From virtual screening hits targeting a cryptic pocket in BACE-1 to a nontoxic brain permeable multitarget anti-Alzheimer lead with disease-modifying and cognition-enhancing effects.

Starting from six potential hits identified in a virtual screening campaign directed to a cryptic pocket of BACE-1, at the edge of the catalytic cleft, we have synthesized and evaluated six hybrid compounds, designed to simultaneously reach BACE-1 secondary and catalytic sites and to exert additional activities of interest for Alzheimer's disease (AD). We have identified a lead compound with potent in vitro activity towards human BACE-1 and cholinesterases, moderate Aß42 and tau antiaggregating activity, and brain permeability, which is nontoxic in neuronal cells and zebrafish embryos at concentrations above those required for the in vitro activities. This compound completely restored short- and long-term memory in a mouse model of AD (SAMP8) relative to healthy control strain SAMR1, shifted APP processing towards the non-amyloidogenic pathway, reduced tau phosphorylation, and increased the levels of synaptic proteins PSD95 and synaptophysin, thereby emerging as a promising disease-modifying, cognition-enhancing anti-AD lead.

An "all-in-one" strategy based on the organic molecule DCN-4CQA for effective NIR-fluorescence-imaging-guided dual phototherapy.

Dual phototherapy combining photodynamic therapy (PDT) and photothermal therapy (PTT) is considered to be a more effective therapeutic method against cancer than single treatment. Therefore, the development of a single material with both near-infrared (NIR)-laser-triggered PDT and PTT abilities is highly desirable but remains a great challenge. A design philosophy for photosensitizers for integrated PDT and PTT treatment has been put forward: (1) a high molar extinction coefficient in the NIR region; (2) suitable LUMO and T1 energy levels to regulate intersystem crossing for effective singlet oxygen (1O2) generation for PDT; and (3) the suppression of fluorescence emission to enhance the process of nonradiative transition with appropriate chemical modifications. Herein, an "all-in-one" functional material, di-cyan substituted 5,12-dibutylquinacridone (DCN-4CQA), for diagnosis and therapy was obtained. DCN-4CQA possesses dual-functional phototherapeutic activity and NIR fluorescence and it was produced via a facile synthesis process from the classic organic photoelectric material quinacridone. We then prepared smart water-soluble nanoparticles (NPs), DCN-4CQA/F127, using Pluronic® 127 (F127) as a drug carrier. The NPs exhibited excellent biocompatibility, robust photostability, NIR fluorescence, a high photothermal conversion efficiency (η = 47.3%), and sufficient 1O2 generation (ΦΔ = 24.3%) under NIR laser irradiation. Remarkably, the DCN-4CQA/F127 NPs significantly inhibited tumor growth in mice subjected to NIR laser irradiation. This study provides a new route for the development of highly efficient, low-cytotoxicity photosensitizers for fluorescence-imaging-guided PTT/PDT.

Biosyntheses characterization of alkaloids and flavonoids in Sophora flavescens by combining metabolome and transcriptome.

Sophora flavescens are widely used for their pharmacological effects. As its main pharmacological components, alkaloids and flavonoids are distributed in the root tissues wherein molecular mechanisms remain elusive. In this study, metabolite profiles are analyzed using metabolomes to obtain biomarkers detected in different root tissues. These biomarkers include alkaloids, phenylpropanoids, and flavonoids. The high-performance liquid chromatography analysis results indicate the differences in principal component contents. Oxymatrine, sophoridine, and matrine contents are the highest in the phloem, whereas trifolirhizin, maackiain, and kushenol I contents are the highest in the xylem. The transcript expression profiles also show tissue specificity in the roots. A total of 52 and 39 transcripts involved in alkaloid and flavonoid syntheses are found, respectively. Among them, the expression levels of LYSA1, LYSA2, AO2, AO6, PMT1, PMT17, PMT34, and PMT35 transcripts are highly and positively correlated with alkaloids contents. The expression levels of 4CL1, 4CL3, 4CL12, CHI5, CHI7, and CHI9 transcripts are markedly and positively correlated with flavonoids contents. Moreover, the quantitative profiles of alkaloids and flavonoids are provided, and the pivotal genes regulating their distribution in S. flavescens are determined. These results contribute to the existing data for the genetic improvement and target breeding of S. flavescens.

Biosynthesis, total synthesis, and biological profiles of Ergot alkaloids.

While the use of ergot alkaloids in folk medicine has been practiced for millennia, systematic investigations on their therapeutic potential began about 100 years ago. Subsequently, Albert Hofmann's discovery of lysergic acid diethylamide (LSD) and its intense psychedelic properties garnered worldwide attention and prompted further studies of this compound class. As a result, several natural ergot alkaloids were discovered and unnatural analogs were synthesized, and some were used to treat an array of maladies, including Alzheimer's and Parkinson's disease. While LSD was never commercially approved, recent clinical studies have found it can be an innovative and effective treatment option for several psychiatric disorders. Ongoing biosynthetic and total synthetic investigations aim to understand the natural origins of ergot alkaloids, help develop facile means to produce these natural products and enable their continued use as medicinal chemistry lead structures. This review recounts major developments over the past 20 years in biosynthetic, total synthetic, and pharmaceutical studies. Many ergot alkaloid biosynthetic pathways have been elucidated, with some of them subsequently applied toward "green" syntheses. New chemical methodologies have fostered a fast and efficient access to the ergoline scaffold, prompting some groups to investigate biological properties of natural product-like ergot alkaloids. Limited pharmaceutical applications have yet to completely bypass the undesirable side effects of ergotism, suggesting further studies of this drug class are likely needed and will potentially harness major therapeutic significance.

Enantioselective total syntheses of (+)-stemofoline and three congeners based on a biogenetic hypothesis.

The powerful insecticidal and multi-drug-resistance-reversing activities displayed by the stemofoline group of alkaloids render them promising lead structures for further development as commercial agents in agriculture and medicine. However, concise, enantioselective total syntheses of stemofoline alkaloids remain a formidable challenge due to their structural complexity. We disclose herein the enantioselective total syntheses of four stemofoline alkaloids, including (+)-stemofoline, (+)-isostemofoline, (+)-stemoburkilline, and (+)-(11S,12R)-dihydrostemofoline, in just 19 steps. Our strategy relies on a biogenetic hypothesis, which postulates that stemoburkilline and dihydrostemofolines are biogenetic precursors of stemofoline and isostemofoline. Other highlights of our approach are the use of Horner-Wadsworth-Emmons reaction to connect the two segments of the molecule, an improved protocol allowing gram-scale access to the tetracyclic cage-type core, and a Cu-catalyzed direct and versatile nucleophilic alkylation reaction on an anti-Bredt iminium ion. The synthetic techniques that we developed could also be extended to the preparation of other Stemona alkaloids.

Chemical and Biological Aspects of Montanine-Type Alkaloids Isolated from Plants of the Amaryllidaceae Family.

Plants of the Amaryllidaceae family are promising therapeutic tools for human diseases and have been used as alternative medicines. The specific secondary metabolites of this plant family, called Amaryllidaceae alkaloids (AA), have attracted considerable attention due to their interesting pharmacological activities. One of them, galantamine, is already used in the therapy of Alzheimer's disease as a long acting, selective, reversible inhibitor of acetylcholinesterase. One group of AA is the montanine-type, such as montanine, pancracine and others, which share a 5,11-methanomorphanthridine core. So far, only 14 montanine-type alkaloids have been isolated. Compared with other structural-types of AA, montanine-type alkaloids are predominantly present in plants in low concentrations, but some of them display promising biological properties, especially in vitro cytotoxic activity against different cancerous cell lines. The present review aims to summarize comprehensively the research that has been published on the Amaryllidaceae alkaloids of montanine-type.

Antibiotic-Potentiating Activity of Phanostenine Isolated from Cissampelos sympodialis Eichler.

Cissampelos sympodialis Eichler is well studied and investigated for its antiasthmatic properties, but there are no data in the literature describing antibacterial properties of alkaloids isolated from this botanical species. This work reports the isolation and characterization of phanostenine obtained from roots of C. sympodialis and describes for the first time its antimicrobial and antibiotic modulatory properties. Phanostenine was first isolated from Cissampelos sympodialis and its antibacterial activities were determined. Chemical structures of the alkaloid isolate were determined using spectroscopic and chemical analyses. Phanostenine was also tested for its antibacterial activity against standard strains and clinical isolates of Escherichia coli and Staphylococcus aureus. Minimal inhibitory concentration (MIC) was determined in a microdilution assay and for the evaluation of antibiotic resistance-modifying activity. MIC of the antibiotics was determined in the presence or absence of phanostenine at sub-inhibitory concentrations. The evaluation of antibacterial activity by microdilution assay showed activity for all strains with better values against S. aureus ATCC 12692 and E. coli 27 (787.69 mm). The evaluation of aminoglycoside antibiotic resistance-modifying activity showed reduction in the MIC of the aminoglycosides (amikacin, gentamicin and neomycin) when associated with phanostenine, MIC reduction of antibiotics ranging from 21 % to 80 %. The data demonstrated that phanostenine possesses a relevant ability to modify the antibiotic activity in vitro. We can suggest that phanostenine presents itself as a promising tool as an adjuvant for novel antibiotics formulations against bacterial resistance.

Crystal Structures of Flavone C-Glycosides from Oolong Tea Leaves: Chafuroside A Dihydrate and Chafuroside B Monohydrate.

Chafuroside A and chafuroside B are flavone C-glycosides isolated from oolong tea leaves. They have a number of beneficial pharmacological activities related to antiinflammation at various concentrations. However, no crystallographic study of chafurosides has yet been reported. In the present study, the crystal structures of chafuroside A and chafuroside B were investigated using single-crystal X-ray diffraction. The asymmetric unit of the chafuroside A crystal consists of one chafuroside A and two water molecules, and that of chafuroside B contains one chafuroside B and one water molecule. The flavone moiety of chafuroside A is curved, i.e., the angle between the best-fit planes of the chromene and phenyl rings is 18.9°, whereas the chafuroside B flavone moiety is relatively flat. A comparison of the curvatures of the flavone moieties of various C-glycosides showed that the curvature of chafuroside A is significantly larger than those of the others. This structural feature might contribute to the differences between the strengths of the pharmacological activities of chafurosides A and B.

Sparstolonin B: A Unique Anti-Inflammatory Agent.

Toll-like receptors are transmembrane proteins which sense and transmit infectious and inflammatory responses to the cells expressing them. Therapeutic strategies for the blockade of excessive Toll-like receptor signaling are being actively pursued for several diseases. Recently, Sparstolonin B, isolated from Chinese herb, which suppresses selectively Toll-like receptors has been studied in various inflammatory models. The objective of this review is to summarize the current literature regarding the use of Sparstolonin B in various in vitro and in vivo studies and to provide an overview regarding the potential use of this agent in different inflammatory diseases. Additionally, the current knowledge regarding the role of Toll-like receptors in inflammatory disease and the usage of various Toll-like receptor antagonists will be summarized. Based on our review, we believe Sparstolonin B could serve as a potential therapeutic agent for treatment of Toll-like receptor-mediated inflammatory disorders.

Self-emulsifying drug delivery system for enhanced solubility of asenapine maleate: design, characterization, in vitro, ex vivo and in vivo appraisal.

Self-emulsifying drug delivery systems (SES) were developed to improve oral bioavailability of asenapine maleate (ASM), an antipsychotic drug with challenging amphiphobic nature and extensive pre-systemic metabolism. ASM-SES was prepared by choosing the proportion of oil, surfactant, co-surfactant from constructed phase diagram. The in vitro and ex vivo evaluation was done. In vivo evaluation was done through pharmacokinetic and pharmacodynamic studies. Role of lymphatic absorption was studied by lymphatic absorption inhibition study. A formulation consisting of 9.9%, 59.4%, 29.7% and 1% of oil, surfactant, co-surfactant, and drug respectively was considered as optimized formulation. After various evaluation test, the globule size and zeta potential for optimized formulation (SES4) were found to be 137.9 nm and -28.8 mV respectively. A maximum of 99.64 ± 0.16% of ASM was released from SES4 in 60 minutes of time. The flux (ex vivo study) increased by 2.33 folds, which prove the enhanced release and permeation of ASM when loaded into SES. The animals administered with SES4 showed higher activity and good pharmacodynamic response than the control and ASM-Suspension, which may be due to the greater availability of the drug. The maximum pharmacodynamic response was observed at the tmax determined by Pharmacokinetic studies. The bioavailability increased by 1.64 folds with 16.55 ± 3.11% as extend of lymphatic absorption (r = 0.9732). Good in vitro in vivo correlation was observed. ASM-SES is a novel approach to effectively deliver ASM and improve the oral bioavailability.

In Vitro DNA Adduction Resulting from Metabolic Activation of Diosbulbin B and 8-Epidiosbulbin E Acetate.

Diosbulbin B (DBB) and 8-epidiosbulbin E acetate (EEA), belonging to furan-containing diterpenoid lactones, are the primary components of Dioscorea bulbifera L. (DB), a traditional Chinese medicine herb. Our earlier studies indicated that consumption of DBB or EEA induced acute hepatotoxicities. Both DBB and EEA were bioactivated by P450 3A4 to generate the corresponding cis-enedial reactive metabolites which are associated with the hepatotoxicities. It has been proposed that the electrophilic intermediates attack cellular nucleophiles such as protein or DNA, thought to be a mechanism of triggering toxicities. The purposes of our present study were to define the interaction of the electrophilic reactive metabolites originating from DBB and EEA with 2'-deoxyguanosine (dGuo), 2'-deoxycytidine (dCyd), and 2'-deoxyadenosine (dAdo) and to characterize DNA adducts arising from the reactive metabolites of DBB and EEA. The reactive metabolites of DBB and EEA were found to covalently bind to the exocyclic and endocyclic nitrogens of dCyd, dGuo, and dAdo to generate oxadiazabicyclo[3.3.0]octaimine adducts. The reactive metabolites of DBB and EEA also attacked dGuo, dAdo, and dCyd of calf thymus DNA. The DNA adducts possibly contribute to the toxicologies of DBB and EEA.

Identification of Novel Vacuolin-1 Analogues as Autophagy Inhibitors by Virtual Drug Screening and Chemical Synthesis.

Autophagy is a fundamental cellular degradation process which is essential for cell homeostasis, and dysfunctional autophagy has been associated with a variety of human diseases, such as cancer. Several autophagy chemical modulators have been applied in a number of preclinical or clinical trials against these autophagy related diseases, especially cancer. Small molecule vacuolin-1 potently and reversibly inhibits both endosomal-lysosomal trafficking and autophagosome-lysosome fusion, yet the molecular mechanisms underlying vacuolin-1 mediated autophagy inhibition remain unknown. Here, we first performed the virtual drug screening and identified 14 vacuolin-1 analogues as autophagy inhibitors. Based on these virtual screening results, we further designed and synthesized 17 vacuolin-1 analogues, and found that 13 of them are autophagy inhibitors and a couple of them are as potent as vacuolin-1. In summary, these studies expanded the pool of useful autophagy inhibitors and reveal the structural-activity relationship of vacuolin-1 analogues, which is useful for future development of vacuolin-1 analogues with high potency and for identification of the molecular targets of vacuolin-1.

Total Synthesis of the Claimed Structure of (±)-Hyptinin and Structural Revision of Natural Hyptinin.

A total synthesis of (±)-hyptinin was achieved via a convergent route using the key phosphonate, cyclic ketone, and aryl Grignard components. The 1H and 13C NMR spectra of natural hyptinin did not agree with those of the synthesized compound. In particular, there were considerable differences between the signals assigned to the protons and carbons surrounding the lactone carbonyl group for the natural and synthesized compounds. The NMR data strongly suggested that the naturally occurring compound, hyptinin, was a structural isomer of the synthesized compound. The structure of the natural compound was eventually established as (+)-ß-apopicropodophyllin, based on the synthesis results.

Constituents of the Roots of Dichapetalum pallidum and Their Anti-Proliferative Activity.

As part of our search for bioactive compounds from the Dichapetalaceae, repeated chromatographic purification of the roots of a hitherto unexamined species, Dichapetalum pallidum, led to the isolation of the newly occurring 7-hydroxydichapetalin P (1) and the known dichapetalins A (2) and X (3). Also isolated were the known compounds friedelin-2,3-lactone (4), friedelan-3-one (6), friedelan-3ß-ol (7) and pomolic (8), as well as the dipeptide aurantiamide acetate (5). The compounds were characterized by direct interpretation of their IR, 1D NMR and 2D NMR spectral data and by comparison of their physico-chemical data, including their chromatographic profiles, with the literature and authentic samples in our compound library for the genus Dichapetalum. The compounds were assayed for their anti-proliferative activities against the human T-lymphocytic leukemia (Jurkat), acute promyelocytic leukemia (HL-60) and T-lymphoblast-like leukemia (CEM) cell lines. Overall, dichapetalin X showed the strongest (3.14 µM) and broadest cytotoxic activities against all the leukemic cell lines tested, exhibiting even stronger activities than the standard compound, curcumin.

Isolation of insecticidal components in Inula salsoloides Ostenf. and characterisation of their activities.

The ethanol extract from Inula salsoloides (Turcz.) Ostenf was found to cause high mortality against Plutella xylostella L. (Lepidoptera: Plutellidae). The active components were isolated and identified. Two compounds were obtained and identified to be inulasalsolin and taraxasterol. Both compounds showed anti-feedant effects against third instar larvae of P. xylostella with AFC50 of 0.030 and 0.053 mg/mL and insecticidal activities with LC50 of 0.19 and 0.49 mg/mL, respectively. The two compounds also exhibited high toxicity to cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae) with LC50 values of 0.021 and 0.098 mg/mL. This is the first report on the study of insecticidal components of I. salsoloides and their activity against insects.

NMR reassignment of stictic acid isolated from a Sumatran lichen Stereocaulon montagneanum (Stereocaulaceae) with superoxide anion scavenging activities.

The phytochemical study of Stereocaulon montagneanum harvested in Sumatra (Indonesia) led to the isolation of 11 known compounds including two metabolites not previously described in the genus Stereocaulon, peristictic acid (8) and menegazziaic acid (10). The complete 1H and 13C NMR spectral assignments of stictic acid derivatives are reported with some revisions. Five depsidones belonging to the stictic acid chemosyndrome were superoxide anion scavengers as potent as ascorbic acid and with no toxicity on two human cell lines.

Squarrosine A and Pyrrolhuperzine A, New Lycopodium Alkaloids from Thai and Philippine Huperzia squarrosa.

Two new Lycopodium alkaloids, squarrosine A (1) and pyrrolhuperzine A (2), were isolated from the Thai and Philippine plant Huperzia squarrosa. (R)-2-Piperidineacetic acid (5) was a known alkaloid, but has now been isolated for the first time from a natural source. Their structures were elucidated using extensive spectroscopic analyses and, for pyrrolhuperzine A (2), confirmation by chemical transformation. The new compounds exhibited moderate acetylcholinesterase inhibitory activities.

Novel tricyclics (e.g., GSK945237) as potent inhibitors of bacterial type IIA topoisomerases.

During the course of our research on the lead optimisation of the NBTI (Novel Bacterial Type II Topoisomerase Inhibitors) class of antibacterials, we discovered a series of tricyclic compounds that showed good Gram-positive and Gram-negative potency. Herein we will discuss the various subunits that were investigated in this series and report advanced studies on compound 1 (GSK945237) which demonstrates good PK and in vivo efficacy properties.

A multilayer screening approach toward the discovery of novel Pf-DHFR inhibitors.

A small yet diverse xanthone library was build and computationally docked against wild type Pf-DHFR by Molegro Virtual Docker (MolDock). For analysis of results an integrated approach based on re-ranking, scaling (based on heavy atom counts), pose clustering and visual inspection was implemented. Standard methods such as self-docking (for docking), EF analysis, average rank determinations (for size normalization), and cluster quality indices (for pose clustering) were used for validation of results. Three compounds X5, X113A and X164B displayed contact footprints similar to the known inhibitors with good scores. Finally, 16 compounds were extracted from ZINC data base by similarity based screening, docking score and drug/lead likeness. Out of these 16 compounds, 11 displayed very close contact footprints to experimentally known inhibitors, indicating there potential utility in further drug discovery efforts.

Galanthamine, Plicamine, and Secoplicamine Alkaloids from Zephyranthes candida and Their Anti-acetylcholinesterase and Anti-inflammatory Activities.

Sixteen new alkaloids belonging to the galanthamine (1-6), plicamine (7-14), and secoplicamine (15 and 16) classes, together with eight known analogues (17-24), were isolated from Zephyranthes candida. The structures of 1-16 were determined by extensive spectroscopic analyses, and the absolute configurations of 1, 2, 7, 8, and 17 were confirmed by single-crystal X-ray diffraction analysis. The orientation of 3-OCH3 in N-methyl-5,6-dihydroplicane (22) was revised. Alkaloids 3, 12-14, and 18-21 exhibited anti-acetylcholinesterase activities with IC50 values ranging from 0.48 to 168.7 µM. Compounds 10-12, 14, and 16 showed in vitro anti-inflammatory activities with IC50 values ranging from 7.50 to 23.55 µM.