Possible Interaction: Catechin and Quercetin

“ Quercetin and fisetin, known as catechol-containing flavonoids, could positively affect the absorption of catechins due to their strong affinity for catechol-O-methyl transferase (COMT), which can methylate and cause the excretion of catechins.”

“Furthermore, various combinations of quercetin with catechin or epicatechin exerted an antagonistic effect on anti-DPPH(•) activity.”

“It was confirmed that BACH1 serves as an essential and direct negative regulator of the Keap1-Nrf2 signaling pathway and the antioxidant synergism between quercetin and catechin.”

“This synergism was probably due to the combined inhibitory effect of phenolics present in the leaf extracts (i.e., quercetin and gallic acid) and catechin , as detected by HPTLC.”

“Based on these findings, we predicted that quercetin would inhibit activities of Src family kinases with greater potency than apigenin and catechin.”

“Taking the above results into account, we proposed a possible mechanism of 6,8-dinitrosocatechin formation and discuss the importance of quercetin to prevent the quinone formation from 6,8-dinitrosocatechin in the gastric lumen, taking the interactions between quercetin and catechins into account.”

“However, the counteracting action of quercetin on lipid peroxidation is shared by other phenolics, such as catechins (Kalender et al. 2012).”

“This study shows that the polyphenols quercetin and catechin synergistically act in reducing platelet recruitment via inhibition of PKC-dependent NADPH oxidase activation.”

“Besides, the cotreatment of quercetin with catechin significantly (p < 0.05) restored the impaired expression of toll‐like receptor 4, myeloid differentiation primary response gene 88, and some downstream effectors (IRAK1, TRAF6, and TAK1).”

“Results showed that the combined treatment of quercetin with catechin synergistically attenuated LPS‐stimulated increase of some proinflammatory molecules, including nitric oxide, tumor necrosis factor α, interleukin‐1β, nitric oxide synthase, and cyclooxygenase‐2.”

“The synergistic anti‐inflammatory effect of quercetin and catechin was investigated using lipopolysaccharide (LPS)‐stimulated macrophage RAW 264.7 cells.”

“These results suggest that quercetin and catechin possessed synergistic anti‐inflammatory effects, which may be attributed to their roles in suppressing the activation of TLR4–MyD88‐mediated NF‐κB and mitogen‐activated protein kinases signaling pathways.”

“Previous studies have shown that the use of catechins and quercetin separately can improve the musculoskeletal function in cachectic animals.”