Fenugreek extract improves diabetes-induced endothelial dysfunction via the arginase 1 pathway.

Endothelial dysfunction (ED) is an initiating trigger and key factor in vascular complications, leading to disability and mortality in individuals with diabetes. The research concerning therapeutic interventions for ED has gained considerable interest. Fenugreek, a commonly used edible plant in dietary consumption, has attracted significant attention due to its management of diabetes and its associated complications. The research presented in this study examines the potential therapeutic benefits of fenugreek in treating ED and investigates the underlying mechanism associated with its effects. The analysis on fenugreek was performed using 70% ethanol extract, and its chemical composition was analyzed using ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). In total, we identified 49 compounds present in the fenugreek extract. These compounds encompass flavonoids, saponins, and phospholipids. Then, the models of ED in streptozotocin-induced diabetic mice and high glucose-induced isolated rat aortas were established for research. Through vascular function testing, it was observed that fenugreek extract effectively improved ED induced by diabetes or high glucose. By analyzing the protein expression of arginase 1 (Arg1), Arg activity, Arg1 immunohistochemistry, nitric oxide (NO) level, and the protein expression of endothelial nitric oxide synthase (eNOS), p38 mitogen-activated protein kinase (p38 MAPK), and p-p38 MAPK in aortas, this study revealed that the potential mechanism of fenugreek extract in anti-ED involves the downregulation of Arg1, leading to enhanced NO production. Furthermore, analysis of serum exosomes carrying Arg activity indicates that fenugreek may decrease the activity of Arg transported by serum exosomes, potentially preventing the increase in Arg levels triggered by the uptake of serum exosomes by vascular endothelial cells. In general, this investigation offers valuable observations regarding the curative impact of fenugreek extract on anti-ED in diabetes, revealing the involvement of the Arg1 pathway in its mechanism.

Serum metabonomics study on antidiabetic effects of fenugreek flavonoids in streptozotocin-induced rats.

Fenugreek is a well-known medicinal plant used for treatment of diabetes. In this study, the antidiabetic effect of fenugreek flavonoids was investigated by metabonomics based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Fenugreek flavonoids were purified using polyamide resin and D101 macroporous adsorption resin, characterized by UPLC-Q-TOF-MS, and administered to streptozotocin (STZ)-induced diabetic rats for 28 days. Pharmacological study results indicated that fenugreek flavonoids exerted a strong antidiabetic effect characterized by significant reduction of fasting blood glucose (P < 0.01), increase in serum insulin level (P < 0.01) and liver glycogen content (P < 0.01), attenuation of weight loss, and improvement of pancreatic islet and kidney conditions. The antidiabetic effect of fenugreek flavonoids was further analyzed by metabonomics. Serum samples of health and diabetic rats treated or not with fenugreek flavonoids were evaluated by UPLC-Q-TOF-MS, followed by principal component analysis (PCA) and orthogonal projection to latent structures squares-discriminant analysis (OPLS-DA). The PCA model revealed significant differences among the animal groups, and OPLS-DA identified fenugreek flavonoids-induced changes of 11 potential biomarkers involved in lipid metabolism (docosahexaenoic acid, arachidonic acid, sphinganine, sphingosine­1­phosphate, and lysophosphatidylcholines 20:4, 18:2, 16:0, and 20:2), amino acid metabolism (hippuric acid and tryptophan), and kidney function-related metabolism (2­phenylethanol glucuronide). Our study demonstrates that flavonoids are bioactive components of fenugreek with potent antidiabetic activity, which exert their therapeutic effects by multiple mechanisms, including reducing insulin resistance, improving gluconeogenesis, and protecting islet cells and kidneys from damage.

Metabonomics study of the therapeutic mechanism of fenugreek galactomannan on diabetic hyperglycemia in rats, by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

Fenugreek is a traditional plant for the treatment of diabetes. Galactomannan, an active major component in fenugreek seeds, has shown hypoglycemic activity. The present study was performed to investigate the therapeutic mechanism underlying fenugreek galactomannan (F-GAL) in treating diabetes, using a metabonomics approach based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS). The F-GAL used for study was highly purified, and its yield, purity, and galactose/mannose ratio were characterized by capillary zone electrophoresis (CZE) and a modified phenol-sulfuric acid method. After treatment of streptozotocin (STZ)-induced diabetic rats with F-GAL for 28days, urine and serum samples were analyzed by UPLC-QTOF/MS. Multivariate statistical approaches such as principal component analysis (PCA) and orthogonal projection to latent structures squares-discriminant analysis (OPLS-DA) were applied to distinguish the non-diabetic/untreated, diabetic/untreated, and diabetic/F-GAL-treated groups. Then, potential biomarkers were identified that may help elucidate the underlying therapeutic mechanism of F-GAL in diabetes. The results demonstrated that there was a clear separation among the three groups in the PCA model. Fourteen potential biomarkers were identified by OPLS-DA, and they were determined to be produced in response to the therapeutic effects of F-GAL. These biomarkers were involved in histidine metabolism, tryptophan metabolism, energy metabolism, phenylalanine metabolism, sphingolipid metabolism, glycerophospholipid metabolism, and arachidonic acid metabolism. In conclusion, our study demonstrates that a metabonomics approach is a powerful, novel tool that can be used to evaluate the underlying therapeutic mechanisms of herb extracts.