Cytotoxic biflavonoids from Selaginella delicatula

A Biflavonoid-Rich Extract from Selaginella doederleinii Hieron. against Throat Carcinoma via Akt/Bad and IKKβ/NF-κB/COX-2 Pathways

Selaginella doederleinii Hieron. is a common pharmacological plant, and this folk herbal medicine and its complex preparations have been widely used for the treatment of throat carcinoma (TC) and several associated complications in traditional Chinese medicine. This study was aimed at investigating the specific anti-throat carcinoma impacts and potential mechanisms of a biflavonoid-rich extract from S. doederleinii (SD-BFRE). The phytochemical profiling of SD-BFRE was performed by HPLC-ESI-QTOF-MS and UPLC-PDA, and the detailed pharmacological effects and mechanisms were respectively evaluated in vitro and in vivo. MTT assay, the Transwell assay and flow cytometry were performed to evaluate the abilities of SD-BFRE on inhibiting cell infiltrative growth in TC cells (Hep-2 and FaDu) in in vitro experiments. In vivo experiments used Hep-2 tumor-bearing nude mice to evaluate the anti-TC effect of SD-BFRE. Western blotting was used to explore the potential apoptotic pathway of TC cells. Here, we found that SD-BFRE exhibited anti-proliferation and pro-apoptotic effects in TC cells. Mechanistic studies have identified that SD-BFRE can suppress the activity of IKKβ and IκB-α kinase and then down-regulate the effector proteins of NF-κB/COX-2 signaling. Moreover, SD-BFRE induced apoptosis partly by regulating the Akt/Bad/caspase signaling pathway. Taken together, this study firstly demonstrated that SD-BFRE exerted its anti-TC effects by way of IKKβ/NF-κB/COX-2 and Akt/Bad pathways and might represent a potential chemotherapeutic agent for throat carcinoma.

Siamenflavones A-C, three undescribed biflavonoids from Selaginella siamensis Hieron. and biflavonoids from spike mosses as EGFR inhibitor

Three undescribed biflavonoids (BFVs), siamenflavones A-C along with twelve BFVs were isolated from Selaginella siamensis Hieron. and Selaginella bryopteris (L.) Baker (Selaginellaceae). The chemical structures of undescribed compounds were established through comprehensive spectroscopic techniques, chemical correlations, and X-ray crystallography. The ten isolated BFVs, siamenflavones A-C, delicaflavone, chrysocauflavone, robustaflavone, robustaflavone-4-methylether, amentoflavone, tetrahydro-amentoflavone, and sciadopitysin were evaluated for the antiproliferative effects against four human cancer cell lines A549, H1975, HepG2 and T47D. Delicaflavone and robustaflavone 4'-methylether exerted strong effects on the four human cancer cell lines. Siamenflavone B, delicaflavone and robustaflavone 4'-methylether showed potent inhibitory activities against wild-type EGFR. The inhibition of the compounds was further supported by molecular docking and predictive intermolecular interactions. Molecular dynamics simulation studies of siamenflavone B and robustaflavone-4'-methylether complexed to EGFR-TK further supported inhibition of the compounds to the ATP binding site. Finally, analysis of pharmacokinetic and electronic properties using density-functional theory and known drug index calculations suggest that the compounds are pharmaceutically compatible for drug administration.

Cytotoxic Biflavonoids from Selaginella braunii

A new biflavonoid, (2″ S)-8″-C-methyl-2″,3″-dihydrorobustaflavone-4′-methyl ether (1) and 5 known robustaflavones (2-6) were isolated from the 70% EtOH extract of Selaginella braunii for the first time. The structures of 1 and the known compounds were identified by performing a comprehensive analysis of spectroscopic data including ultraviolet-visible, high-resolution electrospray ionization mass spectrometry, 1-dimensional and 2-dimensional nuclear magnetic resonance, and circular dichroism spectra. Compounds 1-6 were determined for cytotoxic activity against 3 human cancer cell lines (SMMC-7721, MCF-7, and A549). Compound 1 exerted apparent antiproliferative effects on SMMC-7721, MCF-7, and A549 cells, with IC50 values of 18.6, 16.7, and 25.5 μM, respectively.

Flavonoids from Selaginella doederleinii Hieron and Their Antioxidant and Antiproliferative Activities

Selaginella doederleinii Hieron. (S. doederleinii) is a traditional herb that is widely used in China to treat several ailments, but mainly cancer. Studies have been carried out to determine the phytochemicals ascribed to its pharmacological activity. However, both phytochemical and pharmacological profiles have not been fully explored as few compounds have been reported. This study evaluated the flavonoid content of the ethanol extract and its four fractions (petroleum ether, dichloromethane, ethyl acetate, and n-butanol) together with their antioxidant activity (DPPH and FRAP assays). Further, the antiproliferative activity was evaluated. Two new secondary metabolites (1 and 3) were isolated from S. doederleinii, which comprised of an apigenin skeleton with a phenyl attached at C-8 of ring A and an acetyl group. Additionally, other known metabolites 2 and 4–16 were isolated, whereby compounds 2, 4, 5, 8, 12, 15, and 16 were reported for the first time in this species. These compounds were evaluated for their antioxidative potentials by both DPPH and FRAP assays, and for their antiproliferative activities by the MTT assay on three human cancer cell lines: colon cancer (HT-29), cervical cancer (HeLa), and lung cancer (A549). Compound 7 exhibited the best activity on the three cancer cell lines (HT-29, HeLa, A549) by inhibiting the rate of growth of the cancer cells in a dose-dependent manner with IC₅₀ values of 27.97, 35.47, and 20.71 µM, respectively. The structure–activity relationship of the pure compounds was highlighted in this study. Hence, the study enriched both the phytochemical and pharmacological profiles of S. doederleinii.

Two new flavonol glycosides from Selaginella tamariscina

Two new flavonol glycosides 3,5,7-trimethoxyflavone-4'-O-[5'''-O-p-coumaroyl-β-D-apiofuranoyl-(1'''→2'')-β-D-glucopyranoside] (1) and 3,5,7-trimethoxyflavone -4'-O-β-D-glucopyranoside (2) were isolated from Selaginella tamariscina. The structures of 1 and 2 were elucidated on the basis of chemical and spectral analysis, including 1D, 2D NMR analyses and HRESIMS spectrometry. Two compounds were evaluated for cytotoxic activities against A-375, MCF-7, MDA-MB-231 and MDA-MB-468 cell lines by MTT assay. Unfortunately, two compounds displayed no cytotoxic activities.

DK, Ragunathan V, Tiwari P, A. S, P BD. Molecular docking, validation, dynamics simulations, and pharmacokinetic prediction of natural compounds against the SARS-CoV-2 main-protease

The study aims to evaluate the potency of two hundred natural antiviral phytocompounds against the active site of the Severe Acquired Respiratory Syndrome - Coronavirus - 2 (SARS-CoV-2) Main-Protease (Mpro) using AutoDock 4.2.6. The three- dimensional crystal structure of the Mpro (PDB Id: 6LU7) was retrieved from the Protein Data Bank (PDB), the active site was predicted using MetaPocket 2.0. Food and Drug Administration (FDA) approved viral protease inhibitors were used as standards for comparison of results. The compounds theaflavin-3-3'-digallate, rutin, hypericin, robustaflavone, and (-)-solenolide A with respective binding energy of -12.41 (Ki = 794.96 pM); -11.33 (Ki = 4.98 nM); -11.17 (Ki = 6.54 nM); -10.92 (Ki = 9.85 nM); and -10.82 kcal/mol (Ki = 11.88 nM) were ranked top as Coronavirus Disease - 2019 (COVID-19) Mpro inhibitors. The interacting amino acid residues were visualized using Discovery Studio 3.5 to elucidate the 2-dimensional and 3-dimensional interactions. The study was validated by i) re-docking the N3-peptide inhibitor-Mpro and superimposing them onto co-crystallized complex and ii) docking decoy ligands to Mpro. The ligands that showed low binding energy were further predicted for and pharmacokinetic properties and Lipinski's rule of 5 and the results are tabulated and discussed. Molecular dynamics simulations were performed for 50 ns for those compounds using the Desmond package, Schrödinger to assess the conformational stability and fluctuations of protein-ligand complexes during the simulation. Thus, the natural compounds could act as a lead for the COVID-19 regimen after in-vitro and in- vivo clinical trials.Communicated by Ramaswamy H. Sarma.

Proceedings of Chemistry, Pharmacology, Pharmacokinetics and Synthesis of Biflavonoids

Biflavonoids, composed of two monoflavonoid residues, occur naturally in angiosperms, bryophytes, ferns, and gymnosperms. More than 592 biflavonoids have been structurally elucidated, and they can be classified into two groups of C-C and C-linear fragments-C, based on whether the linker between the two residues contains an atom. As the linker can be established on two arbitrary rings from different residues, the C-C type contains various subtypes, as does the C-linear fragment-C type. Biflavonoids have a wide range of pharmacological activities, including anti-inflammatory, antioxidant, antibacterial, antiviral, antidiabetic, antitumor, and cytotoxic properties, and they can be applied in Alzheimer's disease and Parkinson's disease. This review mainly summarizes the distribution and chemistry of biflavonoids; additionally, their bioactivities, pharmacokinetics, and synthesis are discussed.

Two new selariscinins from Selaginella tamariscina (Beauv.) Spring

Two new selariscinins named selariscinin F (1) and selariscinin G (2), along with one known selariscinin D (3) were isolated from Selaginella tamariscina. The structures of 1-3 were elucidated on the basis of chemical and spectral analysis, including 1D, 2D NMR analyses and HRESIMS.

Deciphering the Molecular Mechanism Responsible for Efficiently Inhibiting Metastasis of Human Non-Small Cell Lung and Colorectal Cancer Cells Targeting the Matrix Metalloproteinases by Selaginella repanda

Selaginella species are known to have antimicrobial, antioxidant, anti-inflammatory, anti-diabetic as well as anticancer effects. However, no study has examined the cytotoxic and anti-metastatic efficacy of Selaginella repanda (S. repanda) to date. Therefore, this study aimed to evaluate the potential anti-metastatic properties of ethanol crude extract of S. repanda in human non-small-cell lung (A-549) and colorectal cancer (HCT-116) cells with possible mechanisms. Effect of S. repanda crude extract on the growth, adhesion, migration and invasion of the A-549 and HCT-116 were investigated. We demonstrated that S. repanda crude extract inhibited cell growth of metastatic cells in a dose and time dependent manner. Incubation of A-549 and HCT-116 cells with 100-500 µg/mL of S. repanda crude extract significantly inhibited cell adhesion to gelatin coated surface. In the migration and invasion assay, S. repanda crude extract also significantly inhibited cellular migration and invasion in both A-549 and HCT-116 cells. Moreover, reverse transcription-polymerase chain reaction, and real-time PCR (RT-PCR) analysis revealed that the activity and mRNA level of matrix metalloproteinase-9 (MMP-9), matrix metalloproteinase-2 (MMP-2) and membrane type 1-matrix metalloproteinase (MT1-MMP) were inhibited. While the activity of tissue inhibitor matrix metalloproteinase 1 (TIMP-1); an inhibitor of MMPs was stimulated by S. repanda crude extract in a concentration-dependent manner. Therefore, the present study not only indicated the inhibition of motility and invasion of malignant cells by S. repanda, but also revealed that such effects were likely associated with the decrease in MMP-2/-9 expression of both A-549 and HCT-116 cells. This further suggests that S. repanda could be used as a potential source of anti-metastasis agent in pharmaceutical development for cancer therapy.

Viburnum stellato-tomentosum Extract Suppresses Obesity and Hyperglycemia through Regulation of Lipid Metabolism in High-Fat Diet-Fed Mice

The potential biological activities of Viburnum stellato-tomentosum (VS), a plant mainly found in Costa Rica, have yet to be reported. Supplementation of VS extract for 17 weeks significantly decreased body weight gain, fat weight, fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and triglyceride levels in high-fat diet (HFD)-fed C57BL/6J mice. The molecular mechanisms underlying the anti-obesity and glucose-lowering effects of VS extract were investigated. VS extract suppressed adipocyte hypertrophy by regulating lipogenesis-related CCAAT/enhancer-binding protein α (C/EBPα) and insulin sensitivity-related peroxisome proliferator-activated receptor γ (Pparg) expression in adipose tissue (AT) and hepatic steatosis by inhibiting C/EBPα and lipid transport-related fatty acid binding protein 4 (FABP4) expression. VS extract enhanced muscular fatty acid β-oxidation-related AMP-activated protein kinase (AMPK) and PPARα expression with increasing Pparg levels. Furthermore, VS extract contained a much higher content of amentoflavone (AMF) (29.4 mg/g extract) compared to that in other Viburnum species. AMF administration decreased Cebpa and Fabp4 levels in the AT and liver, as well as improved insulin signaling-related insulin receptor substrate 1 (Irs1) and glucose transporter 1 (Glut1) levels in the muscle of HFD-fed mice. This study elucidated the in vivo molecular mechanisms of AMF for the first time. Therefore, VS extract effectively diminished obesity and hyperglycemia by suppressing C/EBPα-mediated lipogenesis in the AT and liver, enhancing PPARα-mediated fatty acid β-oxidation in muscle, and PPARγ-mediated insulin sensitivity in AT and muscle.

Seladelicatulasine A-G, C27 steroidal glycosides with cholinesterase inhibitory activities from Selaginella delicatula

Seven undescribed C₂₇ steroidal glycosides, Seladelicatulasine A-G, including six cholestanol glycosides and one spirostanol glycoside, were isolated from Selaginella delicatula. Their structures were elucidated by 1D/2D NMR spectra and HRESIMS analyses. The absolute configurations of the sugars were determined by enzymatic hydrolysis and GC/MS analyses. These cholestanol glycosides were isolated from the family Selaginellaceae for the first time. Seladelicatulasine F is characterized as a rare B-5,6-secosteroid. In addition, all the compounds were evaluated for their inhibitory activities against cholinesterase (AChE/BChE) and monoamine oxidase (MAO-A/MAO-B). These steroidal glycosides displayed selective inhibition activities on cholinesterase. Seladelicatulasine A, B and E inhibited the AChE activity with IC₅₀ values of 0.31, 0.09, and 0.04 μM, respectively. Seladelicatulasine A and F showed the strongest inhibition activity on BChE with IC₅₀ values of 0.37 and 0.65 μM, respectively.

Trichocladabiflavone A, a chalcone-flavonone type biflavonoid from Selaginella trichoclada Alsto

A chalcone-flavonone type biflavonoid, trichocladabiflavone A (1), along with eight known biflavonoids (2-9) were isolated from the 70% EtOH extract of Selaginella trichoclada. Their structures were elucidated by extensive spectroscopic analyses. Compound 1 was the first chalcone-flavonone type biflavonoid reported in the genus Selaginella. Moreover, compound 1 exhibited moderate cytotoxicity against DU145, MCF-7 and PC3 human cancer cell lines.

A New Optical Biflavonoid, (2″R)-2″,3″-Dihydrorobustaflavone 7,4′-Dimethyl Ether, and Other Constituents from Selaginella trichoclada Alsto

A new optical biflavonoid, (2” R)-2″,3″-dihydrorobustaflavone 7,4′-dimethyl ether (1), and 6 known compounds (2-7) were isolated for the first time from the 70% ethanol extract of Selaginella trichoclada Alsto. The structures of the compounds were confirmed by extensive spectroscopic data analyses. Racemic compound 1 was separated by chiral-phase high-performance liquid chromatography, and the absolute configurations of (±)-1 were defined by circular dichroism spectroscopic data. Compound 1 exhibited moderate cytotoxicity against MCF-7, A549, and HepG2 human cancer cell lines.

Naturally occurring biflavonoids with amyloid β aggregation inhibitory activity for development of anti-Alzheimer agents

Amyloid β (Aβ) aggregation plays an essential role in promoting the progression of Alzheimer's disease (AD). Therefore, the inhibition of Aβ aggregation is a potential therapeutic approach for AD. Herein, twenty-seven biflavonoids with different inter-flavonyl linkages and methoxy substitution patterns were isolated from several plants, and their Aβ₄₀ aggregation inhibitory activity was evaluated by the thioflavin-T fluorescence assay. Amentoflavone (1) and its monomethoxy derivatives (2, 3, and 5) exhibited the most potent inhibitory activity, with IC₅₀ values of approximately 5 μM. It was clarified that increasing the number of methoxy substituents on the biflavonoid structures attenuated the inhibitory activity. Moreover, the linkage and the methoxy substitution pattern had a marked influence on the inhibitory activity. Our investigation strongly supports that biflavonoids can be considered a new type of anti-Alzheimer agents that may be successfully developed for AD patients.

A new byciclic monoterpene glucoside and a new biflavone from the male reproduction organs of Wollemia nobilis

In this work, the fifth part of an ongoing phytochemical study on Wollemia nobilis was reported. The attention was now focused on the male reproduction organs of which the content in both primary and secondary metabolites was analyzed. Twenty compounds, belonging to seven different classes of natural compounds, were identified from the ethanolic extract by means of Column Chromatography and NMR and MS Spectroscopy. They all represent new compounds for the studied organ whereas some of them are also new constituents of the genus or even previously undescribed phytochemicals. Their presence was able to display a general overview of these organs from the phytochemical standpoint and to provide more elements in confirmation with the current botanical classification of the species. Moreover, they add a further experimental evidence of the tendency of this species to accumulate different metabolites in different organs. This characteristic as well as the occurrence of several compounds with added value, make this plant a possible candidate for large scale cultivation with extractive purposes to obtain useful phytochemicals for botanicals and pharmaceutical fields. Moreover, they offer the opportunity to develop an additional method of conservation and protection for this endangered and very rare species.

Probing the Antiallergic and Anti-inflammatory Activity of Biflavonoids and Dihydroflavonols from Dietes bicolor

Dietes bicolor (Iridaceae) is an ornamental plant used by African local healers to treat diarrhea and dysentery. A new dihydroflavonol, (2R,3R)-3,5,7-trihydroxy-8-methoxyflavanone (1); two known dihydroflavonols, trans-3-hydroxy-5-methoxy-6,7-methylenedioxyflavanone (2) and trans-3-hydroxy-5,7-dimethoxyflavanone (3); the known isoflavone orobol 7,3'-di-O-methyl ether (4); the known biflavones lanaroflavone (5), robustaflavone (6), and amentoflavone (7); and β-sitosterol (8) were isolated from the CH₂Cl₂ fraction of D. bicolor leaves. The extract showed potent activity in antiallergic and anti-inflammatory assays. The structures of the isolates were identified by spectroscopic and spectrometric methods. Compounds 6 and 7 (400 μM) exhibited antiallergic activity by inhibiting antigen-induced β-hexosaminidase release at 45.7% and 46.3%, respectively. Moreover, 6 and 7 exerted anti-inflammatory activity as demonstrated by the inhibition of superoxide anion generation with an IC₅₀ value of 1.0 μM as well as the inhibition of elastase release with IC₅₀ values of 0.45 and 0.75 μM, respectively. The anti-inflammatory activity was further explained by the virtual docking of the isolated compounds to the binding sites in the human neutrophil elastase (HNE) crystal structure using Discovery Studio 2.5. It was concluded that the biflavonoids bind directly to HNE and inhibit its enzymatic activity based on the CDOCKER algorithm. The data provided evidence for the potential use of D. bicolor against certain diseases related to allergy and inflammation.

A review of the use of pteridophytes for treating human ailments

The aim of this review was to explore the pharmacological activity of early tracheophytes (pteridophytes) as an alternative medicine for treating human ailments. As the first vascular plants, pteridophytes (aka, ferns and fern allies) are an ancient lineage, and human beings have been exploring and using taxa from this lineage for over 2000 years because of their beneficial properties. We have documented the medicinal uses of pteridophytes belonging to thirty different families. The lycophyte Selaginella sp. was shown in earlier studies to have multiple pharmacological activity, such as antioxidant, anti-inflammatory, anti-cancer, antidiabetic, antiviral, antimicrobial, and anti-Alzheimer properties. Among all the pteridophytes examined, taxa from the Pteridaceae, Polypodiaceae, and Adiantaceae exhibited significant medicinal activity. Based on our review, many pteridophytes have properties that could be used in alternative medicine for treatment of various human illnesses. Biotechnological tools can be used to preserve and even improve their bioactive molecules for the preparation of medicines against illness. Even though several studies have reported medicinal uses of ferns, the possible bioactive compounds of several pteridophytes have not been identified. Furthermore, their optimal dosage level and treatment strategies still need to be determined. Finally, the future direction of pteridophyte research is discussed.

Analysis of the Total Biflavonoids Extract from Selaginella doederleinii by HPLC-QTOF-MS and Its In Vitro and In Vivo Anticancer Effects

Selaginella doederleinii Hieron has been traditionally used as a folk antitumor herbal medicine in China. In this paper, the phytochemical components of the total biflavonoids extract from S. doederleinii were studied by using high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF MS/MS) in negative ion mode, and their in vitro and in vivo anticancer effects were evaluated. Four types of biflavonoids from S. doederleinii, including IC3′–IIC8′′, IC3′–IIC6′′, IC3′–IIC3′′′, and C–O linked biflavonoids were examined originally using QTOF MS/MS. The fragmentation behavior of IC3′–IIC3′′′ linked biflavonoids was reported for the first time. A total of twenty biflavonoids were identified or tentatively characterized and eight biflavonoids were found from S. doederleinii for the first time. Furthermore, the 3-(4,5-Dimethyl-2-thizolyl)-2,5-diphenyltertazolium bromide (MTT) assay and xenograft model of mouse lewis lung cancer(LLC) in male C57BL/6 mice revealed favorable anticancer properties of the total biflavonoids extracts from S. doederleinii. The results of this work could provide useful knowledge for the identification of biflavonoids in herbal samples and further insights into the chemopreventive function of this plant.

A Review on the Phytochemistry, Pharmacology, and Pharmacokinetics of Amentoflavone, a Naturally-Occurring Biflavonoid

Amentoflavone (C30H18O10) is a well-known biflavonoid occurring in many natural plants. This polyphenolic compound has been discovered to have some important bioactivities, including anti-inflammation, anti-oxidation, anti-diabetes, and anti-senescence effects on many important reactions in the cardiovascular and central nervous system, etc. Over 120 plants have been found to contain this bioactive component, such as Selaginellaceae, Cupressaceae, Euphorbiaceae, Podocarpaceae, and Calophyllaceae plant families. This review paper aims to profile amentoflavone on its plant sources, natural derivatives, pharmacology, and pharmacokinetics, and to highlight some existing issues and perspectives in the future.

Selagintriflavonoids with BACE1 inhibitory activity from the fern Selaginella doederleinii

Eight triflavonoids, selagintriflavonoids A-H, were isolated from whole herbs of Selaginella doederleinii. The structures of compounds selagintriflavonoids A-C consisted of three naringenin units, whereas those of selagintriflavonoids D-H consisted of apigenin and two naringenin moieties. The structures and absolute configurations of the compounds were determined based on NMR, HRESIMS, and experimental and calculated electronic circular dichroism (ECD) data. The ability of the compounds to inhibit β-secretase (BACE1) was also evaluated. All compounds exhibited BACE1 inhibition with IC₅₀ values ranging from 0.75 to 46.99 μM. Selagintriflavonoid A exhibited the strongest inhibition (0.75 μM) and is thus a promising compound for treating Alzheimer's disease.

Theoretical Study about the Effect of Halogen Substitution on the Reactivity of Antitumor 3-Formylchromones and Their Free Radicals

The mandatory presence of a chlorine atom on the aromatic ring of 6-hydroxy-3-formyl angular chromones, on the respiration inhibition of mammary carcinoma mouse, is explained through a computational study of these compounds. This study analyzes the reactivity of the neutral molecules and their free radicals, in gas phase and with water solvation, incorporated by the polarizable continuum medium (PCM) approach. Electrophilic reactivities were evaluated using Fukui (f+) and Parr (P+) functions. The stabilities of radical species formed by the abstraction of a hydrogen atom from the O-H bond were evaluated by bond dissociation enthalpy (BDE) and spin density (SD) calculations. This study has potential implications for the design of chromone analogues as anticancer compounds.

Total synthesis of I3,II8-biapigenin and ridiculuflavone A

The first total synthesis of I3,II8-biapigenin and ridiculuflavone A was achieved via Sonogashira and rhodium-catalyzed oxidative coupling as the key steps.

An antifungal protein from Ginkgo biloba binds actin and can trigger cell death

Ginkbilobin is a short antifungal protein that had been purified and cloned from the seeds of the living fossil Ginkgo biloba. Homologues of this protein can be detected in all seed plants and the heterosporic fern Selaginella and are conserved with respect to domain structures, peptide motifs, and specific cysteine signatures. To get insight into the cellular functions of these conserved motifs, we expressed green fluorescent protein fusions of full-length and truncated ginkbilobin in tobacco BY-2 cells. We show that the signal peptide confers efficient secretion of ginkbilobin. When this signal peptide is either cleaved or masked, ginkbilobin binds and visualizes the actin cytoskeleton. This actin-binding activity of ginkbilobin is mediated by a specific subdomain just downstream of the signal peptide, and this subdomain can also coassemble with actin in vitro. Upon stable overexpression of this domain, we observe a specific delay in premitotic nuclear positioning indicative of a reduced dynamicity of actin. To elucidate the cellular response to the binding of this subdomain to actin, we use chemical engineering based on synthetic peptides comprising different parts of the actin-binding subdomain conjugated with the cell-penetrating peptide BP100 and with rhodamine B as a fluorescent reporter. Binding of this synthetic construct to actin efficiently induces programmed cell death. We discuss these findings in terms of a working model, where ginkbilobin can activate actin-dependent cell death.

In vitro activity of the hydroethanolic extract and biflavonoids isolated from Selaginella sellowii on Leishmania (Leishmania) amazonensis

This study is the first phytochemical investigation of Selaginella sellowii and demonstrates the antileishmanial activity of the hydroethanolic extract from this plant (SSHE), as well as of the biflavonoids amentoflavone and robustaflavone, isolated from this species. The effects of these substances were evaluated on intracellular amastigotes of Leishmania (Leishmania) amazonensis, an aetiological agent of American cutaneous leishmaniasis. SSHE was highly active against intracellular amastigotes [the half maximum inhibitory concentration (IC50) = 20.2 µg/mL]. Fractionation of the extract led to the isolation of the two bioflavonoids with the highest activity: amentoflavone, which was about 200 times more active (IC50 = 0.1 μg/mL) and less cytotoxic than SSHE (IC50 = 2.2 and 3 μg/mL, respectively on NIH/3T3 and J774.A1 cells), with a high selectivity index (SI) (22 and 30), robustaflavone, which was also active against L. amazonensis (IC50 = 2.8 µg/mL), but more cytotoxic, with IC50 = 25.5 µg/mL (SI = 9.1) on NIH/3T3 cells and IC50 = 3.1 µg/mL (SI = 1.1) on J774.A1 cells. The production of nitric oxide (NO) was lower in cells treated with amentoflavone (suggesting that NO does not contribute to the leishmanicidal mechanism in this case), while NO release was higher after treatment with robustaflavone. S. sellowii may be a potential source of biflavonoids that could provide promising compounds for the treatment of cutaneous leishmaniasis.

Crystal structure of 4-(6-chloro-4-oxo-4H-chromen-3-yl)-2-methyl-amino-3-nitro-4H,5H-pyrano[3,2-c]chromen-5-one chloro-form monosolvate

In the title compound, C23H14Cl4N2O7, the pyran ring has an envelope conformation with the methine C atom as the flap. The chromene rings are almost planar (r.m.s. deviations of 0.027 and 0.018 Å) and their mean planes are inclined to one another by 85.61 (10)°. The mean planes of the pyran ring and the chromene ring fused to it are inclined to one another by 7.41 (13)°. The mol-ecular structure is stabilized by an intra-molecular N-H⋯O hydrogen bond, generating an S(6) ring motif. In the crystal, mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R (2) 2(12) ring motif. The dimers are linked by pairs of C-H⋯O hydrogen bonds, enclosing R (2) 2(18) ring motifs, forming chains along [010]. Within the chains there are C-H⋯π inter-actions. The chains are linked via slipped parallel π-π inter-actions, forming a three-dimensional structure [the shortest inter-centroid distance is 3.7229 (19) Å].

Spectroscopic (FT-IR and FT-Raman) investigation, first order hyperpolarizability, NBO, HOMO-LUMO and MEP analysis of 6-nitrochromone by ab initio and density functional theory calculations

The vibrational spectral analysis is carried out using FT-Raman and FT-IR spectroscopy in the range 3500-50 cm(-1) and 4000-400 cm(-1), respectively, for 6-nitrochromone (6NC). The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimization and normal coordinates force field calculation based on ab initio HF and DFT gradient calculations employing the HF/6-311++G(d,p) and B3LYP/6-311++G(d,p) basis set. Stability of the molecule has been analyzed using NBO analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Thermodynamic properties like entropy, heat capacity, zero-point energy and Mulliken's charge analysis have been calculated for the 6NC. The complete assignments were performed on the basis of total energy distribution (TED) of the vibrational modes with scaled quantum mechanical (SQM) method. The MEP map shows the negative potential sites are on oxygen atoms as well as the positive potential sites are around the hydrogen atoms.

Comparison of cytotoxic activities of extracts from Selaginella species

BACKGROUND

Selaginella species are resurrection plants, which are known, possess various molecular bioactivities depending on species, but only a few species have been detailed observe in the advanced research.

OBJECTIVE

The objective of the following study is to compare the chemical profiles of different species of Selaginella and to investigate cytotoxicity and induction of apoptosis activities of some species of Selaginella.

MATERIALS AND METHODS

The high-performance liquid chromatography (HPLC) method was developed for chemical analysis. Ethyl acetate, ethanol and water-soluble extracts from seven Selaginella species were submitted to 3-(4,5-dimenthyl thizol-2-yl)-2,5-diphenyl tetrazolium bromide assay, flow cytometry, deoxyribonucleic acid (DNA) laddering analysis and caspase-3 expression using Bel-7402, HT-29 and HeLa cells.

RESULTS

The HPLC analysis revealed two major common peaks, which were identified as amentoflavone and robustaflavone and another three main peaks in their chromatograms. The results showed that S. labordei, Selaginella tamariscina and Selaginella uncinata had relatively stronger activities on Bel-7402 and HeLa cells and Selaginella moellendorfii had moderate antiproliferation activities, but Selaginella remotifolia and Selaginella pulvinata had almost no inhibitory activities. The main active components were in the ethyl acetate extracts which had abundant biflavonoids. The effects of these extracts on cell proliferation and apoptosis in different cells were not the same, they were more apparent on HeLa cells than on HT-29 cells. The assay of DNA laddering analysis and caspase-3 expression further confirmed that inducing cell apoptosis was one of antitumor mechanisms and antitumor activities of Selaginella species were related to apoptosis induced by caspase family.

CONCLUSION

S. labordei, S. tamariscina and S. uncinata would be potential antitumor agents.

Synthesis and SAR studies of bis-chromenone derivatives for anti-proliferative activity against human cancer cells

A novel family of 3-((4-oxo-4H-chromen-3-yl)methyl)-4H-chromen-4-one (bis-chromone) derivatives were designed, synthesized and studied for their anti-cancer activity using the XTT assay for the growth inhibition against various human cancer cells. Among them, 3-((5-(cyclohexylmethoxy)-4-oxo-4H-chromen-3-yl)methyl)-7-methoxy-4H-chromen-4-one and 3-((5-(cyclohexylmethoxy)-4-oxo-4H-chromen-3-yl)methyl)-7-hydroxy-4H-chromen-4-one showed micromolar level of in vitro anti-proliferative activity against human cancer cell lines. The SAR studies indicated bis-chromone as a basic scaffold to design anticancer agents. The 5-cyclohexylmethoxy on the first chromenone ring and electron donating group such as CH3, OCH3 or hydrogen bonding group (OH) on the other chromenone ring of bis-chromone increased the activity. However, saturation of one of chromenone to chromanone in bis-chromones decreased the activity.

A new modified sesquiterpene glycoside from Cupressus chengiana

A new sesquiterpene glycoside, cupressusoside (1), and five known compounds were isolated from the 70% aqueous ethanol extract of the branches and leaves of Cupressus chengiana. Their structures were elucidated by using spectroscopic methods. All the isolates expressed no remarkable cytotoxic activity against colon carcinoma (HCT-8) and breast cancer (MCF-7) cell lines, with IC50>40 mg/mL.

Ferns and lycopods--a potential treasury of anticancer agents but also a carcinogenic hazard

Many species of seedless vascular plants-ferns and lycopods-have been used as food and folk medicine since ancient times. Some of them have become the focus of intensive research concerning their anticancer properties. Studies on the anticancer effect of crude extracts are being increasingly replaced by bioactivity-guided fractionation, as well as detailed assessment of the mechanism of action. Numerous compounds-especially flavonoids such as amentoflavone and protoapigenone, and also simpler phenolic compounds, steroids, alkaloids and terpenoids-were isolated and found to be cytotoxic, particularly pro-apoptotic, or to induce cell cycle arrest in cancer cell lines in vitro. In in vivo experiments, some fern-derived compounds inhibited tumour growth with little toxicity. On the other hand, many ferns-not only the well-known Bracken (Pteridium)-may pose a significant hazard to human health due to the fact that they contain carcinogenic sesquiterpenoids and their analogues. The objective of this review is to summarise the recent state of research on the anticancer properties of ferns and lycopods, with a focus on their characteristic bioactive constituents. The carcinogenic hazard posed by ferns is also mentioned.