New abietane and tigliane diterpenoids from the roots of Euphorbia fischeriana and their cytotoxic activities.

Three new abietane and two new tigliane diterpenoids were isolated from the roots Euphorbia fischeriana. Their structures were elucidated by spectroscopic methods and quantum chemical calculation. Compounds 4 and 5 exhibited the inhibitory activities against human cancer cells HeLa and HepG2, with IC50 ranging from 3.54 to 11.45 µM.

Diverse gallotannins with α-glucosidase and α-amylase inhibitory activity from the roots of Euphorbia fischeriana steud.

A phytochemical investigation of the roots of Euphorbia fischeriana Steud. led to the isolation of eleven undescribed gallotannins, fishertannins A-K, together with four known analogues. Their structures were elucidated by the comprehensive spectroscopic data including UV, IR, HR-ESI-MS, and NMR, while the absolute configurations of the sugar moiety were determined by the acid hydrolysis and HPLC analyses. Fishertannin A possessed an unusual skeleton comprised of acetophenone, galloyl group, arabinofuranosyl and glucopyranosyl moieties. Fishertannin B, fishertannin H, fishertannin K, 1,2,3-tri-O-galloyl-ß-D-glucopyranose, 3,4,6-tri-O-galloyl-D-glucopyranose, and 1,6-di-O-galloyl-ß-D-glucopyranose displayed the potent α-glucosidase inhibitory activities with the IC50 values of 15.48-177.13 µM. Examination of the structure-activity relationships (SAR) demonstrated that the galloyl and glucopyranosyl moieties played a key role in the inhibitory activity for both α-glucosidase and α-amylase inhibitory activity. Among all isolates, 1,2,3-tri-O-galloyl-ß-D-glucopyranose showed the most potent and highly specific inhibitory activity against α-glucosidase with an IC50 value of 15.48 ± 0.60 µM. The kinetic analysis of 1,2,3-tri-O-galloyl-ß-D-glucopyranose disclosed the mixed inhibition type on α-glucosidase, and the molecular docking visualized the stable binding with the catalytic pocket of α-glucosidase (pdb 3A4A). These findings indicated the excellent antidiabetic potential of the gallotannins from E. fischeriana, while 1,2,3-tri-O-galloyl-ß-D-glucopyranose could be developed as a promising candidate for the treatment of T2DM with fewer side effects.

Identification and Biosynthesis of Pro-Inflammatory Sulfonolipids from an Opportunistic Pathogen Chryseobacterium gleum.

Sulfonolipids (SoLs) are a unique class of sphingolipids featuring a sulfonate group compared to other sphingolipids. However, the biological functions and biosynthesis of SoLs in human microbiota have been poorly understood. Here, we report the discovery and isolation of SoLs from a human opportunistic pathogen Chryseobacterium gleum DSM16776. We show for the first time the pro-inflammatory activity of SoLs with mice primary macrophages. Furthermore, we used both in vivo heterologous expression and in vitro biochemical reconstitution to characterize two enzymes, cysteate synthase and cysteate fatty acyltransferase, that are specifically involved in the biosynthesis of SoLs rather than other sphingolipids. Based on these two SoL-specific enzymes, our bioinformatics analysis showed a wider distribution of SoL biosynthetic genes in microbes that had not been reported as SoL producers. We selected four of these strains and verified their cysteate synthase and cysteate fatty acyltransferase activities in SoL biosynthesis. Considering this wider distribution of SoL-specific biosynthetic enzymes in the context of SoLs' activity in mediating inflammation, a common and fundamental biological process, it may suggest a more comprehensive function of SoLs at play.

[A new alkaloid from Ervatamia hainanensis].

In order to study the alkaloids from branches and leaves of Ervatamia hainanensis, silica gel, ODS, Sephadex LH-20 and HPLC chromatography were used to obtain six alkaloids from the branches and leaves of E. hainanensis with use of. Based on the physicochemical properties and spectral data, their structures were identified as 10-hydroxydemethylhirsuteine(1), 3R-hydroxycoronaridine(2), 3-(2-oxopropyl)coronaridine(3), pandine(4), 16-epi-vobasine(5), and 16-epi-vobasinic acid(6). Among them, compound 1 was a new monoterpenoid indole alkaloid, and compounds 5 and 6 were obtained from this plant for the first time.

Fischdiabietane A, an Antitumoral Diterpenoid Dimer Featuring an Unprecedented Carbon Skeleton from Euphorbia fischeriana.

Fischdiabietane A (1), a novel asymmetric diterpenoid dimer with a unique nonacyclic 6/6/6/5/7/6/6/6/6 ring system possessing unprecedented 2-oxaspiro[4.5]decane-1-one and 2-oxabicyclo[3.2.2]nonane frameworks in D/E/F rings, was isolated from the roots of Euphorbia fischeriana. Its structure was determined by spectroscopic techniques, electronic circular dichroism calculations, and X-ray diffraction experiments. Notably, 1 is the first abietane-type [4 + 2] Diels-Alder dimer identified from nature. The IC50 of 1 against T47D cells was about sixfold higher than that of cisplatin (the positive control). Furthermore, 1 induced apoptosis in T47D cells through the activation of caspase-3 and the degradation of poly(ADP-ribose) polymerase.

Bufadienolides from the Eggs of the Toad Bufo bufo gargarizans and Their Antimelanoma Activities.

Toads produce potent toxins, named bufadienolides, to defend against their predators. Pharmacological research has revealed that bufadienolides are potential anticancer drugs. In this research, we reported nine bufadienolides from the eggs of the toad Bufo bufo gargarizans, including two new compounds (1 and 3). The chemical structures of 1 and 3, as well as of one previously reported semisynthesized compound (2), were elucidated on the basis of extensive spectroscopic data interpretation, chemical methods, and X-ray diffraction analysis. Compound 1 is an unusual 19-norbufadienolide with rearranged A/B rings. A biological test revealed that compounds 2 and 4-8 showed potent cytotoxic activities toward human melanoma cell line SK-MEL-1 with IC50 values less than 1.0 µM. A preliminary mechanism investigation revealed that the most potent compound, 8, could induce apoptosis via PARP cleavage, while 5 and 6 significantly suppressed angiogenesis in zebrafish. Furthermore, an in vivo biological study showed that 5, 6, and 8 inhibit SK-MEL-1 cell growth significantly.

Monoterpenoid indole alkaloids from the fruits of Gelsemium elegans and their anti-inflammatory activities.

Two novel monoterpenoid indole alkaloids (MIAs), gelsechizines A-B (1-2), along with four known ones (3-6) were isolated from the fruits of Gelsemium elegans. Compound 1 features a new carbon skeleton with two additional carbon atoms forming a 4-methylpyridine unit. Their structures with absolute configurations were elucidated by NMR, MS, X-ray diffraction and electronic circular dichroism (ECD) calculations. Compounds 1-3 showed significant anti-inflammatory effects in vivo and in vitro, which may be related to the inhibition of the trecruitment of neutrophils and macrophages as well as the secretion of TNF-α and IL-6. Preliminary structure-activity relationship analysis revealed that the ß-N-acrylate moiety plays an important role in the anti-inflammatory effect.

Impaired meningeal lymphatic drainage in patients with idiopathic Parkinson's disease.

Animal studies implicate meningeal lymphatic dysfunction in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease (PD). However, there is no direct evidence in humans to support this role1-5. In this study, we used dynamic contrast-enhanced magnetic resonance imaging to assess meningeal lymphatic flow in cognitively normal controls and patients with idiopathic PD (iPD) or atypical Parkinsonian (AP) disorders. We found that patients with iPD exhibited significantly reduced flow through the meningeal lymphatic vessels (mLVs) along the superior sagittal sinus and sigmoid sinus, as well as a notable delay in deep cervical lymph node perfusion, compared to patients with AP. There was no significant difference in the size (cross-sectional area) of mLVs in patients with iPD or AP versus controls. In mice injected with α-synuclein (α-syn) preformed fibrils, we showed that the emergence of α-syn pathology was followed by delayed meningeal lymphatic drainage, loss of tight junctions among meningeal lymphatic endothelial cells and increased inflammation of the meninges. Finally, blocking flow through the mLVs in mice treated with α-syn preformed fibrils increased α-syn pathology and exacerbated motor and memory deficits. These results suggest that meningeal lymphatic drainage dysfunction aggravates α-syn pathology and contributes to the progression of PD.

1ß-OH-arenobufagin induces mitochondrial apoptosis in hepatocellular carcinoma through the suppression of mTOR signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Chansu, dried secretions from Bufonidae, has long been used for cancer treatment as a traditional Chinese medicine. In searching for effective anti-hepatoma agents from Chansu, our preliminary drug screening found that a bufadienolide, namely 1ß-hydroxyl-arenobufagin (1ß-OH-ABF), displays anti-hepatoma activities. However, the anti-hepatoma effects and molecular mechanisms of 1ß-OH-ABF have not been defined. AIM OF THE STUDY: To evaluate the anti-hepatoma activity of 1ß-OH-ABF against liver cancer Hep3B and HepG2 cells in vitro and in vivo, as well as explore the underlying mechanisms. MATERIALS AND METHODS: The anti-proliferative effects of 1ß-OH-ABF on liver cancer Hep3B, HepG2, HuH7, SK-HEP-1 and normal hepatocyte LO2 cells were examined by MTT assay and colony formation assay. Hoechst 33258 staining and Annexin V-FITC/PI staining assay were used to analyze apoptosis induced by 1ß-OH-ABF. The collapse of the mitochondrial membrane potential (ΔΨm) was detected by JC-1 staining assay. Western blotting was used to examine the expression levels of targeted proteins. The role of mTOR in 1ß-OH-ABF-induced apoptosis was investigated using small interfering RNA (siRNA) transfection. Zebrafish xenograft model was established to evaluate the anti-hepatoma effects of 1ß-OH-ABF in vivo. RESULTS: We found that 1ß-OH-ABF inhibits the proliferation of Hep3B, HepG2, HuH7, SK-HEP-1 cells but has little cytotoxicity towards LO2 cells. 1ß-OH-ABF induces mitochondria dysfunction and triggers mitochondria apoptotic pathway, which is accompanied by the loss of ΔΨm, upregulation and translocation of Bax, as well as cleavages of caspase-9, caspase-3 and PARP. Mechanistically, 1ß-OH-ABF markedly decreases the expression level of p-AKT/AKT and p-mTOR (Ser2248 and Ser2481)/mTOR in a time-dependent manner. Inhibition of mTOR by siRNA strengthens 1ß-OH-ABF-mediated apoptosis. Critically, 1ß-OH-ABF shows a marked in vivo anti-hepatoma effect on human Hep3B cell xenografts in zebrafish model. CONCLUSION: 1ß-OH-ABF induces mitochondrial apoptosis through the suppression of mTOR signaling in vitro and in vivo, indicating that 1ß-OH-ABF may serve as a potential agent for the treatment of liver cancer.

Molecular mechanisms of bufadienolides and their novel strategies for cancer treatment.

Bufadienolides are cardioactive C24 steroids with an α-pyrone ring at position C17. In the last ten years, accumulating studies have revealed the anticancer activities of bufadienolides and their underlying mechanisms, such as induction of autophagy and apoptosis, cell cycle disruption, inhibition of angiogenesis, epithelial-mesenchymal transition (EMT) and stemness, and multidrug resistance reversal. As Na+/K+-ATPase inhibitors, bufadienolides have inevitable cardiotoxicity. Short half-lives, poor stability, low plasma concentration and oral bioavailability in vivo are obstacles for their applications as drugs. To improve the drug potency of bufadienolides and reduce their side effects, prodrug strategies and drug delivery systems such as liposomes and nanoparticles have been applied. Therefore, systematic and recapitulated information about the antitumor activity of bufadienolides, with special emphasis on the molecular or cellular mechanisms, prodrug strategies and drug delivery systems, is of high interest. Here, we systematically review the anticancer effects of bufadienolides and the molecular or cellular mechanisms of action. Research advancements regarding bufadienolide prodrugs and their tumor-targeting delivery strategies are critically summarized. This work highlights recent scientific advances regarding bufadienolides as effective anticancer agents from 2011 to 2019, which will help researchers to understand the molecular pathways involving bufadienolides, resulting in a selective and safe new lead compound or therapeutic strategy with improved therapeutic applications of bufadienolides for cancer therapy.

Triterpene saponins from the seeds of Erythrophleum fordii and their cytotoxic activities.

Erythrosides A-G, seven undescribed oleanane-type triterpenoid saponins, were isolated from the seeds of Erythrophleum fordii. Their structures with absolute configurations were determined by extensive spectroscopic analysis including one-dimensional [1D] and two-dimensional [2D] nuclear magnetic resonance [NMR], high-resolution electrospray ionization mass spectroscopy [HR-ESI-MS] analysis, and chemical methods. Erythrosides A-G featured a diverse oligosaccharide chain containing 4-6 pentoses or hexoses at C-3 and a monoterpenic acid or a (E)-cinnamic acid unit at the C-21 position. Of particular interest, erythrosides A-C, E and F contained a rare alpha xylose in their sugar chains. The bioassay results indicated that erythrosides A-C showed moderate cytotoxic activities against human lung cancer cell line PC9 with IC50 values of 13.14, 16.67 and 17.59 µM, respectively (the positive control, Taxol, IC50 = 0.60 nM).

New cadinane sesquiterpenoids from Mikania micrantha.

Chemical investigation of the aerial parts of Mikania micrantha led to the isolation of eight sesquiterpenoids and ten diterpenoids, including five cadinane sesquiterpenoids (1-5), three bisabolene sesquiterpenoids (6 - 8), nine ent-kaurane diterpenoids (9-17), and an abietane diterpenoid (18). Among them, 1 - 3 are new and feature a rare lactone or furan ring derived from C-6 isopropyl group side chain. Compound 18 was isolated from genus Mikania for the first time, and was also the first example of abietane-type diterpenoids from this plant. Their structures were elucidated on the basis of extensive spectroscopic analyses (1D and 2D NMR, HRESIMS, and ECD). All compounds were examined for their inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophage cells, and compound 18 exhibited pronounced inhibition on NO production (IC50 = 11.04 µM), being comparable to the positive control, quercetin (IC50 = 11.15 µM).

Alopecuroides A-E, Matrine-Type Alkaloid Dimers from the Aerial Parts of Sophora alopecuroides.

Five new matrine-type alkaloid dimers, alopecuroides A-E, were isolated from the aerial parts of Sophora alopecuroides. Alopecuroides A and B represent the first dimeric matrine-type alkaloids possessing a cyano group and an epoxy moiety. Alopecuroides C and D are dimeric matrine-type alkaloids connected via C-2-C-9' and C-10-C-3' bonds, respectively. The chemical structures of alopecuroides A-E were elucidated by spectroscopic methods combined with single-crystal X-ray diffraction analysis. The anti-inflammatory effects of alopecuroides A-E were evaluated, and alopecuroide B exhibited the most significant activity, better than that of matrine, the representative compound from S. alopecuroides.

Xanthchrysones A-C: Rearranged Phenylpropanoyl-Phloroglucinol Dimers with Unusual Skeletons from Xanthostemon chrysanthus.

Three pairs of dimeric phenylpropanoyl-phloroglucinol enantiomers, (+)- and (-)-xanthchrysones A-C [(+)- and (-)-1-3], as well as their postulated biosynthetic precursors, were isolated and identified from the leaves of Xanthostemon chrysanthus. Compound 1 featured an unprecedented bis-phenylpropanoyl-benzo[b]cyclopent[e] oxepine tricyclic backbone. Compounds 2 and 3 represent the first examples of 1-(cyclopentylmethyl)-3-(3-phenylpropanoyl)benzene scaffold. The structures and absolute configurations of 1-3 were determined by spectroscopic and X-ray diffraction analysis as well as electronic circular dichroism (ECD) calculation. Both (+)-2 and (-)-2 showed moderate antibacterial activities including several multidrug-resistant strains.

Jatrogricaine A: a new diterpenoid with a 5/6/6/4 carbon ring system from the stems of Jatropha podagrica.

Jatrogricaine A (1), a new diterpenoid possessing a 5/6/6/4 carbon ring system, together with eight known diterpenoids (2-9) were isolated from the stems of Jatropha podagrica. Their structures were elucidated by extensive spectroscopic methods and the absolute configuration of 1 was determined by single crystal X-ray diffraction analysis. All compounds were evaluated for their anti-inflammatory activities in vitro, and compound 3 showed significant inhibitory effects against nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 macrophage cells with an IC50 of 13.44 ± 0.28 µmol·L-1, being comparable to the positive control, quercetin (IC50 17.00 ± 2.10 µmol·L-1).

Anti-tumor effects and 3D-quantitative structure-activity relationship analysis of bufadienolides from toad venom.

Toad venom (venenum bufonis, also called Chan'su) has been widely used for centuries in China to treat different diseases, especially for cancer. Bufadienolides are mainly responsible for the anti-cancer effects of toad venom. However, systematic chemical composition and cytotoxicity as well as key pharmacophores of these bufadienolides from toad venom have not yet been defined clearly. To enrich the understanding of the diversity of bufadienolides and to find bufadienolides with better activities from toad venom. This study was carried out to isolate chemical constituents, research their anti-tumor effects and mechanisms by MTT assay, flow cytometry and Western blotting, and develop a CoMFA and CoMSIA quantitative structure-activity relationship (QSAR) model for illustrating the vital relationship between the chemical structures and cytotoxicities. Among 47 natural bufadienolides, most of bufadienolides (21 compounds isolated in this study and 26 compounds isolated previously) could significantly inhibit the proliferation of cancer cells, and compounds 1, 8, 12, 18 and 19 showed the most potent inhibitory activity against four types of human tumor cells. Compound 18 induced G2/M cell cycle arrest and apoptosis. Moreover, 3D contour maps generated from CoMFA and CoMSIA identified several pharmacophores of bufadienolides responsible for the anti-tumor activities. Our study might provide reliable information for future structure modification and rational drug design of bufadienolides with anticancer activities in medical chemistry.

Rearranged Phloroglucinol-Monoterpenoid Adducts from Callistemon rigidus.

Callisretones A (1) and B (2), two rearranged phloroglucinol-monoterpenoid adducts featuring an unprecedented isopropylcyclopenta[b]benzofuran backbone, together with their postulated biosynthetic precursors (3-9), were isolated from Callistemon rigidus. The previously assigned absolute configurations of viminalins H (7), L (8), and N (9) were revised and unequivocally established by X-ray diffraction data. A putative biosynthetic pathway toward callisretones A and B involving the rearrangement of the terpenoid motif is proposed. In addition, 1 and 2 showed inhibitory effects on nitric oxide production with IC50 values of 15.3 ± 1.0 and 17.7 ± 1.1 µM, respectively.

Erratum: Identification of Na+/K+-ATPase inhibition-independent proarrhythmic ionic mechanisms of cardiac glycosides.

A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.

Two new diterpenoid lactones isolated from Andrographis paniculata.

In the present study, two new diterpenoid lactones, 3-deoxy-andrographoside (1) and 14-deoxy-15-methoxy-andrographolide (2), were isolated from the aerial parts of Andrographis paniculata. Their structures were elucidated by combination of NMR, MS, and chemical methods. The configurations of 1 and 2 were established based on the analysis of ROESY data and single crystal X-ray diffraction experiment.

Identification of Na+/K+-ATPase inhibition-independent proarrhythmic ionic mechanisms of cardiac glycosides.

The current study explored the Na+/K+-ATPase (NKA) inhibition-independent proarrhythmic mechanisms of cardiac glycosides (CGs) which are well-known NKA inhibitors. With the cytosolic Ca2+ chelated by EGTA and BAPTA or extracellular Ca2+ replaced by Ba2+, effects of bufadienolides (bufalin (BF) and cinobufagin (CBG)) and cardenolides (ouabain (Oua) and pecilocerin A (PEA)) on the L-type calcium current (I Ca,L) were recorded in heterologous expression Cav1.2-CHO cells and human embryonic stem cell-derived cardiomyocytes (hESC-CMs). BF and CBG demonstrated a concentration-dependent (0.1 to100 µM) I Ca,L inhibition (maximal ≥50%) without and with the NKA activity blocked by 10 µM Oua. BF significantly shortened the action potential duration at 1.0 µM and shortened the extracellular field potential duration at 0.01~1.0 µM. On the other hand, BF and CBG at 100 µM demonstrated a strong inhibition (≥40%) of the rapidly activating component of the delayed rectifier K+ current (I Kr) in heterologous expression HEK293 cells and prolonged the APD of the heart of day-3 Zebrafish larva with disrupted rhythmic contractions. Moreover, hESC-CMs treated with BF (10 nM) for 24 hours showed moderate yet significant prolongation in APD90. In conclusion, our data indicate that CGs particularly bufadienolides possess cytosolic [Ca2+]i- and NKA inhibition- independent proarrhythmic potential through I Ca,L and I Kr inhibitions.