Nardonaphthalenones A and B from the roots and rhizomes of Nardostachys chinensis Batal

Stability of valeriana-type iridoid glycosides from rhizomes of Nardostachys jatamansi and their protection against H2O2-induced oxidative stress in SH-SY5Y cells

Nardostachys jatamansi is close to Valerian in consideration of their same psychoactive effects, such as sedation and neuroprotection. Valeriana-type iridoids are major active components of Valerian, but few valeriana-type iridoids have been isolated from N. jatamansi. Iridoid-targeting chemical investigation of the rhizomes of N. jatamansi resulted in the isolation of seven valeriana-type iridoid glycosides, four of which are previously undescribed. Their structures were determined through NMR spectroscopy, high-resolution mass spectrometry, and optical rotation experiments. In addition, the inaccurate configurations of patrinalloside and 6″-acetylpatrinalloside from previous reports were corrected. These compounds, unstable due to alcoholic solvents, were more stable in the mixtures than in purified forms, as monitored by the qNMR method, supporting the use of natural products as mixtures. Furthermore, the isolates, as well as crude and solvent partition extracts, were found to have a protective effect against hydrogen-peroxide-induced toxicity in human neuroblastoma cells, as confirmed by assays for cell viability and antioxidation. These findings suggest the potential therapeutic application of the valeriana-type iridoid glycosides isolated herein with improved biochemical stability.

Phytochemistry Meets Geochemistry—Blumenol C Sulfate: A New Megastigmane Sulfate from Palicourea luxurians (Rubiaceae: Palicoureeae)

There is a previously neglected influence of geochemical conditions on plant phytochemistry. In particular, high concentrations of dissolved salts can affect their biosynthesis of natural products. Detoxification is most likely an important aspect for the plant, but additional natural products can also give it an expanded range of bioactivities. During the phytochemical analysis a Palicourea luxurians plant collected in a sulfate-rich environment (near the Río Sucio, Costa Rica) showed an interesting natural product in this regard. The structure of this compound was determined using spectroscopic and computational methods (NMR, MS, UV, IR, CD, optical rotation, quantum chemical calculations) and resulted in a megastigmane sulfate ester possessing a β-ionone core structure, namely blumenol C sulfate (1, C₁₃H₂₂O₅S). The levels of sulfur and sulfate ions in the leaves of the plant were determined using elemental analysis and compared to the corresponding levels in comparable plant leaves from a less sulfate-rich environments. The analyses show the leaves from which we isolated blumenol C sulfate (1) to contain 35% more sulfur and 80% more sulfate than the other samples. Antimicrobial and antioxidant activities of compound 1 were tested against Escherichia coli, E. coli ampR and Bacillus subtilis as well as measured using complementary in vitro FRAP and ATBS assays, respectively. These bioactivities are comparable to those determined for structurally related megastigmanes. The sulfur and sulfate content of the plant leaves from the sulfate-rich environment was significantly higher than that of the other plants. Against this background of salt stress, we discuss a possible biosynthesis of blumenol C sulfate (1). Furthermore, there appears to be no benefit for the plant in terms of extended bioactivities. Hence, the formation of blumenol C sulfate (1) probably primarily serves the plant detoxification process.

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.

A review on traditional uses, phytochemistry, pharmacology, toxicology and the analytical methods of the genus Nardostachys

ETHNOPHARMACOLOGICAL RELEVANCE

The plants of the genus Nardostachys (Caprifoliaceae) have been used for a long history in different cultural systems of medicine, including Chinese, Ayurvedic, Korean folk medicine and Islamic, for treatments of disorders in nervous, digestive, cardiovascular and integumentary systems.

AIM OF THE REVIEW

This review aims to provide comprehensive information on Nardostachys plants including botany update, traditional uses, data mining of uses in traditional Chinese medicine (TCM) and current Chinese medicinal patents, chemical constituents, pharmacological effects, toxicity and analytical method studies.

MATERIALS AND METHODS

Studies of the genus Nardostachys were collected via Google Scholar and Baidu Scholar, ScienceDirect, SciFinder, Wiley Online Library, ACS Publications, NLM/NCBI, Web of Science, CNKI, WANFANG DATA, EMBASE, Huabeing database and Traditional Chinese Medicine Resource Network and libraries. Some local books, PhD or MS's dissertations were also included. The literatures cited in this review covered the period from 1962 to March 2021. The Plant List and Kew Herbarium Catalogue databases were used to authenticate the scientific name.

RESULTS

Botany description of Nardostachys genus is updated. Analysis of the literatures indicates that Nardostachys species are valuable herbs with therapeutic potentials for various disorders. Data mining on ancient TCM prescriptions and current Chinese medicinal patents containing Nardostachys revealed its common compatibility with other herbs in China. Phytochemical studies identified terpenoids and phenolic compounds as the main constituents in the genus Nardostachys and sesquiterpenoids as the major bioactive components. Experimental studies demonstrated that crude extracts, major fractions and the main constituents from Nardostachys species mainly exhibited pharmacological activities on nervous, digestive, cardiovascular and skin systems. Further, in vivo and in vitro toxicological studies demonstrated that Nardostachys plants showed either no or low toxicities, except at high doses. Finally, methods of qualitative and quantitative analyses on chemical constituents of genus Nardostachys were summarized, including TLC/HPTLC, GC and HPLC/UPLC methods, combined with common detectors including PDA, DAD and MS.

CONCLUSIONS

This review summarizes the progress on phytochemistry, pharmacology, toxicology and analytical methods of the genus Nardostachys. Studies demonstrate traditional uses of the genus Nardostachys, and reveal novel bioactive effects for clinical uses. These achievements expand our knowledge on the genus Nardostachys and its clinical value.

Plant Species of Sub-Family Valerianaceae-A Review on Its Effect on the Central Nervous System

Valerianaceae, the sub-family of Caprifoliaceae, contains more than 300 species of annual and perennial herbs, worldwide distributed. Several species are used for their biological properties while some are used as food. Species from the genus Valeriana have been used for their antispasmodic, relaxing, and sedative properties, which have been mainly attributed to the presence of valepotriates, borneol derivatives, and isovalerenic acid. Among this genus, the most common and employed species is Valerianaofficinalis. Although valerian has been traditionally used as a mild sedative, research results are still controversial regarding the role of the different active compounds, the herbal preparations, and the dosage used. The present review is designed to summarize and critically describe the current knowledge on the different plant species belonging to Valerianaceae, their phytochemicals, their uses in the treatment of different diseases with particular emphasis on the effects on the central nervous system. The available information on this sub-family was collected from scientific databases up until year 2020. The following electronic databases were used: PubMed, Scopus, Sci Finder, Web of Science, Science Direct, NCBI, and Google Scholar. The search terms used for this review included Valerianaceae, Valeriana, Centranthus, Fedia, Patrinia, Nardostachys, Plectritis, and Valerianella, phytochemical composition, in vivo studies, Central Nervous System, neuroprotective, antidepressant, antinociceptive, anxiolytic, anxiety, preclinical and clinical studies.

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.

Iridoid glycosides isolated from Nardostachys chinensis batal with NO production inhibitory activity

Investigation into the chemical diversity of Nardostachys chinensis Batal led to the discovery of three new (1-3) and one known (4) iridoid glycosides. Their structures were established through spectroscopic methods including 1 D and 2 D NMR experiments and HRESIMS analysis. Inhibitory effects of 1-4 on nitric oxide production were investigated in lipopolysaccaride (LPS)-mediated RAW 264.7 cells, and they displayed IC₅₀ values in the range 7.8-15.2 μM.

Dinardokanshones C-E, isonardoeudesmols A-D and nardoeudesmol D from Nardostachys jatamansi DC

Dinardokanshones C-E, three sesquiterpenoid dimers comprising an unusual nornardosinane-type sesquiterpenoid core and an aristolane-type sesquiterpenoid unit conjugated by an extra pyran or furan ring, together with monomeric sesquiterpenoids isonardoeudesmols A-D and nardoeudesmol D, were isolated from the underground parts of Nardostachys jatamansi DC. Structures of the eight compounds were elucidated by analysis of the extensive spectroscopic data, and their absolute configurations were established by analysis of NOESY and X-ray diffraction data, combined with computational electronic circular dichroism (ECD) calculations. The results of SERT activity assay revealed that isonardoeudesmol D and nardoeudesmol D significantly inhibited SERT activity, while dinardokanshones D-E and isonardoeudesmols B-C significantly enhanced SERT activity, among which dinardokanshone D exhibited the strongest effect.