Insights into Molecular Interactions and Biological Effect of Natural Stilbenoids at the TRPA1 Ion Channel.

Natural stilbenoids, polyphenolic compounds notably found in Scots pine and Norway spruce, have been shown to exhibit analgesic and anti-inflammatory effects through the TRPA1 channel, making them promising hits for the development of novel agents to treat inflammatory diseases and pain. In this study, we computationally investigated the putative binding sites of natural stilbenoids at the TRPA1 channel. Specifically, we employed molecular docking and MD simulation approaches to explore three known ligand binding sites at TRPA1.

Investigating the Effectiveness of Different Porous Nanoparticles as Drug Carriers for Retaining the Photostability of Pinosylvin Derivative.

Pinosylvin monomethyl ether (PsMME) is a natural compound known for its valuable bioactive properties, including antioxidant and anti-inflammatory effects. However, PsMME's susceptibility to photodegradation upon exposure to ultraviolet (UV) radiation poses a significant limitation to its applications in the pharmaceutical field. This study, for the first time, introduces a strategy to enhance the photostability of PsMME by employing various nanoformulations.

Formation of Tetrahydrofurano-, Aryltetralin, and Butyrolactone Norlignans through the Epoxidation of 9-Norlignans.

Epoxidation of the C=C double bond in unsaturated norlignans derived from hydroxymatairesinol was studied. The intermediate epoxides were formed in up to quantitative conversions and were readily further transformed into tetrahydrofuran, aryltetralin, and butyrolactone products-in diastereomeric mixtures-through ring-closing reactions and intramolecular couplings. For epoxidation, the classical Prilezhaev reaction, using stoichiometric amounts of -chloroperbenzoic acid (CPBA), was used.

Synthesis and Evaluation of Anisomelic acid-like Compounds for the Treatment of HPV-Mediated Carcinomas.

The vast majority of cervical and 75% of oropharyngeal carcinomas are triggered by infection with a type of high-risk oncogenic human papillomavirus (HPV). It is well-known that E6 and E7 oncoproteins are critical for viral-induced cancer, and hence, they represent valuable targets for therapeutic intervention in HPV-mediated cancers. Our earlier research on the cembranoid, anisomelic acid (AA) showed that, AA has the potential to induce apoptosis in HPV cells by the depletion of E6 and E7 oncoproteins.

Tsuji-Wacker-Type Oxidation beyond Methyl Ketones: Reacting Unprotected Carbohydrate-Based Terminal Olefins through the "Uemura System" to Hemiketals and α,β-Unsaturated Diketones.

Aerobic Pd(AcO)/pyridine-catalyzed oxidation of unprotected carbohydrate-based terminal alkenes was studied. In accordance with previous reports, the initial reaction step gave methyl ketones. However, our substrates partially gave subsequent α,β-water elimination and alcohol oxidation to α,β-unsaturated 2,5-diketones.

Oxidative Transformations of Lignans.

Numerous oxidative transformations of lignan structures have been reported in the literature. In this paper we present an overview on the current findings in the field. The focus is put on transformations targeting a specific structure, a specific reaction, or an interconversion of the lignan skeleton.

Chemical characterization of high-molar-mass fractions in a Norway spruce knotwood ethanol extract.

The low-molar-mass (LMM) fraction, only, i.e., the GC-eluting compounds, which are mainly lignans, has been characterized in Norway spruce knotwood hydrophilic extracts previously.

Content, composition, and stereochemical characterisation of lignans in berries and seeds.

In seed extracts of five oilseed species, in bran extracts of three cereal species, and in seed and/or whole berry extracts of 10 berry species, the concentrations of a large number of lignans and the enantiomeric composition of selected lignans were determined. In the case of sesame and hemp seeds, the lignan content and composition of the whole seeds was compared to that of the hulled seeds. The results showed that cloudberry seeds are the third most lignan-rich food source after linseeds and whole sesame seeds, and that most of the berry species analysed were more lignan-rich than the cereal brans.

Lignans as food constituents with estrogen and antiestrogen activity.

Phytoestrogens are plant-derived food ingredients assumed to contribute to the prevention of hormone-dependent cancers, osteoporosis, cardiovascular disease, and menopausal symptoms. Lignans occur in numerous food plants and various structures; they are common constituents of human diet, and estrogen activity has been assessed for lignan metabolites formed in the mammalian intestine. We examined natural lignans and semisynthetic norlignans for estrogen and antiestrogen activity.

Controlled growth of single-walled carbon nanotubes for unique nanodevices.

The controlled growth of bent and horizontally aligned single-walled carbon nanotubes (SWNTs) is demonstrated in this study. The bent SWNTs growth is attributed to the interaction between van der Waals force with substrate and aerodynamic force from gas flow. The curvature of bent SWNTs can be tailored by adjusting the angle between gas flow and step-edge direction.

Measuring the fluorescent quantum efficiency of indocyanine green encapsulated in nanocomposite particulates.

We present results of a fluorescent quantum efficiency (Φ(F)) study on the encapsulation of the near-infrared dye indocyanine green (ICG) in bioresorbable calcium phosphate nanoparticles (CPNPs). The Φ(F) (described as the ratio of photons emitted to photons absorbed) provides a quantitative means of describing the fluorescence of an arbitrary molecule. However, standard quantum efficiency measurement techniques provide only the Φ(F) of the smallest fluorescing unit-in the case of a nanoparticle suspension, the nanoparticle itself.

Electrical properties and far infrared optical conductivity of boron-doped single-walled carbon nanotube films.

Here we report a new approach for producing clean and homogeneous boron-doped single-walled carbon nanotubes. This approach combines the homogeneous dispersion of B(n)O(m)(+) ionic molecules over the nanotube surfaces in a liquid solution, with a high temperature chemical reaction that incorporates the boron atoms into the sp(2) carbon network of the nanotube wall. A comparative study of sheet resistance versus optical transmission in nanotube network films with and without boron-doping is also presented.

Charge transfer and weak chemisorption of oxygen molecules in nanoporous carbon consisting of a disordered network of nanographene sheets.

The adsorption/desorption processes of oxygen are investigated in nanoporous carbon (activated carbon fiber (ACF)) consisting of a disordered network of nanographene sheets. The heat-induced desorption at 200 °C shows the decomposition of oxygen-including functional groups weakly bonded to nanographene edges. The removal of these oxygen-including negatively charged functional groups brings about a change in the type of majority carriers, from holes to electrons, through charge transfer from the functional groups to the interior of nanographene sheets.

Curvature-induced D-band Raman scattering in folded graphene.

Micro-Raman scattering from folds in single-layer graphene sheets finds a D-band at the fold for both incommensurate and commensurate folding, while the parent single-layer graphene lacks a D-band. A coupled elastic-continuum/tight-binding calculation suggests that this D-band arises from the spatially inhomogeneous curvature around a fold in a graphene sheet. The polarization dependence of the fold-induced D-band further reveals that the inhomogeneous curvature acts as a very smooth, ideal one-dimensional defect along the folding direction.

Polarized Rayleigh back-scattering from individual semiconductor nanowires.

A complete understanding of the interaction between electromagnetic radiation and semiconductor nanowires (NWs) is required in order to further develop a new generation of opto-electronic and photonic devices based on these nanosystems. The reduced dimensionality and high aspect ratio of nanofilaments can induce strong polarization dependence of the light absorption, emission and scattering, leading in some cases to the observation of optical antenna effects. In this work we present the first systematic study of polarized Rayleigh back-scattering from individual crystalline semiconductor NWs with known crystalline structure, orientation and diameters.

Cavity-enhanced stimulated raman scattering from short GaP nanowires.

We report the first observation of stimulated Raman scattering (SRS) from semiconductor nanowires (SNWs). Using continuous wave (CW) excitation (514.5 nm), very strong nonlinear SRS was observed in backscattering from short segments of crystalline GaP NWs with diameter d = 210 nm when the wire length L < 1.

Adsorption of ammonia on graphene.

We report on experimental studies of NH3 adsorption/desorption on graphene surfaces. The study employs bottom-gated graphene field effect transistors supported on Si/SiO2 substrates. Detection of NH3 occurs through the shift of the source-drain resistance maximum ('Dirac peak') with the gate voltage.

A selective de-O-methylation of guaiacyl lignans to corresponding catechol derivatives by 2-iodoxybenzoic acid (IBX). The role of the catechol moiety on the toxicity of lignans.

We report here the first selective de-O-methylation of a large panel of guaiacyl lignans to the corresponding catechol derivatives by using IBX as primary oxidant under green conditions (dimethyl carbonate-H(2)O solvent) through an in situ reduction procedure. The influence of the catechol moiety on the cytotoxicity and genotoxicity of new lignan derivatives has been investigated. The results obtained indicated that the presence of the catechol moiety sharply enhances the clastogenic potential (e.

Encapsulation of organic molecules in calcium phosphate nanocomposite particles for intracellular imaging and drug delivery.

Encapsulation of imaging agents and drugs in calcium phosphate nanoparticles (CPNPs) has potential as a nontoxic, bioresorbable vehicle for drug delivery to cells and tumors. The objectives of this study were to develop a calcium phosphate nanoparticle encapsulation system for organic dyes and therapeutic drugs so that advanced fluoresence methods could be used to assess the efficiency of drug delivery and possible mechanisms of nanoparticle bioabsorption. Highly concentrated CPNPs encapsulating a variety of organic fluorophores were successfully synthesized.

Near-infrared emitting fluorophore-doped calcium phosphate nanoparticles for in vivo imaging of human breast cancer.

Early detection is a crucial element for the timely diagnosis and successful treatment of all human cancers but is limited by the sensitivity of current imaging methodologies. We have synthesized and studied bioresorbable calcium phosphate nanoparticles (CPNPs) in which molecules of the near-infrared (NIR) emitting fluorophore, indocyanine green (ICG), are embedded. The ICG-CPNPs demonstrate exceptional colloidal and optical characteristics.

n-Type behavior of graphene supported on Si/SiO(2) substrates.

Results are presented from an experimental and theoretical study of the electronic properties of back-gated graphene field effect transistors (FETs) on Si/SiO(2) substrates. The excess charge on the graphene was observed by sweeping the gate voltage to determine the charge neutrality point in the graphene. Devices exposed to laboratory environment for several days were always found to be initially p-type.

Probing graphene edges via Raman scattering.

We present results of a Raman scattering study from the region near the edges of n-graphene layer films. We find that a Raman band (D) located near 1344 cm(-1) (514.5 nm excitation) originates from a region next to the edge with an apparent width of approximately 70 nm (upper bound).

Transparent boron-doped carbon nanotube films.

We report results of studies on the sheet resistance and optical transmission of thin films of boron-doped single-walled carbon nanotubes (SWNTs). Boron doping was carried out by exposure of SWNTs to B 2O 3 and NH 3 at 900 degrees C and 1-3 atom % boron was found in the SWNT bundles via electron energy loss spectroscopy (EELS). Boron doping was found to downshift the positions of the optical absorption bands associated with the van Hove singularities (E 11 (s) E 22 (s) and E 11 (m)) by approximately 30 meV relative to their positions in acid-treated and annealed SWNTs.

Synthesis and raman scattering from Zn(1-x)Mn(x)S diluted magnetic semiconductor nanowires.

The growth of Diluted Magnetic Semiconducting (DMS) Zn(1-x)Mn(x)S (0 < or = x < 0.6) nanowires (NWs) using a three-zone furnace and two solid sources is reported. The approach is generally applicable to many binary and ternary NW systems that grow by the Vapor-Liquid-Solid growth mechanism.

Electronic properties of semiconductor nanowires.

This paper provides a review of the state-of-the-art electronic-structure calculations of semiconductor nanowires. Results obtained using empirical k.p, empirical tight-binding, semi-empirical pseudopotential, and with ab initio methods are compared.