The present study investigated the main components of fenugreek(Trigonella foenum-graecum L.) leaf flavonoids(FLFs) and their antioxidant activity. FLFs were prepared and enriched by solvent extraction, and the flavonoids were characterized by high-performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry(HPLC-Q-TOF-MS/MS). The protective effect of FLFs against H_2O_2-induced stress damage to L02 hepatocytes was also investigated. Firstly, the cell viability was measured by MTT assay. The oxidative stress injury model was induced by H_2O_2 in L02 cells. The release of lactate dehydrogenase(LDH), the content of reduced glutathione(GSH) and malondialdehyde(MDA), and the activities of superoxide dismutase(SOD) and catalase(CAT) were measured by assay kits. Hoechst fluorescence staining was performed to observe the cell apoptosis. The expression levels of c-Jun N-terminal kinase(JNK), extracellular signal-regulated kinase 1/2(ERK1/2), nuclear factor erythroid-2 related factor 2(Nrf2), heme oxygenase 1(HO-1), and their phosphorylated proteins were detected by Western blot. Based on the MS fragment ion information and data in databases, FLFs contained eight flavonoids with quercetin and kaempferol as the main aglycons. The cell viabi-lity assay revealed that as compared with the conditions in the H_2O_2 treatment group, 3.125-25 μg·mL~(-1) FLFs could increase the viability of L02 cells, reduce LDH release and MDA content in a dose-dependent manner, potentiate the activities of SOD, CAT, and GSH, decrease the phosphorylation of JNK and ERK1/2 proteins, and up-regulate the expression of Nrf2 and HO-1. The results of fluorescence staining showed that the nucleus of the H_2O_2 treatment group showed concentrated and dense strong blue fluorescence, while the blue fluorescence intensity of the FLFs group decreased significantly. FLFs showed a protective effect against H_2O_2-induced oxidative damage in L02 cells, and the underlying mechanism is associated with the enhancement of cell capability in clearing oxygen free radicals and the inhibition of apoptosis by the activation of the MAPKs/Nrf2/HO-1 signaling pathway. The antioxidant effect of fenugreek leaf is related to its rich flavonoids.
Antioxidants/pharmacology* ; Apoptosis ; Flavonoids/pharmacology* ; Hepatocytes/metabolism* ; NF-E2-Related Factor 2/metabolism* ; Oxidative Stress ; Plant Leaves/metabolism* ; Superoxide Dismutase/metabolism* ; Tandem Mass Spectrometry ; Trigonella/metabolism*

OBJECTIVETo investigate the effect of 4-hydroxyisoleucine (4-HIL), an active component of Trigonella Foenum-graecum L. on high glucose induced insulin resistance (IR) in 3T3-L1 adipocytes, and to explore underlying molecular mechanisms.

METHODS3T3-L1 adipocytes were treated with 25 mmol/L glucose and 0.6 nmol/L insulin to induce IR. They were intervened by different concentrations of 4-HIL (at 5, 10, and 20 micromol/L). [3H]-Deoxy-D-glucose up-taking method was used to detect the glucose uptake. The mRNA expression of cellular tumor necrosis factor-alpha (TNF-alpha) was detected by polymerase chain reaction (PCR). The content of TNF-alpha in the culture supernatant was detected by enzyme-linked immunosorbent assay (ELISA). Palmitic acid (PA) acted as the control.

RESULTSAfter intervened by 25 mmol/L glucose and 0.6 nmol/L insulin for 18 h, the insulin-stimulated glucose transportation in 3T3-L1 adipocytes was inhibited by 63%. The mRNA expression of cellular TNF-alpha in adipocytes significantly increased, when compared with that in normal adipocytes (P < 0.05). The level of TNF-alpha secreted in the culture supernatant was increased by 70 pg/mL (P < 0.05). Similar changes occurred in the PA group. After exposure to 4-HIL (5, 10, or 20 micromol/L) for 24 h, the glucose transportation was increased by 35%, 50%, and 60%, respectively. PCR results showed that along with increasing 4-HIL concentrations, the mRNA expression of cellular TNF-alpha showed a decreasing trend, showing statistical difference when compared with the model group and the PA group (P < 0.05). Compared with the model group, the TNF-alpha level in the supernatant was respectively reduced by 10 pg/mL, 18 pg/mL, and 39 pg/mL after intervention (P < 0.05).

CONCLUSION4-HIL could remarkably improve high glucose-induced IR in 3T3-L1 adipocytes. Meanwhile, 4-HIL could inhibit the secretion of TNF-alpha.

3T3-L1 Cells ; Adipocytes ; drug effects ; metabolism ; Animals ; Glucose ; adverse effects ; metabolism ; Insulin ; metabolism ; Insulin Resistance ; Isoleucine ; analogs & derivatives ; pharmacology ; Male ; Mice ; Trigonella ; chemistry ; Tumor Necrosis Factor-alpha ; metabolism

AIMTo establish a rapid and sensitive LC-MSn method for the identification of trigonelline and its main metabolites in rat urine.

METHODSAfter optimizing the detection conditions of LC-MSn chromatography and mass spectrometry using trigonelline, its ionization and cleavage in ESI-MS and ESI-MSn modes were summarized, then serving as the basis for the metabolite analysis of trigonelline in rat urine. The 0-48 h urine samples of rats were collected after iv 8 mg x kg(-1) trigonelline, then, the samples were purified through C18 solid-phase extraction cartridge. The purified samples were analyzed by LC-MSn.

RESULTSThe structures of trigonelline metabolites were elucidated according to the changes of the molecular weights of the metabolites (deltaM) and their cleavage pattern in ESI-ITMSn. As a result, two phase I metabolites and the parent drug were identified existing in rat urine, and two phase II metabolites were identified.

CONCLUSIONThe LC-MSn method is rapid and high sensitive and specific, it is suitable for the identification of trigonelline and its metabolites in rat urine.

Alkaloids ; chemistry ; isolation & purification ; metabolism ; Animals ; Chromatography, High Pressure Liquid ; methods ; Hypoglycemic Agents ; chemistry ; isolation & purification ; metabolism ; Male ; Plants, Medicinal ; chemistry ; Rats ; Rats, Wistar ; Sensitivity and Specificity ; Spectrometry, Mass, Electrospray Ionization ; methods ; Trigonella ; chemistry