1,720,986 research outputs found
Loading and release of the complex [Pt(DTBTA)(DMSO)Cl]Cl·CHCl3 with the 2,2′-dithiobis(benzothiazole) ligand into mesoporous silica and studies of antiproliferative activity on MCF-7 cells
Full text linkSynthetic delivery systems have great potential for overcoming problems associated with systemic toxicity that accompanies chemotherapy with the use of cisplatin and family of platinum anticancer drugs. Mesoporous silicates have been studied in context of drug delivery and drug targeting. In this paper we report the studies of loading and release of a platinum complex, [Pt(DTBTA)(DMSO)Cl]Cl∙CHCl3 (1) where DTBTA = 2,2′-dithiobis(benzothiazole), that was recently synthesized and structurally characterized. Evaluation in vitro of antitumor activity against a human breast cancer cell line (MCF-7) showed a very potent activity of complex(1). Therefore, we thought to incorporate this compound into MCM41 mesoporous silica and into analogous support functionalized with amino groups (MCM41-NH2). The complex(1) encapsulation efficiency % (EE%) in MCM41 and in MCM41-NH2, respectively, was evaluated by using UV–Vis spectroscopy. The porosimetry and IR spectra confirmed that the drug was within the pores in MCM-41 and that the complex(1) binds MCM41-NH2 with the aminopropyl functional groups of the mesoporous channels, respectively. The study of release was performed by using UV–Vis spectroscopy at 37 ± 1 °C in 0.1 M phosphate buffer solution (PBS) having pH 7.4 to simulate the physiological pH of blood. In order to investigate the efficacy of MCM-41/complex(1) and MCM41-NH2/complex(1) conjugates, we have measured their ability to kill cancer cells of MCF-7 (human breast cancer). MTT test and cytofluorimetric assay of exposure of phosphatidylserine to the outer membrane were carried out to measure cytotoxicity and apoptosis induced by MCM41/complex(1) and MCM41-NH2/complex(1). The investigated systems were very efficient for pharmaceutical controlled release and a promising agent for combination therapies
Synthesis, structural characterization, anti-proliferative and antimicrobial activity of binuclear and mononuclear Pt(II) complexes with perfluoroalkyl-heterocyclic ligands
No full textIn this paper we report the synthesis of four Pt(II) complexes with 5-perfluoroalkyl-1,2,4-oxadiazolyl-pyridine and 3-perfluoroalkyl-1-methyl-1,2,4-triazolyl-pyridine ligands. Two binuclear complexes [PtCl(pfibap)2](μ-Cl)2(1), [Pt2(μ-Cl)2(pfioap)4]Cl2(2), and two mononuclear [PtCl2(pfptp)] (3), [PtCl2(pfhtp)2] (4), were synthesized with the ligands: 2-(5-perfluoropropyl)-1,2,4-oxadiazole-3yl)-pyridine (pfpop), 2-(5-perfluoroheptyl-1,2,4-oxadiazole-3yl)-pyridine (pfhop), 2-(3-perfluoropropyl-1-methyl-1,2,4-triazole-5yl)-pyridine (pfptp), 2-(3-perfluoroheptyl-1-methyl-1,2,4-triazole-5yl)-pyridine (pfhtp), and were structurally characterized. All complexes were tested in vitro on three tumor cell lines MCF-7 (human breast cancer), Hela (epithelioid cervix carcinoma), HCT-116 (human colorectal carcinoma). Compounds 1 and 2 showed a dose-dependent anti-proliferative effect against the three tumor cell lines whereas they did not affect viability of intestinal normal-like differentiated Caco-2 cells. Results showed that both the compounds act as pro-apoptotic agents inducing a clear shift of viable cells towards early apoptosis, while they do not exert any necrotic effect. They also caused cell cycle perturbation with significant decrease in the percentage of cells in the G0/G1 phase, accompanied by a concomitant percentage increase of cells in the G2/M phase, and appearance of a subG1-cell population. Moreover, all complexes showed antimicrobial activity against Escherichia coli, Kocuria rhizophila and two Staphylococcus aureus strains and a different behavior in binding activity to DNA
Nanowire iron(III) coordination polymer based on 1,2,4-triazolo[1,5-a]pyrimidine and chloride ligands
Full text linkThe neutral ligand 1,2,4-triazolo[1,5-a]pyrimidine (tp) has been employed to prepare a new coordination compound of Fe(III), [FeCl 3 (tp) 2 ] n (1). Compound 1 was investigated by single crystal X-ray diffraction and found to be a coordination polymer forming a ladder structure based on metal–ligand interactions, while H-bonding and aromatic interactions contribute to the supramolecular self-assembly into a 3D nanostructured material. The polymeric assembly is retained also in solution, where a metallo-supramolecular polymer based on coordinative metal–ligand binding is present, as shown by dynamic light scattering (DLS) measurements. The redox properties of the Fe(III) coordination polymer have also been investigated in different solvents and its nanowire structure has been assessed by Atomic Force Microscopy (AFM) imaging of the species deposited onto a freshly cleaved mica surface
Organotin(IV) Adducts of 5,7-Diphenyl-1,2,4-triazolo[1,5-a] pyrimidine and 5,7-Ditertbutyl-1,2,4-triazolo[1,5-a] pyrimidine
No full textSintesi, caratterizzazione strutturale e attività biologica in vitro di organostagno(IV) con derivati di 1,2,4-triazolo[1,5-a]pirimidina
No full textSINTESI, CARATTERIZZAZIONE STRUTTURALE E ATTIVITÀ BIOLOGICA IN VITRO DI ORGANOSTAGNO(IV) CON DERIVATI DI 1,2,4-TRIAZOLO[1, 5-a]PIRIMIDINA
Maria Assunta Girasolo a, Simona Rubino a, Piera Sabatino b
aDip.to di Scienze e Tecnologie Molecolari e Biomolecolari, Università di Palermo, Viale delle Scienze, Palermo, Italy
bDip.to di Chimica G. Ciamician, Università di Bologna,via F. Selmi 2, Bologna, Italy
La struttura delle 1,2,4-triazolo[1,5-a]pirimidine1 è analoga a quella delle purine da cui differiscono per la presenza di un atomo di azoto pirimidinico in posizione “testa di ponte” e la scomparsa del protone acido dell’anello a cinque membri. Data la somiglianza tra questi sistemi, i composti di coordinazione delle 1,2,4-triazolo-[1,5-a]pirimidine possono essere considerati come sistemi modello per vari composti di coordinazione esistenti in natura. Recentemente sono stati sintetizzati e caratterizzati alcuni composti di diorganostagno(IV) con 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine2 (dptp), di cui viene qui riportata la struttura ai raggi X, e con l’acido 7-ammino-2-(metiltio)-[1,2,4]triazolo[1,5-a]pirimidina-6-carbossilico.
Figura 1: Struttura cristallina e molecolare dell’addotto [n-Bu2SnCl2(dptp)] (1)
Il composto (1) presenta una coordinazione bipiramidale trigonale distorta intorno all’atomo di Sn; il legante dptp, che lega tramite N(3), occupa la posizione trans rispetto ad uno dei due atomi di Cl mentre le tre posizioni equatoriali sono occupate dal rimanente atomo di Cl e dai due leganti n-butilici. L’impaccamento tridimensionale della molecola è caratterizzato sia da un network di legami a H tra i gruppi C-H e gli atomi di Cl sia da interazioni aromatiche tra gli anelli aromatici presenti. L’attività citotossica di (1) è stata testata sulla linea cellulare umana U937 di linfoma istiocitico. Le cellule sono state trattate per 24 h in un range di concentrazioni compreso tra 0.5-20 μM dell’addotto (1), in comparazione al cisplatino. I risultati ottenuti hanno dimostrato che alla concentrazione di 20 μM, n-Bu2SnCl2(dptp) induce una marcata riduzione della vitalità cellulare che risulta essere del 5.5%, valore molto più basso del cisplatino, che alla stessa concentrazione risulta del 44%. Il composto è quindi più attivo del cisplatino. I complessi R2SnL2 sono stati ottenuti per reazione di R2SnO (R = Me, n-Bu, n-Oct ) con l’acido 7-ammino-2-(metiltio)-[1,2,4]triazolo[1,5-a]pirimidina-6-carbossilico3 (HL) in metanolo a riflusso. La natura dei prodotti ottenuti è stata indagata analizzando i dati spettroscopici 1H-NMR, IR e 119Sn Mössbauer. Esaminando i parametri Mössbauer possiamo osservare che i valori di splitting di quadrupolo sono più grandi dei valori osservati in complessi di diorganostagno(IV) con geometria tetraedrica. Dobbiamo quindi presumere che lo stagno espanda il numero di coordinazione dando luogo a strutture bipiramidali trigonali, cis- o trans-R2, o ottaedriche trans-R2 fortemente distorte.
Bibliografia
1Salas,J.M.;Romero,M.A.;Sánchez,M.P.;Quirós,M.,Coord. Chem. Rev.,1999,1119,193. 2Girasolo,M.A.;Canfora,L.;Sabatino,P.;Schillaci,D.;Foresti,E.;Rubino,S.;Ruisi,G.;Stocco,G., J.Inorg.Biochem.,2012,106,156. 3Ruisi,G.,Canfora,L.;Bruno,G.;Rotondo,A.;Mastropietro, T.F.;Debbia,E.A.;Girasolo,M.A.;Megna,B., J.Organomet. Chem.,2010,695,546
Novel platinum(II) complexes with heterociclyc ligands: Synthesis and structural chracterization.
No full textAn array of mononuclear complexes of Pt(II) with triazine and (benzimidazolyl)pyridine heterocycles is reported. The mononuclear complexes [PtCl2(Kdptdn)] [dbtdn=5,6- diphenyl-3-(2-pyridyl)-1,2,4-triazine-4’,4’’-disulfonate sodium salt hydrate], [PtCl2(bbp)] [bbp=2,6-bis(2-benzimidazolyl)pyridine] and [PtCl2(H2dpt)]PtCl4 [dpt=5,6-diphenyl-3-(2- pyridyl)-1,2,4-triazine] have been prepared and structurally characterized. Both neutral and ionic complexes are present, with bifunctional Pt(II) moieties, whose size and shape enable them to behave as novel scaffolds for DNA binding
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
Non-covalent interactions in organotin(IV) derivatives of 5,7-ditertbutyl- and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine as recognition motifs in crystalline self- assembly and their in vitro antistaphylococcal activity
Full text linkNon-covalent interactions are known to play a key role in biological compounds due to their
stabilization of the tertiary and quaternary structure of proteins [1]. Ligands similar to purine rings,
such as triazolo pyrimidine ones, are very versatile in their interactions with metals and can act as
model systems for natural bio-inorganic compounds [2]. A considerable series (twelve novel
compounds are reported) of 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) and 5,7-diphenyl-
1,2,4-triazolo[1,5-a]pyrimidine (dptp) were synthesized and investigated by FT-IR and 119Sn
Mössbauer in the solid state and by 1H and 13C NMR spectroscopy, in solution [3]. The X-ray
crystal and molecular structures of Et2SnCl2(dbtp)2 and Ph2SnCl2(EtOH)2(dptp)2 were described, in
this latter pyrimidine molecules are not directly bound to the metal center but strictly H-bonded,
through N(3), to the -OH group of the ethanol moieties. The network of hydrogen bonding and
aromatic interactions involving pyrimidine and phenyl
rings in both complexes drives their self-assembly. Noncovalent
interactions involving aromatic rings are key
processes in both chemical and biological recognition,
contributing to overall complex stability and forming
recognition motifs. It is noteworthy that in
Ph2SnCl2(EtOH)2(dptp)2 π–π stacking interactions between
pairs of antiparallel triazolopyrimidine rings mimick basepair
interactions physiologically occurring in DNA (Fig.1).
Mössbauer spectra suggest for Et2SnCl2(dbtp)2 a
distorted octahedral structure, with C-Sn-C bond angles
lower than 180°. The estimated angle for Et2SnCl2(dbtp)2
is virtually identical to that determined by X-ray diffraction. Ph2SnCl2(EtOH)2(dptp)2 is
characterized by an essentially linear C-Sn-C fragment according to the X-ray all-trans structure.
The compounds were screened for their in vitro antibacterial activity on a group of reference
staphylococcal strains susceptible or resistant to methicillin and against two reference Gramnegative
pathogens [4] . We tested the biological activity of all the specimen against a group of
staphylococcal reference strains (S. aureus ATCC 25923, S. aureus ATCC 29213, methicillin
resistant S. aureus 43866 and S. epidermidis RP62A) along with Gram-negative pathogens (P.
aeruginosa ATCC9027 and E. coli ATCC25922). Ph2SnCl2(EtOH)2(dptp)2 showed good
antibacterial activity with a MIC value of 5 μg mL-1 against S. aureus ATCC29213 and also
resulted active against methicillin resistant S. epidermidis RP62A
Complexes of diorganotin(IV) with aminoacids and a dipeptide. Synthesis and structural investigations.
No full textThe aim of this work is to synthesize complexes of Arginine, effector of recognition,
with organotin(IV) ions (R2Sn2+, R =Me, nBu) which are known to possess antitumour, antimicrobial, anti-inflammatory activities.
The complexes were investigated by FT-IR and 119Sn Můssbauer.While identical stoichiometries
are present for Me2Sn(Arg)2 and Me2Sn(Boc-Arg)2 complexes, 119Sn Můssbauer
spectra give a clear evidence of different coordination modes.
L-Arginine appears to behave as a chelating ligand through carboxylate and a-NH2
groups in the former, while in Nα-Boc-L-Arginine complex, the Nα-protected amino group
being exempted from coordination, only the carboxylate groups are effectors of bonding to
the organometallic moieties.
The L-Ala-L-Arg dipeptide complex appears to adopt a trigonal-bipyramidal geometry
at tin, the organometallic moiety being coordinated by α-amino, deprotonated peptide
nitrogen and terminal carboxylate groups. FT-IR spectra give a clear indication that guanidino
groups in all the complexes are not involved in coordination, since ν(C=N-H) frequency
of the terminal guanidino group is fairly constant and unshifted relative to the free ligand
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