Search

The parasitic plants from the genus Cuscuta have been studied from different perspectives, such as their phytochemistry, pharmacology, taxonomy, as weeds, and as a model plant for plant-plant interactions. This review attempts to discuss the host plants’ influence on the phytochemistry and pharmacology of parasitic plants like Cuscuta from the evidence that has been published until recent years in specialized literature and which has not been addressed in detail. Also, the relationship between haustorium development from the parasitic plant and its attachment to the host plant vascular system is discussed and related to the phytochemical and pharmacological information available. In addition, the genus Cuscuta’s main applications description in patents is also explored. Finally, some important recommendations are suggested for further studies in Cuscuta or any other parasitic plant. This state-of-the art about the genus Cuscuta can be a valuable source of organized information for those researchers developing projects in a great variety of aspects related to this genus.

The synthesis in one-pot reactions and structural characterization of six new tri-n-butyltin(IV) derivatives of Schiff bases are reported. The compounds are derived from a condensation reaction between l-alanine, l-valine, l-isoleucine, l-methionine, l-phenylalanine or l-tryptophan and 3,5-di-tert-butyl-2-hydroxybenzaldehyde. Characterization was completed using elemental analysis, infrared spectroscopy, mass spectrometry, one- and two-dimensional solution NMR (1H, 13C and 119Sn) as well as solid-state 119Sn NMR. In addition, the crystal structures of three of the compounds were confirmed using single-crystal X-ray diffraction. Although five-coordinated and polymeric in the solid state, the tin compounds are four-coordinated and monomeric in solution. The coordination environment around the triorganotin units comprises three carbon atoms and two oxygen atoms from two ligands in a trigonal bipyramidal geometry. The anti-proliferative effect of these compounds on the cervical carcinoma cell lines HeLa, CaSki and ViBo was screened in vitro, the compounds showing cytotoxic activity against all three strains and null or low cytotoxic activity (necrotic) as well. Copyright © 2016 John Wiley & Sons, Ltd.

Coordination compounds with cobalt(II), nickel(II), copper(II) and zinc(II) and the ligand 2,6-bis(2,6-diethylphenyliminomethyl)pyridine (L) were synthesized and fully characterized by IR and UV-Vis-NIR spectroscopy, elemental analysis, magnetic susceptibility and X-ray diffraction for two representative cases. These novel compounds were designed to study their activity as anti-proliferative drugs against different human cancer cell lines. The tridentate ligand forms heptacoordinated compounds from nitrate metallic salts, where the nitrate acts in a chelating form to complete the seven coordination positions. In vitro cell growth inhibition was measured for Co(II), Cu(II) and Zn(II) complexes, as well as for the free ligand. Upon coordination, the IC50 value of the transition-metal compounds is improved compared to the free ligand. The copper(II) and zinc(II) compounds are the most promising candidates for further in vitro and in vivo studies. The activity against colon and prostate cell lines merits further research, in views of the limited therapeutic options for such cancer types.

Synthesis, spectroscopy, characterization, structures, and cytotoxicity studies of 2,6-bis(2,6-diisopropylphenyliminomethyl)pyridine (LLL) ruthenium compounds are described. The starting compound [RuCl3(LLL)] has been fully characterized using IR spectroscopy, UV–vis spectroscopy, electrospray ionization mass spectrometry, and NMR spectroscopy. In addition, the crystal structure of the ligand LLL has been determined using single-crystal X-ray diffraction. With the ruthenium(III) trichloride compound as starting material, a new family of Ru(II) complexes with a number of neutral and charged bidentate co-ligands have been synthesized and used for characterization and cytotoxicity studies. The synthesis of the corresponding [RuIILLL(LL)Cl]+/0 complexes with co-ligands— LL is 1,10-phenanthroline, 2,2′-bipyridyl, 2-(phenylazo)pyridine, 2-(phenylazo)-3-methylpyridine, 2-(tolylazo)pyridine, or the anionic 2-picolinate—is reported. Analytical, spectroscopic (IR spectroscopy, UV–vis spectroscopy, 1H NMR spectroscopy, and electrospray ionization mass spectrometry), and structural characterization of the new compounds is described. Crystal structure analyses of two Ru(II) compounds show a slightly distorted octahedral Ru(II) geometry with tridentate LLL coordinated in a planar meridional fashion, and the chelating co-ligand (LL) and a chloride ion complete the octahedron. The co-ligand plays a significant role in modulating the physicochemical and cytotoxic properties of these new ruthenium complexes. The in vitro cytotoxicity of these new Ru(II) complexes (half-maximal inhibitory concentration, IC50, of 0.5–1.5 μM), in comparison with the parent Ru(III) compound (half-maximal inhibitory concentration of 3.9–4.3 μM) is higher for several of the human cancer cell lines tested. The cytotoxic activity of some of the new ruthenium compounds is even higher than that of cisplatin in the same cancer cell lines. The cytotoxicity of these new anticancer compounds is discussed in the light of structure-based activity relationships, and a possible mechanism of action is suggested. Synthesis, spectroscopy, structures, and cytotoxicity studies of new Ru(III) and Ru(II) compounds with a substituted bis(arylimino)pyridine ligand and bidentate co-ligands are reported. The co-ligands play a significant role in modulating the physicochemical and cytotoxic properties. The in vitro cytotoxicity data are discussed in the light of structure-based activity relationships (SARs). Highlights

The oxidative cyclization of 2,6-bis[2,4-di-tert-butyl-6-(methylidenylamino)phenol]-pyridine (L1) in acetonitrile, through the cobalt(II) coordination compound of L1, has resulted in a convenient route for the preparation of 2,6-bis[5,7-di-tert-butyl-1,3-benzoxazol-2-yl]-pyridine (L3). The X-ray diffraction analysis of L3 shows a planar molecule, with the oxygen atoms from the benzoxazole rings oriented to the pyridine nitrogen atom (conformer L3a). Ab initio calculations indicate that from the three possible planar conformers of L3, the more stable is L3a. The solid state conformation of the free ligand L3 and the relative energy of the three calculated conformers indicated stabilizing N → O interactions. Calculations of the protonated derivative of L3, compound 7, indicated that the most stable conformer has the benzoxazole nitrogen atoms pointing to the protonated pyridine NH (7c). The X-ray crystal analysis of ligand L3 coordinated to cobalt(II) nitrate, compound 4 is presented and conformer L3c is found in this compound. Two acid:base complexes [Zn(NO3)2(H2O)2][L3c]2, compound 5, and [NEt2H2Cl][L3c], compound 6, have also been investigated. Complex 5 crystallized and its X-ray diffraction analysis is reported, whereas compound 6 was studied in solution by NMR, mass spectrometry and ab initio calculations. Both complexes show that conformer L3c can form stable hydrogen bonding associations, with molecules having the motif YH2 (Y = N or O), that are of interest for building up supramolecular associations.

Two novel triorganotin carboxylate complexes of the biologically active urocanic acid have been synthesized and characterized. Elemental analysis, melting point, spectroscopic techniques – IR, 1H, 13C and 119Sn NMR – mass spectrometry and X-ray diffraction studies have been used for structural characterization. Crystal structures of the tin(IV) derivatives show that urocanic acid acts as a bridging bidentate ligand through its imidazole nitrogen atom and its carboxylic group, producing a polymeric one-dimensional chain. The molecular structures of the complexes, catena-poly-tri(n-butyl)tin(IV) 3-(3H-imidazol-4-yl)prop-2-enoate (1) and catena-poly-triphenyltin(IV) 3-(3H-imidazol-4-yl)prop-2-enoate (2), present a distorted trigonal–bipyramidal configuration. This is further confirmed by 119Sn NMR in the solid state. The tin(IV) derivatives form double-stranded ribbons via N―H…O―H bonds. Nevertheless, the compounds are essentially monomeric in solution, with a tetrahedral configuration as observed by 119Sn NMR in solution. The cytotoxic activity of the titled compounds has been tested against six human cell lines and the corresponding IC50 values are reported. Both tin(IV) compounds have a high to very high in vitro cytotoxic activity against the tumor cell lines K562, HCT-15 and MCF-7. Compound 1 is 86 times more active than cisplatin in the HTC-15 cell line. Copyright © 2012 John Wiley & Sons, Ltd.

El molibdeno es utilizado por los sistemas biologicos principalmente por sus propiedades oxido-reductoras, en las que se transfiere en cada reaccion un electron, ademas de que permite la migracion de atomos de azufre, oxigeno e hidrogeno, principalmente. El molibdeno forma parte de dos cofactores enzimaticos que se encuentran extensamente distribuidos en la naturaleza: FeMoco, caracterizado por una estructura multinuclear que contiene un cumulo de composicion 4Fe-4S y otro cumulo de composicion Mo-3Fe-4S; y el cofactor conocido como Moco, que en su estructura aloja un ion molibdeno. FeMoco se encuentra en la nitrogenasa, enzima que cataliza la transformacion del nitrogeno elemental en amoniaco. Moco se encuentra en un vasto numero de enzimas que han sido clasificadas en tres familias: la familia de las xantina oxidasas, la familia de las sulfito oxidasas, y la familia de las DMSO reductasas. La importancia de estas familias de enzimas hace que las deficiencias y/o anomalias de este metal en los sistemas biologicos sean determinantes para la continuidad de la vida. De hecho, del molibdeno y sus cofactores depende el ciclo del nitrogeno y en el ser humano, las anomalias en la bioquimica de los procesos que involucran molibdeno (Moco), se asocian a dano neurologico progresivo, xantinuria, gota o hiperuricemia. Este articulo hace una revision detallada de las nuevas evidencias del papel que el molibdeno y Moco tienen en los sistemas biologicos

The synthetic, spectroscopic, structural, and biological studies of a bis(arylimino)pyridine Ru(III) chloride compound containing the ligand, 2,6-bis(2,4,6-trimethylphenyliminomethyl)pyridine are reported. The bis(arylimino)pyridine ligand, with three donor nitrogen atoms, was synthesized by condensation of 2,6-pyridinedicarboxaldehyde with 2,4,6-trimethylaniline. The Ru(III) complex, with formula [RuCl 3(L1)](H 2O) (RuL1), where L1 = 2,6-bis(2,4,6-trimethylphenyliminomethyl)pyridine, was structurally determined on the basis of analytical and spectroscopic (IR, UV-vis, ESI-MS) studies. A straightforward strategy to fully characterize the paramagnetic compound using advanced (1)H NMR is reported. This new complex is a prototype for a series of new anticancer Ru(III) and Ru(II) compounds with improved cytostatic properties; likely to be modified in a desirable manner due to the relatively facile ligand modification of the bis(imino)pyridines and their molecular architecture. The present Ru(III) complex is the first example of this family of Ru(III)/Ru(II) anticancer compounds with the aimed physicochemical characteristics. Although the ligand itself is moderately active in selected cell lines (EVSA-T and MCF-7), the activity of the [Ru(L1)Cl 3] complex has increased significantly for a broad range of cancer cell lines tested in vitro (IC 50 values = 11 approximately 17 microM). Reaction of the RuL1 species with the DNA model base 9-ethylguanine (9EtGua) was found to produce in a redox reaction the species trans-[Ru(II)(L1)(9EtGua) 2(H 2O)](ClO 4) 2 (abbreviated as RuL1-9EtGua), which was studied in solution and also in the solid state, by X-ray crystallography. The structure comprises the as yet unknown trans-bis(purine)Ru(II) unit.

A new Au(III) coordination compound with the ligand 2-(phenylazo)pyridine has been synthesized and fully characterized by means of elemental analysis, IR, UV–visible, conductivity measurements, NMR, electrospray ionization (ESI-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The chemical stability of the cation in this compound, [Au(azpy)Cl2]+ (abbreviated: Au-azpy), was analyzed by means of several physicochemical methods. While stable in the solid state, stability studies performed with the gold compound in solution showed an unexpected and unprecedented reactivity. A cationic organic derivative of 2-(phenylazo)pyridine, (abbreviated: pyrium), was produced from the solution and has been isolated as its chloride salt and characterized by crystal structure determination, elemental analysis, NMR, ESI-MS and conductivity studies in solution. This cyclization reaction is reported for the first time in the case of gold coordination compounds. The Au adduct and the pyrium cation were investigated as potential cytotoxic and anticancer agents, and both show moderate to high cytotoxic properties in cisplatin-sensitive and cisplatin-resistant ovarian carcinoma cell lines, A2780; and cisplatin-sensitive and cisplatin-resistant murine lymphocytic leukemia cell lines, L1210. Significant anticancer activity against the cisplatin resistant cell lines was found for the pyrium salt, ruling out the occurrence of cross resistance phenomena.

The effect of ruthenium red analogues on several thylakoid photosynthetic activities has been investigated. RR, RV, RRPh1, RRPh2 and Ph inhibit ATP synthesis and electron flow from water to MV (basal, phosphorylating and uncoupled) as their concentration increases, thus, they act as a Hill reaction inhibitor. They inhibit uncoupled electron transport through PSII from water to DCPIP and partially from DPC to DCPIP. However, these compounds do not affect uncoupled PSI electron transport from DCPIP to MV. Therefore, the target of interaction is at the level of OEC and the span P680 to QA for RR, RRPh1 and RRPh2. Chlorophyll a fluorescence studies corroborate the already found interference sites and may affect the disconnection between chlorophyll molecules within the LHCII and/or between antennae and RCs, or decreases the exciton to reach the RC and inhibition of PSII occurs. RRPh2 is six times more active than RR. Finally, Ph inhibits electron flow interacting at the level of QB.

The recent finding that the inhibition of Ca2+-stimulated respiration by ruthenium red is mainlydue to a binuclear ruthenium complex (Ru360) present in the commercial samples of the classicalinhibitor ruthenium red (Ying et. al., 1991), showed that this complex is the more potent andspecific inhibitor of the mitochondrial calcium uniporter. This work was aimed to provideinsights into the mechanism by which Ru360 and other ruthenium-related compounds inhibitscalcium uptake. Ruthenium red and a synthesized analog (Rrphen) were compared with Ru360.The inhibition by this binuclear complex was noncompetitive, with a K i of 9.89 nM. Thenumber of specific binding sites for Ru360 was 6.2 pmol/mg protein. Ruthenium red and Ru360were mutually exclusive inhibitors. Bound La3+ was not displaced by Ru360. Rrphen was theleast effective for inhibiting calcium uptake. The results support the notion of a specific bindingsite in the uniporter for the polycationic complexes and a negative charged region from thephospholipids in the membrane, closely associated with the uniporter inhibitor-binding site.

The title compound, [RuCl3(C12H8N2)(C2H6OS)]·CHCl3, contains six crystallographically independent formula units in the asymmetric cell. The structure features alternating layers of the main mol­ecule and CHCl3 arranged parallel to (011).

Starting from the Ru(III) complex, [RuCl3(L1)](H2O) (L1: 2,6-bis(2,4,6-trimethylphenyliminomethyl)pyridine), the chemical reactivity and cytotoxic activity of a new family of Ru(II) complexes with a number of bidentate co-ligands have been studied. The synthesis of the Ru(II)-bis(arylimino)pyridine complexes with the co-ligands 1,10-phenanthroline (phen), 2,2′dipyridyl-(bpy), 2-(phenylazo)pyridine (azpy), 2-(phenylazo)-3-methylpyridine (3mazpy), 2-(tolylazo)pyridine (tazpy), and 2-picolinate (pic) is reported. These new six complexes, with L1 and different bidentate N donor co-ligands, have been designed to allow the binding of a monodentate chloride ligand, which would be easily hydrolysed in vitro. Elemental analysis and several spectroscopic techniques (IR, UV-Vis, 1D and 2D 1H NMR and ESI-MS) have been used for the characterization of the new Ru(II) compounds. In addition, the crystal structure of the chlorido(2-picolinato)(2,6-bis(2,4,6-trimethylphenyliminomethyl)pyridine)ruthenium(II) was solved and shows a slightly distorted octahedral geometry for the Ru(II) centre with the tridentate L1 ligand coordinated in a planar mer fashion, with the bidentate ligand in a perpendicular orientation and a monodentate chloride, trans to the coordinating oxygen of the picolinate ion. The in vitro cytotoxic properties of these new Ru(II) complexes in comparison with the parent, starting Ru(III)-compound (IC50 values = 11–17 μM) appear to be encouraging for a broad range of cancer cell-lines tested (IC50 values = 0.4–10 μM). Some of them show better cytotoxic effects than cisplatin on a straight comparison with the same cancer cell lines. The cytotoxicity data are discussed in the light of structure–activity relationships and these ruthenium(II) compounds could well be promising next generation candidates worth further investigation.

Synthesis, structure and properties of two new flavanone complexes of Ru(ii) are described. The new complexes form during the reaction of ruthenium(iii) chloride with 3-aminoflavone (3-af) dissolved in an aliphatic alcohol. The formed products depend on the alcohol used and were found to be: cis-dichloridobis(3-imino-2-methoxyflavanone)ruthenium(ii)·3H(2)O (1) from a methanolic solution and cis-dichloridobis(3-imino-2-ethoxyflavanone)ruthenium(ii)·2H(2)O (2) from an ethanolic solution, in which the original ligand 3-af had been converted by dehydrogenative alcoholysis to an entirely new ligand. This paper presents the X-ray structure and detailed (1)H-NMR analysis of both new compounds, as well as the study of their antiproliferative activity. The coordination of Ru(ii) is octahedral with [RuCl(2)N(2)O(2)] chromophores, having trans chlorides and common Ru-L distances. Both 1 and 2 are highly cytotoxic towards the cisplatin resistant EJ and L1210 cell lines, and both complexes are as active as cisplatin in the sensitive cell lines. They display the ability to overcome cisplatin resistance in the drug resistant sub-lines EJcisR and L1210R. The present evidence suggests that the mechanism of biological activity may be different for these ruthenium compounds compared to cisplatin.