Two dimeric clerodane diterpene glycosides, namely, bistinospinosides A (1) and B (2), were isolated from the roots of Tinospora sagittata. Their structures were elucidated by extensive spectroscopic data interpretation. The compounds feature an unusual 1,4-epoxycyclohexane ring in their structures and may be biosynthetically constructed via an intermolecular Diels–Alder [4+2] cycloaddition from the corresponding clerodane diterpene. The compounds were evaluated in a nitric oxide inhibitory assay using J774.1 macrophage-like cells.

•Thirteen flavonoid glycosides were isolated from oil cakes of Camellia japonica seeds.•Four novel kaempferol 3-O-glycosides were structurally elucidated.•Chemical profiling of oil cake extract was characterized by HPLC-PDA analysis.•Extract and flavonoids 1–12 exhibited potent inhibitory activities against AGEs formation.•Oil cakes of Japanese Camellia are potential health materials against AGEs related diseases.Phytochemical investigation of the oil cakes of Camellia japonica L. seeds resulted in the isolation and structural elucidation of thirteen flavonoid glycosides (1–13), including four novel compounds (6, 10–12). Chemical profiling of the oil cake extract was characterized by HPLC-PDA analysis. The extract and isolated compounds 1–12 exhibited potent inhibitory activities against advanced glycation end-products (AGEs) formation between d-ribose and bovine serum albumin (BSA). The major compound 7 exhibited the most potent inhibitory activity among the isolated compounds. The extract and 7 also inhibited AGEs formation between human serum albumin (HSA) and three intermediates: glycolaldehyde (GA), methyl glyoxal (MGO), and glyoxal (GO). Moreover, extract and compound 7 decreased the GA-HSA enhanced expression of macrophage inflammatory protein-1β (MIP-1β) mRNA in differentiated U937 cells. The extract and its flavonoid glycoside constituents from the oil cakes of C. japonica seeds possessed potential usability as health materials against AGE-associated chronic diseases.Download high-res image (205KB)Download full-size image

Recently, growing evidence of the pivotal roles of peroxisome proliferator-activated receptor (PPAR) β/δ in various physiological functions, including lipid homeostasis, cancer, and inflammation, has raised interest in this receptor. In this study, the naturally occurring dimeric alkaloid picrasidine N (1) from Picrasma quassioides was identified as a novel PPARβ/δ agonist from a library consisting of plant extracts and natural compounds using a mammalian one-hybrid assay, and this compound was characterized. Compound 1 activated PPARβ/δ but did not activate or slightly activated PPARα and PPARγ. Furthermore, a peroxisome proliferator response element-driven luciferase reporter gene assay demonstrated that 1 enhanced PPARβ/δ transcriptional activity. Moreover, 1 selectively induced mRNA expression of ANGPTL4, which is a PPAR target gene. This observation is quite different from previously identified synthetic PPARβ/δ agonists, which can induce the expression of not only ANGPTL4 but also other PPAR target genes, such as ADRP, PDK4, and CPT-1. These results demonstrate that 1 is a potent subtype-selective and gene-selective PPARβ/δ agonist, suggesting its potential as a lead compound for further drug development. This compound would also be a useful chemical tool for elucidating the mechanism of PPARβ/δ-regulated specific gene expression and the biological significance of PPARβ/δ.

Picrasidine C (1), a dimeric β-carboline-type alkaloid isolated from the root of Picrasma quassioides, was identified to have PPARα agonistic activity by a mammalian one-hybrid assay from a compound library. Among the PPAR subtypes, 1 selectively activated PPARα in a concentration-dependent manner. Remarkably, 1 also promoted PPARα transcriptional activity by a peroxisome proliferator response element-driven luciferase reporter assay. Furthermore, 1 induced the expression of PPARα-regulated genes involved in lipid, glucose, and cholesterol metabolism, such as CPT-1, PPARα, PDK4, and ABCA1, which was abrogated by the PPARα antagonist MK-886, indicating that the effect of 1 was dependent on PPARα activation. This is the first report to demonstrate 1 to be a subtype-selective PPARα agonist with potential application in treating metabolic diseases, such as hyperlipidemia, atherosclerosis, and hypercholesterolemia.

•Five canthinone alkaloids were shown to be cerebral protective agents.•N-3, C-4, and C-9 substitutions affect the cerebral protective effect.•Picrasidine O suppresses neuronal hyperexcitability caused by glutamic acid.•Picrasidine O shows improvement effects on brain tissue damage.•Picrasidine O has no effect on heart rate or mean systolic blood pressure.Considerable attention has been paid to cerebral protective drugs as a potential therapy for dementia. Screening of a natural compound library here resulted in identification of five canthinone alkaloids, viz., picrasidine L (1), picrasidine O (2), eurycomine E (3), 3-ethyl-canthin-5,6-dione (4), and 3-ethyl-4-methoxy-canthin-5,6-dione (5), as novel cerebral protective agents. The structure–activity relationship indicated that C-4, C-9, and N-3 substitutions greatly affected their cerebral protective effect. Among these, compound 2 exhibited a cerebral protective effect through suppressing neuronal hyperexcitability due to an increase in the excitatory neurotransmitter glutamic acid. Furthermore, compound 2 did not affect heart rate and mean systolic blood pressure. This investigation suggests that compound 2 has potential for further development as a cerebral protective drug.

Phytochemical investigation of the roots of Euphorbia fischeriana resulted in the isolation of 23 diterpenoids (1–23), which were classified into five subtypes, namely, ent-rosane (1–9), ent-abietane (10–16), ent-kaurane (17), ingenane (18–22), and lathyrane (23). The chemical structures of eight new compounds, namely, euphorin A (4), B (5), C (7), D (9), E (13), F (14), G (15), and H (16), were elucidated on the basis of extensive 1D and 2D NMR spectroscopic analyses, as well as single crystal X-ray structure analysis. A number of compounds (2, 6, 7, 10, 11, 13, 16, 19, 20, 22, and 23) showed inhibitory activity on the formation of mammospheres in human breast cancer MCF-7 cells at a final concentration of 10 μM, suggesting the potential of these bioactive diterpenoids for further investigation of the action targeting cancer stem cells.

The discovery of new drugs that target cancer stem cells (CSCs) is a critical approach to overcome the major difficulties of the metastasis, chemotherapeutic resistance and recurrence for successful cancer therapy. Chemical investigation of the roots of Euphorbia fischeriana resulted in the isolation of eight ent-atisane diterpenoids (1–8), including two new compounds: 19-O-β-D-glucopyranosyl-ent-atis-16-ene-3,14-dione (7) and 19-O-(6-galloyl)-β-D-glucopyranosyl-ent-atis-16-ene-3,14-dione (8). The structures were elucidated on extensive spectroscopic analyses, as well as chemical transformations. ent-3β-Hydroxyatis-16-ene-2,14-dione (5), 7 and its aglycon, ent-19-hydroxy-atis-16-ene-3,14-dione (7a), showed significant inhibitory activity on mammosphere formation in human breast cancer MCF-7 cells at a final concentration of 10 μM.

•Twelve triterpenoid saponins, five previously known, were isolated from Silene armeria.•Two possess a unique 3,4-seco-oleanane sapogenin structure.•Oxidation of C-23 of the sapogenin is a key factor in Silene saponin biosynthesis.Twelve triterpenoid saponins, including seven compounds (i.e., armerosides A–G) hitherto unknown, were isolated from whole plants of Silene armeria. Their structures were established based on extensive spectroscopic analyses and chemical methods. From a biosynthetic perspective, C-23 oxidation of the sapogenin appears to be a key factor in the glycosylation pathway.

•Determination of saponins in Ardisia crenanta by UFLC-ESI–MS method.•Twenty-two saponins including two new were identified.•Absolute and relative quantitative methods for the determination of eight marker saponins.•The first systematic analytical study of saponins in Ardisa species.Ardisia plant species have been used in traditional medicines, and their bioactive constituents of 13,28-epoxy triterpenoid saponins have excellent biological activities for new drug development. In this study, a fast and simple method based on ultrafast liquid chromatography coupled to electrospray ionization mass spectrometry (UFLC–MS) was developed to simultaneously identify and quantitatively analyze triterpenoid saponins in Ardisia crenata extracts. In total, 22 triterpenoid saponins, including two new compounds, were identified from A. crenata. The method exhibited good linearity, precision and recovery for the quantitative analysis of eight marker saponins. A relative quantitative method was also developed using one major saponin (ardisiacrispin B) as the standard to break through the choke-point of the lack of standards in phytochemical analysis. The method was successfully applied to quantitatively analyze saponins in commercially available plant samples. This study describes the first systematic analysis of 13,28-epoxy-oleanane-type triterpenoid saponins in the genus Ardisia using LC-ESI–MS. The results can provide the chemical support for further biological studies, phytochemotaxonomical studies and quality control of triterpenoid saponins in medicinal plants of the genus Ardisia.

•Six canthinone alkaloids are novel PTP1B inhibitors.•Picrasidine L is the competitive PTP1B inhibitor with the best inhibitory selectivity.•Picrasidine L was shown to promote activity in the insulin signaling pathway.•C-4, C-9 and N-3 substitutions greatly affected PTP1B inhibitory activity.Considerable attention has been paid to protein tyrosine phosphatase 1B (PTP1B) inhibitors as a potential therapy for diabetes. Screening of a natural compound library resulted in six canthinone alkaloids, namely, picrasidine L (1), 3,4-dimethyl-canthin-5,6-dione (2), 4-ethyl-3-methyl-canthin-5,6-dione (3), eurycomine E (4), 5-methoxy-canthin-6-one (5), and 5-acethoxy-canthin-6-one (6), as novel PTP1B inhibitors. Among these, 1 is the competitive PTP1B inhibitor with the best inhibitory selectivity between PTP1B and other PTPs and was shown to promote activity in the insulin signaling pathway in cell-based assays. Molecular docking simulations and structure–activity relationship analysis of 1 will add to its potential as a lead compound in future anti-insulin-resistant drug developments.

Aloperine (ALO), one of the alkaloids isolated from Sophora alopecuroides L., is traditionally used for various diseases including neuronal disorders. This study investigated the protective effects of ALO on neonatal rat primary-cultured hippocampal neurons injured by oxygen–glucose deprivation and reperfusion (OGD/RP). Treatment with ALO (25, 50, and 100 mg/l) attenuated neuronal damage (p < 0.01), with evidence of increased cell viability (p < 0.01) and decreased cell morphologic impairment. Furthermore, ALO increased mitochondrial membrane potential (p < 0.01), but inhibited intracellular-free calcium [Ca2+]i (p  < 0.01) elevation in a dose-dependent manner at OGD/RP. ALO also reduced the intracellular reactive oxygen species and malondialdehyde production and enhanced the antioxidant enzymatic activities of catalase, superoxide dismutase, glutathione peroxidase and the total antioxidant capacity. The results suggested that ALO has significant neuroprotective effects that can be attributed to anti-oxidative stress.

•Two new cycloartanes were isolated from roots of Euphorbia fischeriana.•Cycloartanes 1–4 showed human CYP3A4 promoter activity.•CYP3A4 promoter activity of 2 involved in a PXR-independent pathway.•C-17 side chain structure of cycloartane is important for the activity.A chemical study of the roots of Euphorbia fischeriana resulted in the isolation of seven triterpenes (1–7), including two new compounds: (24R,S)-3β-24,31-epoxy-24-methylcycloartane (1) and (24R,S)-3β,31-dihydroxy-24-methoxy-24-methylcycloartane (2). Their structures were elucidated through extensive spectroscopic analyses. Cycloartanes 1–4 showed significant human CYP3A4 promoter activity through a series of luciferase reporter assays. Of these compounds, 3 and 4 activated the pregnane X receptor (PXR) and induced CYP3A4 mRNA expression in human primary hepatocytes. However, despite showing the most potent human CYP3A4 promoter activity via a PXR-independent pathway, 2 did not affect CYP3A4 mRNA expression in human primary hepatocytes. This difference is correlated to substitutions in C-24 and C-25 of the cycloartane structure.

Five novel tigliane-type diterpenes, stelleracins A–E (3–7), a novel flavanone dimer, chamaeflavone A (8), and six known compounds were isolated from the roots of Stellera chamaejasme. Their structures were elucidated by extensive spectroscopic analyses. The isolated compounds were evaluated for anti-HIV activity in MT4 cells. New compounds 3–5 showed potent anti-HIV activity (EC90 0.00056–0.0068 μM) and relatively low or no cytotoxicity (IC50 4.4–17.2 μM). These new compounds represent promising new leads for development into anti-AIDS clinical trial candidates.

Protein tyrosine phosphatase 1B (PTP1B) is a major negative regulator in insulin- and leptin-signaling cascades as well as a positive regulator in tumorigenesis, and much attention has been paid to PTP1B inhibitors as potential therapies for diabetes, obesity, and cancer. In the present study, the screening of a compound library of licorice flavonoids allowed for the discovery of several compounds, including licoagrone (3), licoagrodin (4), licoagroaurone (5), and isobavachalcone (6), as new PTP1B inhibitors. It was revealed that these compounds inhibit the activity of PTP1B in different modes and with different selectivities and that they exhibit different cellular activity in the insulin-signaling pathway. Glycybenzofuran (1), a competitive PTP1B inhibitor, showed both excellent inhibitory selectivity against PTP1B and cellular activity on the insulin-stimulated Akt phosphorylation level. The similarity of its action profiling in the insulin-signaling pathway suggested its potential as a new anti-insulin-resistant drug candidate.

Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a major cellular energy sensor and master regulator of metabolic homeostasis; thus, AMPK plays a central role in studies on diabetes and related metabolic diseases. From the rhizomes of Polygonatum odoratum (Mill.) Druce, six homoisoflavonoids (1–6) and one dihydrochalcone (7) were isolated, and the structures of polygonatones A–D (4–7) were elucidated by various spectroscopic analyses. Compounds 1–7 were evaluated for their effect on AMPK activation. The amount of active phosphorylated AMPK and acetyl-CoA carboxylase in rat liver epithelial IAR-20 cells increased when the cells were incubated with the aforementioned compounds. Specifically, (3R)-5,7-dihydroxyl-6-methyl-8-methoxyl-3-(4′-hydroxylbenzyl)-chroman-4-one (1), (3R)-5,7-dihydroxyl-6,8-dimethyl-3-(4′-hydroxylbenzyl)-chroman-4-one (2), (3R)-5,7-dihydroxyl-6-methyl-3-(4′-hydroxylbenzyl)-chroman-4-one (3), and polygonatone D (7) exhibited significant activation effects.

•Eight lignoids were isolated from Ribes nigrumleaves.•First report of 7,7′-epoxylignans, sesquilignans and dilignans in Grossulariaceae.•Six lignoids and a flavonol showed potent superoxide anion scavenging activity.•The structure–activity relationship was discussed.Phytochemical investigation of the leaves of Ribes nigrum resulted in the isolation of fourteen compounds, including four 7,7′-epoxylignans, three tetrahydrofuran-type sesquilignans, and a spirocyclic dilignan. Their structures were elucidated by extensive spectroscopic analyses and by chemical transformations. The isolated compounds were evaluated for their antioxidant activities using superoxide anion scavenging assay and DPPH free radical scavenging assay. Ribesin D and ribesin G showed the most potent superoxide anion scavenging activity with EC50 values of 1.24 and 1.12 μM, respectively, and the structure–activity relationship was discussed.7,7′-Epoxylignans, tetrahydrofuran-type sesquilignans and spirocyclic dilignans were isolated from leaves of Ribes nigrum. Ribesin D and ribesin G showed potent superoxide anion scavenging activity.

The present phytochemical study firstly reported isolation of the individual chemical constituents from Sorbus pohuashanensis. Total 18 compounds of seven types have been isolated. Five triterpenes and six other compounds identified are firstly reported from the genus Sorbus. Phenylmethanol α-L-arabinofuranosyl(1→6)-β-D-glucopyranoside is firstly reported from the family Rosaceae. The quite limited but simultaneous occurrence of (3S,5S)-3-(β-D-glucopyranosyloxy)-5-hydroxyhexonic acid ethyl ester and parasorboside suggested the close genetic relationship between S. pohuashanensis and Sorbus aucuparia.Graphical abstractHighlights► The first phytochemical study on Sorbus pohuashanensis. ► Total 18 compounds of seven types have been isolated. ► Five triterpenes and six compounds are firstly from the genus Sorbus. ► Close genetic relationship between S. pohuashanensis and Sorbus aucuparia. ► The first report of phenolic glycoside 12 from the family Rosaceae.

Significant attention has been devoted to studying hairy root cultures as a promising strategy for production of various valuable secondary metabolites. These offer many advantages, such as high growth rate, genetic stability and being hormone-free. In this study, a detailed phytochemical investigation of the secondary metabolites of Coleus forskohlii hairy root cultures was undertaken and which resulted in the isolation of 22 compounds, including four forskolin derivatives and a monoterpene. Their structures were elucidated by extensive spectroscopic analyses. These compounds could be classified into four groups viz.: labdane-type diterpenes, monoterpenes, triterpenes and phenylpropanoid dimers. Apart from one compound, all labdane type diterpenes are oxygenated at C-11 as in forskolin and a scheme showing their biosynthetic relationships is proposed.Graphical abstractPhytochemical investigation of the secondary metabolites of Coleus forskohlii hairy root cultures resulted in isolation of 22 compounds, including four forskolin derivatives and a monoterpene.Highlights► Secondary metabolites of Coleus forskohlii hairy roots were investigated. ► Twenty two compounds including four forskolin derivates and a monoterpene were isolated. ► A biosynthetic pathway to forskolin is proposed.

Three novel 1-alkyldaphnane-type diterpenes, stelleralides A–C (4–6), and five known compounds were isolated from the roots of Stellera chamaejasme L. The structures of 4–6 were elucidated by extensive spectroscopic analyses. Several isolated compounds showed potent anti-HIV activity. Compound 4 showed extremely potent anti-HIV activity (EC90 0.40 nM) with the lowest cytotoxicity (IC50 4.3 μM) and appears to be a promising compound for development into anti-AIDS clinical trial candidates.

A 70% EtOH extract from the bark of Syringareticulata has shown significant antioxidant activity. Chemical study on the extract resulted in the isolation of seventeen compounds (1–17), including a novel oleoside-type secoiridoid glucoside, reticuloside (1), and the structures were elucidated on the basis of extensive spectroscopic analyses. Among the isolated compounds, jaspolyoside (2), oleuropein (4) and 2-(3,4-dihydroxy)-phenylethyl-β-d-glucopyranoside (17), showed the most potent superoxide anion scavenging activity with the EC50 values of 4.97, 2.57 and 4.97 μM, respectively. The structure–activity relationship indicated that the presence of 2-(3,4-dihydroxyphenyl)-ethoxy group is important for exhibiting the activity.

A simple hydrophilic-interaction chromatography (HILIC) method was developed for the identification and quantification of 14 nucleosides and nucleobases, namely cytosine, uracil, cytidine, guanine, hypoxanthine, xanthine, uridine, thymine, inosine, guanosine, thymidine, 2′-deoxyadenosine, 2′-deoxyinosine and 2′-deoxyuridine in two traditional Chinese medicines, Geosaurus and Leech. The separation was achieved on a TSKgel Amide-80 column (150 mm × 2.0 mm, 3.0 μm) with a mixture of acetonitrile and 10 mM aqueous ammonium acetate as the mobile phase at a flow rate of 0.2 mL/min. The temperature was set at 30 °C and UV detection wavelength was set at 260 nm. All calibration curves showed good linearity (R2 > 0.9957) within the test ranges. The overall intra- and inter-day RSD ranged from 0.4 to 3.4% and from 0.7 to 3.3%, respectively. The LOD and LOQ were in the range of 0.07–30.49 ng/mL and 0.26–60.98 ng/mL, respectively. The repeatability of the method was in the range of 2.2–5.8% for Geosaurus and 1.4–5.5% for Leech. The recoveries of the samples were in the range of 91.4–100.9% for Geosaurus, and 91.9–99.3% for Leech. The established method was applied successfully for the analysis of nucleosides and nucleobases in 22 commercially available samples collected from different regions in China and Japan. Our data showed that HILIC had advantages as a useful tool for the study of the bioactive components in Geosaurus and Leech as well as their quality control, and could therefore be used for the determination of the analytes in pharmaceutical products and biological fluids.

Two new 2-arylbenzofurans, glycybenzofuran (1) and cyclolicocoumarone (2), together with 10 known flavonoids including licocoumarone (3), glycyrrhisoflavone (4), glisoflavone (5), cycloglycyrrhisoflavone (6), isoliquiritigenin (7), licoflavone A (8), apigenin (9), isokaempferide (10), glycycoumarin (11), and isoglycycoumarin (12), were isolated from the roots of Glycyrrhiza uralensis and their structures were determined by extensive spectroscopic analyses. Compounds 1 and 5 showed significant protein tyrosine phosphatase-1B (PTP1B) inhibitory activity in vitro with the IC50 values of 25.5 and 27.9 μM, respectively. The structure–activity relationship indicated that the presence of prenyl group and ortho-hydroxy group is important for exhibiting the activity. Kinetic analysis indicated that compound 1 inhibits PTP1B by a competitive mode, whereas compound 5 by a mixed mode.

A novel α-tetralonyl derivative, juglanone, was isolated from the fresh unripe fruits of Juglans mandshurica. Its structure was determined by spectroscopic analyses and from chemical evidence. Juglanone exhibited significant antioxidant activity in assays for 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide dismutase-like activity with IC50 values of 10.1 and 9.0 μM, respectively. It also showed moderate cytotoxic activity against HL-60 human myeloid leukemia with an IC50 value of 19.7 μM.

Phytochemical investigation of the methanolic extract from the aerial parts of Agrimonia pilosa led to the isolation of three compounds, (−)-aromadendrin 3-O-β-d-glucopyranoside (1), desmethylagrimonolide 6-O-β-d-glucopyranoside (2), and 5,7-dihydroxy-2-propylchromone 7-O-β-d-glucopyranoside (3), together with nine known compounds, agrimonolide 6-O-glucoside, takanechromone C, astragalin, afzelin, tiliroside, luteolin, quercetin, isoquercetrin, and quercitrin. Their structures were determined by various spectroscopic analysis and chemical transformations.Phenolic compounds (1–3) together with nine known compounds were isolated from the aerial parts of Agrimonia pilosa.

Ten new triterpenoid saponins (1−10), named rubusides A−J, and 21 known saponins (11−31) were isolated from the roots of Rubus ellipticus var. obcordatus. The structures of 1−10 were established on the basis of spectroscopic analyses, mainly NMR and MS, and chemical degradations. The compounds demonstrated inhibitory activities against α-glucosidase with IC50 values in the range 0.65−3.09 mM.

The composition of steam-distilled essential oils from the leaves of Alpinia zerumbet (Pers.) B. L. Burtt. et R. M. Sm. cultivated in Okinawa Island was investigated by GC-MS analysis. The seasonal variation of the main volatile constituents was also investigated. Analysis of the essential oil identified 17 compounds. It showed the predominant presence of monoterpenic constituents, representing 95% of the essential oil. p-Cymene was the most abundant compound, followed by 1,8-cineole, terpinen-4-ol, alpha-pinene, beta-pinene and limonene. The amount of sesqiterpenic content of the essential oil was small, mostly represented by beta-caryophyllene and alpha-caryophyllene. One of the phenylpropanoid derivatives, methyl cinnamate, was also detected. The essential oils from the leaves collected at ten different collection periods for over 5 years showed significant differences in their compositions. p-Cymene, terpinen-4-ol and 1,8-cineole were the most predominant constituents over the periods with a few exceptions. The content rates of p-cymene were abundant in summer, still high in late autumn and early winter, and decreased in mid-winter and early spring. In contrast, the contents of terpinen-4-ol and 1,8-cineole were high in winter, but decreased around summer. On enantiomeric distribution, terpinen-4-ol and alpha-pinene were suggested to relate to seasonal transformation. (+)-Terpinen-4-ol had a tendency to decrease in high temperatures and huge precipitations. It was also suggested that (−)-alpha-pinene was more sensitive to climate change than (+)-alpha-pinene.

Triterpenoid saponins, impatienosides A–G, together with 12 known saponins, were isolated from the whole plants of Impatiens siculifer. Their structures were established on the basis of extensive 1D and 2D NMR and MS analyses coupled with chemical degradation. Cytotoxic activities of the isolated saponins were evaluated against three human cancer cell lines: human myeloid leukemia HL-60 cells, human stomach KATO-III adenocarcinoma, and human lung A549 adenocarcinoma.Triterpenoid saponins, impatienosides A–G, together with 12 known saponins, were isolated from the whole plants of Impatiens siculifer.

Five new pregnane glycosides, cynanosides K–O (1–5) with a 14,15-seco-pregnane-type skeleton as the aglycon, together with five known compounds, cynascyroside C, sublanceoside E1, sublanceoside I1, atratoside A and atratoside B, were isolated from the roots of Cynanchum atratum. Their structures were determined on the basis of spectroscopic analysis and chemical evidence.

•Five novel steroidal glycosides were isolated from Polygonatum odoratum.•Three cholestane glycosides with unique Δ14,16-unsaturated D-ring structure.•Compound 7 showed significant antifungal activity.Much attention has been paid to cholestane-type steroidal glycosides because of their importance from the perspectives of both chemical diversity and significant biological activities. A phytochemical investigation of the rhizomes of Polygonatum odoratum (Liliaceae) resulted in the isolation of three novel cholestane-type steroidal glycosides (1–3) with unique Δ14,16-unsaturated D-ring structures as well as two novel spirostane-type steroidal saponins (4 and 5) and three known steroidal glycosides (6–8). Their structures were determined by various spectroscopic methods and chemical reactions. Steroidal saponin 7 showed significant antifungal activity against Candida albicans JCM1542 (MIC 3.1 μg/mL) and Aspergillus fumigatus JCM1738 (MIC 6.3 μg/mL).Download full-size image

Eleven new 14,15-seco-pregnane-type steroidal glycosides, cynanosides P1–P5, Q1–Q3, R1–R3, and a novel 12,13-seco-14,18-nor-pregnane-type steroidal glycoside, cynanoside S, were isolated from the roots of Cynanchum atratum, together with four known compounds, atratoside C, sublanceoside E3, chekiangensoside C and cynatroside B. Their structures were determined on the basis of spectroscopic analysis and chemical evidence.

Ethnopharmacological relevanceMasiningan is a traditional medicine consisting of six crude drugs that have been used for treating constipation and diabetes mellitus in both Japan and China. Masiningan has been reported to have significant PTP1B inhibitory activity and to affect cells in the insulin-signaling pathway. The aim of the present study is to identify the PTP1B inhibitory compounds in Masiningan.Materials and methodsBioactivity peaks were identified by analytical HPLC profiling and PTP1B inhibitory activity profiling of sub-fractions from Masiningan extract. The bioactive compounds were isolated by tracking two identified bioactive peaks, and the chemical structures were determined by spectroscopic analyses. The bioactive compounds were further investigated for their inhibitory effect against PTP1B by enzymatic kinetic analysis, molecular docking simulation, inhibitory selectivity against other PTPs, and cellular activity in the insulin signal transduction pathway.ResultsFrom Masiningan, magnolol (1) and chrysophanol (2) were isolated as compounds that exhibited significant dose-dependent inhibitory activities against PTP1B, with IC50 values of 24.6 and 12.3 μM, respectively. Kinetic analysis revealed that 1 is a non-competitive and that 2 is a competitive PTP1B inhibitor. In the molecular docking simulation, compound 2 was stably positioned in the active pocket of PTP1B, and the CDOCKER energy was calculated to be 24.3411 kcal/mol. Both compounds demonstrated remarkably high selectivity against four PTPs and revealed cellular activity against the insulin signal transduction pathway.ConclusionsMagnolol (1) and chrysophanol (2) were identified as the principle PTP1B inhibitory active compounds in Masiningan, and their actions were investigated in detail. These findings demonstrated the effectiveness of Masiningan on diabetes mellitus through the inhibition of PTP1B at a molecular level as well as the potential of magnolol (1) and chrysophanol (2) as lead compounds in future anti-diabetes drug development.Download high-res image (150KB)Download full-size image

BackgroundPregnane X receptor (PXR) is a key regulator of the induction of drug metabolizing enzymes. PXR has been studied for its importance in drug-drug or herb-drug interactions, and it is also a molecular target for the treatment of inflammatory and metabolic diseases.PurposeThis study aims to determine new natural PXR-ligands from traditional plant medicines.MethodsThe PXR activation activity was measured by a mammalian one hybrid assay of PXR. Identification of the active compound from Alisma rhizome (the rhizomes of Alisma orientale) was carried out by bioassay-guided fractionation method. The transcriptional activity of the liver-enriched nuclear receptors was measured by the luciferase reporter assay. The interaction between the SRC-1 and PXR was measured by a mammalian 2-hybrid assay. The expression of endogenous CYP3A4 mRNA in both cultured hPXR-overexpressing hepatoma cells and human primary hepatocytes were measured by quantitative RT-PCR method.ResultsThe extract of Alisma rhizome showed the most potent activation activity by screening of a library of medicinal plant extracts. Alisol B 23-acetate (ABA) was identified to be the active compound of Alisma rhizome. ABA caused a concentration-dependent increase on the PXR-dependent transactivation of a luciferase reporter gene, but did not affect the ligand binding activity of the liver-enriched nuclear receptors, such as CAR, LXR, FXR, PPARα, PPARδ and PPARγ, emphasizing that ABA is a potent and specific agonist of PXR. With ABA treatment, the direct interaction between the ligand-binding domain of PXR and the receptor interaction domain of SRC1 was observed. ABA also induced the expression of endogenous CYP3A4 mRNA in both cultured hPXR-overexpressing hepatoma cells and human primary hepatocytes.ConclusionSince the rhizomes of Alisma orientale are used for a wide range of ailments in traditional Chinese medicine and Japanese Kampo medicine, this study could possibly extend into the clinical usage of these medicines via the mechanism of PXR activation.Download high-res image (117KB)Download full-size image