Palladium(II) and platinum(II) complexes of derivatives of 2-(4′-aminophenyl)benzothiazole as potential anticancer agents

The synthesis, structural characterization and in vitro biological evaluation of two 2-(4′-aminophenyl)benzothiazole based ligands and their corresponding Pd(II) and Pt(II) complexes is reported. Their design was based on the selective anticancer action of phenylbenzothiazole in conjunction with the cytotoxicity of the metallic center, aiming at targeted and synergistic effectiveness of the complexes as anticancer agents. All compounds were fully characterized with IR, NMR and MS analysis and their binding to CT-DNA was investigated by UV–Vis spectroscopy, fluorescence, circular dichroism, viscometry, and thermal denaturation. The data indicate that both ligands interact with CT-DNA via a combined mode of action involving both groove binding and non-classical intercalation, while in the case of the complexes covalent bond formation takes place as well. The in vitro cytotoxicity and cell uptake studies in human breast carcinoma cell line (MCF-7 and MDA-MB-231) as well as in healthy human skin fibroblasts (DSF) show uptake of the intact complexes by cancer cells and increased activity against cancer cell lines. © 2016 Elsevier B.V

Re(I) tricarbonyl complex of 1,10-phenanthroline-5,6-dione: DNA binding, cytotoxicity, anti-inflammatory and anti-coagulant effects towards platelet activating factor

The complex fac-[Re(CO)3(phendione)Cl] (1) (where phendione = 1,10-phenanthroline-5,6-dione) has been synthesized and fully characterized by UV-visible, FTIR, and NMR techniques. The DNA binding properties of 1 are investigated by UV-spectrophotometric (melting curves), covalent binding assay, CV (cyclic voltammetry), circular dichroism (CD) and viscosity measurements. Experimental data indicate that 1 fits into the major groove without disrupting the helical structure of the B-DNA in contrast to the free phendione which intercalates within the base pairs of DNA. Upon irradiation, complex 1 promotes the cleavage of plasmid pBR322 DNA from supercoiled form I to nicked form II via a proton coupled electron transfer mechanism. This comes as a result of experimental data in anaerobic/aerobic conditions and in the presence of DMSO. The biological activities of 1 and its precursors [Re(CO)5Cl] and phendione are tested towards a series of cancerous cell lines as glioblastoma (T98G), prostate cancer (PC3) and breast cancer (MCF-7) as well as platelet activating factor (PAF)-aggregation. Moreover, all the aforementioned compounds are tested for their ability to modulate PAF-basic metabolic enzyme activities in preparations of rabbit leukolytes. The in vitro experiments indicate that phendione has a better antitumor effect than cisplatin whereas [Re(CO) 5Cl] is a better PAF inhibitor than both the phendione ligand and 1. Moreover, for the first time it is indicated that [Re(CO)5Cl], with a IC50 of 17 nM is comparable to the widely used PAF receptor antagonists, BN52021 and WEB2170 with IC50 of 30 and 20 nM, respectively, whereas 1 affects PAF-catabolism. © 2014 Elsevier Inc

Solid-phase synthesis of a biotin derivative and its application to the development of anti-biotin antibodies

A biotin derivative, namely biotin-aminocaproic acid-lysine (BAL), was synthesized with solid-phase chemistry, conjugated to a carrier-protein, and used for rabbit immunization. The aminocaproic acid-lysine "long-arm" was used in order to project the biotin-hapten above the carrier-protein surface. Lysine was selected due to its Nε-amino group, through which BAL was conjugated to the carrier-protein. BAL was synthesized on a commercially available resin with the Fmoc-solid-phase strategy; this has simplified the experimental procedure, overcome the need for intermediate purification steps, and led to a final product of high purity, with high yield. The anti-BAL antibodies recognized free biotin, as shown with an in-house-developed ELISA, in which biotin conjugated to a synthetic "lysine-dendrimer" was used to coat the ELISA microwells. In immunocytology and Western-blot experiments, the anti-BAL antibodies led to similar results with those obtained with streptavidin. Synthetic derivatives of hapten molecules that can be easily prepared with solid-phase chemistry, such as BAL, may be used for the development of specific antibodies for the corresponding hapten. © 2009 Springer Science+Business Media, LLC

Synthesis haptens and development of an immunoassay for the olive fruit fly pheromone

An enzyme-linked immunosorbent assay (ELISA) for the olive fruit fly pheromone, Bactrocera oleae Gmelin, was developed. The assay uses polyclonal antibodies, raised in rabbits, against (±)-β-[3-(1,7-dioxaspiro[5.5] undecane)]propionic acid, 2 (hapten I), conjugated to the KLH (keyhole limpet hemocyanin) by the carbodiimide method. A second hapten, (±)-δ-[3- (1,7-dioxaspiro[5.5]undecane)]-butylamine, 3 (hapten II), after conjugation to a biotin moiety, was used for indirect immobilization onto ELISA microwells precoated with the glycoprotein avidin. The developed ELISA method measures the synthetic olive fruit fly pheromone in concentrations ranging between 0.08 and 10 μg/mL and shows great promise for practical applications for pheromone detection in environmental and biological samples. The results obtained strongly indicate that this technique, to our knowledge the first insect pheromone enzyme-linked immunosorbent assay so far reported, is a fast, sensitive, inexpensive, and highly convenient method for the analysis of a volatile and low molecular weight compound such as 1,7-dioxaspiro[5.5]undecane, 1

Determination of natural olive fruit fly pheromone in insect samples by enzyme linked immunoassays

The olive fruit fly pheromone avidin-biotin ELISA immunoassay, based on the use of polyclonal G antibodies derived from rabbits (reported previously) and a newer assay, based on the use of polyclonal Y antibodies isolated from the eggs of laying hens (reported in this paper), were applied successfully for the analysis of natural pheromone in virgin adult female olive fruit flies. According to the results obtained, the pheromone content in the glands of adult female olive fruit flies increases from the third to the ninth day of their age. During the calling period, the female olive fruit flies seem to emit ∼1.1 μg pheromone/insect/day at least. The immunoassay, based on the Y antibodies, is slightly more sensitive (detection limit 40 ng/mL) than the assay based on polyclonal anti-pheromone rabbit antiserum (detection limit 80 ng/mL). As revealed by thorough cross-reactivity studies, including 14 structurally similar to the olive fruit fly pheromone molecules, the newer immunoassay is less selective than the previous one and seems to cross react with few molecules bearing the spiroketal moiety. © 2007 Elsevier B.V. All rights reserved

A triphenylphosphonium-functionalized mitochondriotropic nanocarrier for efficient co-delivery of doxorubicin and chloroquine and enhanced antineoplastic activity

Drug delivery systems that target subcellular organelles and, in particular, mitochondria are considered to have great potential in treating disorders that are associated with mitochondrial dysfunction, including cancer or neurodegenerative diseases. To this end, a novel hyperbranched mitochondriotropic nanocarrier was developed for the efficient co-delivery of two different (both in chemical and pharmacological terms) bioactive compounds. The carrier is based on hyperbranched poly(ethyleneimine) functionalized with triphenylphosphonium groups that forms ~100 nm diameter nanoparticles in aqueous media and can encapsulate doxorubicin (DOX), a well-known anti-cancer drug, and chloroquine (CQ), a known chemosensitizer with arising potential in anticancer medication. The anticancer activity of this system against two aggressive DOX-resistant human prostate adenocarcinoma cell lines and in in vivo animal studies was assessed. The co-administration of encapsulated DOX and CQ leads to improved cell proliferation inhibition at extremely low DOX concentrations (0.25 μM). In vivo experiments against DU145 human prostate cancer cells grafted on immunodeficient mice resulted in tumor growth arrest during the three-week administration period and no pervasive side effects. The findings put forward the potential of such targeted low dose combination treatments as a therapeutic scheme with minimal adverse effects. © 2017 by the authors. Licensee MDPI, Basel, Switzerland

Synthesis and in vitro evaluation of gold nanoparticles functionalized with thiol ligands for robust radiolabeling with99mTc

Radiolabeled gold nanoparticles (AuNPs) have been widely used for cancer diagnosis and therapy over recent decades. In this study, we focused on the development and in vitro evaluation of four new Au nanoconjugates radiolabeled with technetium-99m (99m Tc) via thiol-bearing ligands attached to the NP surface. More specifically, AuNPs of two different sizes (2 nm and 20 nm, referred to as Au(2) and Au(20), respectively) were functionalized with two bifunctional thiol ligands (referred to as L1H and L2H). The shape, size, and morphology of both bare and ligand-bearing AuNPs were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. In vitro cytotoxicity was assessed in 4T1 murine mammary cancer cells. The AuNPs were successfully radiolabeled with99mTc-carbonyls at high radiochemical purity (>95%) and showed excellent in vitro stability in competition studies with cysteine and histidine. Moreover, lipophilicity studies were performed in order to determine the lipophilicity of the radiolabeled con-jugates, while a hemolysis assay was performed to investigate the biocompatibility of the bare and functionalized AuNPs. We have shown that the functionalized AuNPs developed in this study lead to stable radiolabeled nanoconstructs with the potential to be applied in multimodality imaging or for in vivo tracking of drug-carrying AuNPs. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Development and immunochemical evaluation of antibodies Y for the poorly immunogenic polypeptide prothymosin alpha

Since conserved mammalian polypeptides are believed to exhibit enhanced immunogenicity in avian species, hens were immunized against the poorly immunogenic, highly conserved mammalian polypeptide prothymosin alpha (ProTα), i.e. against either non-conjugated ProTα (isolated from bovine thymus) or ProTα conjugated to keyhole limpet hemocyanin (ProTα/KLH). The antibodies Y were isolated from the egg yolk and evaluated through suitable dot-blot and ELISA systems in parallel with antibodies G isolated from the antiserum of rabbits immunized against the same immunogens. As revealed, antibodies Y and G of low titer and/or affinity were obtained against non-conjugated ProTα, while antibodies Y against ProTα/KLH had a better apparent titer, could better discriminate between ProTα and the closely related bioactive peptide thymosin alpha 1, and were obtained at much larger quantities than the corresponding antibodies G. © 2005 Elsevier Inc. All rights reserved

Structural assessment and biological evaluation of two N3S bombesin derivatives

The aim of the present study is the evaluation of the 99mTc complexes of two bombesin-like peptides: Gly1′-Gly2′-Cys3′- Aca-BN[2-14] (BN-1.1) and Gly1′-Gly2′-Cys3′-Aca-BN[7-14] (BN-1.1p). The BN derivatives were synthesized according to the solid phase peptide synthesis method, and characterized by ESI-MS and NMR. 185/187Re-BN-1.1 and 185/187Re-BN-1.1p were also identified by ESI-MS and NMR. The 99mTc complexes were stable over time in human plasma, while they degraded rapidly in kidney-liver homogenates. The peptides and their 99mTc complexes showed high affinity for the human GRP receptors expressed in PC-3 cells. The rate of internalization of these radiolabeled biomolecules was found to be time-dependent. Also, it was found that there was no long-term retention of the radioactive metabolites into the cells. Tissue distribution of the radiopeptides was evaluated in normal mice and in prostate cancer experimental models. Significant uptake of radioactivity was observed in the pancreas of PC-3 tumor-bearing SCID mice. Dynamic studies of both radiopeptides showed satisfactory tumor images. © 2009 American Chemical Society