Discovery of baloxavir sodium as a novel anti-CCHFV inhibitor: Biological evaluation of in vitro and in vivo.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic bunyavirus with a fatality rate of up to 40%. Currently, there are no licensed antiviral drugs for the treatment of CCHF; thus, the World Health Organization (WHO) listed the disease as a priority. A unique viral transcription initiation mechanism called "cap-snatching" is shared by influenza viruses and bunyaviruses. Thus, we tested whether baloxavir (an FDA-approved anti-influenza drug that targets the "cap-snatching" mechanism) could inhibit CCHFV infection. In cell culture, baloxavir acid effectively inhibited CCHFV infection and targeted CCHFV RNA transcription/replication. However, it has weak oral bioavailability. Baloxavir marboxil (the oral prodrug of baloxavir) failed to protect mice against a lethal dose challenge of CCHFV. To solve this problem, baloxavir sodium was synthesized owing to its enhanced aqueous solubility and pharmacokinetic properties. It consistently and significantly improved survival rates and decreased tissue viral loads. This study identified baloxavir sodium as a novel scaffold structure and mechanism of anti-CCHF compound, providing a promising new strategy for clinical treatment of CCHF after further optimization.

Comprehensive Evaluation of Biological Effects of Pentathiepins on Various Human Cancer Cell Lines and Insights into Their Mode of Action.

Pentathiepins are polysulfur-containing compounds that exert antiproliferative and cytotoxic activity in cancer cells, induce oxidative stress and apoptosis, and inhibit glutathione peroxidase (GPx1). This renders them promising candidates for anticancer drug development. However, the biological effects and how they intertwine have not yet been systematically assessed in diverse cancer cell lines. In this study, six novel pentathiepins were synthesized to suit particular requirements such as fluorescent properties or improved water solubility. Structural elucidation by X-ray crystallography was successful for three derivatives. All six underwent extensive biological evaluation in 14 human cancer cell lines. These studies included investigating the inhibition of GPx1 and cell proliferation, cytotoxicity, and the induction of ROS and DNA strand breaks. Furthermore, selected hallmarks of apoptosis and the impact on cell cycle progression were studied. All six pentathiepins exerted high cytotoxic and antiproliferative activity, while five also strongly inhibited GPx1. There is a clear connection between the potential to provoke oxidative stress and damage to DNA in the form of single- and double-strand breaks. Additionally, these studies support apoptosis but not ferroptosis as the mechanism of cell death in some of the cell lines. As the various pentathiepins give rise to different biological responses, modulation of the biological effects depends on the distinct chemical structures fused to the sulfur ring. This may allow for an optimization of the anticancer activity of pentathiepins in the future.

7-Acylamino-3H-1,2-benzoxathiepine 2,2-dioxides as new isoform-selective carbonic anhydrase IX and XII inhibitors.

A series of 3H-1,2-benzoxathiepine 2,2-dioxides incorporating 7-acylamino moieties were obtained by an original procedure starting from 5-nitrosalicylaldehyde, which was treated with propenylsulfonyl chloride followed by Wittig reaction of the bis-olefin intermediate. The new derivatives, belonging to the homosulfocoumarin chemotype, were assayed as inhibitors of the zinc metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). Four pharmacologically relevant human (h) isoforms were investigated, the cytosolic hCA I and II and the transmembrane, tumour-associated hCA IX and XII. No relevant inhibition of hCA I and II was observed, whereas some of the new derivatives were effective, low nanomolar hCA IX/XII inhibitors, making them of interest for investigations in situations in which the activity of these isoforms is overexpressed, such as hypoxic tumours, arthritis or cerebral ischaemia.

Investigation of the Pentathiepin Functionality as an Inhibitor of Feline Immunodeficiency Virus (FIV) via a Potential Zinc Ejection Mechanism, as a Model for HIV Infection.

A small diverse library of pentathiepin derivatives were prepared to evaluate their efficacy against the nucleocapsid protein function of the feline immunodeficiency virus (FIV) as a model for HIV, using an in vitro cell culture approach. This study led to the development of nanomolar active compounds with low toxicity.

Antimicrobial, Cytotoxic, Anti-Inflammatory, and Antioxidant Activity of Culinary Processed Shiitake Medicinal Mushroom (Lentinus edodes, Agaricomycetes) and Its Major Sulfur Sensory-Active Compound-Lenthionine.

The antimicrobial, cytotoxic, anti-inflammatory, and antioxidant properties of aqueous extracts of raw and culinary processed shiitake mushrooms were evaluated and compared with those of lenthionine (1,2,3,5,6-penta-thiepane), the principal aroma-bearing substance of the shiitake medicinal mushroom (Lentinus edodes). Antimicrobial activity was tested using a panel of 4 strains of bacteria, 2 yeasts, and 2 fungi. Cytotoxic properties were evaluated against 3 cell lines (HepG2, HeLa, PaTu), whereas the anti-inflammatory activity of tested samples was assayed based on their ability to attenuate the secretion of the cytokine tumor necrosis factor-α. Antioxidant activity was measured using in vitro DPPH and ABTS assays. It was found that lenthionine possesses significant antimicrobial properties; it is remarkably effective in inhibiting the growth of yeasts and fungi (minimum inhibitory concentration, 2-8 µg/mL) and thus is comparable to standard antifungal agents. Lenthionine is also able to decrease significantly the production of tumor necrosis factor-a and thus could be at least partly responsible for the observed anti-inflammatory effect of shiitake. On the other hand, lenthionine does not seem to contribute significantly to the well-known anticancer and antioxidant effects of the mushroom.

Baloxavir: First Global Approval.

Baloxavir marboxil (Xofluza™; baloxavir) is an oral cap-dependent endonuclease inhibitor that has been developed by Roche and Shionogi. The drug blocks influenza virus proliferation by inhibiting the initiation of mRNA synthesis. In February 2018, baloxavir received its first global approval in Japan for the treatment of influenza A or B virus infections. Phase III development is underway in the USA, EU and other countries for this indication. This article summarized the milestones in the development of baloxavir leading to this first global approval for influenza A or B virus infections.

Indium(III) chloride catalyzed highly diastereoselective domino synthesis of indenodithiepines and indenodithiocines.

An atom-economical diastereoselective synthesis of indenodithiepines and indenodithiocines has been developed via a domino reaction of propargylic alcohols and dithioacetals in the presence of InCl3 as a catalyst. A range of functionalized dithiepines and dithiocines, fused to the indene ring, were obtained in good to excellent yields under mild conditions.

The unexpected and facile molybdenum mediated formation of tri- and tetracyclic pentathiepins from pyrazine-alkynes and sulfur.

The synthesis of a novel family of pentathiepino-pyrrolo[1,2-a]pyrazine derivatives is reported. These compounds are formed by the reaction of alkynyl-substituted heterocyclic precursors with elemental sulfur in the presence of molybdenum oxo bis-tetrasulfide under very mild conditions.

The first naturally occurring thiepinols and thienol from an endolichenic fungus Coniochaeta sp.

Coniothiepinols A (1) and B (2) and coniothienol A (3), the first naturally occurring thiepinols (1 and 2) and thienol (3), have been isolated from the crude extract of an endolichenic fungus Coniochaeta sp. 1 possesses a unique 8-oxa-2-thia-bicyclo[3.2.1]octane skeleton, and its structure was assigned by NMR spectroscopy and X-ray crystallography. 1 showed significant activity against the gram-positive bacteria, Enterococcus faecium and Enterococcus faecalis.

Discovery of a novel class of AKT pleckstrin homology domain inhibitors.

AKT, a phospholipid-binding serine/threonine kinase, is a key component of the phosphoinositide 3-kinase cell survival signaling pathway that is aberrantly activated in many human cancers. Many attempts have been made to inhibit AKT; however, selectivity remains to be achieved. We have developed a novel strategy to inhibit AKT by targeting the pleckstrin homology (PH) domain. Using in silico library screening and interactive molecular docking, we have identified a novel class of non-lipid-based compounds that bind selectively to the PH domain of AKT, with "in silico" calculated K(D) values ranging from 0.8 to 3.0 micromol/L. In order to determine the selectivity of these compounds for AKT, we used surface plasmon resonance to measure the binding characteristics of the compounds to the PH domains of AKT1, insulin receptor substrate-1, and 3-phosphoinositide-dependent protein kinase 1. There was excellent correlation between predicted in silico and measured in vitro K(D)s for binding to the PH domain of AKT, which were in the range 0.4 to 3.6 micromol/L. Some of the compounds exhibited PH domain-binding selectivity for AKT compared with insulin receptor substrate-1 and 3-phosphoinositide-dependent protein kinase 1. The compounds also inhibited AKT in cells, induced apoptosis, and inhibited cancer cell proliferation. In vivo, the lead compound failed to achieve the blood concentrations required to inhibit AKT in cells, most likely due to rapid metabolism and elimination, and did not show antitumor activity. These results show that these compounds are the first small molecules selectively targeting the PH domain of AKT.

Alkylenesulfanyl-bridged bithienyl cores for simultaneous tuning of electronic, filming, and thermal properties of oligothiophenes.

DPY and DPE alkylenesulfanyl-bridged bithienyls were prepared by a highly effective ring-closing reaction via arylalkylsulfonium intermediate and used as inner cores in oligothiophenes. HOMO-LUMO energy levels, conformational flexibility, and intrinsic asymmetry of the cores are reflected in the electronic, film-forming, and thermal properties of the corresponding oligomers.

Electroactive self-assembled monolayers on gold via bipodal dithiazepane anchoring groups.

Novel dithiazepane-functionalized ferrocenyl-phenylethynyl oligomers 1 and 2 have been synthesized. Self-assembled monolayers (SAMs) of these ferrocene derivatives have been studied by X-ray photoelectron spectroscopy, ellipsometry, and cyclic voltammetry. It has been shown by XPS that monolayers of the dithiazepane-anchored molecules on gold electrodes contain gold-thiolate species. Cyclic voltammetry of the SAMs were characteristic of stable electroactive monolayers even for single-component SAMs of 1 and 2, with the more ideal responses recorded for the two-component SAMs diluted with undecanethiol. The small variation in peak splittings at progressively higher scan rates in these SAMs makes dithiazepane-bridged redox species promising candidates for further studies on molecular wires with bipodal anchoring.

Planar chirality due to a polysulfur ring in natural pentathiepin cytotoxins. Implications of planar chirality for enantiospecific biosynthesis and toxicity.

A low-energy pathway for pentathiepin racemization has been found using density functional theory (DFT) calculations. 3-[1,2,3,4,5]pentathiepin-6-yl-propylamine served as a model compound for tunicate-derived pentathiepins. Pentathiepin racemization becomes a low-energy process in the presence of a thiolate ion nucleophile. It is unknown whether the biosynthetic process for pentathiepins is enantiospecific (Bentley, R. (2005) Chem. Soc. Rev. 34, 609) or whether toxicity differs between enantiomers. However, the ease of thiolate ion attack on the polysulfur ring suggests that nucleophiles may induce optical instability on the laboratory time scale. The DFT study predicts that enantiospecific behaviors such as toxicity differences between P- and M-pentathiepins would be difficult to determine experimentally. The computed results fit into a broader picture that nucleophiles assist in ring-opening and equilibration reactions of polysulfanes.

Push-pull bithienyl chromophore with an unusual transverse path of conjugation.

The synthesis, structure, and electronic properties of a novel cross-conjugated 10H-bisthienodithiocin-10-dicyanoethylene are reported. The X-ray single-crystal structure of the compound reveals a nonplanar conformation. The FT-IR and FT-Raman spectra of the compound show a great resemblance, which is a spectroscopic observation common to many push-pull systems. The UV-vis spectrum in CHCl3 displays a strong absorption at 370 nm accompanied by a shoulder at 430 nm so that the optical gap is 2.88 eV. On the other hand, the electrochemical gap amounts to 2.38 V. DFT and TDDFT quantum chemical calculations, at the B3LYP/6-31G** level, have been also performed to (i) determine the minimum-energy molecular structure, (ii) gain knowledge about the equilibrium atomic charges distribution, the topologies, and absolute energies of the frontier molecular orbitals around the gap and about the molecular vibrations which give rise to the most outstanding Raman bands experimentally evidenced, and (iii) to analyze the nature of the vertical one-electron excitations associated to the strongest UV-vis absorptions.

Platinum (II) complexes with stereochemically-defined thiepane dioxide diamine ligands as anticancer drugs.

Platinum (II) complexes are accredited with biological activities. New complexes with thiepane dioxide diamine as ligands, characterized by defined stereochemical features, a flexible 7-membered thiepane moiety and by C2 symmetry, were prepared. The complexes, related to the diamino cyclohexane family of platinum complexes, were soluble in dimethyl sulfoxide with the solvent substituting one chloride ion. These positively-charged complexes were tested against a human carcinoma cell line A431 and its cisplatin-resistant counterpart A431/Pt and were found to show: i) capability in bypassing cisplatin-resistance; ii) cytotoxicity comparable to that of oxaliplatin; iii) lower activity than cisplatin. In both cells lines, [PtCl(DACH)(DMSO)]+ was more cytotoxic than oxaliplatin. The best activity was shown by the platinum complexes with ligands which presented C2 symmetry.

A general procedure for the synthesis of stereochemically pure conduritol derivatives practical also for solid-phase chemistry.

A straightforward synthetic protocol apt to synthesize a library constituted by all conduritol stereoisomers in solution phase is described and successfully applied to some polymer-supported substrates. During the solid-phase sequence, an unprecedented rearrangement of a resin-bound sulfone performed under the Ramberg-Bäcklund conditions appears of particular interest. Upon treatment with Me(3)Si-I, thiepanes supported on resin are found to undergo regio- and stereospecific ring contraction to a six-membered ring system with traceless cleavage from the solid support.

HPLC quantitation of the four stereoisomers of benzoxathiepin derivatives with cellulose phenyl type chiral stationary phase and circular dichroism detection.

The chiral separation of a new antianginal agent has been investigated on a chiral cellulose column with UV and circular dichroism (CD) detection. This benzoxathiepin derivative under development has two stereogenic centers whose (R,S) stereoisomer shows an interesting antianginal activity. After optimisation of the mobile phase composition, a baseline-resolved separation of the four stereoisomers was achieved on a Chiralcel OJ-H chiral column by using methanol-ethanol-diethylamine (25:75:0.1, v/v/v) as mobile phase. The CD detection system allowed quantitation and a linear response was observed within a 10-200 microg mL-1 concentration range (r2=0.9966) and limit of quantification down to 2 microg mL-1 was achieved.

Encapsulation of shiitake (Lenthinus edodes) flavors by spray drying.

Powdery encapsulation of shiitake flavors, extracted from dried shiitake, was investigated by spray drying. Flavor retention increased with an increase in drying air temperature and solid content, and decreased with an increase in dextrose equivalents of maltodextrin. A heat-treatment of the extract liquid made the lenthionine concentration increase, but did not influence the concentrations of the other flavors. The formation of lenthionine with heat-treatment could be described by the consecutive unimolecular-type first order reaction. Lenthionine content in a spray-dried powder prepared with the heated extracted liquid significantly increased. alpha-Cyclodextrin was the most suitable encapsulant of alpha-, beta-, and gamma-cyclodextrins to prepare the spray-dried powder, including lenthionine. The flavor retentions were markedly increased by using of alpha-cyclodextrin and maltodextrin in combination as an encapsulant.

2,3-Dihydro-dithiin and -dithiepine-1,1,4,4-tetroxides: small molecule non-peptide antagonists of the human galanin hGAL-1 receptor.

The neuropeptide galanin modulates several physiological functions such as cognition, learning, feeding behavior, and depression, probably via the galanin 1 receptor (GAL-R1). Using an HTS assay based on 125I-human galanin binding to the human galanin-1 receptor (hGAL-R1), we discovered a series of 1,4-dithiin and dithiipine-1,1,4,4-tetroxides that exhibited binding affinity IC50's to hGAL-R1 ranging from 190 to 2700 nM. Two of the dithiepin analogues, 7 and 23, behaved pharmacologically as hGAL-R1 antagonists in secondary assays involving adenylate cyclase activity and GTP binding to G-proteins. Analogues 7 and 23 were also active in functional assays involving galanin, reversing the inhibitory effect of galanin on acetylcholine (ACh) release in rat brain hippocampal slices and electrically-stimulated guinea pig ileum twitch.