Nous agents de contrast en IRM per al diagnòstic de tumors cerebrals

Investigadores de la UAB y del Institut Català de Nanociència I Nanotecnologia (ICN2) han desarrollado una partícula a base de polímeros de coordinación a nanoescala (NCP) construida con iones metálicos de hierro(III) paramagnético capaces de mostrar un alto contraste en T1 y T2 para la Imagen por Resonancia magnética (IRM) in vivo, permitiendo la obtención simultánea de imágenes de contraste positivo y negativo en un período de tiempo muy corto. Este trabajo abre nuevas posibilidades en la obtención de nanopartículas fácilmente biodegradables y no tóxicas con mejores propiedades como agentes de contraste duales T1 / T2 en IRM para el diagnóstico de tumores.Investigadors de la UAB i de l'Institut Català de Nanociència I Nanotecnologia (ICN2) han desenvolupat una partícula a base de polímers de coordinació a nanoescala (NCP) construïda amb ions metàl·lics de ferro(III) paramagnètic capaços de mostrar un alt contrast en T1 i T2 per a la Imatge per Ressonància magnètica (IRM) in vivo, permetent l'obtenció simultània d'imatges de contrast positiu i negatiu en un període de temps molt curt. Aquest treball obre noves possibilitats en l'obtenció de nanopartícules fàcilment biodegradables i no tòxics amb millors propietats com a agents de contrast duals T1 / T2 a IRM per al diagnòstic de tumors.Researchers from the UAB and the Institut Català de Nanociència I Nanotecnologia (ICN2) have developed a nanoscale coordination polymer particle (NCP) built using paramagnetic iron(III) metal ions able to exhibit T1 and T2 high contrast potential for the magnetic resonance image (MRI) in vivo, allowing simultaneous recording of positive and negative contrast images in a very short period of time. This work opens new possibilities in constructing easily biodegradable and nontoxic nanoparticles with improved T1/T2 dual-mode MRI contrast enhancement for tumour diagnosis

Purificación y caracterización parcial del primer inhibidor de carboxipeptidasa aislado de pimiento amarillo (capsicum annuum L.)

Si bien los inhibidores de proteasas han sido considerados por mucho tiempo como factores anti-nutricionales; estudios recientes han demostrado la capacidad de estas moléculas de resistir el proceso gastrointestinal, atravesar el tracto digestivo y llegar a la sangre de manera intacta. De este modo, podrían ejercer su actividad biológica en sangre y tejidos periféricos como moléculas anticancerígenas, antitrombóticas, antimaláricas y antiangiogénicas, entre otras. Varias de estas actividades biológicas han sido descritas para los inhibidores de metalocarboxipeptidasas (IMCP). Los IMCPs están escasamente investigados en el reino vegetal, la mayoría de ellos pertenece a la familia Solanaceae y poseen características estructurales especiales que les proporcionan una extrema estabilidad biofisicoquímica. En este trabajo reportamos el aislamiento y purificación parcial del primer IMCP aislado de Capsicum annuum al que denominamos YBPCI. El extracto crudo fue parcialmente purificado mediante tratamiento térmico a 100 ºC y posterior cromatografía de afinidad empleando Carboxipeptidasa A inmovilizada en glioxil-agarosa. Los pasos de purificación fueron evaluados mediante el estudio del perfil proteico por SDS-PAGE y cuantificación proteica. El YBPCI presentó un peso molecular de 4 060 Da (valor obtenido mediante espectrometría de masas MALDI-TOF) y una I0.5 de 0.4 µg ml-1. Además, demostramos la estabilidad a la temperatura, fuerza salina y a valores extremos de pH, realizando finalmente un ensayo de simulación gástrica in-vitro y comprobando que el YBPCI mantiene su actividad inhibitoria intacta. Estos resultados alientan el estudio de su potencial actividad biológica, con el fin de emplear dicha molécula como potencial aditivo natural de alimentos, explotando así su capacidad conservante.Universidad Nacional de La Plat

Purificación y caracterización parcial del primer inhibidor de carboxipeptidasa aislado de pimiento amarillo (capsicum annuum L.)

Si bien los inhibidores de proteasas han sido considerados por mucho tiempo como factores anti-nutricionales; estudios recientes han demostrado la capacidad de estas moléculas de resistir el proceso gastrointestinal, atravesar el tracto digestivo y llegar a la sangre de manera intacta. De este modo, podrían ejercer su actividad biológica en sangre y tejidos periféricos como moléculas anticancerígenas, antitrombóticas, antimaláricas y antiangiogénicas, entre otras. Varias de estas actividades biológicas han sido descritas para los inhibidores de metalocarboxipeptidasas (IMCP). Los IMCPs están escasamente investigados en el reino vegetal, la mayoría de ellos pertenece a la familia Solanaceae y poseen características estructurales especiales que les proporcionan una extrema estabilidad biofisicoquímica. En este trabajo reportamos el aislamiento y purificación parcial del primer IMCP aislado de Capsicum annuum al que denominamos YBPCI. El extracto crudo fue parcialmente purificado mediante tratamiento térmico a 100 ºC y posterior cromatografía de afinidad empleando Carboxipeptidasa A inmovilizada en glioxil-agarosa. Los pasos de purificación fueron evaluados mediante el estudio del perfil proteico por SDS-PAGE y cuantificación proteica. El YBPCI presentó un peso molecular de 4 060 Da (valor obtenido mediante espectrometría de masas MALDI-TOF) y una I0.5 de 0.4 µg ml-1. Además, demostramos la estabilidad a la temperatura, fuerza salina y a valores extremos de pH, realizando finalmente un ensayo de simulación gástrica in-vitro y comprobando que el YBPCI mantiene su actividad inhibitoria intacta. Estos resultados alientan el estudio de su potencial actividad biológica, con el fin de emplear dicha molécula como potencial aditivo natural de alimentos, explotando así su capacidad conservante.Universidad Nacional de La Plat

Platinum-Based Nanoformulations for Glioblastoma Treatment : The Resurgence of Platinum Drugs?

Current therapies for treating Glioblastoma (GB), and brain tumours in general, are inefficient and represent numerous challenges. In addition to surgical resection, chemotherapy and radiotherapy are presently used as standards of care. However, treated patients still face a dismal prognosis with a median survival below 15-18 months. Temozolomide (TMZ) is the main chemotherapeutic agent administered; however, intrinsic or acquired resistance to TMZ contributes to the limited efficacy of this drug. To circumvent the current drawbacks in GB treatment, a large number of classical and non-classical platinum complexes have been prepared and tested for anticancer activity, especially platinum (IV)-based prodrugs. Platinum complexes, used as alkylating agents in the anticancer chemotherapy of some malignancies, are though often associated with severe systemic toxicity (i.e., neurotoxicity), especially after long-term treatments. The objective of the current developments is to produce novel nanoformulations with improved lipophilicity and passive diffusion, promoting intracellular accumulation, while reducing toxicity and optimizing the concomitant treatment of chemo-/radiotherapy. Moreover, the blood-brain barrier (BBB) prevents the access of the drugs to the brain and accumulation in tumour cells, so it represents a key challenge for GB management. The development of novel nanomedicines with the ability to (i) encapsulate Pt-based drugs and pro-drugs, (ii) cross the BBB, and (iii) specifically target cancer cells represents a promising approach to increase the therapeutic effect of the anticancer drugs and reduce undesired side effects. In this review, a critical discussion is presented concerning different families of nanoparticles able to encapsulate platinum anticancer drugs and their application for GB treatment, emphasizing their potential for increasing the effectiveness of platinum-based drugs

Carboxyl group (-CO2H) functionalized coordination polymer nanoparticles as efficient platforms for drug delivery

Functionalization of nanoparticles can significantly influence their properties and potential applications. Although researchers can now functionalize metal, metal oxide, and organic polymer nanoparticles with a high degree of precision, controlled surface functionalization of nanoscale coordination polymer particles (CPPs) has remained a significant challenge. The lack of methodology is perhaps one of the greatest roadblocks to the advancement of CPPs into high added-value drug delivery applications. Here, we report having achieved this goal through a stepwise formation and functionalization protocol. We fabricated robust nanoparticles with enhanced thermal and colloidal stabilities by incorporation of carboxyl groups and these surface carboxyl groups could be subsequently functionalized through well-known peptide coupling reactions. The set of chemistries that we employed as proof-of-concept enabled a plethora of new functional improvements for the application of CPPs as drug delivery carriers, including enhanced colloidal stabilities and the incorporation of additional functional groups such as polyethylene glycol (PEG) or fluorescent dyes that enabled tracking of their cellular uptake. Finally, we ascertained the cytotoxicity of the new CPP nanoparticles loaded with camptothecin to human breast adenocarcinoma (MCF-7). Efflux measurements show that the encapsulation of camptothecin enhances the potency of the drug 6.5-fold and increases the drug retention within the cell. Multifunctional CPPs: Robust and biocompatible coordination polymer nanoparticles (CPPs) with enhanced thermal and colloidal stabilities were obtained by incorporation of carboxyl groups on the amorphous structure. The surface carboxyl groups can be subsequently functionalized, generating a multifunctional nanoplatform for theranostic applications such as drug delivery and imaging (see scheme; EDC=1-ethyl-3-(3-dimethylaminopropyl)carbodiimide; NHS=N-hydroxysuccinimide)

Cell-penetrating peptide-conjugated copper complexes for redox-mediated anticancer therapy

Metal-based chemotherapeutics like cisplatin are widely employed in cancer treatment. In the last years, the design of redox-active (transition) metal complexes, such as of copper (Cu), has attracted high interest as alternatives to overcome platinum-induced side-effects. However, several challenges are still faced, including optimal aqueous solubility and efficient intracellular delivery, and strategies like the use of cell-penetrating peptides have been encouraging. In this context, we previously designed a Cu(II) scaffold that exhibited significant reactive oxygen species (ROS)-mediated cytotoxicity. Herein, we build upon the promising Cu(II) redox-active metallic core and aim to potentiate its anticancer activity by rationally tailoring it with solubility- and uptake-enhancing functionalizations that do not alter the ROS-generating Cu(II) center. To this end, sulfonate, arginine and arginine-rich cell-penetrating peptide (CPP) derivatives have been prepared and characterized, and all the resulting complexes preserved the parent Cu(II) coordination core, thereby maintaining its reported redox capabilities. Comparative in vitro assays in several cancer cell lines reveal that while specific solubility-targeting derivatizations (i.e., sulfonate or arginine) did not translate into an improved cytotoxicity, increased intracellular copper delivery via CPP-conjugation promoted an enhanced anticancer activity, already detectable at short treatment times. Additionally, immunofluorescence assays show that the Cu(II) peptide-conjugate distributed throughout the cytosol without lysosomal colocalization, suggesting potential avoidance of endosomal entrapment. Overall, the systematic exploration of the tailored modifications enables us to provide further understanding on structure-activity relationships of redox-active metal-based (Cu(II)) cytotoxic complexes, which contributes to rationalize and improve the design of more efficient redox-mediated metal-based anticancer therapy

Pt(IV)-based nanoscale coordination polymers : antitumor activity, cellular uptake and interactions with nuclear DNA

Cisplatin has been for many years the gold standard chemotherapeutic drug for the treatment of a wide range of solid tumors, even though its use is commonly associated with serious side effects including non-selective toxicity, myelosuppression or development of cisplatin resistance, among others complications. Over the last decade, a number of nanoparticle formulations were developed to reduce its side effects and improve the selectivity and efficacy of this drug. In this study, we have developed a novel nanoparticle platform based on nanoscale coordination polymer named (Zn-Pt(IV)-NCPs) which contains a Pt(IV) prodrug, Zn and the linker ligand 1,4-Bis(imidazol-1-ylmethyl)benzene (bix). The main objective has been to gain insights into the mechanism of action of this nanostructured material in comparison with cisplatin and the free Pt(IV) prodrug in order to establish a correlation between nanostructuration and therapeutic activity. Zn-Pt(IV)-NCPs nanoparticles displayed an average size close to 200 nm as determined by DLS, a good stability in physiologic environments, and a controlled drug release of Pt. In vitro studies demonstrated that Pt(IV)-NCPs showed an enhanced cytotoxic effect against cell culture of cervical cancer, neuroblastoma and human adenocarcinoma cells in comparison with free Pt(IV) prodrug. Although no difference in cell uptake of Pt was observed for any of the three cell lines assayed, a higher amount of Pt bound to the DNA was found in the cells treated with the nanostructured Pt(IV) prodrug. These studies suggest that the nanostructuration of the prodrug facilitate its activation and induce a change in the mechanism of action related to an increased interaction with the DNA as corroborated by the studies of direct interaction of the Pt(IV) prodrug, nanostructured or not, with DNA

Biochemical characterization of the YBPCI miniprotein, the first carboxypeptidase inhibitor isolated from Yellow Bell Pepper (<i>Capsicum annuum</i> L) : A novel contribution to the knowledge of miniproteins stability

The cystine-knot metallocarboxypeptidase inhibitors (MCPIs) are peptides that contribute to control proteolytic activity, involved in storage, growth and maintenance of plants. Lately studies reported several MCPIs with potential use in biomedical applications; as anti-cancer, anti-thrombotic, anti-malaric and anti-angiogenic agents. We report the isolation, purification, chemical stability and biochemical characterization of a novel carboxypeptidase A inhibitor (YBPCI) isolated from Capsicum annuum L. var. Yellow Bell Pepper, the first cystine-knot miniprotein (CKM) of the species. We demonstrate the stability of YBPCI (IC50 = 0.90 μg/ml) to high temperatures, high salt concentration and extreme pH values. MALDI-TOF/MS analysis detected a molecular weight of 4057 Da, and peptide mass fingerprint resulted in no matches with other protease inhibitors. In vitro gastrointestinal digestion subjecting YBPCI to pH 2 incubation and proteolytic attack resulted in complete inhibitory activity. To summarize, there are no reports to date of carboxypeptidase inhibitors in C. annuum species, giving our report much more relevance.Facultad de Ciencias ExactasCentro de Investigación de Proteínas Vegetale

The cytosolic carboxypeptidases CCP2 and CCP3 catalyze posttranslational removal of acidic amino acids

The posttranslational modification of carboxy-terminal tails of tubulin plays an important role in the regulation of the microtubule cytoskeleton. Enzymes responsible for deglutamylating tubulin have been discovered within a novel family of mammalian cytosolic carboxypeptidases. The discovery of these enzymes also revealed the existence of a range of other substrates that are enzymatically deglutamylated. Only four of six mammalian cytosolic carboxypeptidases had been enzymatically characterized. Here we complete the functional characterization of this protein family by demonstrating that CCP2 and CCP3 are deglutamylases, with CCP3 being able to hydrolyze aspartic acids with similar efficiency. Deaspartylation is a novel posttranslational modification that could, in conjunction with deglutamylation, broaden the range of potential substrates that undergo carboxy-terminal processing. In addition, we show that CCP2 and CCP3 are highly regulated proteins confined to ciliated tissues. The characterization of two novel enzymes for carboxy-terminal protein modification provides novel insights into the broadness of this barely studied process

pH-Responsive Relaxometric Behaviour of Coordination Polymer Nanoparticles Made of a Stable Macrocyclic Gadolinium Chelate

Lanthanide-containing nanoscale particles have been widely explored for various biomedical purposes, however, they are often prone to metal leaching. Here we have created a new coordination polymer (CP) by applying, for the first time, a stable Gdchelate as building block in order to prevent any fortuitous release of free lanthanide(III) ion. The use of the Gd-DOTA-4AmP complex as a design element in the CP allows not only for enhanced relaxometric properties (maximum r=16.4 mmsat 10 MHz), but also for a pH responsiveness (Δr=108 % between pH 4 and 6.5), beyond the values obtained for the low molecular weight Gd-DOTA-4AmP itself. The CP can be miniaturised to the nanoscale to form colloids that are stable in physiological saline solution and in cell culture media and does not show cytotoxicity