Unravelling the Antifibrinolytic Mechanism of Action of the 1,2,3-Triazole Derivatives.

A new family of antifibrinolytic drugs has been recently discovered, combining a triazole moiety, an oxadiazolone, and a terminal amine. Two of the molecules of this family have shown activity that is greater than or similar to that of tranexamic acid (TXA), the current antifibrinolytic gold standard, which has been associated with several side effects and whose use is limited in patients with renal impairment. The aim of this work was to thoroughly examine the mechanism of action of the two ideal candidates of the 1,2,3-triazole family and compare them with TXA, to identify an antifibrinolytic alternative active at lower dosages. Specifically, the antifibrinolytic activity of the two compounds (1 and 5) and TXA was assessed in fibrinolytic isolated systems and in whole blood. Results revealed that despite having an activity pathway comparable to that of TXA, both compounds showed greater activity in blood. These differences could be attributed to a more stable ligand-target binding to the pocket of plasminogen for compounds 1 and 5, as suggested by molecular dynamic simulations. This work presents further evidence of the antifibrinolytic activity of the two best candidates of the 1,2,3-triazole family and paves the way for incorporating these molecules as new antifibrinolytic therapies.

1,2,3-Triazole Derivatives as Novel Antifibrinolytic Drugs.

Fibrinolysis is a natural process that ensures blood fluidity through the removal of fibrin deposits. However, excessive fibrinolytic activity can lead to complications in different circumstances, such as general surgery or severe trauma. The current antifibrinolytic drugs in the market, aminocaproic acid (EACA) and tranexamic acid (TXA), require high doses repetitively to maintain their therapeutic effect. These high doses are related to a number of side effects such as headaches, nasal symptoms, or gastrointestinal discomfort and severely limit their use in patients with renal impairment. Therefore, the discovery of novel antifibrinolytics with a higher specificity and lower dosage could vastly improve the applicability of these drugs. Herein, we synthesized a total of ten compounds consisting of a combination of three key moieties: an oxadiazolone, a triazole, and a terminal amine. The IC50 of each compound was calculated in our clot lysis assays, and the best candidate (1) provided approximately a 2.5-fold improvement over the current gold standard, TXA. Molecular docking and molecular dynamics were used to perform a structure-activity relationship (SAR) analysis with the lysine binding site in the Kringle 1 domain of plasminogen. This analysis revealed that 1,2,3-triazole was crucial for the activity, enhancing the binding affinity through pi-pi stacking and polar interactions with Tyr72. The results presented in this work open the door to further investigate this new family as potential antifibrinolytic drugs.

Nanoparticles for Triple Drug Release for Combined Chemo- and Photodynamic Therapy.

A pH-responsive drug delivery system (DDS) based on mesoporous silica nanoparticles (MSNs) has been prepared for the delivery of three anticancer drugs with different modes of action. The novelty of this system is its ability to combine synergistic chemotherapy and photodynamic therapy. A photoactive conjugate of a phthalocyanine (Pc) and a topoisomerase I inhibitor (topo-I), namely camptothecin (CPT), linked by a poly(ethylene glycol) (PEG) chain has been synthesized and then loaded into the mesopores of MSNs. Doxorubicin (DOX), which is a topoisomerase II inhibitor (topo-II), has also been covalently anchored to the outer surface of the MSNs through a dihydrazide PEG linker. In the acidic environment of tumor cells, selective release of the three drugs takes place. In vitro studies have demonstrated the endocytosis of the system into HeLa and HepG2 cells, and the subsequent release of the three drugs into the cytoplasm and nucleus. Furthermore, the cytotoxic effect of DOX, CPT and Pc has been assessed in vitro before and upon light irradiation.

Porphycenes and Related Isomers: Synthetic Aspects.

Porphyrins, called the pigments of life, have been studied for decades. However, the first constitutional isomer of porphyrin, porphycene, was not synthesized until 1986. This milestone marked the beginning of a new era in the field of porphyrinoids and presented opportunities for the creation of an abundance of new pigments. The unique structural and electronic features of these compounds give rise to interesting physical and optical properties with applications in biomedicine and materials science. This review focuses on the synthetic methodologies available for the preparation of porphycenes (functionalized porphycenes, extended porphycenes, benzoporphycenes, naphthoporphycenes, and heteroanalogues) and the other known isomers, namely, corrphycene, hemiporphycene, and isoporphycene. Although the classical synthetic approaches are discussed, particular emphasis is placed on improvements to the known methodologies and recent advances in the field.

Stable 5,5'-Substituted 2,2'-Bipyrroles: Building Blocks for Macrocyclic and Materials Chemistry.

The preparation and characterization of a family of stable 2,2'-bipyrroles substituted at positions 5 and 5' with thienyl, phenyl, TMS-ethynyl, and vinyl groups is reported herein. The synthesis of these new bipyrroles comprises three steps: formation of the corresponding 5,5'-unsubstituted bipyrrole, bromination, and Stille or Suzuki coupling. The best results in the coupling are obtained using the Stille reaction under microwave irradiation. The new compounds have been fully characterized by UV-vis absorption, fluorescence, and IR spectroscopies and cyclic voltammetry. X-ray single-crystal analysis of four of the synthesized bipyrroles indicates a trans coplanar geometry of the pyrrole rings. Furthermore, the substituents at positions 5,5' remain coplanar to the central rings. This particular geometry extends the π-conjugation of the systems, which is in agreement with a red-shifting observed for the λmax of the substituted molecules compared to the unsubstituted bipyrrole. All of these new compounds display a moderate fluorescence. In contrast with unsubstituted bipyrroles, these bipyrroles are endowed with a high chemical and thermal stability and solubility in organic solvents.

Modifications of microvascular EC surface modulate phototoxicity of a porphycene anti-ICAM-1 immunoconjugate; therapeutic implications.

Inflammation and shear stress can upregulate expression of cellular adhesion molecules in endothelial cells (EC). The modified EC surface becomes a mediating interface between the circulating blood elements and the endothelium, and grants opportunity for immunotherapy. In photodynamic therapy (PDT), immunotargeting might overcome the lack of selectivity of currently used sensitizers. In this study, we hypothesized that differential ICAM-1 expression modulates the effects of a drug targeted to surface ICAM-1. A novel porphycene-anti-ICAM-1 conjugate was synthesized and applied to treat endothelial cells from macro and microvasculature. Results show that the conjugate induces phototoxicity in inflamed, but not in healthy, microvascular EC. Conversely, macrovascular EC exhibited phototoxicity regardless of their state. These findings have two major implications; the relevance of ICAM-1 as a modulator of drug effects in microvasculature, and the potential of the porphycene bioconjugate as a promising novel PDT agent.

Tautomerization in 2,7,12,17-tetraphenylporphycene and 9-amino-2,7,12,17-tetraphenylporphycene: influence of asymmetry on the direction of the transition moment.

Femtosecond transient absorption anisotropy studies have been performed for two porphycenes of different symmetry. In 2,7,12,17-tetraphenylporphycene, the chemical identity of two trans forms implies a change in the S(0)-S(1) transition-moment direction upon tautomerization. Exploiting this phenomenon, the rates of double hydrogen transfer in both the S(0) and S(1) states (1.4×10(12)  s(-1) and 2.7×10(11)  s(-1) , respectively) have been determined by performing time-resolved anisotropy studies. In the asymmetric 9-amino-2,7,12,17-tetraphenylporphycene, tautomerization occurs with a similar rate in the ground state. In the S(1) state, the reaction is hindered in its vibrationally relaxed form, but the excitation spectra suggest that it may occur for an unrelaxed molecule. Unlike all porphycenes that have been studied so far, 9-amino-2,7,12,17-tetraphenylporphycene does not reveal significant changes in anisotropy owing to intramolecular double hydrogen transfer; rather, the transition-moment directions are similar in the two tautomeric forms. Analysis of the molecular orbitals allows for an explanation of the "locking" of the transition moments: it is due to a large splitting of the two HOMO orbitals, which retain the order of their energies in the two tautomers.

Synthesis of 2-arylamino substituted 5,6-dihydropyrido[2,3-d]pyrimidine-7(8H)-ones from arylguanidines.

A practical protocol was developed for the synthesis of 2-arylamino substituted 4-amino-5,6-dihydropyrido[2,3-d]pyrimidin-7(8H)-ones from α,ß-unsaturated esters, malononitrile, and an aryl substituted guanidine via the corresponding 3-aryl-3,4,5,6- tetrahydropyrido[2,3-d]pyrimidin-7(8H)-ones. Such compounds are formed upon treatment of 2-methoxy-6-oxo-1,4,5,6-tetrahydropyridine-3-carbonitriles with an aryl substituted guanidine in 1,4-dioxane and are converted to the desired 4-aminopyridopyrimidines with NaOMe/MeOH through a Dimroth rearrangement. The overall yields of this three-step protocol are, generally speaking, higher than the multicomponent reaction, previously developed by our group, between an α,ß-unsaturated ester, malononitrile, and an aryl substituted guanidine.

Dual fluorescence in 9-amino-2,7,12,17-tetraphenylporphycene.

The absorption spectrum of the asymmetric 9-amino-2,7,12,17-tetraphenylporphycene shows new, strongly red-shifted bands compared to the symmetric parental 2,7,12,17-tetraphenylporphycene and to the also asymmetric 9-acetoxy-2,7,12,17-tetraphenylporphycene. Dual emission is also observed with relative contributions that depend strongly on the excitation wavelength and temperature. The gap between the two fluorescence bands is 84 nm. Tautomerization in both the ground and excited states is shown to account for these observations, the 9-amino group being particularly able to selectively lower the energy of the first excited singlet state of just one of the trans tautomers. Introduction of amino groups in porphycenes may be a convenient way to gain a deeper insight into the tautomerization mechanisms in this macrocyclic core.

Revising Protein Corona Characterization and Combining ITC and Nano-DSC to Understand the Interaction of Proteins With Porous Nanoparticles.

The exposure of nanoparticles (NPs) to biological fluids leads to the formation of a protein coating that is known as protein corona (PC). Since PC formation is influenced by the physicochemical properties of the nanoparticles, the understanding of the interplay of the factors that participate in this process is crucial for the development of nanomaterials as cell-targeted delivery vehicles. In general, it is accepted that the PC formation is a complex and dynamic process, which depends on the composition of the medium and the properties of the NP mainly size, shape, and superficial charge. Interestingly, although the interaction between the protein and the NP is essentially a superficial phenomenon, the influence of the roughness of the nanoparticle surface has been scarcely studied. In this work, the influence of superficial roughness and porosity has been studied with the aid of nanodifferential scanning calorimetry (nano-DSC) and isothermal titration calorimetry (ITC) using mesoporous silica nanoparticles (MSNs) as an NP model. The interaction process of the proteins with the NP surface was analyzed by ITC measurements, while the stability and denaturation of the proteins was monitored by nano-DSC. Thanks to the complementarity of these two techniques, a more complete insight into the PC formation on the pores has been accomplished.

Glycyrrhetinic Acid-Functionalized Mesoporous Silica Nanoparticles for the Co-Delivery of DOX/CPT-PEG for Targeting HepG2 Cells.

A pH-triggered mesoporous silica nanoparticle (MSN)-based nano-vehicle for the dual delivery of doxorubicin (DOX)/camptothecin-PEG (CPT-PEG) has been prepared. To enhance its selectivity, the nanoparticles were decorated with glycyrrhetinic acid (GA) to target HepG2 cells. The highly insoluble CPT was derivatized with a reductive-cleavable PEG chain to improve its loading within the MSN. The preparation of these particles consisted of four steps. First, CPT-PEG was loaded within the pores of the MSN. Then, dihydrazide polyethylene glycol chains were introduced onto the surface of an aldehyde-functionalized MSN by means of a hydrazone bond. Afterwards, DOX was covalently attached to the other end of the dihydrazide polyethylene glycol chains. Finally, the resulting nanoparticles were decorated with GA by formation of an imine bond between the amino group of DOX and a benzaldehyde-GA derivative. The system was stable at physiological conditions and the release of both drugs was negligible. However, at acidic pH, a burst release of DOX and a gradual release of CPT-PEG takes place. GA-decorated drug delivery systems (DDS) selectively internalizes into HepG2. In vitro tests demonstrated that this system shows a great cytotoxicity towards HepG2 cells. Furthermore, glutathione cleavage of CPT prodrug assures the formation of free CPT leading to a synergistic effect in combination with DOX.

Preparation and Applications of Organo-Silica Hybrid Mesoporous Silica Nanoparticles for the Co-Delivery of Drugs and Nucleic Acids.

Combination therapies rely on the administration of more than one drug, with independent mechanisms of action, aiming to enhance the efficiency of the treatment. For an optimal performance, the implementation of such therapies requires the delivery of the correct combination of drugs to a specific cellular target. In this context, the use of nanoparticles (NP) as platforms for the co-delivery of multiple drugs is considered a highly promising strategy. In particular, mesoporous silica nanoparticles (MSN) have emerged as versatile building blocks to devise complex drug delivery systems (DDS). This review describes the design, synthesis, and application of MSNs to the delivery of multiple drugs including nucleic acids for combination therapies.

Nanosized hybrid oligoamide foldamers: aromatic templates for the folding of multiple aliphatic units.

Oligoamide sequences comprised of both 8-amino-2-quinolinecarboxylic acid "Q" and 6-aminomethyl-2-pyridinecarboxylic acid "P" have been synthesized. It was found that the aliphatic amine of P greatly facilitates amide couplings, as opposed to the aromatic amine of Q, which enabled us to prepare sequences having up to 40 units. The conformation and conformational stability of these oligomers were characterized in the solid state using X-ray crystallography and in solution using NMR and various chromatographic techniques. Q(n) oligomers adopt very stable helically folded conformations whereas P(n) oligomers do not fold and impart conformational preferences distinct from those of Q units. When a P(n) segments is attached at the end of a Q(4) segment, a couple P units appear to follow the folding pattern imposed by the Q(n) segment, but P units remote from the Q(n) segment do not fold. When a P(n) segment is inserted between two Q(4) segments, the P(n) segment adopts the canonical helical conformation imposed by the Q units at least up to two full helical turns (n = 5). However, the overall stability of the helix tends to decrease as the number of P units increases. When noncontiguous P units separated by Q(4) segments are incorporated in a sequence, they all adopt the helical conformation imposed by Q monomers and the overall helix stability increases when helix length increases. For example, a 40mer with a sequence (PQ(4))(8) folds into a rod-like helix spanning over 16 turns with a length of 5.6 nm. This investigation thus demonstrates that remarkably long (nanometers) yet well-defined foldamers can be efficiently synthesized stepwise and that their helical stability may be continuously tuned upon controlling the ratio and sequence of P and Q monomers.

A bisfullerene-bis(dipyrrinato)zinc complex: electronic coupling and charge separation in an easy-to-assemble synthetic system.

Getting connected: The use of a bis(dipyrrinato)zinc(II)) linker allows the facile tethering of two C(60) subunits and gives rise to an electronically coupled system that allows effective charge separation following photoexcitation (see figure).

Singlet oxygen photosensitisation by the fluorescent probe Singlet Oxygen Sensor Green.

The fluorescent probe Singlet Oxygen Sensor Green is able to produce singlet oxygen under exposure to UV or visible radiation.

Isothiocyanate-Functionalized Mesoporous Silica Nanoparticles as Building Blocks for the Design of Nanovehicles with Optimized Drug Release Profile.

A straightforward methodology for the synthesis of isothiocyanate-functionalized mesoporous silica nanoparticles (MSNs) by exposure of aminated MSNs to 1,1'-thiocarbonyldi-2(1H)-pyridone is reported. These nanoparticles are chemically stable, water tolerant, and readily react with primary amines without the formation of any by-product. This feature allows the easy modification of the surface of the nanoparticles for tuning their physical properties and the introduction of gatekeepers on the pore outlets. As a proof-of-concept, amino-isothiocyanate-functionalized MSNs have been used for the design of a nanocontainer able to release the drug Ataluren. The release profile of the drug can be easily fine-tuned with the careful choice of the capping amine.

Extended 2,2'-Bipyrroles: New Monomers for Conjugated Polymers with Tailored Processability.

The synthesis of 2,2'-bipyrroles substituted at positions 5,5' with pyrrolyl, N-methyl-pyrrolyl and thienyl groups and their application in the preparation of conducting polymers is reported herein. The preparation of these monomers consisted of two synthetic steps from a functionalized 2,2'-bipyrrole: Bromination of the corresponding 2,2'-bipyrrole followed by Suzuki or Stille couplings. These monomers display low oxidation potential compared to pyrrole because of the extended length of their conjugation pathway. The resulting monomers can be polymerized through oxidative/electropolymerization. Electrical conductivity and electrochromic properties of the electrodeposited polymeric films were evaluated using 4-point probe measurements and cyclic voltammetry to evaluate their applicability in electronics.

Vértigo posicional paroxístico benigno primario y secundario a neuritis vestibular. Estudio de casos y controles / Primary and Secondary Benign Paroxysmal Positional Vertigo due to Peripheral Acute Vestibular Syndrome: A Case-Control Study

Introducción y objetivo: El objetivo de nuestro estudio fue demostrar las diferencias clínicas entre el vértigo posicional paroxístico benigno (VPPB) idiopático y secundario a síndrome vestibular agudo periférico (SVA). Método: Estudio de casos y controles, retrospectivo. La recolección de datos fue tomada de historias clínicas de nuestro hospital. Datos demográficos y clínicos de pacientes con diagnóstico de VPPB idiopático y secundario a SVA, fueron recogidos para el análisis. Además, en el grupo de los casos, se realizó una correlación entre el déficit vestibular periférico, medido a través del video head impulse test (vHIT), y el número de maniobras y tiempo hasta la resolución del VPPB. Resultados: Se incluyeron 72 pacientes, 64% mujeres. En el grupo control se incluyeron 50 pacientes con VPPB idiopático y 22 con VPPB secundario a SVA en el grupo de los casos. En el VPPB secundario, el canal semicircular posterior estuvo afectado en el 100% (OR: 1.2; IC 95% [1,088 - 1,436]). Ambos grupos mostraron una resolución del vértigo del 90% y 89%, respectivamente. El grupo de VPPB secundario tuvo 4 veces más riesgo de recurrencia (OR: 4.18; IC 95% [1.410 - 12.406]); necesitaron más maniobras (3.32 ± 2.2 vs. 1.7 ± 1.3, p = 0.004) y tiempo (61.9 días ± 73.1 vs. 12.9 días ± 9.6, p = 0.007) para la resolución del VPPB. Se encontraron correlaciones significativas entre la diferencia de ganancia media del reflejo vestíbulo-ocular (RVO) y el número de maniobras (r = 0.462, p = 0.030) y el tiempo hasta la resolución (r = 0.577, p = 0.008). Discusión: Existen diferencias clínicas entre el VPPB idiopático y secundario a SVA, principalmente en términos de canal semicircular afecto, mayor número de maniobras y tiempo en días hasta la resolución del VPPB. Además, de determinar que a mayor déficit vestibular en un paciente con VPPB secundario a SVA, necesitará un mayor número de maniobras y un tiempo prolongado hasta la resolución del VPPB. Conclusiones: ... (AU)

Introduction and Objective: The aim of our study was to demonstrate the clinical differences between idiopathic benign paroxysmal positional vertigo (BPPV) and BPPV secondary to acute peripheral vestibular syndrome (APVS). Method: Retrospective case-control study. Data collection was obtained from medical records at our hospital. Demographic and clinical data of patients diagnosed with idiopathic BPPV and BPPV secondary to APVS were collected for analysis. Additionally, in the case group, a correlation was performed between peripheral vestibular deficit, measured through the video head impulse test (vHIT), and the number of maneuvers and time until resolution of BPPV. Results: Seventy-two patients were included, with 64% being women. The control group included 50 patients with idiopathic BPPV and 22 with BPPV secondary to APVS in the case group. In secondary BPPV, the posterior semicircular canal was affected in 100% of cases (OR: 1.2; 95% CI [1.088 - 1.436]). Both groups showed a vertigo resolution rate of 90% and 89%, respectively. The secondary BPPV group had a 4-fold higher recurrence risk (OR: 4.18; 95% CI [1.410 - 12.406]); they required more maneuvers (3.32 ± 2.2 vs. 1.7 ± 1.3, p = 0.004) and more time (61.9 days ± 73.1 vs. 12.9 days ± 9.6, p = 0.007) for BPPV resolution. Significant correlations were found between the difference in mean gain of the vestibulo-ocular reflex (VOR) and the number of maneuvers (r = 0.462, p = 0.030) and the time until resolution (r = 0.577, p = 0.008). Discussion: Clinical differences exist between idiopathic BPPV and BPPV secondary to APVS, primarily in terms of the affected semicircular canal, a higher number of maneuvers, and a longer time in days until BPPV resolution. Furthermore, it was determined that a greater vestibular deficit in a patient with secondary BPPV to APVS requires a higher number of maneuvers and an extended time until BPPV resolution. Conclusions: ... (AU)

Electron-transfer and acid-base properties of a two-electron oxidized form of quaterpyrrole that acts as both an electron donor and an acceptor.

Electron-transfer interconversion between the four-electron oxidized form of a quaterpyrrole (abbreviated as P4 for four pyrroles) and the two-electron oxidized form (P4H2) as well as between P4H2 and its fully reduced form (P4H4) bearing analogous substituents in the alpha- and beta-pyrrolic positions was studied by means of cyclic voltammetry and UV-visible spectroelectrochemistry combined with ESR and laser flash photolysis measurements. The two-electron oxidized form, P4H2, acts as both an electron donor and an electron acceptor. The radical cation (P4H2*+) and radical anion (P4H2*-) are both produced by photoinduced electron transfer from dimeric 1-benzyl-1,4-dihydronicotinamide to P4H2, whereas the cation radical form of the compound is also produced by electron-transfer oxidation of P4H2 with [Ru(bpy)3]3+. The ESR spectra of P4H2*+ and P4H2*- were recorded at low temperature and exhibit spin delocalization over all four pyrrole units. Thus, the two-electron oxidized form of the quaterpyrrole (P4H2) displays redox and electronic features analogous to those seen in the case of porphyrins and may be considered as a simple, open-chain model of this well-studied tetrapyrrolic macrocycle. The dynamics of deprotonation from P4H2*+ and disproportionation of P4H2 were examined by laser flash photolysis measurements of photoinduced electron-transfer oxidation and reduction of P4H2, respectively.

Functionalized 2,2'-Bipyrroles: Building Blocks for Pyrrolic Macrocycles.

Functionalized N-unsubstituted 2,2'-bipyrroles are basic building blocks for the preparation of pyrrolic macrocycles and natural products, such as prodigiosines. The aim of this review is to provide a description of the most important methodologies used to prepare 2,2'-bipyrroles and their central role as building blocks for the synthesis of porphyrinoids and property-defining structural elements therein.