1,720,981 research outputs found
A facile one-pot synthesis of 8-oxo-7,8-dihydro-(2′-deoxy)adenosine in water
Full text linkReaction of 2-mercaptoethanol with 8-bromo-2′-deoxyadenosine and 8-bromo-adenosine in aqueous solution and in the presence of triethylamine gave the 8-oxo-adenine derivatives in very good yields. Some mechanistic details are reported.Fil: Chatgilialoglu, Chryssostomos. Consiglio Nazionale delle Ricerche; ItaliaFil: Navacchia, Maria Luisa. Consiglio Nazionale delle Ricerche; ItaliaFil: Postigo, Jose Alberto. Universidad de Belgrano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
The radical-based reduction with (TMS)3SiH 'on water'
Full text linkReduction of different organohalides, bromonucleosides among them, was successfully carried out in yields ranging from 75% to quantitative, using (TMS)3SiH in a heterogeneous system with water as the solvent. Our procedure, employing 2-mercaptoethanol as the catalyst and the hydrophobic diazo-compound ACCN as the initiator, illustrates that (TMS)3SiH can be the radical-based reducing agent of choice in aqueous medium. (TMS) 3SiH does not suffer from any significant reaction with water and can safely be used with additional benefit, such as ease of purification and environmental compatibility.Fil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Ferreri, Carla. Consiglio Nazionale delle Ricerche; ItaliaFil: Navacchia, Maria Luisa. Consiglio Nazionale delle Ricerche; ItaliaFil: Chatgilialoglu, Chryssostomos. Consiglio Nazionale delle Ricerche; Itali
Molecular Hybridization as a Strategy for Developing Artemisinin-Derived Anticancer Candidates
No full textArtemisinin is a natural compound extracted from Artemisia species belonging to the Asteraceae family. Currently, artemisinin and its derivatives are considered among the most significant small-molecule antimalarial drugs. Artemisinin and its derivatives have also been shown to possess selective anticancer properties, however, there are several limitations and gaps in knowledge that retard their repurposing as effective anticancer agents. Hybridization resulting from a covalent combination of artemisinin with one or more active pharmacophores has emerged as a promising approach to overcome several issues. The variety of hybridization partners allows improvement in artemisinin activity by tuning the ability of conjugated artemisinin to interact with various molecule targets involved in multiple biological pathways. This review highlights the current scenario of artemisinin-derived hybrids with potential anticancer activity. The synthetic approaches to achieve the corresponding hybrids and the structure–activity relationships are discussed to facilitate further rational design of more effective candidates
Bile Acid Conjugates with Anticancer Activity: Most Recent Research
No full textThe advantages of a treatment modality that combines two or more therapeutic agents in cancer therapy encourages the study of hybrid functional compounds for pharmacological applications. In light of this, we reviewed recent works on hybrid molecules based on bile acids. Due to their biological properties, as well as their different chemical/biochemical reactive moieties, bile acids can be considered very interesting starting molecules for conjugation with natural or synthetic bioactive molecules
The removal efficiency of emerging organic contaminants{,} heavy metals and dyes: intrinsic limits at low concentrations
No full textIn this work{,} we exploit Langmuir adsorption isotherms to compare the performance of different materials (adsorbents) in removing organic contaminants (adsorbates) from water. The removal efficiency observed reaches an intrinsic limit at low concentrations. We also demonstrate quantitatively how multi-step adsorption processes achieve better purification efficiency than single-step adsorption performed using much smaller amounts of adsorbent material. We demonstrate how such performance is strongly affected by adsorbent concentration. Only the use of both the parameters obtained from Langmuir adsorption isotherm (Qm and KL) modelling allows one to compare materials tested under different experimental conditions by different groups{,} whereas most published reviews focus only on Qm which is rather limited for comparing the performance of different materials studied under different conditions. Finally{,} we present some guidelines for data reporting in future work and reviews
Gold-nanoparticle extraction and reversed-electrode-polarity stacking mode combined to enhance capillary electrophoresis sensitivity for conjugated nucleosides and oligonucleotides containing thioether linkers
No full textWe present a capillary electrophoresis method for determining two different C8-conjugated deoxyadenosines, and for oligonucleotides containing them, in which a psoralen or an acridine molecule is bonded to the base via a short alkyl chain containing sulfur ethers at both ends. The sensitivity of the micellar electrokinetic chromatography (MEKC) method was increased by using two preconcentration techniques, micro solid-phase extraction (μSPE) followed by reversedelectrode-polarity stacking mode (REPSM). Variables that affect the efficiency of the extraction in μSPE and preconcentration by REPSM, including the type and volume of extraction nanoparticle, concentration, and injection time, were investigated. Under the optimum conditions, enrichment factors obtained were in the range 360–400. The limits of detection (LODs) at a signal-to-noise ratio of 3 ranged from
2 to 5 nmol L−1. The relative recoveries of labelled adenosines from water samples were 95–103 %. The proposed method provided high enrichment factors and good precision and accuracy with a short analysis time. On the basis of the advantages of simplicity, high selectivity, high sensitivity, and good reproducibility, the proposed method may have great potential for biochemical applications
Aumento della sensibilità nella determinazione di nucleosidi marcati mediante accoppiamento di tecniche di preconcentrazione-online/μ-SPE e MEKC
No full textLo scopo del presente lavoro è lo sviluppo di un metodo analitico per la determinazione di alcuni nucleosidi marcati ottenuti per tioalchilazione della deossi-Adenosina mediante Elettroforesi Capillare. I composti studiati hanno rilevanza farmacologica in quanto possono trovare impiego come antibiotici, antivirali e/o antitumorali [1]. Il metodo sviluppato è basato sulla combinazione di due tecniche di pre-concentrazione off-line ed on-line: 1) la micro estrazione in fase solida (Micro Solid Phase Extraction, μ-SPE) e 2) l’iniezione con polarità inversa dell’elettrodo (Reverse Electrode Polarity Stacking Mode REPSM) seguiti dalla separazione in Micellar Electrokinetic Chromatography (MEKC). In particolare si sono studiati i parametri che influenzano il limite di rilevabilità del metodo. La micro estrazione in fase solida è stata condotta utilizzando nanoparticelle d’oro (AuNP) il cui impiego in numerosi campi, tra cui la chimica analitica e la nanomedicina (ad esempio come drug carriers e biosensori) è aumentato negli ultimi anni. Il loro ampio utilizzo è dovuto alle particolari proprietà chimico-fisiche di queste nanoparticelle tra cui la possibilità di essere usate come mezzo adsorbente [2].
In condizioni ottimali il metodo proposto ha permesso di ottenere fattori di arricchimento pari a 300-400 volte rispetto alla MEKC tradizionale, con percentuali relative di recupero dei nucleosidi marcati comprese tra il 95% ed il 103%; infine i limiti di rivelazione (LODs) del metodo, calcolati in base ad un rapporto segnale/rumore pari a 3, hanno raggiunto i livelli di poche nM.
Si può perciò concludere che il metodo sviluppato consente di ottenere elevati fattori di concentrazione con buona precisione e accuratezza il tutto in un breve tempo di analisi. Inoltre, sulla base della semplicità, dell’elevata selettività e sensibilità e della buona riproducibilità, il metodo ha dimostrato grandi potenzialità per applicazioni di tipo biochimico.
[1] Capobianco, Marchesi, Perrone, Navacchia, Bioconjugate Chemistry, 24, 1398−1407, 2013
[2] Duncan, Kim, Rotello, Journal of Controlled Release, 148, 122–127, 201
Evaluation of Anticancer Activity of Nucleoside–Nitric Oxide Photo-Donor Hybrids
No full textHerein, we report the synthesis of a new hybrid compound based on a 2′-deoxyuridine nucleoside conjugated with a NO photo-donor moiety (dU-t-NO) via CuAAC click chemistry. Hybrid dU-t-NO, as well as two previously reported 2′-deoxyadenosine based hybrids (dAdo-S-NO and dAdo-t-NO), were evaluated for their cytotoxic and cytostatic activities in selected cancer cell lines. dAdo-S-NO and dAdo-t-NO hybrids displayed higher activity with respect to dU-t-NO. All hybrids showed effective release of NO in the micromolar range. The photochemical behavior of the newly reported hybrid, dU-t-NO, was studied in the RKO colon carcinoma cell line, whereas the dAdo-t-NO hybrid was tested in both colon carcinoma RKO and hepatocarcinoma Hep 3B2.1-7 cell lines to evaluate the potential effect of NO released upon irradiation on cell viability. A customized irradiation apparatus for in vitro experiments was also designed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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