RESUMO
The leaves of Engelhardia roxburghiana Wall (LERW) has been used as sweet tea in China throughout history. In this study, the ethanol extract of LERW (E-LERW) was prepared and the compositions were identified by HPLC-MS/MS. It indicates that astilbin was the predominant component in E-LERW. In addition, E-LERW was abundant in polyphenols. Compared to astilbin, E-LERW presented much more powerful antioxidant activity. The E-LERW also had stronger affinity with α-glucosidase and exerted more vigorous inhibitory effect on the enzyme. Alloxan-induced diabetic mice had significantly elevated glucose and lipid levels. Treatment with E-LERW at the medium dose (M) of 300 mg/kg could reduce the levels of glucose, TG, TC, and LDL by 16.64%, 12.87%, 32.70%, and 22.99%, respectively. In addition, E-LERW (M) decreased food intake, water intake, and excretion by 27.29%, 36.15%, and 30.93%, respectively. Moreover, E-LERW (M) therapy increased the mouse weight and insulin secretion by 25.30% and 494.52%. With respect to the astilbin control, E-LERW was more efficient in reducing the food and drink consumption and protecting pancreatic islet and body organs from alloxan-induced damage. The study demonstrates that E-LERW may be a promising functional ingredient for the adjuvant therapy of diabetes.
RESUMO
BACKGROUND: Nardostachys jatamansi DC. is a common medicinal herb used to treat cardiovascular diseases, particularly hypertension. Previously, our lab characterized the chemical compounds of N. jatamansi. However, the bioactive compounds of N. jatamansi and their mechanisms of action on blood pressure and blood vessels are unknown. PURPOSE: The vasorelaxant effects of the methanolic extract (MeOH ext.) of the roots and rhizomes of N. jatamansi, its main compounds, and their underlying mode of action, were investigated. METHODS: The main compounds of N. jatamansi were isolated and identified using UHPLC-TOF MS. The antihypertensive effect of N. jatamansi extracts and (-)-aristolone were determined using spontaneously hypertensive rats. The extracts, fractions, and compounds were also evaluated for their vasorelaxant effects on U46619 contractile responses in isolated thoracic aortic and mesenteric arterial rings. The endothelial-dependent relaxation, as well as the regulatory pathways and targets of (-)-aristolone, were studied in-vitro and ex-vivo. Molecular docking and biophysical characterization (Surface plasmon resonance) studies were utilized to investigate the molecular interaction between (-)-aristolone and the target protein. RESULTS: MeOH ext. (200 mg/kg) reduces the systolic and diastolic blood pressure in spontaneously hypertensive rats. MeOH ext. and its ethyl acetate fraction (EtOAc Fr.), but not the H2O fraction, had a significant relaxing effect on the thoracic aorta. (-)-aristolone and kanshone H from EtOAc Fr. induced vasorelaxation of the thoracic aorta and mesenteric artery. In human umbilical vein endothelial cells, (-)-aristolone treatment upregulated phosphorylation of Akt (T308) and eNOS. Molecular docking and surface plasmon resonance experiments revealed an interaction between (-)-aristolone and phosphoinositide-dependent protein kinase 1 (PDK1), an upstream protein kinase that phosphorylates Akt at T308. Treatment with PDK1 inhibitor PHT-427 and eNOS inhibitor L-NAME consistently inhibited (-)-aristolone-induced vasorelaxation. In addition, KATP channel inhibitor glibenclamide dramatically inhibited the vasorelaxant effects of (-)-aristolone and kanshone H in the endothelium-denuded thoracic aorta. Finally, (-)-aristolone lowers hypertensive rats' systolic and diastolic blood pressure. CONCLUSIONS: The extracts of N. jatamansi promote vasorelaxation and alleviate hypertension. The essential chemicals responsible for producing vasorelaxation effects are (-)-aristolone and kanshone H, which activate the PDK1-Akt-eNOS-NO relaxing pathway and stimulate the opening of the KATP channel. These findings point to N. jatamansi and aristolone as possible antihypertensive agents.