Metabolism profiles of nuciferine in rats using ultrafast liquid chromatography with tandem mass spectrometry

Nuciferine protects against folic acid-induced acute kidney injury by inhibiting ferroptosis

BACKGROUND AND PURPOSE

Acute kidney injury is a common clinical problem with no definitive or specific treatment. Therefore, the molecular mechanisms of acute kidney injury must be fully understood to develop novel treatments. Nuciferine, a major bioactive compound isolated from the lotus leaf, possesses extensive pharmacological activities. Its effect on folic acid-induced acute kidney injury, however, remains unknown. Here, we aimed to clarify the pharmacological effects of nuciferine and its mechanisms of action in acute kidney injury.

EXPERIMENTAL APPROACH

The effects of nuciferine on folic acid-induced acute kidney injury in mice were investigated. HK-2 human proximal tubular epithelial cells and HEK293T HEK cells were used to evaluate the protective effect of nuciferine on RSL3-induced ferroptosis.

KEY RESULTS

Nuciferine treatment mitigated the pathological alterations, ameliorated inflammatory cell infiltration and improved kidney dysfunction in mice with folic acid-induced acute kidney injury. In HK-2 and HEK293T cells, nuciferine significantly prevented RSL3-induced ferroptotic cell death. Mechanistically, nuciferine significantly inhibited ferroptosis by preventing iron accumulation and lipid peroxidation in vitro and in vivo. Moreover, knockdown of glutathione (GSH) peroxidase 4 (GPX4) abolished the protective effect of nuciferine against ferroptosis.

CONCLUSION AND IMPLICATIONS

Nuciferine ameliorated renal injury in mice with acute kidney injury, perhaps by inhibiting the ferroptosis. Nuciferine may represent a novel treatment that improves recovery from acute kidney injury by targeting ferroptosis.

Metabolic Profiling of Nuciferine In Vivo and In Vitro

Nuciferine (NF) is one of the main constituents of Lotus (Nelumbo nucifera) leaves which have been widely used in both food and drug formulations in China. Although possessing a broad spectrum of bioactivities, the metabolic characteristics of NF are inadequately unknown after oral gavage with this NF. The present study was performed to characterize its metabolism in vivo and in vitro. After NF oral gavage with mice, a total of 55 metabolites, containing 14 novel phase I metabolites and 18 novel phase II metabolites, were identified with high-resolution mass spectrometry-based metabolomics. Recombinant enzyme screenings showed that multiple cytochrome P450s, two UDP-glucuronosyltransferases (UGT1A4, UGT1A9), and several sulfotransferases (SULTs) participated in the metabolism of NF. In silico prediction and molecular docking of NF to the polymorphic enzymes (CYPs) provided additional support for the above experiments. This research details metabolic characteristics and provides an important reference basis for further application of NF.

Pharmacokinetics of Nuciferine and N-Nornuciferine, Two Major Alkaloids From Nelumbo nucifera Leaves, in Rat Plasma and the Brain

The leaf of the lotus (Nelumbo nucifera) is a natural plant resource used as both food and herbal medicine (He-Ye) in China. Alkaloids are considered the major bioactive compound of the herb and exhibit various biological activities, including anti-hyperlipidemia, anti-obesity, anti-inflammatory, and anti-hyperuricemic effects. Nuciferine (NF) and N-nuciferine (N-NF) are two major alkaloids found in the herb. In the present work, the plasma and brain pharmacokinetics of the two compounds were investigated after oral and intravenous (i.v.) administration of a lotus leaf alkaloid fraction to SD rats via ultra-performance liquid chromatography coupled with photodiode array detection and brain microdialysis. After oral administration (50 mg/kg), the two compounds NF and N-NF were rapidly absorbed into the blood and reached a mean maximum concentration (C_max) of 1.71 μg/mL at 0.9 h and 0.57 μg/mL at 1.65 h, respectively. After i.v. administration (10 mg/kg), NF and N-NF were found to have a relatively wide volume of distribution (V_{d, λz}, 9.48 and 15.17 L/kg, respectively) and slow elimination half-life (t_{1/2, λz}, 2.09 and 3.84 h, respectively). The oral bioavailability of NF and N-NF was estimated as 58.13% and 79.91%, respectively. After i.v. dosing (20 mg/kg), the two compounds rapidly crossed the blood-brain barrier and reached their C_max (in unbound form): 0.32 and 0.16 μg/mL at 0.89 and 1.22 h, respectively. Both alkaloids had widespread distribution in the brain, with V_{d, λz}/F-values of 19.78 L/kg and 16.17 L/kg, respectively. The mean t_{1/2, λz} values of NF and N-NF in the brain were 1.24 and 1.39 h, respectively. These results can help us to better understand the characteristics and neuro-pharmacological effects of the lotus alkaloid fraction.

Rapid characterization of the absorbed chemical constituents of Tangzhiqing formula following oral administration using UHPLC-Q-TOF-MS

Tangzhiqing formula, a Chinese herbal formula, is used for the treatment of type II diabetes and prediabetes. Although its effectiveness has been certified by clinical use, its absorbed chemical constituents are not comprehensively represented. Thence, in order to reveal potential bioactive components and metabolism of Tangzhiqing formula, an ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry method was developed. A total of 86 absorbed components, including 38 prototype compounds and 48 metabolites, were identified in rat plasma, urine, and feces after oral administration of Tangzhiqing formula. This was the first systematic study on the chemical constituents and metabolic profiling of Tangzhiqing formula. The results indicated that alkaloids and flavonoids were main absorbed components, and glucuronidation and sulfation were the major metabolites. Moreover we concluded that alkaloids and flavonoids first underwent demethylation and hydrolysis reactions before biotransformed to phase II metabolites. This study provided valuable data for safety estimation of Tangzhiqing formula, which will be advantageous for clinical application.