A Simple and Rapid UPLC-PDA Method for Quality Control of Nardostachys jatamansi

Degradation Profiling of Nardosinone at High Temperature and in Simulated Gastric and Intestinal Fluids

Nardosinone, a predominant bioactive product from Nardostachys jatamansi DC, is well-known for its promising therapeutic applications, such as being used as a drug on anti-inflammatory, antidepressant, cardioprotective, anti-neuroinflammatory, anti-arrhythmic, anti-periodontitis, etc. However, its stability under varying environmental conditions and its degradation products remain unclear. In this study, four main degradation products, including two previously undescribed compounds [2-deoxokanshone M (64.23%) and 2-deoxokanshone L (1.10%)] and two known compounds [desoxo-narchinol A (2.17%) and isonardosinone (3.44%)], were firstly afforded from the refluxed products of nardosinone in boiling water; their structures were identified using an analysis of the extensive NMR and X-ray diffraction data and the simulation and comparison of electronic circular dichroism spectra. Compared with nardosinone, 2-deoxokanshone M exhibited potent vasodilatory activity without any of the significant anti-neuroinflammatory activity that nardosinone contains. Secondly, UPLC-PDA and UHPLC-DAD/Q-TOF MS analyses on the degradation patterns of nardosinone revealed that nardosinone degraded more easily under high temperatures and in simulated gastric fluid compared with the simulated intestinal fluid. A plausible degradation pathway of nardosinone was finally proposed using nardosinonediol as the initial intermediate and involved multiple chemical reactions, including peroxy ring-opening, keto-enol tautomerization, oxidation, isopropyl cleavage, and pinacol rearrangement. Our findings may supply certain guidance and scientific evidence for the quality control and reasonable application of nardosinone-related products.

Aristolone in Nardostachys jatamansi DC. induces mesenteric vasodilation and ameliorates hypertension via activation of the KATP channel and PDK1-Akt-eNOS pathway

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, K_ATP 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 K_ATP channel. These findings point to N. jatamansi and aristolone as possible antihypertensive agents.

Antidepressant activities and regulative effects on serotonin transporter of Nardostachys jatamansi DC

ETHNOPHARMACOLOGICAL RELEVANCE

Nardostachys jatamansi (D.Don) DC. (family Caprifoliaceae, NJ) is well-documented and commonly used in the systems of traditional medicine in China, Tibet, Nepal, Bhutan, India and Japan for curing digestive and neuropsychiatric disorders with a long history of medication. However, the possible action mechanisms of antidepressant effects of NJ remain unraveled.

AIM OF THE STUDY

The aim of this study was to systematically investigate chemical substances of NJ and their effects on serotonin transporter (SERT) in antidepressant activity.

MATERIALS AND METHODS

Antidepressant effects of total methanol extract of NJ were evaluated by tail suspension test (TST) and open field test (OFT). Then the total extract was analyzed by ultra-high-performance liquid chromatography (UHPLC) method, and its effect on SERT activity was evaluated by high content assay (HCA) to determine half maximal effective concentration (EC₅₀). This total extract was subfractioned into twenty subfractions by preparative high-performance liquid chromatography (p-HPLC) method, and 'subfraction-SERT activity' relationship curve was fitted with medians of the retention time of those subfractions and their SERT activity values. Then, the fraction NJFr.01 enriched with SERT enhancers was optimized, prepared and analyzed by UHPLC method. Antidepressant effects of the fraction NJFr.01 were evaluated by TST and OFT. Further, major constituents of the total extract and fraction NJFr.01 were isolated by p-HPLC and identified by extensive nuclear magnetic resonance (NMR) analyses and comparisons with those reported data, and their SERT activities were also evaluated. Finally, antagonistic effects of chlorogenic acid and desoxo-narchinol A against fluoxetine on SERT were evaluated.

RESULTS

Results of TST and OFT demonstrated antidepressant effects of toatal extract of NJ. The EC₅₀ of total extract on SERT enhancement was 31.63 μg/mL. The fitted 'subfraction-SERT activity' relationship curve revealed that fraction NJFr.01 was enriched with SERT enhancing constituents. Both total extract and fraction NJFr.01 significantly enhanced SERT activity, while the rest fraction NJFr.02 didn't show any SERT activity. Then, antidepressant effects of fraction NJFr.01 were demonstrated by TST and OFT. Further, phytochemistry investigation and UHPLC analyses confirmed the identification of fourteen constituents in the total extract of NJ, including 7-oxonardinoperoxide (1), desoxo-narchinol A (2), kanshone B (3), narchinol B (4), nardosinonediol (5), kanshone A (6), 1-hydroxylaristolone (7), debilon (8), nardosinone (9), kanshone H (10), 1,8,9,10-tetradehydroaristolan-2-one (11), (-)-aristolone (12), 1(10)-aristolene-2-one (13) and jatamol A (14), and seven constituents in the fraction NJFr.01, including chlorogenic acid (15), 8α-dihydrogeniposide (16), 7-deoxy-8-epi-loganic acid (17), adoxosidic acid (18), 8-epi-loganic acid (19), 8α-6,7-dihydroapodantheroside acetate (20) and 6″-acetylpatrinalloside (21). Their structures were established by NMR analyses and comparisons with those reported data. HCA results of these constituents demonstrated the major components of fraction NJFr.01 enhanced SERT activity. Antagonistic results showed that chlorogenic acid and desoxo-narchinol A reversed inhibition effect of fluoxetine on SERT activity.

CONCLUSION

This study first systematically expatiated the roles of SERT activity in antidepressant effects of NJ, including total methanol extract and the water-soluble fraction NJFr.01 enriched with SERT enhancing constituents. This is the first report of natural SERT enhancing extract and fractions with antidepressant potential in NJ.