Insulin-mimetic selaginellins from Selaginella tamariscina with protein tyrosine phosphatase 1B (PTP1B) inhibitory activity

Real-time monitoring of dephosphorylation process of phosphopeptide and rapid assay of PTP1B activity based on a 100 MHz QCM biosensing platform

The misregulation of protein phosphatases is a key factor in the development of many human diseases, notably cancers. Here, based on a 100 MHz quartz crystal microbalance (QCM) biosensing platform, the dephosphorylation process of phosphopeptide (P-peptide) caused by protein tyrosine phosphatase 1B (PTP1B) was monitored in real time for the first time and PTP1B activity was assayed rapidly and sensitively. The QCM chip, coated with a gold (Au) film, was used to immobilized thiol-labeled single-stranded 5'-phosphate-DNAs (P-DNA) through Au-S bond. The P-peptide, specific to PTP1B, was then connected to the P-DNA via chelation between Zr4+ and phosphate groups. When PTP1B was injected into the QCM flow cell where the P-peptide/Zr4+/MCH/P-DNA/Au chip was placed, the P-peptide was dephosphorylated and released from the Au chip surface, resulting in an increase in the frequency of the QCM Au chip. This allowed the real-time monitoring of the P-peptide dephosphorylation process and sensitive detection of PTP1B activity within 6 min with a linear detection range of 0.01-100 pM and a detection limit of 0.008 pM. In addition, the maximum inhibitory ratios of inhibitors were evaluated using this proposed 100 MHz QCM biosensor. The developed 100 MHz QCM biosensing platform shows immense potential for early diagnosis of diseases related to protein phosphatases and the development of drugs targeting protein phosphatases.

Antiobesity and antidiabetes effects of Cyperus rotundus rhizomes presenting protein tyrosine phosphatase, dipeptidyl peptidase 4, metabolic enzymes, stress oxidant and inflammation inhibitory potential

Diabetes is a significant global health concern that increases the vulnerability to various chronic illnesses. In view of this issue, the current research aimed to examine the effects of administering an extract derived from the tubers of Cyperus rotundus L (CrE) on obesity, type 1 diabetes, and liver-kidney toxicity. Through the utilization of HPLC-DAD analysis, it was discovered that the extract contained several components, including quercetin (47.8%), luteolin glucoside (17%), luteolin (7.56%), apigenin-7-glucoside (6.29%), naringinin (4.52%), and seven others. In vitro experiments they have demonstrated that CrE effectively inhibited key digestive enzymes associated with obesity and type 2 diabetes, such as DPP-4, PTP1B, lipase, and α-amylase, as evidenced by their respective IC50 values are about 23, 51,83, and 67 μg/ml respectively. Furthermore, when diabetic rats were administered CrE, the activity of pancreatic enzymes linked to inflammation, namely 5-lipoxygenase (5-LO), hyaluronidase (HAase), and myeloperoxidase (MPO), was significantly suppressed by 48, 41, 75, and 47%, respectively. Moreover, CrE exhibited protective effects on pancreatic β-cells by inhibiting the formation of thiobarbituric acid reactive substances (TBARS) by 65% and the induction of superoxide Dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities by 62, 108, and 112% respectively as compared to diabetic untreated rat. Additionally, CrE significantly inhibited the activities of intestinal, pancreatic, and serum lipase and α-amylase activities. In diabetic rats, CrE administration suppressed glycogen phosphorylase (GP) stimulated glycogen synthase (GS) activities by 45 and 30%; and this increased liver glycogen content by 45%. Furthermore, CrE modulated key hepatic enzymes involved in carbohydrate metabolism, including hexokinase (HK), glucose-6-phosphate dehydrogenase (G6PD), glucose-6-phosphatase (G6P), and fructose-1,6-bisphosphatase (FBP). Notably, the average food and water intake (AFI and AWI) of diabetic rats treated with CrE was reduced by 15 and 16% respectively as compared to those without any treatment. Therefore, this study demonstrated the effectiveness of Cyperus rotundus tubers in preventing and treating obesity and diabetes.

Selaginellin derivatives from Selaginella tamariscina and evaluation for anti-breast cancer activity

A phytochemical investigation of Selaginella tamariscina led to the isolation of 17 selaginellin derivatives. Their inhibitory activities against breast cancer cells were screened, and preliminary structure-activity relationships were also established. Among them, dimeric selaginellin 17 showed potential activity against MDA-MB-231 cells with an IC50 value of 3.2 ± 0.1 μM, corresponding to 4-fold higher potency than the reference compound 5-FU (IC50 14.8 ± 0.2 μM). Mechanistic studies indicated that 17 could cause G2/M phase arrest in MDA-MB-231 cells and induce apoptosis accompanied by increased ROS levels.

Natural STAT3 Inhibitors for Cancer Treatment: A Comprehensive Literature Review

Cancer is one of the leading causes of mortality and morbidity worldwide, affecting millions of people physically and financially every year. Over time, many anticancer treatments have been proposed and studied, including synthetic compound consumption, surgical procedures, or grueling chemotherapy. Although these treatments have improved the daily life quality of patients and increased their survival rate and life expectancy, they have also shown significant drawbacks, including staggering costs, multiple side effects, and difficulty in compliance and adherence to treatment. Therefore, natural compounds have been considered a possible key to overcoming these problems in recent years, and thorough research has been done to assess their effectiveness. In these studies, scientists have discovered a meaningful interaction between several natural materials and signal transducer and activator of transcription 3 molecules. STAT3 is a transcriptional protein that is vital for cell growth and survival. Mechanistic studies have established that activated STAT3 can increase cancer cell proliferation and invasion while reducing anticancer immunity. Thus, inhibiting STAT3 signaling by natural compounds has become one of the favorite research topics and an attractive target for developing novel cancer treatments. In the present article, we intend to comprehensively review the latest knowledge about the effects of various organic compounds on inhibiting the STAT3 signaling pathway to cure different cancer diseases.

DMSO-promoted direct δ-selective arylation of p-quinone methenylpiperidine bearinides to generate fuchsones under metal-free conditions by employing p-QMs themselves or substituted phenols as aryl sources

Fuchsones have wide applications in modern society. Present methods for generating fuchsones have many disadvantages and there are significant limitations for further exploration of fuchsone applications. Herein, we describe a DMSO-promoted direct δ-selective arylation of p-QMs to synthesize symmetrical and unsymmetrical fuchsones under metal-free conditions by employing p-QMs themselves or substituted phenols as aryl sources. As unprecedented methods, these novel strategies present a great advantage and significance for further exploration of fuchsones and the development of new applications.

Three New Benzophenone Derivatives from Selaginella tamariscina

Six compounds including three new benzophenones, selagibenzophenones D-F (1-3), two known selaginellins (4-5) and one known flavonoid (6), were isolated from Selaginella tamariscina. The structures of new compounds were established by 1D-, 2D-NMR and HR-ESI-MS spectral analyses. Compound 1 represents the second example of diarylbenzophenone from natural sources. Compound 2 possesses an unusual biphenyl-bisbenzophenone structure. Their cytotoxicity against human hepatocellular carcinoma HepG2 and SMCC-7721 cells and inhibitory activities on lipopolysaccharide-induced nitric oxide (NO) production in RAW264.7 cells were evaluated. Compound 2 showed moderate inhibitory activity against HepG2 and SMCC-7721 cells, and compounds 4 and 5 showed moderate inhibitory activity to HepG2 cells. Compounds 2 and 5 also exhibited inhibitory activities on lipopolysaccharide-induced nitric oxide (NO) production.

Synthesis of π-Extended Benzofulvenes: A Pd-Catalyzed Cascade Annulation Process Comprising C-C Bond Formation Followed by 1,6-Conjugate Addition

A Pd-catalyzed cascade annulation process comprising C-C bond formation followed by 1,6-conjugate addition for π-extended benzofulvenes is reported. This process is compatible with a wide range of functionalities for both the p-quinone methides and internal alkynes, leading to diverse π-extended benzofulvenes. Additionally, this strategy is also applicable for aryne annulation with p-quinone methides.

Three New Selaginellin Derivatives from Selaginella pulvinata and Their α-Glucosidase Inhibitory Activity

Three new selaginellin derivatives, selaginpulvilins V-X (1-3), together with seven known analogs (4-10) were isolated from whole plants of Selaginella pulvinata. Their structures were determined by extensive spectroscopic methods including 1D and 2D NMR, HR-ESI-MS and chemical derivatization method. Compound 1 represents a rare example of naturally occurring selaginellin with an alkynylphenol-trimmed skeleton. Biological evaluation showed that compounds 2, 6 and 8 displayed moderate inhibition against α-glucosidase with IC₅₀ values of 3.71, 2.04 and 4.00 μM, respectively.

A systematic analysis of anti-diabetic medicinal plants from cells to clinical trials

Background

Diabetes is one of the fastest-growing health emergencies of the 21st century, placing a severe economic burden on many countries. Current management approaches have improved diabetic care, but several limitations still exist, such as decreased efficacy, adverse effects, and the high cost of treatment, particularly for developing nations. There is, therefore, a need for more cost-effective therapies for diabetes management. The evidence-based application of phytochemicals from plants in the management of diseases is gaining traction.

Methodology

Various plants and plant parts have been investigated as antidiabetic agents. This review sought to collate and discuss published data on the cellular and molecular effects of medicinal plants and phytochemicals on insulin signaling pathways to better understand the current trend in using plant products in the management of diabetes. Furthermore, we explored available information on medicinal plants that consistently produced hypoglycemic effects from isolated cells to animal studies and clinical trials.

Results

There is substantial literature describing the effects of a range of plant extracts on insulin action and insulin signaling, revealing a depth in knowledge of molecular detail. Our exploration also reveals effective antidiabetic actions in animal studies, and clear translational potential evidenced by clinical trials.

Conclusion

We suggest that this area of research should be further exploited in the search for novel therapeutics for diabetes.

Methyl jasmonate induces selaginellin accumulation in Selaginella convoluta

INTRODUCTION

Selaginellins are specialized metabolites and chemotaxonomic markers for Selaginella species. Despite the growing interest in these compounds as a result of their bioactivities, they are accumulated at low levels in the plant. Hence, their isolation and chemical characterization are often difficult, time consuming, and limiting for biological tests. Elicitation with the phytohormone methyl jasmonate (MeJA) could be a strategy to increase the content of selaginellins addressing their low availability problem, that also impairs pharmacological investigations.

MATHERIALS AND METHODS

In this study, we examined MeJA elicitation in Selaginella convoluta plants, a medicinal plant found in northeastern Brazil, by treating them with two different concentrations (MeJA: 50 and 100 µM), followed by chemical profiling after 12, 24 and 48 h after application. Samples were harvested and analyzed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS).

RESULTS AND DISCUSSCION

MeJA treatment significantly impacted the chemical phenotype. Regarding shoots differences in the time-dependent increased accumulation of all metabolites when plants were subjected to 100 µM MeJA were observed while in roots, most metabolites had their concentrations decreased in a time-dependent fashion at the same conditions. Results support organ, MeJA concentration and time post-treatment dependence of specialized metabolite accumulation, mainly the flavonoids and selaginellins. The amount of Selaginellin G in shoots of MeJA-treated specimens increased in 5.63-fold relative to control. The molecular networking approach allowed for the putative annotation of 64 metabolites, among them, the MeJA treatment followed by targeted metabolome analysis also allowed to annotate seven unprecedented selaginellins. Additionally, the in silico bioactive potential of the annotated selaginellins highlighted targets related to neurodegenerative disorders, antiproliferative, and antiparasitic issues. Taken together, data point out MeJA exposure as a strategy to induce potentially bioactive selaginellins accumulation in S. convoluta, this approach could enable a deep investigation about the metabolic function of these metabolites in the genus as well as regarding pharmacological exploration of the undervalued potential.

In Vitro and In Vivo Evaluation of the Antidiabetic Activity of Solidago virgaurea Extracts

Background

Solidago virgaurea (Asteraceae) has been used for more than 700 years for treating cystitis, chronic nephritis, urolithiasis, rheumatism, and inflammatory diseases. However, the antidiabetic activity of Solidago virgaurea has been rarely studied.

Methods

Three extracts of Solidago virgaurea were prepared, and their antidiabetic potentials were evaluated by various cell-free, cell-based, and in vivo studies.

Results

We found that the Solidago virgaurea contained multiple bioactive phytochemicals based on the GC-MS analysis. The Solidago virgaurea extracts effectively inhibited the functions of the carbohydrate digestive enzyme (α-glucosidase) and protein tyrosine phosphatase 1B (PTP1B), as well as decreased the amount of advanced glycation end products (AGEs). In the L6 myotubes, the Solidago virgaurea methanolic extract remarkably enhanced the glucose uptake via the upregulation of glucose transporter type 4 (GLUT4). The extract also significantly downregulated the expression of PTP1B. In the streptozotocin-nicotinamide induced diabetic mice, the daily intraperitoneal injection of 100 mg/kg Solidago virgaurea methanolic extract for 24 days, substantially lowered the postprandial blood glucose level with no obvious toxicity. The extract's anti-hyperglycemic effect was comparable to that of the glibenclamide treatment.

Conclusion

Our findings suggested that the Solidago virgaurea extract might have great potential in the prevention and treatment of diabetes.

Selaginella tamariscina Inhibits Glutamate-Induced Autophagic Cell Death by Activating the PI3K/AKT/mTOR Signaling Pathways

Glutamate-induced neural toxicity in autophagic neuron death is partially mediated by increased oxidative stress. Therefore, reducing oxidative stress in the brain is critical for treating or preventing neurodegenerative diseases. Selaginella tamariscina is a traditional medicinal plant for treating gastrointestinal bleeding, hematuria, leucorrhea, inflammation, chronic hepatitis, gout, and hyperuricemia. We investigate the inhibitory effects of Selaginella tamariscina ethanol extract (STE) on neurotoxicity and autophagic cell death in glutamate-exposed HT22 mouse hippocampal cells. STE significantly increased cell viability and mitochondrial membrane potential and decreased the expression of reactive oxygen species, lactate dehydrogenase release, and cell apoptosis in glutamate-exposed HT22 cells. In addition, while glutamate induced the excessive activation of mitophagy, STE attenuated glutamate-induced light chain (LC) 3 II and Beclin-1 expression and increased p62 expression. Furthermore, STE strongly enhanced the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) phosphorylation activation. STE strongly inhibited glutamate-induced autophagy by activating the PI3K/Akt/mTOR signaling pathway. In contrast, the addition of LY294002, a PI3K/Akt inhibitor, remarkably suppressed cell viability and p-Akt and p62 expression, while markedly increasing the expression of LC3 II and Beclin-1. Our findings indicate that autophagy inhibition by activating PI3K/Akt/mTOR phosphorylation levels could be responsible for the neuroprotective effects of STE on glutamate neuronal damage.

Iron(III)-catalyzed tandem annulation of indolyl-substituted p-quinone methides with ynamides for the synthesis of cyclopenta[b]indoles

The unique reactivity of indolyl-substituted p-QMs as a new type of two-carbon synthon has been explored for the first time in a novel iron(III)-catalyzed tandem annulation. This (2+2) annulation/retro-4π electrocyclization/imino-Nazarov cyclization cascade reaction is characterized by an unusual structural reconstruction of indolyl-substituted p-QMs, leading to an expeditious assembly of synthetically important functionalized cyclopenta[b]indoles.

The traditional and modern uses of Selaginella tamariscina (P.Beauv.) Spring, in medicine and cosmetic: Applications and bioactive ingredients

ETHNOPHARMACOLOGICAL RELEVANCE

Extracts of the plant Selaginella tamariscina (P.Beauv.) Spring (spike moss) are used for a long time in Asia, for the treatment of multiple diseases and conditions. Aqueous and alcoholic leave extracts are used by local communities. In China, the plant (Juan bai) is listed on the Pharmacopoeia. In South Korea, the use of this plant (Kwon Baek) is mentioned in the book Dongui-Bogam (Heo Jun 1613), at the origin of the Hyungsang medicine. S. tamariscina is traditionally used in Vietnam (mong lung rong), Thailand (dok hin), Philippines (pakong-tulog) and other Asian countries.

AIM OF THE STUDY

To provide an analysis of the multiple traditional and current uses of S. tamariscina extracts (STE) in the field of medicine and cosmetic. The review is also intended at identifying the main natural products at the origin of the many pharmacological properties reported with these extracts (anti-inflammatory, antioxidant, antidiabetic, antibacterial, antiallergic, anticancer effects).

METHODS

Extensive database retrieval, such as SciFinder and PubMed, was performed by using keywords like " Selaginella tamariscina", "spike moss", "Selaginellaceae ". Relevant textbooks, patents, reviews, and digital documents were consulted to collate all available scientific literature and to provide a complete science-based survey of the topic.

RESULTS

Different solvents and methods are used to prepare STE. The process can largely modify the natural product content and properties of the extracts. STE display a range of pharmacological effects, useful to treat metabolic disorders, several inflammatory diseases and various cancers. A specific carbonized extract (S. tamariscina carbonisatus) has shown hemostatic effects, whereas standard STE can promote blood circulation. Many patented STE-containing cosmetic preparations are reviewed here. Several biflavonoids (chiefly amentoflavone) and phenolic compounds (selaginellin derivatives) are primarily responsible for the observed pharmacological properties. Potent inhibitors of protein tyrosine phosphatase 1 B (PTP1B), phosphodiesterase-4 (PDE4), and repressor of pro-inflammatory cytokines expression have been identified from STE.

CONCLUSION

The traditional use of STE supports the research performed with this plant. There are robust experimental data, based on in vitro and in vivo models, documenting the use of STE to treat type 2 diabetes, several inflammatory diseases, and some cancers (in combination with standard chemotherapy). Selaginella tamariscina (P.Beauv.) is a prime reservoir for amentoflavone, and many other bioactive natural products. The interest of the plant in medicine and cosmetic is amply justified.

Synthesis and evaluation of 3-(phenylethynyl)-1,1'-biphenyl-2-carboxylate derivatives as new HIF-1 inhibitors

Selaginellins are a type of rare natural products from the genus Selaginella with unusual alkynyl phenol skeletons and extensive biological activities. Previous structural simplification of these natural compounds afforded a series of diaryl acetylene derivatives with hypoxia-inducible factor 1 (HIF-1) inhibitory activity. In this study, we synthesized thirty compounds by stepwise optimization using methyl 3-(4-methoxylphenyl ethynyl)-[4'-methoxyl-1,1'-biphenyl]-2-carboxylate (1a) as a lead compound and evaluated their HIF-1 inhibitory activity by dual luciferase reporter assay. Among them, compound 9i displayed the most potent HIF-1 inhibitory activity (IC₅₀ = 1.5 ± 0.03 μM) with relatively low cytotoxicity. Under hypoxia, compound 9i showed no effect on the accumulation of HIF-1α protein in western blot analysis, but could down-regulate the expression of VEGF mRNA, the downstream target gene of HIF-1 pathway. Cell-based activity assay demonstrated that compound 9i could inhibit the hypoxia-induced migration, invasion and proliferation of HeLa cells at the concentrations of 1 ~ 5 μM. In mouse breast cancer xenograft model, compound 9i exhibited obvious tumor growth inhibition and very low toxicity at a dose of 15 mg/kg. The results suggested that compound 9i would be a potential antitumor agent via HIF-1 pathway inhibition.

Tandem (2 + 2) Annulation/Retro-4π Electrocyclization/Imino-Nazarov Cyclization Reaction of p-Quinone Methides with Ynamides: Expeditious Construction of Functionalized Aminoindenes

A new tandem annulation of p-quinone methides (p-QMs) with ynamides is described. This cascade reaction features a unique combination of (2 + 2) annulation, retro-4π electrocyclization, and imino-Nazarov cyclization, wherein vinyl p-quinone methides (p-VQMs) as one of the key intermediates have been identified chemically. Significantly, an unusual structural reconstruction of p-QMs involving the cleavage of the C5-C6 bond and the late-stage formation of the C4-C6 bond is involved, leading to a methodology development for the construction of functionalized aminoindenes.

Cross-Coupling as a Key Step in the Synthesis and Structure Revision of the Natural Products Selagibenzophenones A and B

Selagibenzophenone A (1) and its isomer selagibenzophenone B (2) were recently described as natural products from Selaginella genus plants with PDE4 inhibitory activity. Herein, we report the first total syntheses of both compounds. By comparing spectroscopic data of the synthetic compounds with reported data for the isolated material, we demonstrate that the structure of one of the two natural products was incorrectly assigned, and that in fact isolated selagibenzophenone A and selagibenzophenone B are identical compounds. The synthetic strategy for both 1 and 2 is based on a cross-coupling reaction and on the addition of organometallic species to assemble the framework of the molecules. Identifying a suitable starting material with the correct substitution pattern is crucial because its pattern is reflected in that of the targeted compounds. These syntheses are finalized via global deprotection. Protecting the phenols as methoxy groups provides the possibility for partial control over the selectivity in the demethylation thanks to differences in the reactivity of the various methoxy groups. Our findings may help in future syntheses of derivatives of the biologically active natural product and in understanding the structure–activity relationship.

Discovery of 5-(3-bromo-2-(2,3-dibromo-4,5-dimethoxybenzyl)-4,5-dimethoxybenzylidene)thiazolidine-2,4-dione as a novel potent protein tyrosine phosphatase 1B inhibitor with antidiabetic properties

Protein tyrosine phosphatase 1B (PTP1B) is a well-validated target in therapeutic interventions for type 2 diabetes mellitus (T2DM), however, PTP1B inhibitors containing negatively charged nonhydrolyzable pTyr mimetics are difficult to convert to the corresponding in vivo efficacy owing to poor cell permeability and oral bioavailability. In this work, molecules bearing less acidic heterocycle 2,4-thiazolidinedione and hydantoin were designed, synthesized and evaluated for PTP1B inhibitory potency, selectivity and in vivo antidiabetic efficacy. Among them, compound 5a was identified as a potent PTP1B inhibitor (IC₅₀ = 0.86 μM) with 5-fold selectivity over the highly homologous TCPTP. Long-term oral administration of 5a at a dose of 50 mg/kg not only significantly reduced blood glucose levels, triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) levels but also ameliorated insulin sensitivity in diabetic BKS db mice. Moreover, 5a enhanced the insulin-stimulated phosphorylation of IRβ, IRS-1 and Akt in C2C12 myotubes. A histopathological evaluation of liver and pancreas demonstrated that 5a increased liver glycogen storage and improved islet architecture with more β-cells and fewer α-cells in diabetic mice. Thus, our work demonstrated that compound 5a could serve as a lead compound for the discovery of new antidiabetic drugs.

Selaginellins from the genus Selaginella: isolation, structure, biological activity, and synthesis

Covering: 2007 to 2020 Selaginellins are a small group of pigments exclusively found in the ancient genus Selaginella. Since the first report of selaginellin from S. sinensis in 2007, more than 110 selaginellins with diverse polyphenolic skeletons have been reported. This review provides extensive coverage of the selaginellins discovered from 2007 to 2020, including 61 natural ones and 52 synthetic analogues. The isolation, chemical structures, plausible biosynthetic pathways, bioactivity, and total synthesis of these selaginellins have been summarized for the first time, and this highlights the fact that the vast uninvestigated Selaginella species may serve as a potential treasure trove of chemically diverse selaginellins waiting to be discovered.

Comparison of Chemical Composition and Biological Activities of Eight Selaginella Species

Selaginella P. Beauv. is a group of vascular plants in the family Selaginellaceae Willk., found worldwide and numbering more than 700 species, with some used as foods and medicines. The aim of this paper was to compare methanolic (MeOH) and dichloromethane (DCM) extracts of eight Selaginella species on the basis of their composition and biological activities. Six of these Selaginella species are underinvestigated. Using ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) analysis, we identified a total of 193 compounds among the tested Selaginella species, with flavonoids predominating. MeOH extracts recovered more constituents that were detected, including selaginellins, the occurrence of which is only typical for this plant genus. Of all the tested species, Selaginella apoda contained the highest number of identified selaginellins. The majority of the compounds were identified in S. apoda, the fewest compounds in Selaginella cupressina. All the tested species demonstrated antioxidant activity using oxygen radical absorption capacity (ORAC) assay, which showed that MeOH extracts had higher antioxidant capacity, with the half maximal effective concentration (EC₅₀) ranging from 12 ± 1 (Selaginella myosuroides) to 124 ± 2 (Selaginella cupressina) mg/L. The antioxidant capacity was presumed to be correlated with the content of flavonoids, (neo)lignans, and selaginellins. Inhibition of acetylcholinesterase (AChE) was mostly discerned in DCM extracts and was only exhibited in S. myosuroides, S. cupressina, Selaginella biformis, and S. apoda extracts with the half maximal inhibitory concentration (IC₅₀) in the range of 19 ± 3 to 62 ± 1 mg/L. Substantial cytotoxicity against cancer cell lines was demonstrated by the MeOH extract of S. apoda, where the ratio of the IC₅₀ HEK (human embryonic kidney) to IC₅₀ HepG2 (hepatocellular carcinoma) was 7.9 ± 0.2. MeOH extracts inhibited the production of nitrate oxide and cytokines in a dose-dependent manner. Notably, S. biformis halved the production of NO, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 at the following concentrations: 105 ± 9, 11 ± 1, and 10 ± 1 mg/L, respectively. Our data confirmed that extracts from Selaginella species exhibited cytotoxicity against cancer cell lines and AChE inhibition. The activity observed in S. apoda was the most promising and is worth further exploration.

The total flavonoids from Selaginella tamariscina (beauv.) Spring improve glucose and lipid metabolism in db/db mice

Objectives

This study aimed to investigate the glucose and lipid metabolism improving effect of the total flavonoids from Selaginella tamariscina (Beauv.) Spring (TFST) on db/db mice, and to study its mechanism of action.

Materials and Methods

The db/db mice were divided into 5 groups: the normal group (NC), the diabetic group (DM), the gliclazide group (GZ), the DM+TFST (110 mg/kg), and the DM+TFST (220 mg/kg). The body weight, blood glucose, INS, GC, TC, TG, LDL, and HDL were detected. HE staining was used to observe the liver and pancreas. Urine was tested by UPLC-QTOF-MS to study the metabolic differences of each group, coupled with SIMCA-P13.0 for PCA and OPLS-DA analysis, to identify potential biomarkers, find the metabolic pathway. Western blot was used to examine liver tissue of mice for studying effect of TFST on the PPAR-γ/PI3K/GLU4 pathway.

Results

TFST can reduce the weight and levels of TC, TG, and LDL-C, increase the level of GC in blood, and reduce the fat accumulation and inflammation in the liver, and repair the islet cell. 13 biomarkers were identified, they are mainly involved in amino acid metabolism, and purine and pyrimidine metabolism. The results of Western blot show TFST can improve the utilization rate of GLU4 by regulating PPAR-γ and PI3K expression in the liver of db/db mice.

Conclusion

TFST can improve glucose and lipid metabolism of DM, which relates to regulation of the PPAR-γ/PI3K/GLU4 signaling pathway, and affect the amino acid metabolism, purine, and pyrimidine metabolism.

Multiflorumisides HK, stilbene glucosides isolated from Polygonum multiflorum and their in vitro PTP1B inhibitory activities

A phytochemical study on a 70% EtOH extract of dried roots of Polygonum multiflorum resulted in the isolation of four undescribed stilbene glucosides, namely multiflorumisides HK (1-4). The structures of the natural products were elucidated by 1D and 2D nuclear magnetic resonance (NMR) as well as mass spectroscopy analyses. Among them, multiflorumiside J (3) and multiflorumiside K (4) belong to rare tetramer stilbene glucosides. Moreover, the in vitro inhibitory activities against protein tyrosine phosphatase 1B (PTP1B) were evaluated and the putative biosynthetic pathway was proposed. Notably, compounds 1-4 showed the inhibitory activity against PTP1B with the IC₅₀ values of 1.2, 1.7, 1.5 and 4.6 μm, respectively. Based on the obtained results, stilbene glucosides could be the potential PTP1B inhibitors of P. multiflorum.

Naphthacemycins from a Streptomyces sp. as Protein-Tyrosine Phosphatase Inhibitors

Nine new naphthacemycins (1-9), along with one known naphthacemycin (10) were isolated from the culture of Streptomyces sp. N12W1565. Their structures were elucidated on the basis of spectroscopic analysis, including UV, NMR, and HRESIMS. All the compounds showed significant activity, with IC₅₀ values less than 10 μM against protein-tyrosine phosphatase 1B (PTP1B). The anti-PTP1B structure-activity relationship of naphthacemycins (1-10) is discussed. These findings provide a promising starting point for the development of naphthacemycins as potential anti-PTP1B agents.

Glucose Uptake Stimulatory and PTP1B Inhibitory Activities of Pimarane Diterpenes from Orthosiphon stamineus Benth

Seven pimarane diterpenes (1–7) were isolated from Orthosiphon stamineus Benth. by assay-guided isolation. All of the isolates possessed a 2-deoxy-2-((7-nitro-2,1,3-benzoxadiazol-4-yl)amino)-d-glucose uptake effect in 3T3-L1 adipocytes at concentrations of 5 and 10 μM. Most of them showed potent inhibition against protein tyrosine phosphatase 1B with IC₅₀ values ranging from 0.33 to 9.84 μM. In the kinetic study, all inhibition types were exposed for the examined potencies, including mixed-competitive (1), non-competitives (3 and 5), competitive (6), and uncompetitive (7). The results suggested that O. stamineus and its pimarane diterpenes might exert the hypoglycemic effect via the insulin signaling pathway targeting inhibition of protein tyrosine phosphatase 1B (PTP1B) activity.

Synthesis of novel natural product-like diaryl acetylenes as hypoxia inducible factor-1 inhibitors and antiproliferative agents

The selaginellin derivatives are a type of novel natural pigments with an unusual alkynyl phenol skeleton from the genus Selaginella. Some of these natural compounds were previously reported to show important bioactivities, including anticancer activity, cardiovascular protection and phosphodiesterase-4 inhibition. We designed and synthesized fifteen biphenyl-containing diaryl acetylene derivatives mimicking the skeleton of natural alkynyl phenols. In MTT assay in cancer cells, compounds 1c, 2d, 2g, 2h, 2i and 2j exhibited potent antiproliferative activity. The evaluation of Hypoxia Inducible Factor-1 (HIF-1) pathway inhibitory activity in dual luciferase assay demonstrated that most tested compounds exhibited moderate to good activities. Compounds 1a, 2f and 2h displayed high HIF-1 inhibitory activities and relatively low cytotoxicity, demonstrating great potential as HIF-1 inhibitors. These results afford a new strategy for the discovery of new HIF-1 inhibitors and anti-proliferative agents from natural or synthetic diaryl acetylene derivatives.

Evaluation of Anti-Tyrosinase and Antioxidant Properties of Four Fern Species for Potential Cosmetic Applications

Ferns are poorly explored species from a pharmaceutical perspective compared to other terrestrial plants. In this work, the antioxidant and tyrosinase inhibitory activities of hydrophilic and lipophilic extracts, together with total polyphenol content, were evaluated in order to explore the potential cosmetic applications of four Spanish ferns collected in the Prades Mountains (Polypodium vulgare L., Asplenium adiantum-nigrum L., Asplenium trichomanes L., and Ceterach officinarum Willd). The antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, oxygen radical absorbance capacity (ORAC) and xanthine/xanthine oxidase (X/XO) assays. The potential to avoid skin hyperpigmentation was tested by inhibiting the tyrosinase enzyme, as this causes melanin synthesis in the epidermis. All ferns were confirmed as antioxidant and anti-tyrosinase agents, but interestingly hydrophilic extracts (obtained with methanol) were more potent and effective compared to lipophilic extracts (obtained with hexane). Polypodium vulgare, Asplenium adiantum-nigrum, and Ceterach officinarum methanolic extracts performed the best as antioxidants. Polypodium vulgare methanolic extract also showed the highest activity as a tyrosinase inhibitor.

Isolation, Structural Assignment of Isoselagintamarlin A from Selaginella tamariscina and Its Biomimetic Synthesis

Isoselagintamarlin A (1), a selaginellin analogue featured a rare benzofuran unit, was isolated from Selaginella tamariscina. Its complete structural assignment was established through a combination of high-field NMR technique and biomimetic synthesis. Notably, isoselagintamarlin A (1) was successfully synthesized via sequential oxidations and intramolecular cyclization.

Comparing coagulation activity of Selaginella tamariscina before and after stir-frying process and determining the possible active constituents based on compositional variation

CONTEXT

Selaginella tamariscina (P. Beauv.) Spring (Selaginellaceae) (ST) has been widely used in China as a medicine for improving blood circulation. However, its processed product, S. tamariscina carbonisatus (STC), possesses opposite haemostatic activity.

OBJECTIVE

To comprehensively evaluate the activity of ST and STC on physiological coagulation system of rats, and seek potential active substances accounting for the activity transformation of ST during processing.

MATERIALS AND METHODS

The 75% methanol extracts of the whole grass (fine powder) of ST and STC were prepared, respectively. Male Sprague-Dawley rats were randomly divided into five groups: control group, model group, model + ST group, model + STC group and positive control group (model + Yunnanbaiyao). The duration of intragastric administration was 72 h at 12 h intervals. Haemorheology parameters were measured using an LB-2 A cone-plate viscometer and the existed classic methods, respectively. SC40 semi-automatic coagulation analyzer was employed to determine coagulation indices. Meanwhile, HPLC and LC-MS were applied for chemical analyses of ST and STC extracts.

RESULTS

STC shortened tail-bleeding time, increased whole blood viscosity (WBV) and plasma viscosity (PV), decreased erythrocyte sedimentation rate blood (ESR), reduced activated partial thromboplastin time (APTT) and increased the fibrinogen (FIB) content in the plasma of bleeding model rats. Although ST could shorten APTT and TT, the FIB content was significantly decreased by ST. Dihydrocaffeic acid with increased content in STC vs. ST showed haemostatic activity for promoting the platelet aggregation induced by collagen and trap-6, and reducing APTT and PT significantly with a concentration of 171.7 μM in vitro. Amentoflavone with reduced content in STC vs. ST inhibited ADP and AA-induced platelet aggregation significantly with a concentration of 40.7 μM.

DISCUSSION AND CONCLUSIONS

As the processed product of ST, STC showed strong haemostatic activity on bleeding rat through regulating the parameters involved in haemorheology and plasma coagulation system. Two active compounds, dihydrocaffeic acid and amentoflavone, might be partially responsible for the haemostatic and anticoagulant activity of STC and ST, respectively.

A new selaginellin derivative and a new triarylbenzophenone analog from the whole plant of Selaginella pulvinata

Five selaginellin derivatives (1 and 3-6) including a new one, selaginellin T (1), and a new triarylbenzophenone analog, selagibenzophenone A (2), were isolated from the whole plants of Selaginella pulvinata. Their structures were determined by 1D- and 2D-NMR and HR-ESI-MS data. Selagibenzophenone A (2) is the first example of naturally occurring triarylbenzophenone. The results of the phosphodiesterase-4 (PDE4) inhibitory screening assays showed that compounds 1-6 exhibited potent activities with the IC₅₀ values in the range of 1.04-9.35 μM.

Biflavonoids Isolated from Selaginella tamariscina and Their Anti-Inflammatory Activities via ERK 1/2 Signaling

Selaginella tamariscina (S. tamariscina) (Beauv.) Spring (Selaginellaceae) has been used in oriental medicine for the treatment of dysmenorrhea, chronic hepatitis, hyperglycemia, amenorrhea, hematuria, prolapse of the anus and metrorrhagia. In the present study, we isolated two strong anti-inflammatory compounds, the biflavonoids hinokiflavone (H) and 7′-O-methyl hinokiflavone (mH), from S. tamariscina and examined their anti-inflammatory activities in lipopolysaccharide (LPS)-mediated murine macrophages (RAW 264.7) and colon epithelial cells (HT-29). H and mH suppressed the production of the inflammatory mediators nitric oxide (NO), interleukin (IL)-6, IL-8, and tumor-necrosis factor (TNF)-α, which are most highly activated in inflammatory bowel disease (IBD). In addition, Western blot analysis revealed that H and mH suppressed the LPS-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, and the activation of nuclear factor-κB (NF-κB) and extracellular regulated kinases (ERK) 1/2. These results suggest that H and mH are compounds having potent anti-inflammatory effects that could be used to treat such diseases as IBD.

Diselaginellin B, an Unusual Dimeric Molecule from Selaginella pulvinata, Inhibited Metastasis and Induced Apoptosis of SMMC-7721 Human Hepatocellular Carcinoma Cells

Two new unusual dimeric selaginellins, diselaginellins A and B (1 and 2), along with two known derivatives, selaginellin (3) and selaginellin B (4), were isolated from Selaginella pulvinata. Their structures were elucidated by extensive NMR and high-resolution ESIMS data analysis. Compound 2 displayed apoptosis-inducing and antimetastatic activities against the human hepatocellular carcinoma cell line SMMC-7721. A microarray analysis revealed that genes related to metabolism, angiogenesis, and metastasis were altered by 2. The up- and down-regulation of the mRNA levels of related genes was confirmed by RT-qPCR. Metabolism modulation and metastasis inhibition might be the mechanisms of the antitumor properties of diselaginellin B (2).

Novel Mixed-Type Inhibitors of Protein Tyrosine Phosphatase 1B. Kinetic and Computational Studies

The Atlas of Diabetes reports 415 million diabetics in the world, a number that has surpassed in half the expected time the twenty year projection. Type 2 diabetes is the most frequent form of the disease; it is characterized by a defect in the secretion of insulin and a resistance in its target organs. In the search for new antidiabetic drugs, one of the principal strategies consists in promoting the action of insulin. In this sense, attention has been centered in the protein tyrosine phosphatase 1B (PTP1B), a protein whose overexpression or increase of its activity has been related in many studies with insulin resistance. In the present work, a chemical library of 250 compounds was evaluated to determine their inhibition capability on the protein PTP1B. Ten molecules inhibited over the 50% of the activity of the PTP1B, the three most potent molecules were selected for its characterization, reporting Ki values of 5.2, 4.2 and 41.3 µM, for compounds 1, 2, and 3, respectively. Docking and molecular dynamics studies revealed that the three inhibitors made interactions with residues at the secondary binding site to phosphate, exclusive for PTP1B. The data reported here support these compounds as hits for the design more potent and selective inhibitors against PTP1B in the search of new antidiabetic treatment.

Protein tyrosine phosphatase 1B inhibitors from natural sources

Since PTP1B enzyme was discovered in 1988, it has captured the research community's attention. This landmark discovery has stimulated numerous research studies on a variety of human diseases, including cancer, inflammation, and diabetes. Tremendous progress has been made in finding PTP1B inhibitors and exploring PTP1B regulatory mechanisms. This review investigates for the natural PTP1B inhibitors, and focuses on the common characteristics of the discovered structures and structure-activity relationships. To facilitate understanding, all the natural compounds are here divided into five different classes (fatty acids, phenolics, terpenoids, steroids, and alkaloids), according to their skeletons. These PTP1B inhibitors of scaffold structures could serve as a theoretical basis for new concept drug discovery and design.

Amentoflavone suppresses tumor growth in ovarian cancer by modulating Skp2

AIM

Ovarian cancer is one of most common malignancies in women and is associated with high reoccurrence rate and poor prognosis. This study is designed to investigate the anti-tumor effects of amentoflavone (AF), one of the major active ingredients of S. tamariscina, against ovarian cancer.

MATERIALS AND METHODS

Human ovarian cancer cell lines SKOV3 and OVCAR-3 were used in this study. The effect of AF on cell viability was examined by CCK-8 assay. Cell apoptosis and cell cycle distribution was determined by flow cytometry. ROS generation was detected using fluorescent staining. Expression of signaling molecules was determined by western blots. Xenograft model was established to evaluate the therapeutic efficacy of AF in vivo.

KEY FINDINGS

Our results showed that AF could significantly suppress cell proliferation, induce apoptosis and block cell cycle progression. Mechanistically, downregulation of S-phase kinase protein 2 (Skp2) by AF contributed to its anti-tumor effect against ovarian cancer. Furthermore, our results showed that AF repressed the expression of Skp2 through ROS/AMPK/mTOR signaling. The anti-tumor effect of AF against ovarian cancer was also confirmed in a xenograft animal model.

SIGNIFICANCE

Overall, our present findings highlighted the potential of AF in the treatment of ovarian cancer. Moreover, our study also provided a new elucidation regarding the anti-tumor mechanisms of AF.

Inhibitory Effect of Selaginellins from Selaginella tamariscina (Beauv.) Spring against Cytochrome P450 and Uridine 5'-Diphosphoglucuronosyltransferase Isoforms on Human Liver Microsomes

Selaginella tamariscina (Beauv.) has been used for traditional herbal medicine for treatment of cancer, hepatitis, and diabetes in the Orient. Numerous bioactive compounds including alkaloids, flavonoids, lignans, and selaginellins have been identified in this medicinal plant. Among them, selaginellins having a quinone methide unit and an alkylphenol moiety have been known to possess anticancer, antidiabetic, and neuroprotective activity. Although there have been studies on the biological activities of selaginellins, their modulatory potential of cytochrome P450 (P450) and uridine 5'-diphosphoglucuronosyltransferase (UGT) activities have not been previously evaluated. In this study, we investigated the drug interaction potential of two selaginellins on ten P450 isoforms (CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 2J2 and 3A) and six UGT isoforms (UGT1A1, 1A3, 1A4, 1A6, 1A9 and 2B7) using human liver microsomes and liquid chromatography-tandem mass spectrometry. Selaginellin and selaginellin M had high inhibitory potential for CYP2C8-mediated amodiaquine O-demethylation with IC₅₀ values of 0.5 and 0.9 μM, respectively. Selaginellin and selaginellin M also showed medium inhibitory potential against CYP2C9, CYP2J2, UGT1A1, and UGT1A3 (1 μM < IC₅₀ < 5 μM). These two selaginellins had low inhibitory potential against CYP1A2, CYP2A6, CYP2E1, and UGT1A6 (IC₅₀ > 25 μM). This information might be helpful to predict possible drug interaction potential of between selaginellins and co-administered drugs.

A biomimetic semisynthesis enables structural elucidation of selaginellin U: a tautomeric cyclic alkynylphenol from Selaginella tamariscina

Two new lactone-containing selaginellins T and U (1 and 2) together with eleven known selaginellin derivatives (3 and 7-16) were isolated from the whole plant of Selaginella tamariscina. The structure of tautomeric selaginellin U along with its biogenetic pathway was confirmed and proposed by a cross-validation of the semisynthesis of compound 4 from selaginellin (3) and derivation from 2 to 4. Additionally, compounds 3, 13 and 16 exhibited good inhibitory activities against β-site amyloid precursor protein cleaving enzyme 1 (BACE1) with IC₅₀ values of 81.17, 51.13 and 48.89 µM, respectively.

Selagintamarlin A: A Selaginellin Analogue Possessing a 1H-2-Benzopyran Core from Selaginella tamariscina

Selagintamarlin A (1), a novel selaginellin analogue featuring the unique motif of 1H-2-benzopyran, a new selaginpulvilin E (2), together with eight known analogues were isolated from Selaginella tamariscina. Their structures were elucidated by extensive spectroscopic analyses. A plausible biosynthetic pathway of 1 was also postulated. Compound 1 showed remarkable inhibitory activity against phosphodiesterase-4 (PDE4D2), with an IC₅₀ value of 40 nM, which is 20-fold higher than that of the positive control (rolipram). Furthermore, compound 1 significantly inhibited tubulin polymerization.