5-Alkynyl-2′-deoxyuridines, containing bulky aryl groups: evaluation of structure–anti-HSV-1 activity relationship

Steroid-triazole conjugates: A brief overview of synthesis and their application as anticancer agents

Steroids are biomolecules that play pivotal roles in various physiological and drug discovery processes. Abundant research has been fuelled towards steroid-heterocycles conjugates over the last few decades as potential therapeutic agents against various diseases especially as anticancer agents. In this context various steroid-triazole conjugates have been synthesized and studied for their anticancer potential against various cancer cell lines. A thorough search of the literatures revealed that a concise review pertaining the present topic is not compiled. Therefore, in thus review we summarize the synthesis, anticancer activity against various cancer cell lines and structure activity relationship (SAR) of various steroid-triazole conjugates. This review can lay down the path towards the development of various steroid-heterocycles conjugates with lesser side effects and profound efficacy.

Photosensitizing Antivirals

Antiviral action of various photosensitizers is already summarized in several comprehensive reviews, and various mechanisms have been proposed for it. However, a critical consideration of the matter of the area is complicated, since the exact mechanisms are very difficult to explore and clarify, and most publications are of an empirical and "phenomenological" nature, reporting a dependence of the antiviral action on illumination, or a correlation of activity with the photophysical properties of the substances. Of particular interest is substance-assisted photogeneration of highly reactive singlet oxygen (1O2). The damaging action of 1O2 on the lipids of the viral envelope can probably lead to a loss of the ability of the lipid bilayer of enveloped viruses to fuse with the lipid membrane of the host cell. Thus, lipid bilayer-affine 1O2 photosensitizers have prospects as broad-spectrum antivirals against enveloped viruses. In this short review, we want to point out the main types of antiviral photosensitizers with potential affinity to the lipid bilayer and summarize the data on new compounds over the past three years. Further understanding of the data in the field will spur a targeted search for substances with antiviral activity against enveloped viruses among photosensitizers able to bind to the lipid membranes.

Low-Power Near-Infrared-Responsive Upconversion Nanovectors

Activating upconversion nanoparticle-based photoresponsive nanovectors (UCPNVs) by upconversion visible light at low-power near-infrared (NIR) excitation can realize deeper biotissue stimulation with a minimized overheating effect and photodamage. Here, we demonstrate a facile strategy to construct new surface-decorated UCPNVs based on Passerini three-component reaction (P-3CR) in highly convenient and effective manners. Such UCPNVs materials have a tailored deprotecting wavelength that overlaps upconversion blue light. By using 3-perylenecarboxaldehyde, Tm³⁺/Yb³⁺ ion-doped UCNP-containing isocyanides, and antitumor agent chlorambucil as the three components, the resulting monodisperse UCPNV exhibits an efficient release of caged chlorambucil under a very low 976 nm power. This approach expands the synthetic toolbox to enable quick development of UCPNVs for UCNP-assisted low-power NIR photochemistry.

Synthesis and Properties of Perylene-Bridge-Anchor Chromophoric Compounds

The quest to control chromophore/semiconductor properties to enable new technologies in energy and information science requires detailed understanding of charge carrier dynamics at the atomistic level, which can often be attained through the use of model systems. Perylene-bridge-anchor compounds are successful models for studying fundamental charge transfer processes on TiO₂, which remains among the most commonly investigated and technologically important interfaces, mostly because of perylene's advantageous electronic and optical properties. Nonetheless, the ability to fully exploit synthetically the substitution pattern of perylene with linker (= bridge-anchor) units remains little explored. Here we developed 2,5-di-tert-butylperylene (DtBuPe)-bridge-anchor compounds with t-Bu group substituents to prevent π-stacking and one or two linker units in both the peri and ortho positions, by employing a combination of Friedel-Crafts alkylations, bromination, iridium-catalyzed borylation, and palladium-catalyzed cross-coupling reactions. Photophysical characterization and computational analysis by density functional theory (DFT) and time-dependent DFT (TD-DFT) were carried out on four DtBuPe acrylic acid derivatives with a single or a double linker in peri (12b), ortho (15b), peri,peri (18b), and ortho,ortho (21b). The energies of the unoccupied orbitals {LUMO, LUMO + 1, LUMO + 2} are strongly affected by the presence of a π-conjugated linker, resulting in a stabilization of these states and a red shift of their absorption and emission spectra, as well as the loss of vibronic structure in the spectrum of the peri,peri compound, consistent with the strong bonding character of this substitution pattern.

Viologen-Based Rotaxanes from Dibenzo-30-crown-10

Three [2]rotaxanes (4, 7, and 12) and one [3]rotaxane (8) were synthesized based on the dibenzo-30-crown-10/viologen binding motif. To the best of our knowledge, these are the first rotaxanes formed from dibenzo-30-crown-10 and viologens. The rotaxanes were all characterized by ¹H NMR, ¹³C NMR, and HRMS. An X-ray crystal structure of one of the [2]rotaxanes (7) was obtained. This work demonstrates for the first time that dibenzo-30-crown-10 does form pseudorotaxane complexes with viologens in solution.

A fluorescent dye with large Stokes shift and high stability: synthesis and application to live cell imaging

A new fluorescent dye with large Stokes shift and excellent photo-stability for live cell imaging has been developed.

Synthesis and biological evaluation of 13α-estrone derivatives as potential antiproliferative agents

13α-Estrone derivatives containing various substituents on C-3 and C-17 were synthesized, and evaluated by means of MTT assays for in vitro antiproliferative activity against a panel of human adherent cancer cell lines (HeLa, MCF-7, A2780 and A431). Compounds with N-benzyltriazolylmethoxy moieties on C-3 proved to be more potent than their 3-hydroxy or 3-ether counterparts. Some triazoles exerted substantial cytostatic effects against particular tumor cell lines, with submicromolar IC50 values.

Rigid amphipathic nucleosides suppress reproduction of the tick-borne encephalitis virus

Rigid amphipathic fusion inhibitors (RAFIs), 5-arylethynyl uracil nucleosides with bulky aryl groups, appeared to have considerable activity against tick-borne encephalitis virus (TBEV) in cell culture.

Silicon-pyrene/perylene hybrids as molecular rectifiers

We have synthesized two alkenyl (C-6 and C-11 chains) pyrenes and one alkenyl (C-11 chain) perylene as the σ-π systems, which were electro-grafted on H-terminated Si surfaces to form the respective monolayers. The I-V characteristics of the monolayers revealed pronounced rectification in forward bias with a maximum rectification ratio (RR) of 2.5 × 10(5) at 2.5 V for the C-6-pyrene 4b, 1000 at 1.5 V for the C-11-pyrene 4a and 3000-5000 at 1.75 V for the C-11-perylene 3. The higher RR of the devices containing 4b compared to those of 4a and 3 is possibly due to better alignment and packing of the 4b-monolayers on the Si substrate. The rectification was explained using the ab initio molecular-orbital calculations.

Solvatochromic properties of 3,6-di-tert-butyl-8H-indolo[3,2,1-de]acridin-8-one

The spectral and photophysical properties of newly synthesized 3,6-di-tert-butyl-8H-indolo[3,2,1-de]acridin-8-one were studied.

Preparation, preliminary screening of new types of steroid conjugates and their activities on steroid receptors

There were synthesized new types of ribbon type steroidal dimers derived from three types of steroidal skeletons (cholic acid, etienic acid, estrone) using Cu(I) catalyzed 1, 3-dipolar cycloaddition reaction. Steroid parts of the molecular "ribbons" are linked by heterocyclic moiety, namely by 2,6-bis((1H-1,2,3-triazol-1-yl)-methyl)pyridine. Compounds synthesized possess different cytotoxic and hormone receptor modulating activities.

Fluorescent oligonucleotides containing a novel perylene 2′-amino-α-L-LNA monomer: Synthesis and analytical potential

Herein, a novel fluorescent nucleotide analogue, perylene-2′-amino-α-L-LNA, has been prepared and studied within synthetic oligonucleotides of different sequences. The phosphoramidite reagent was synthesized in 85% overall yield starting from 2′-amino-α-L-LNA nucleoside. Incorporation efficiency of the resulting perylene-2′-amino-α-L-LNA monomer (T*) into synthetic oligonucleotides was significantly improved by replacement of the typically used 1H-tetrazole activator with pyridine hydrochloride. Generally, oligonucleotides containing monomerT* showed high binding affinity towards complementary DNA and RNA targets, batochromically shifted excitation/emission wavelengths with respect to the often applied polyaromatic hydrocarbon pyrene, high fluorescent quantum yields and very low target detection limits (5–10 nM). Fluorescence of single stranded LNA/DNA mixmer oligonucleotide having two incorporations of monomersT* was quenched (quantum yield ΦF= 0.21) relative to duplexes of this probe with complementary DNA and RNA (ΦF= 0.42 and 0.35, respectively). On the contrary, a strong fluorescence quenching upon target binding was demonstrated by two short oligonucleotides of analogues sequences containing monomersT* at 5′- and 3′-terminal positions. We explain the hybridization-induced light-up effect observed for double-labeled probe by a reduction of fluorescence quenching due to precise positioning of the fluorophores within the double-stranded complexes. Furthermore, we propose that a covalent link between twoT* monomers in the double-labeled probe provides a remarkable degree of rigidity in the double helix which enforces positioning of the bulky perylene moieties in the nonpolar groove resulting in reduced fluorescence quenching.

New 9-methyl-8-(4-hydroxyphenyl)adenine derivatives as A1 adenosine receptor antagonists

A new series of 9-methyladenines, bearing different bulky groups at the 8-position, were prepared and their affinity for the four human adenosine receptor subtypes were evaluated. All the synthesized compounds showed affinities at the A1, A2A, and A3AR subtypes ranging from nanomolar to micromolar levels with different degrees of A1selectivity, while they resulted nearly inactive at A2BAR. In particular, 9-methyl-8-[4-(4-methylbenzyloxy)phenyl]- adenine showed A1AR affinity in the nanomolar range and good levels of selectivity versus the other receptor subtypes. Furthermore, a functional assay at mouse ileum allowed to assess the potency of selected compounds at A1AR subtype. Results showed that all the tested derivatives are neutral antagonists and theirKbvalues are in good agreement with theKivalues from radioligand binding assay at human A1AR, confirming that the effect is due to inhibition of this subtype.

Perylene-fused BODIPY dye with near-IR absorption/emission and high photostability

A N-annulated perylene unit was successfully fused to the meso- and β-positions of a boron dipyrromethene (BODIPY) core. The newly synthesized BODIPY dye 1b exhibits intensified near-infrared (NIR) absorption and the longest emission maximum ever observed for all BODIPY derivatives. In addition, this dye possesses excellent solubility and photostability, beneficial to practical applications.

Rigid amphipathic fusion inhibitors, small molecule antiviral compounds against enveloped viruses

Antiviral drugs targeting viral proteins often result in prompt selection for resistance. Moreover, the number of viral targets is limited. Novel antiviral targets are therefore needed. The unique characteristics of fusion between virion envelopes and cell membranes may provide such targets. Like all fusing bilayers, viral envelopes locally adopt hourglass-shaped stalks during the initial stages of fusion, a process that requires local negative membrane curvature. Unlike cellular vesicles, however, viral envelopes do not redistribute lipids between leaflets, can only use the energy released by virion proteins, and fuse to the extracellular leaflets of cell membranes. Enrichment in phospholipids with hydrophilic heads larger than their hydrophobic tails in the convex outer leaflet of vesicles favors positive curvature, therefore increasing the activation energy barrier for fusion. Such phospholipids can increase the activation barrier beyond the energy provided by virion proteins, thereby inhibiting viral fusion. However, phospholipids are not pharmacologically useful. We show here that a family of synthetic rigid amphiphiles of shape similar to such phospholipids, RAFIs (rigid amphipathic fusion inhibitors), inhibit the infectivity of several otherwise unrelated enveloped viruses, including hepatitis C and HSV-1 and -2 (lowest apparent IC(50) 48 nM), with no cytotoxic or cytostatic effects (selectivity index > 3,000) by inhibiting the increased negative curvature required for the initial stages of fusion.

5-Alkynyl-2'-deoxyuridines: chromatography-free synthesis and cytotoxicity evaluation against human breast cancer cells

Starting with 5-iodo-2'-deoxyuridine, a series of 5-alkynyl-2'-deoxyuridines (with n-propyl, cyclopropyl, 1-hydroxycyclohexyl, p-tolyl, p-tert-butylphenyl, p-pentylphenyl, and trimethylsilyl alkyne substituents) have been synthesized via the palladium-catalyzed (Sonogashira) coupling reaction followed by a simplified isolation protocol (76-94% yield). The cytotoxic activity of modified nucleosides against MCF-7 and MDA-MB-231 human breast cancer cells has been determined in vitro. 5-Ethynyl-2'-deoxyuridine, the only nucleoside in the series containing a terminal acetylene, is the most potent inhibitor with IC(50) (microM) 0.4+/-0.3 for MCF-7 and 4.4+/-0.4 for MDA-MB-231.

Fluorescent 5-Alkynyl-2′-Deoxyuridines: High Emission Efficiency of a Conjugated Perylene Nucleoside in a DNA Duplex

Four fluorescent 5-alkynyl-2'-deoxyuridines were studied in DNA oligonucleotides and their duplexes. The fluorescence response to hybridization differs dramatically for nucleosides containing a perylene fluorochrome either conjugated or not conjugated to the nucleobase. The conjugated nucleoside, 5-(perylen-3-ylethynyl)-2'-deoxyuridine, shows enhanced long-wavelength emission in the DNA duplex, in contrast to the blue fluorescence of perylene on a flexible linker (in 5-[(perylen-3-yl)methoxyprop-1-ynyl]-2'-deoxyuridine), which is quenched upon duplex formation.

5-Arylethynyl-2'-deoxyuridines, compounds active against HSV-1

Three new 5-arylethynyl-2'-deoxyuridines containing bulky aryls have been prepared and tested against HSV-1 in Vero cells. The introduction of a substituent in the phenyl group of an inactive compound, 5-phenylethynyl-2'-deoxyuridine, leads to the appearance of anti-HSV properties. The most active compounds are those containing a polycyclic aromatic hydrocarbon residue attached to the 5 position of 2'-deoxyuridine through a rigid triple bond.