated the effects of these compounds on several inflammatory pathways, namely, 12-LO, 5-LO, and COX. Using high-resolution respirometry and flow cytometry, we also evaluated some normal cell functions that could be modulated by our compounds. We identified a peracetylated quercetin (compound 6) that exerts potent inhibitory activity toward the platelet 12-LO pathway (IC 50 5 1.53 mM) while having a lesser affinity toward the COX pathway. This study characterizes the peracetylated quercetin (compound 6) as a more selective platelet-type 12-LO inhibitor than baicalein, with no measurable nontargeted effects on the platelet's activation or overall cell's oxygen consumption.

The Metabolites of the Dietary Flavonoid Quercetin Possess Potent Antithrombotic Activity, and Interact with Aspirin to Enhance Antiplatelet Effects

“…In addition to this, a recent study by Doucet et al identified a peracetylated quercetin as a selective inhibitor of the 12-lipoxygenase pathway, a pathway essential for platelet activation through the low-affinity receptor for IgG, FcγRIIa; it may therefore be that the methylated metabolites of quercetin dampen platelet activation through this mechanism. 48 49…”

Apple consumption affects cecal health by regulating 12S-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12(S)-HETE) levels through modifying the microbiota in rats

“…In functional research on apple components, quercetin effectively inhibited the 12-LOX pathway in vitro . 54 PPs, including flavonoids, reduce inflammatory lipid mediator production by inhibiting the inflammatory enzyme pathway. 55 This may explain why apple consumption was associated with a decrease in 12( S )-HETE content, but the exact mechanism remains unclear and requires more in-depth investigation.…”

Single and multiple inhibitors of the biosynthesis of 5‐, 12‐, 15‐lipoxygenase products derived from cinnamyl‐3,4‐dihydroxy‐α‐cyanocinnamate: Synthesis and structure–activity relationship

“…Human embryonic kidney 293 (HEK293) (CRL-1573; ATCC) cells stably transfected with each of the three lipoxygenase enzymes were used to study the inhibitory activity of the test molecules. These cells are easily transfected to express lipoxygenase enzymes and have been a valuable tool to study the cell biology and molecular pharmacology of lipoxygenases (Allain et al, 2015;Chiasson et al, 2020;Doucet et al, 2019;Gerstmeier et al, 2014;Hébert et al, 2023;Mbarik et al, 2019;Touaibia et al, 2018). Preparation of HEK293 cells stably co-expressing human 5-LO and FLAP was previously described (Allain et al, 2015).…”