Two xanthones from Swertia punicea with hepatoprotective activities in vitro and in vivo

Xanthones: Biosynthesis and Trafficking in Plants, Fungi and Lichens

Xanthones are a class of secondary metabolites produced by plant organisms. They are characterized by a wide structural variety and numerous biological activities that make them valuable metabolites for use in the pharmaceutical field. This review shows the current knowledge of the xanthone biosynthetic pathway with a focus on the precursors and the enzymes involved, as well as on the cellular and organ localization of xanthones in plants. Xanthone biosynthesis in plants involves the shikimate and the acetate pathways which originate in plastids and endoplasmic reticulum, respectively. The pathway continues following three alternative routes, two phenylalanine-dependent and one phenylalanine-independent. All three routes lead to the biosynthesis of 2,3',4,6-tetrahydroxybenzophenone, which is the central intermediate. Unlike plants, the xanthone core in fungi and lichens is wholly derived from polyketide. Although organs and tissues synthesizing and accumulating xanthones are known in plants, no information is yet available on their subcellular and cellular localization in fungi and lichens. This review highlights the studies published to date on xanthone biosynthesis and trafficking in plant organisms, from which it emerges that the mechanisms underlying their synthesis need to be further investigated in order to exploit them for application purposes.

Bioactive Compounds from Medicinal Plants in Myanmar

Myanmar is a country with rich natural resources and of these, medicinal plants play a vital role in the primary health care of its population. The people of Myanmar have used their own system of traditional medicine inclusive of the use of medicinal plants for 2000 years. However, systematic and scientific studies have only recently begun to be reported. Researchers from Japan, Germany, and Korea have collaborated with researchers in Myanmar on medicinal plants since 2000. During the past two decades, over 50 publications have been published in peer-reviewed journals. Altogether, 433 phytoconstituents, including 147 new and 286 known compounds from 26 plant species consisting of 29 samples native to Myanmar, have been collated. In this contribution, phytochemical and biological investigations of these plants, including information on traditional knowledge are compiled and discussed.

8-O-β-D-Glucopyranosyl-2-methylchromone, a new chromone glycoside from the Tibetan medicine plant of Swertia punicea Hemsl

A new chromone glycoside, 8-O-β-D-Glucopyranosyl-2-methylchromone (1), together with eight known compounds (2-9) were isolated from the Tibetan medicine plant of Swertia punicea. All compounds of this plant were reported for the first time. The structures of these metabolites were elucidated by analysis of their HR-ESI-MS, 1D and 2D NMR spectroscopic data and comparison with data reported in the literature. In vitro test, all compounds were evaluated for their anti-inflammatory activity through the determination of nitric oxide production. Compounds 1-2 were evaluated for cytotoxic activities against three human cancer cell lines (HeLa, MDA-MB-231 and A375) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. Furthermore, the chemotaxonomic significance of these compounds has also been described.

Xanthones and Cancer: from Natural Sources to Mechanisms of Action

Xanthones are a class of heterocyclic natural products that have been widely studied for their pharmacological potential. In fact, they have been serving as scaffolds for the design of derivatives focusing on drug development. One of the main study targets of xanthones is their anticancer activity. Several compounds belonging to this class have already demonstrated cytotoxic and antitumor effects, making it a promising group for further exploration. This review therefore focuses on recently published studies, emphasizing their natural and synthetic sources and describing the main mechanisms of action responsible for the anticancer effect of promising xanthones.

Short-Time Administration of Xanthone From Garcinia mangostana Fruit Pericarp Attenuates the Hepatotoxicity and Renotoxicity of Type II Diabetes Mice

Objective: Our previous studies reported that xanthone can protect from hyperglycemia-induced diabetes mellitus (DM) via possessing antioxidant activity. An attempt has been made to evaluate the protective effect of xanthone against hepatotoxicity and renotoxicity of high-fat-diet and single-dose-streptozotocin-induced DM mice.Method: In this research, in vitro antioxidant and antidiabetic assays were performed. In vivo oral glucose and maltose tolerance test, metabolic parameters, plasma biochemical markers, oxidative status, etc. were evaluated in experimental mice. In addition, liver/kidney tissue histology and kidney apoptosis were observed using hematoxylin and eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays, respectively.Results: Xanthone exhibited potent in vitro antioxidant and antidiabetic activity. Xanthone treatments to diabetic mice significantly (p < 0.05) improved the biochemical and antioxidant parameters compared to that of the control group. Moreover, xanthone treatments also significantly (p < 0.05) reformed the liver and kidney histological alterations as well as reduced the cellular apoptosis of kidney tissue.Conclusions: All findings together concluded that xanthone could be a dietary supplement for the patient with diabetic complications.

Two new xanthone glycosides from Swertia punicea Hemsl. and their anti-inflammatory activity

Two new xanthone glycosides (1-2), together with seven known analogues (3-9), were isolated from whole herb of Swertia punicea. The structures of these metabolites were established on the basis of detailed spectroscopic analysis and comparison with data reported in the literature. In an in vitro test, all isolates were evaluated for their anti-inflammatory activity. The results revealed that all of them showed significant anti-inflammatory activity with IC₅₀ values ranging from 1.237 to 3.319 mM. Compounds 3, 4, and 5 (IC₅₀ values in the range 1.237-1.987 mM) displayed more potent anti-inflammatory activity than the positive control, indomethacin (IC₅₀ value of 2.004 mM).

Protective activity of tovophyllin A, a xanthone isolated from Garcinia mangostana pericarps, against acetaminophen-induced liver damage: role of Nrf2 activation

Tovophyllin A (TA) ameliorates APAP-induced hepatotoxicity by activating Nrf2 and inhibiting the NF-κB pathway.

Antioxidant, antiapoptotic and amino acid balance regulating activities of 1,7-dihydroxy-3,4,8-trimethoxyxanthone against dimethylnitrosamine-induced liver fibrosis

Liver fibrosis represents the consequences of a sustained wound healing response to chronic liver injury which could be caused by viral, autoimmune, drugs, and so on. Unfortunately, there was no effective therapy available for liver fibrosis in clinic. In this study, we identified the anti-fibrotic effects of 1,7-dihydroxy-3,4,8-trimethoxyxanthone (ZYC-1) on the dimethylnitrosamine (DMN)-induced rat model. ZYC-1 was isolated from Swertia punicea Hemsl and was administrated to DMN-induced rat model. ZYC decreased the hyaluronic acid (HA), type IV collagen (CIV) and hydroxyproline (Hyp) levels and inhibited the expression of α smooth muscle actin (α-SMA) and transforming growth factor beta 1 (TGF-1β). The anti-fibrotic effect of ZYC-1 was also confirmed by Sirius Red staining. Finally, we identified 42 differentially expressed proteins by using proteomics analysis after ZYC-1 treatment, of which 17 were up-regulated and 25 were down-regulated. These Most of the 42 proteins are involved in the oxidative stress pathway, the mitochondrial-mediated apoptotic pathway and the amino acid metabolism pathway. Our study presented the first elucidated mechanisms of xanthone on liver fibrosis in vivo. This study pointed out that ZYC-1 may be used as a lead compound for hepatofibrosis treatment.

Chemical and Biological Research on Herbal Medicines Rich in Xanthones

Xanthones, as some of the most active components and widely distributed in various herb medicines, have drawn more and more attention in recent years. So far, 168 species of herbal plants belong to 58 genera, 24 families have been reported to contain xanthones. Among them, Calophyllum, Cratoxylum, Cudrania, Garcinia, Gentiana, Hypericum and Swertia genera are plant resources with great development prospect. This paper summarizes the plant resources, bioactivity and the structure-activity relationships (SARs) of xanthones from references published over the last few decades, which may be useful for new drug research and development on xanthones.

Xanthones isolated from Gentianella acuta and their protective effects against H2O2-induced myocardial cell injury

In the present study, two new xanthones, (5'S,8'S)-1,3,5,8-tetrahydroxyxanthone(7→2')-1,3,5,8-tetrahydroxy-5',6',7',8'-tetrahydroxanthone (1), 5-hydroxy-3,4,6-trimethoxyxanthone-1-O-β-D-glucopyranoside (2), and eight known xanthones (3-10) were isolated from the whole plants of Gentianella acuta. Their structures were identified by the spectroscopic analyses (HR-ESI-MS, and 1D and 2D NMR). Meanwhile, cell-protective effects against H₂O₂-induced H9c2 cardiomyocyte injury and cytotoxic activities of compounds 1-10 were also determined.

Phytochemistry and Pharmacological Activities of the Genus Swertia (Gentianaceae): A Review

Swertia plants have been considered to be medicinal plants useful for the treatment of various ailments for thousands of years, especially in Asian countries. This is due to the broad variety of chemical compounds that provide multiple ligands for bonding to different endogenous biomacromolecules for patients. Chemical constituents and pharmacological activities of Swertia plants are summarized in this paper. Approximately 419 metabolites and 40 bioactive compounds have been reported from 30 Swertia species, including xanthones, flavonoids, seco-iridiods, iridiods, triterpenoids, alkaloids, volatiles, and other secondary metabolites. The bioactivities of Swertia plants include anticarcinogenic, hepatoprotective, anti-oxidant, hypoglycemic, anthelmintic, antibacterial, antifungal, anti-diabetic, gut, and airways modulatory, metabolizing isozymes inhibitory, neuroprotective, HIV-I reverse transcriptases inhibitory, anticholinergic, and CNS-depressant activities, etc. In addition, biosynthetic pathways of xanthones, and seco-iridiods, two most important secondary metabolites for Swertia, are elucidated. The xanthones biosynthetic pathway is a mixed biosynthetic pathway involved the shikimate and the malonate routes, and the seco-iridoid pathway starts with geraniol derived from IPP which is produced either via the MEP or the MVA pathway. This review will offer a reference for future researches on the protection of natural resources, the investigation of therapeutic basis, new drug development, and so forth. Metabolic pathways of some crucial active compounds were also discussed in this review.

Capsaicin Inhibits Dimethylnitrosamine-Induced Hepatic Fibrosis by Inhibiting the TGF-β1/Smad Pathway via Peroxisome Proliferator-Activated Receptor Gamma Activation

Capsaicin (CPS) exerts many pharmacological effects, but any possible influence on liver fibrosis remains unclear. Therefore, we evaluated the inhibitory effects of CPS on dimethylnitrosamine (DMN) and TGF-β1-induced liver fibrosis in rats and hepatic stellate cells (HSCs). CPS inhibited DMN-induced hepatotoxicity, NF-κB activation, and collagen accumulation. CPS also suppressed the DMN-induced increases in α-SMA, collagen type I, MMP-2, and TNF-α. In addition, CPS inhibited DMN-induced TGF-β1 expression (from 2.3 ± 0.1 to 1.0 ± 0.1) and Smad2/3 phosphorylation (from 1.5 ± 0.1 to 1.1 ± 0.1 and from 1.6 ± 0.1 to 1.1 ± 0.1, respectively) by activating Smad7 expression (from 0.1 ± 0.0 to 0.9 ± 0.1) via PPAR-γ induction (from 0.2 ± 0.0 to 0.8 ± 0.0) (p < 0.05). Furthermore, in HSCs, CPS inhibited the TGF-β1-induced increases in α-SMA and collagen type I expression, via PPAR-γ activation. These results indicate that CPS can ameliorate hepatic fibrosis by inhibiting the TGF-β1/Smad pathway via PPAR-γ activation.

Assessing gastric toxicity of xanthone derivatives of anti-inflammatory activity using simulation and experimental approaches

Xanthones are tricyclic compounds of natural or synthetic origin exhibiting a broad spectrum of therapeutic activities. Three synthetic xanthone derivatives (KS1, KS2, and KS3) with properties typical for nonsteroidal anti-inflammatory drugs (NSAID) were objects of the presented model study. NSAIDs are in common use however; several of them exhibit gastric toxicity predominantly resulting from their direct interactions with the outermost lipid layer of the gastric mucosa that impair its hydrophobic barrier property. Among the studied xanthones, gastric toxicity of only KS2 has been determined in previous pharmacological studies, and it is low. In this study, carried out using X-ray diffraction and computer simulation, a palmitoyloleoylphosphatidylcholine-cholesterol bilayer (POPC-Chol) was used as a model of a hydrophobic layer of lipids protecting gastric mucosa as POPC and Chol are the main lipids in human mucus. X-ray diffraction data were used to validate the computer model. The aim of the study was to assess potential gastric toxicity of the xanthones by analysing their atomic level interactions with lipids, ions, and water in the lipid bilayer and their effect on the bilayer physicochemical properties. The results show that xanthones have small effect on the bilayer properties except for its rigidity whereas their interactions with water, ions, and lipids depend on their protonation state and for a given state, are similar for all the xanthones. As gastric toxicity of KS2 is low, based on MD simulations one can predict that toxicity of KS1 and KS3 is also low.

The protective effects of carvacrol and thymol against paracetamol-induced toxicity on human hepatocellular carcinoma cell lines (HepG2)

Acetaminophen (APAP) overdose could induce liver damage and lead to acute liver failure. The treatment of APAP overdoses could be improved by new therapeutic strategies. Thymus spp., which has many beneficial effects and has been used in folk medicine, is one such potential strategy. In the present study, the hepatoprotective activity of the main constituents of Thymus spp., carvacrol and thymol, were evaluated in light of APAP-induced hepatotoxicity. We hoped to understand the hepatoprotective mechanism of these agents on the antioxidant system and pro-inflammatory cytokines in vitro. Dose-dependent effects of thymol and carvacrol (25, 50, and 100 µM) were tested on cultured HepG2 cells. N-Acetylcysteine (NAC) was tested as positive control. We showed that APAP inhibited HepG2 cell growth by inducing inflammation and oxidative stress. Incubating APAP-exposed HepG2 cells with carvacrol and thymol for 24 h ameliorated this inflammation and oxidative stress. We also evaluated alanine transaminase and lactate dehydrogenase levels of HepG2 cells. We found that thymol and carvacrol protected against APAP-induced toxicity in HepG2 cells by increasing antioxidant activity and reducing pro-inflammatory cytokines, such as tumor necrosis factor α and interleukin 1β. Taking together high-dose thymol and carvacrol treatment has an effect close to NAC treatment in APAP toxicity, but thymol has better treatment effect than carvacrol.

Determination and pharmacokinetic study of four xanthones in rat plasma after oral administration of Gentianella acuta extract by UHPLC-ESI-MS/MS

ETHNOPHARMACOLOGICAL RELEVANCE

Gentianella acuta (Michx.) Hulten belonging to the family of Gentianaceae is an annual plant mainly distributed in north of China, Mongolia plateau, Siberia and Far East areas of Russia. The whole herb was used as folk medicine to treat hepatitis, jaundice, headache and fever in Mongolia native medicine. Xanthones are the main active compounds of G. acuta and possess a lot of pharmacological and biological activities

AIM OF THE STUDY

A selective and sensitive UHPLC-MS/MS method was developed and validated for the determination and pharmacokinetic study of swertianolin, norswertianolin, bellidifolin and demethylbellidifolin (DMB) in rat plasma after oral administration of G. acuta extract.

MATERIALS AND METHODS

Sample preparation involved a liquid-liquid extraction of the analytes with ethyl acetate. Butylparaben was employed as an internal standard. LC separation was achieved on an Agilent SB-C18 RRHD column (1.8 μm, 150 mm × 2.1 mm) at 30°C with an isocratic mobile phase consisting of acetonitrile-water (0.1% formic acid) (90:10, v/v). The detection was accomplished by multiple-reaction monitoring (MRM) scanning with electrospray ionization (ESI) source operating in the negative ionization mode. The optimized mass transition ion-pairs (m/z) monitored for swertianolin, norswertianolin, bellidifolin, DMB and I.S. were 435.1/272.0, 420.8/258.9, 273.0/258.0, 258.9/214.9 and 193.0/92.0, respectively.

RESULTS

The current UHPLC-MS/MS assay was validated for linearity, intra-day and inter-day precisions, accuracy, extraction recovery and stability and was suitable for pharmacokinetic studies of the four xanthones after oral administration of G. acuta extract. The time to reach the maximum plasma concentration (Tmax) was 0.40 ± 0.12 h for swertianolin, 0.27 ± 0.07 h for norswertianolin, 1.00 ± 0.18 h for bellidifolin and 0.94 ± 0.15 h for demethylbellidifolin. The elimination half-time (t1/2) of swertianolin, norswertianolin, bellidifolin and DMB, was 19.7 ± 9.64 h, 11.3 ± 4.51 h, 19.9 ± 8.11 h and 24.9 ± 8.19 h, respectively.

CONCLUSION

This study described a simple, sensitive and validated UHPLC-MS/MS method for simultaneous determination of four xanthones in rat plasma after oral administration of G. acuta extract, and investigated on their pharmacokinetic studies as well.

Neuroprotective effects of 3-O-demethylswertipunicoside against MPTP-induced Parkinson's disease in vivo and its antioxidant properties in vitro

3-O-demethylswertipunicoside (3-ODS) has been reported to protect dopaminergic neurons against neurotoxicity induced by 1-methyl-4-phenylpyridinium (MPP(+)) in PC12 cells. Here, we investigate the neuroprotective effects in vivo and antioxidant activities in vitro of 3-ODS. In the 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP)-treated mouse model of Parkinson's disease (PD), 3-ODS dose-dependently improved motor coordination (as shown by rotarod test), increased the contents of dopamine (DA) and its metabolites in the striatum, and increased the number of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra (SN). In addition, 3-ODS also increased the spine density in hippocampal CA1 neurons. In antioxidant assays, 3-ODS showed a strong capacity in scavenging hydroxyl radical, superoxide anion and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical in a concentration-dependent manner. Taken together, we conclude that 3-ODS attenuates the PD-related motor deficits mainly through its neuroprotective effects, growth-promoting effects on spine density, and its antioxidant activities.