A ß-Glucosyl Sterol Probe for in†situ Fluorescent Labelling in Neuronal Cells to Investigate Neurodegenerative Diseases.

A ß-glucosyl sterol probe bearing a terminal alkyne moiety for fluorescent tagging enables the investigation of the neuronal and intracellular localization of this class of compounds involved in neurodegenerative diseases. The compound showed localization in the neuronal cells, with marked differences in the uptake and metabolism leading to enhanced persistence with respect to the un-glycosylated sterol analogue. In addition, a different impact was observed towards lysosomes, with the simple sterol probe showing the enlargement of the lysosome structures, while the ß-glucosyl sterol was less capable to alter the morphology of this specific organelle.

Folding of Class IIa HDAC Derived Peptides into α-helices Upon Binding to Myocyte Enhancer Factor-2 in Complex with DNA.

Interaction of transcription factor myocyte enhancer factor-2 (MEF2) family members with class IIa histone deacetylases (HDACs) has been implicated in a wide variety of diseases. Though considerable knowledge on this topic has been accumulated over the years, a high resolution and detailed analysis of the binding mode of multiple class IIa HDAC derived peptides with MEF2D is still lacking. To fulfil this gap, we report here the crystal structure of MEF2D in complex with double strand DNA and four different class IIa HDAC derived peptides, namely HDAC4, HDAC5, HDAC7 and HDAC9. All class IIa HDAC derived peptides form extended amphipathic α-helix structures that fit snugly in the hydrophobic groove of MEF2D domain. Binding mode of class IIa HDAC derived peptides to MEF2D is very similar and occur primarily through nonpolar interactions mediated by highly conserved branched hydrophobic amino acids. Further studies revealed that class IIa HDAC derived peptides are unstructured in solution and appear to adopt a folded α-helix structure only upon binding to MEF2D. Comparison of our peptide-protein complexes with previously characterized structures of MEF2 bound to different co-activators and co-repressors, highlighted both differences and similarities, and revealed the adaptability of MEF2 in protein-protein interactions. The elucidation of the three-dimensional structure of MEF2D in complex with multiple class IIa HDAC derived peptides provide not only a better understanding of the molecular basis of their interactions but also have implications for the development of novel antagonist.

A novel genetically-encoded bicyclic peptide inhibitor of human urokinase-type plasminogen activator with better cross-reactivity toward the murine orthologue.

The inhibition of human urokinase-type plasminogen activator (huPA), a serine protease that plays an important role in pericellular proteolysis, is a promising strategy to decrease the invasive and metastatic activity of tumour cells. However, the generation of selective small molecule huPA inhibitors has proven to be challenging due to the high structural similarity of huPA to other paralogue serine proteases. Efforts to generate more specific therapies have led to the development of cyclic peptide-based inhibitors with much higher selectivity against huPA. While this latter property is desired, the sparing of the orthologue murine poses difficulties for the testing of the inhibitor in preclinical mouse model. In this work, we have applied a Darwinian evolution-based approach to identify phage-encoded bicyclic peptide inhibitors of huPA with better cross-reactivity towards murine uPA (muPA). The best selected bicyclic peptide (UK132) inhibited huPA and muPA with Ki values of 0.33 and 12.58 µM, respectively. The inhibition appears to be specific for uPA, as UK132 only weakly inhibits a panel of structurally similar serine proteases. Removal or substitution of the second loop with one not evolved in vitro led to monocyclic and bicyclic peptide analogues with lower potency than UK132. Moreover, swapping of 1,3,5-tris-(bromomethyl)-benzene with different small molecules not used in the phage selection, resulted in an 80-fold reduction of potency, revealing the important structural role of the branched cyclization linker. Further substitution of an arginine in UK132 to a lysine resulted in a bicyclic peptide UK140 with enhanced inhibitory potency against both huPA (Ki = 0.20 µM) and murine orthologue (Ki = 2.79 µM). By combining good specificity, nanomolar affinity and a low molecular mass, the bicyclic peptide inhibitor developed in this work may provide a novel human and murine cross-reactive lead for the development of a potent and selective anti-metastatic therapy.

Disclosing the composition of unknown historical drug formulations: an emblematic case from the Spezieria of St. Maria della Scala in Rome.

This paper reports a pioneering study of an unknown historical drug formulation preserved in the Spezieria of Santa Maria della Scala in Rome, founded at the end of the seventeenth century by the Discalced Carmelites. Due to limited literature related to pharmaceutical remedies and drugs of the Early Modern Era (between the XV and XVIII centuries) and the complexity in their formulations, the study of these drugs represents a great challenge. The untargeted nature of the selected drug required a multi-analytical approach with complementary techniques to formulate a compositional hypothesis: FT-IR spectroscopy, gas chromatography-associated/mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) were successfully employed to identify different organic compounds. Systematic archaeobotanical research was performed as well, allowing us to acquire data related to the possible genus of plants from which these natural compounds derive and their geographical origin. The unknown drug formulation turned out to be a complex mixture used as an ointment with an anti-inflammatory purpose. It mainly contains a mixture of Venetian turpentine; a Pine resin (colophony) from the Pinaceae family; an exudate of a plant from South America, whose identified components are triterpenic compounds such as alpha- and beta-amyrins, betulin and lupeol; and saturated fatty acids which act as carriers and/or to reduce the viscosity of abovementioned exudates and resins. The study of historical drugs is important not only in order to know the practices handed down by the speziali in the past but also to reconstruct historical recipes, which can inspire new dermatological, cosmetic, hygienic and current healing products.Graphical abstract.

Photocrosslinked hydrogels from coumarin derivatives of hyaluronic acid for tissue engineering applications.

Hydrogels are an increasingly attractive choice in the fields of regenerative medicine, wound care and tissue engineering as important forms of bio-scaffolds. For many clinical needs, injectable in situ crosslinkable hydrogels are strongly preferred, due to treatment effectiveness and ease of use. In this study, hyaluronic acid (HA), containing side-arms linked to photo-active coumarin moieties, was used for the preparation of wall-to-wall hydrogels. This photocrosslinkable HA, hereafter called HA-TEG-coumarin, produces colourless aqueous solutions that solidify upon near-UV irradiation (at a specific wavelength of 365 nm) via a clean [2 + 2] photocycloaddition reaction, without by-products formation. The crosslinking event, a robust and non-cytotoxic process, does not require catalysts or radical initiators: in the field of hyaluronan photocrosslinking, this innovative feature is significant to ensure the whole biocompatibility and to avoid collateral reactions. Mechanical and rheological tests showed that hyaluronan derivatives became hydrogels after 3-5 min of irradiation, with average values for bulk and surface elastic moduli of about 32 kPa and 193 kPa, respectively. Fluorescence recovery after photobleaching (FRAP) assay showed that the hydrogels are porous and allow a good permeation for nutrients and growth factors. Cell metabolism and proliferation assays revealed that hydrogel-encapsulated fibroblasts maintained their viability and that HA-TEG-coumarin sustained the proliferation of non-adherent myoblasts. For all of these reasons and thanks to a safe free-radical approach, this novel hyaluronan coumarin derivative could be a good candidate for tissue engineering and regenerative medicine applications.

Diketopyrrolopyrrole Bis-Phosphonate Conjugate: A New Fluorescent Probe for In Vitro Bone Imaging.

The synthesis of a conjugate molecule between an unusual red-fluorescent diketopyrrolopyrrole (DPP) unit and a bis-phosphonate (BP) precursor by a click-chemistry strategy to target bone tissue and monitor the interaction is reported. After thorough investigation, conjugation through a triazole unit between a γ-azido rather than a ß-azido BP and an alkyne-functionalized DPP fluorophore group turned out to be the winning strategy. Visualization of the DPP-BP conjugate on osteoclasts and specific antiresorption activity were successfully demonstrated.

Metal-promoted synthesis of amidines containing the model nucleobases 1-methylcytosine and 9-methyladenine.

The amidine complexes cis-[L(2)PtNH==C(R){1-MeCy(-2H)}]NO(3) (R = Me, 1a; Ph, 1b, Me(3)C, 1c; Ph(2)(H)C, 1d) and cis-[L(2)PtNH==C(R){9-MeAd(-2H)}]NO(3) (R = Me, 2a; Ph, 2b; Me(3)C, 2c; Ph(2)(H)C, 2d), are formed when cis-[L(2)Pt(µ-OH)](2)(NO(3))(2) (L = PPh(3)) reacts with 1-methylcytosine (1-MeCy) and 9-methyladenine (9-MeAd) in solution of MeCN, PhCN, Me(3)CCN and Ph(2)(H)CCN. Reaction of 1a,b and 2a,b with HCl affords the protonated amidines [NH(2)==C(R){1-MeCy(-H)}]NO(3) (R = Me, 3a; Ph, 3b) and [NH(2)==C(R){9-MeAd(-H)}]NO(3) (R = Me, 4a; Ph, 4b) and cis-(PPh(3))(2)PtCl(2) in quantitative yield. Treatment of 3b and 4b with NaOH allows the isolation of the neutral benzimidamides NH(2)-C(Ph){1-MeCy(-2H)} (5b) and NH(2)-C(Ph){9-MeAd(-2H)} (6b). In the solid state 3b shows a planar structure with the hydrogen atom on N(4) cytosine position involved in a strong H-bond with the NO(3)(-) ion. Intermolecular H-bonds between the oxygen of the cytosine ring and one of the H atoms of the amidine-NH(2) group allow the dimerization of the molecule. A detailed analysis of the spectra of 3b in DMF-d(7) at -55 °C indicates the presence of an equilibrium between the species [NH(2)==C(R){1-MeCy(-H)}]NO(3) and [NH(2)==C(R){1-MeCy(-H)}](2)(NO(3))(2), exchanging with trace amounts of water at 25 °C. [(15)N,(1)H]-HMBC experiments for 5b and 6b indicate that the amino tautomer H(2)N-C(Ph){nucleobase(-2H)}, is the only detectable in solution and such structure has been confirmed in the solid state. The reaction of 5b and 6b with cis-L(2)Pt(ONO(2))(2) (L = PPh(3)), in chlorinated solvents, determines the immediate appearance of a pale yellow colour due to the coordination of the neutral amidine, likely in its imino form HN==C(Ph){nucleobase(-H)}, to give the adducts cis-[L(2)PtNH==C(Ph){nucleobase(-H)}](2+). In fact, addition of "proton sponge" leads to the immediate deprotonation of the amidine ligand with formation of the starting complexes 1b and 2b.

Benzocyclotrimers: from the Mills-Nixon effect to gas hosting.

The formal annulation of three bicylic olefins yields a class of molecules termed benzocyclotrimers (BCTs), which have unusual electronic properties. The bonds in the central aromatic ring, for example, alternate in length: rather than resembling a substituted benzene, a BCT instead evokes comparison to a cyclohexatriene. Forty years have passed since the synthesis of heptiptycene, the first BCT, was reported. In the interim, many methods have been developed for preparing tris-bicycloannulated benzenes. More than thirty different BCTs have so far been reported, with a variety of morphological features and properties. Over the same period, yields have increased from just a few percent to almost quantitative conversion. This improvement in synthetic access has expanded interest beyond the original theoretical considerations (bond-length fixation in aromatics) to functional applications (supramolecular scaffolds). In this Account, we describe the evolution of synthetic approaches to BCTs and their derivatives, as well as the applications that are now being explored for these compounds. Early syntheses of BCTs involved chloroolefins treated with butyl lithium. A strained alkyne intermediate was postulated early on, and was indeed trapped in 1981. Subsequent efforts have focused on improving chemoselectivity by mitigating the drastic conditions required for the generation of the alkyne intermediate. Our introduction of Cu(I) to induce lithium-copper exchange was successful in this regard. Further improvement resulted from the use of bicylic bromo(trimethylstannyl)olefins. In an effort to avoid the toxicity of the tin reagents, the Heck reaction and Pd catalysis have been pursued for cyclotrimerizing bicylic bromo- and iodoolefins. Depending on the symmetry of the starting bicylic olefin, two diastereomers can be obtained in the preparation of a BCT: a syn compound with C(3) symmetry and an anti compound with C(s) symmetry. Studying the diastereomeric outcome in a variety of synthetic approaches has yielded valuable insight into the cyclotrimerization reaction. Moreover, highly symmetric compounds, such as a D(3)-symmetric trindane and C(3v)-symmetric sumanene, have been prepared as BCT derivatives. The structure of BCTs offers a versatile three-dimensional scaffold for studying molecular recognition. Like calixarenes, BCTs form complexes with a variety of guest molecules. Recent developments include the trapping of gases in a hydrogen-bonded dimer and the encapsulation of larger molecules within a covalently linked condensation derivative. Future innovations in this fertile research area will likely include highly functionalized curved aromatics, receptors, and sensors.

Chiral polycyclic ketones via desymmetrization of dihaloolefins.

3-Chloronorbornenone (R)-1a (98% ee) was obtained from trichloronorbornene 5 in two steps by the in situ generation of dichloronorbornadiene 2a with t-BuOK and desymmetrization with (-)-ephedrine, followed by hydrolysis with PPTS. The generality of this desymmetrization with (-)-ephedrine was tested with dibromonorbornadiene 2c and other substituted dichloronorbornadienes.

Internal motions in a fulleropyrrolidine tertiary amide with axial chirality.

The kinetic parameters for topomerization around the N-CO bond and enantiomerization around the C-CO bond in N-1-naphthoyl fulleropyrrolidine 1 and N-1-naphthoyl pyrrolidine 2 have been determined by dynamic NMR (line shape simulation and selective inversion transfer). The DeltaS(not =) values are negligible. The DeltaH# value for topomerization of 1 is smaller with respect to that of 2 by 4.3 kcal mol(-1) (explained by the electron-withdrawing effect of fullerene) and the value for enantiomerization is greater by 1.4 kcal mol(-1) (explained by the greater rigidity of the fulleropyrrolidine ring, as confirmed by ab initio analyses).

Efficient cyclotrimerization of bicyclic vic-bromostannylalkenes promoted by copper(I) thiophen-2-carboxylate.

Copper(I) thiophen-2-carboxylate was successfully employed in the trimerization of [2.2.1] bicyclic vic-bromotrimethyltin olefins (in their racemic composition), bearing different functionalities, to invariably obtain almost quantitative yields of the syn and anti tris-annelated benzenes. The two isomers come in different ratios, smaller than or equal to the statistical 1:3 ratio, depending on the steric hindrance opposed by the functionalities. In the case of enantiopure (3-bromo-4,7,7-trimethylbicyclo[2.2.1]hept-2-en-2-yl)trimethylstannane, the 1:9 ratio found with Cu(NO(3))(2).3H(2)O increases to 1:6.