1,721,048 research outputs found
The Olefin Metathesis Reaction in the Synthesis of Resorc[4]arenes with Intriguing Architectures
No full textTetramerization of (E)-2,4-dimethoxycinnamic acid ω-undecenyl ester with ethereal BF3 gave three stereoisomers which were assigned as the chair, cone, and 1,2-alternate conformations. When the three resorc[4]arenes were submitted to olefin metathesis using the second generation Grubbs catalyst, different intra- and inter-molecular products were isolated, depending on conformation and reaction conditions.
Molecular modeling studies showed that a basket-like resorc[4]arene, obtained by olefin metathesis of the cone resorc[4]arene ω-undecenyl ester, provide efficient shape complementarity to fullerenes C60 and C70 .
Both self-assembly and encapsulation phenomena were demonstrated by UV spectroscopy.(1)Istituto Italiano di Tecnologia (IIT), Center for Life Nano Science (IIT@Sapienza), Italy. (2)Progetti per Avvio alla Ricerca, MIUR, 201
Synthesis of a basket-resorc[4]arene via metathesis reaction and encapsulation studies of fullerenes C60 and C70
No full textSynthesis of a basket-resorc[4]arene via metathesis reaction and encapsulation studies of fullerenes C60 and C70
No full textInorganic gold and polymeric poly(lactide-co-glycolide) nanoparticles as novel strategies to ameliorate the biological properties of antimicrobial peptides
No full textCationic antimicrobial peptides (AMPs) are an interesting class of gene-encoded molecules endowed with a broad-spectrum of anti-infective activity and immunomodulatory properties. They represent promising candidates for the development of new antibiotics, mainly due to their membrane-perturbing mechanism of action that very rarely induces microbial resistance. However, bringing AMPs into clinical field is hampered by some intrinsic limitations, encompassing low peptide bioavailability at the target site and high peptide susceptibility to proteolytic degradation. In this regard, nanotechnologies represent an innovative strategy to circumvent these issues. According to the literature, a large variety of nanoparticulate systems has been employed for drug-delivery, bioimaging, biosensors or as nanoantibiotics. The possibility of conjugating different types of molecules, including AMPs, to these systems, allows the production of nanoformulations able to enhance the biological profile of the compound, while reducing its cytotoxicity and prolonging its residence time. In this mini-review, inorganic gold nanoparticles (NPs) and biodegradable polymeric NPs made of poly(lactide-co-glycolide) are described with particular emphasis on examples of conjugation of AMPs to them, to highlight the great potential of such nanoformulations as alternative antimicrobials
“Effective incapsulation of pristine fullerenes C60 and C70 into the solvophobic cavity of a resorc[4]arene derivatized with hydrocarbon chains defining a basket like structure: a supramolecular study based on experiments and theory”
No full textStereo- and regioselective gold(i)-catalyzed hydroamination of 2-(arylethynyl)pyridines with anilines
No full textThe gold-catalyzed hydroamination of 2-(arylethynyl)pyridines with anilines affords stereoselectively Z-enamine products with excellent regioselectivity. The reaction proceeds with moderate to excellent yields and accommodates a diverse range of functional groups on alkynes (ether, bromo, trifluoromethyl, acetyl, and carbomethoxy) and anilines (ether, bromo, chloro, and carbethoxy). The stereochemistry of the obtained enamines is complementary to that reported in previous studies. A plausible explanation for the observed selectivity was attained by means of NMR experiments
Natural products inspired modulators of cancer stem cells-specific signaling pathways notch and hedgehog
No full textIt is nowadays widely accepted that some tumors have a niche of cells endowed with stemness features, which may cause resistance to conventional anticancer therapies and relapse/recurrence of the malignancy. These cells are usually referred to as cancer stem cells (CSCs) and, different from normal cancer cells, are rather quiescent. Targeting CSCs is thus a highly challenging but promising strategy to counteract tumor growth, and to develop innovative anticancer agents. Here, we review the chemical, biological and multidisciplinary efforts that have been spent in targeting CSCs-specific signaling pathways Notch and Hedgehog (Hh) for anticancer drug discovery. In particular, the use of natural products as a valuable source of lead compounds or chemical biology tools is emphasized. Examples of natural products functionalization through semi-synthetic transformations or total syntheses, aimed at improving pharmacokinetics and/or pharmacodynamics properties of natural products in Notch or Hh inhibition, are provided as well
Olefin metathesis reaction as a locking tool for macrocycle and mechanomolecule construction
No full textThe present review deals with an updated visit to the olefin metathesis reaction as a powerful tool for the construction of sophisticated macromolecular architectures. Today, the reaction has proved to be one of the most popular processes, not only for the synthesis of novel cage and huge calixarene-based macrocycles, or more complex structures containing these privileged moieties, but also for the construction of complicated topologically intriguing molecules, such as catenanes, rotaxanes and knots. Notably, their use ranges from chemistry and biology, as catalysts and drug delivery systems, respectively, to materials research, as molecular motors and switches. The reaction effectiveness arises from the intrinsic specificity for the highly stable reactive end-groups (e.g. alkene moieties) and the feasibility to perform the reaction in relatively non-polar solvents, maximizing the supramolecular interactions often involved in the templation strategies. By moving from calixarene-based macrocycles to mechanically interlocked molecules, the review takes into account several synthetic strategies involving the olefin metathesis reaction highlighting its increasing utility and future potential in the synthesis of molecular machines
Molecular recognition of natural products by resorc[4]arene receptors
No full textThis review is aimed at providing an overview of the up-to-now published literature on resorc[4]arene macrocycles exploited as artificial receptors for the molecular recognition of some classes of natural products. A concise illustration of the main synthetic strategies developed to afford the resorc[4]arene scaffold is followed by a report on the principles of the gas-phase investigation of recognition phenomena by mass spectrometry (MS). Emphasis is placed on gas-phase studies of diastereoisomeric complexes generated inside a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer by resorc[4]arene receptors towards a series of natural products, namely amino acids, amphetamine, ethanolamine neurotransmitters, dipeptides, vinca alkaloids and nucleosides. The literature outcomes discussed here, taken largely from our own revisited work, have been completed by references to other studies, in order to draw a broader picture of this rapidly evolving field of research
Flavonoids from Sorocea bonplandii as antiproliferative agents towards breast cancer and leukemia
No full text- …
