Pitaya flowers are a distinctive food ingredient in southern China and are rich in phenolic compounds, offering significant potential for development as functional food ingredients. In this study, the phenolic compounds in pitaya flowers were identified and quantified using high-performance liquid chromatography (HPLC), revealing twelve compounds, including kaempferol, quercetin, isorhamnetin, and their respective glycosides. The antioxidant effect of pitaya flower phenolics was evaluated using an H 2 O 2 -induced oxidative damage model in HepG2 cells. Treatment with pitaya flower phenolics significantly increased cell viability to 67.43% relative to the untreated control group. In addition, the phenolics reduced lactate dehydrogenase (LDH) release to 182% of untreated control levels, restored the activities of superoxide dismutase (SOD), catalase (CAT), and intracellular glutathione (GSH) to 83.3%, 88.9%, and 94.6% of the untreated control group, respectively. Gene expression analysis by quantitative PCR revealed downregulation of Keap1 and upregulation of Nrf2, HO-1, NQO1, and SOD1, suggesting activation of the Keap1/Nrf2/ARE signaling pathway. Docking analysis indicated that flavonols (QE, KA, IS) in pitaya flowers bind Keap1, promoting Nrf2 release and pathway activation. The major phenolics in pitaya flowers (kaempferol-3-O-rutinoside, isorhamnetin-3-O-rubinobioside, kaempferol-3-O-glucoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, and kaempferol-3-O-rubinobioside) were found to alleviate oxidative stress by modulating antioxidant defenses at the transcriptional level. • Twelve phenolic compounds including flavonols were identified in pitaya flowers. • Pitaya flower extracts activate Keap1-Nrf2-ARE pathway in H 2 O 2 -induced HepG2 cells. • Flavonols promote Nrf2 dissociation by binding to Keap1 to response oxidative stress.
Hu et al. (Thu,) studied this question.