Ru(II) Phenanthroline-Based Oligothienyl Complexes as Phototherapy Agents.

Ru(II) polypyridyl complexes have gained widespread attention as photosensitizers for photodynamic therapy (PDT). Herein, we systematically investigate a series of the type [Ru(phen)2(IP-nT)]2+, featuring 1,10-phenanthroline (phen) coligands and imidazo[4,5-f][1,10]phenanthroline ligands tethered to n = 0-4 thiophene rings (IP-nT). The complexes were characterized and investigated for their electrochemical, spectroscopic, and (photo)biological properties. The electrochemical oxidation of the nT unit shifted by -350 mV as n = 1 → 4 (+920 mV for Ru-1T, +570 mV for Ru-4T); nT reductions were observed in complexes Ru-3T (-2530 mV) and Ru-4T (-2300 mV). Singlet oxygen quantum yields ranged from 0.53 to 0.88, with Ru-3T and Ru-4T being equally efficient (∼0.88). Time-resolved absorption spectra of Ru-0T-1T were dominated by metal-to-ligand charge-transfer (3MLCT) states (τTA = 0.40-0.85 µs), but long-lived intraligand charge-transfer (3ILCT) states were observed in Ru-2T-4T (τTA = 25-148 µs). The 3ILCT energies of Ru-3T and Ru-4T were computed to be 1.6 and 1.4 eV, respectively. The phototherapeutic efficacy against melanoma cells (SK-MEL-28) under broad-band visible light (400-700 nm) increases as n = 0 → 4: Ru-0T was inactive up to 300 µM, Ru-1T-2T were moderately active (EC50 ∼ 600 nM, PI = 200), and Ru-3T (EC50 = 57 nM, PI > 1100) and Ru-4T (EC50 = 740 pM, PI = 114,000) were the most phototoxic. The activity diminishes with longer wavelengths of light and is completely suppressed for all complexes except Ru-3T and Ru-4T in hypoxia. Ru-4T is the more potent and robust PS in 1% O2 over seven biological replicates (avg EC50 = 1.3 µM, avg PI = 985). Ru-3T exhibited hypoxic activity in five of seven replicates, underscoring the need for biological replicates in compound evaluation. Singlet oxygen sensitization is likely responsible for phototoxic effects of the compounds in normoxia, but the presence of redox-active excited states may facilitate additional photoactive pathways for complexes with three or more thienyl groups. The 3ILCT state with its extended lifetime (30-40× longer than the 3MLCT state for Ru-3T and Ru-4T) implicates its predominant role in photocytotoxicity.

assessment of antioxidant, neuroprotective, anti-urease and anti-tyrosinase capacities of leaves extracts.

OBJECTIVE: To characterize the chemical profile of methanolic crude extract and its fractions (Ethyl acetate, n-butanol and aqueous) using liquid chromatography-mass spectrometry (LC-MS) analysis, to evaluate their biological and pharmacological properties: antioxidant (1, 1-diphenyl-2-pycrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic) (ABTS), galvinoxyle free radical scavenging, reducing power, phenanthroline and ß carotene-linoleic acid bleaching assays), enzymes inhibitory ability against several enzymes [acetyl-cholinesterase (AChE), buthyrylcholinesterase (BChE), urease and tyrosinase]. METHODS: Secondary metabolites were extracted from Tamarix africana air-dried powdered leaves by maceration, the crude extract was fractionated using different solvents with different polarities (Ethyl acetate, n-butanol and aqueous). The amount of polyphenols, flavonoids and tannins (hydrolysable and condensed) were determined using colorimetric assays. A variety of biochemical tests were carried out to assess antioxidant and oxygen radical scavenging properties using DPPH, ABTS, galvinoxyle free radical scavenging, reducing power, phenanthroline and ß carotene-linoleic acid bleaching methods. Neuroprotective effect was examined against acetylcholinesterase and buthy-rylcholinesterase enzymes. The anti-urease and anti-tyrosinase activities were performed against urease and tyrosinase enzymes respectively. The extract's components were identified using LC-MS and compared to reference substances. RESULTS: The results indicated that Tamarix africana extracts presented a powerful antioxidant activity in all assays and exhibited a potent inhibitory effect against AChE and BChE as well as urease and tyrosinase enzymes. LC-MS analysis identified amount of eight phenolic compounds were revealed in this analysis; Apigenin, Diosmin, Quercetin, Quercetine-3-glycoside, Apigenin 7-O glycoside, Rutin, Neohesperidin and Wogonin in methanolic extract and its different fractions of Tamarix africana from leaves. CONCLUSIONS: Based on these findings, it is reasonable to assume that Tamarix africana could be considered as a potential candidate for pharmaceutical, cosmetics, and food industries to create innovative health-promoting drugs.

Phytochemicals, Antioxidant and Antimicrobial Potentials and LC-MS Analysis of Centaurea parviflora Desf. Extracts.

Centaurea parviflora (C. parviflora), belonging to the family Asteraceae, is an Algerian medicinal plant used in folk medicine to treat different diseases related to hyperglycemic and inflammatory disorders, as well as in food. The present study aimed to assess the total phenolic content, in vitro antioxidant and antimicrobial activity and phytochemical profile of the extracts of C. parviflora. The extraction of phenolic compounds from aerial parts was conducted using solvents of increasing polarity starting from methanol, resulting in crude extract (CE), to chloroform extract (CHE), ethyl acetate extract (EAE) and butanol extract (BUE). The total phenolic, flavonoid and flavonol contents of the extracts were determined using the Folin-Ciocalteu and AlCl3 methods, respectively. The antioxidant activity was measured with seven methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, galvinoxyl free-radical-scavenging test, 2,2'-Azino-Bis(3-Ethylbenzothiazoline-6-Sulfonic Acid) (ABTS) assay, cupric reducing antioxidant capacity (CUPRAC), reducing power, Fe+2-phenanthroline reduction assay and superoxide-scavenging test. The disc-diffusion method aimed at testing the sensitivity of bacterial strains toward our extracts. A qualitative analysis with thin-layer chromatography of the methanolic extract was performed. Moreover, HPLC-DAD-MS was used to establish the phytochemical profile of the BUE. The BUE was found to contain high amounts of total phenolics (175.27 ± 2.79 µg GAE/mg E), flavonoids (59.89 ± 0.91 µg QE/mg E) and flavonols (47.30 ± 0.51 µg RE/mg E). Using TLC, different components such as flavonoids and polyphenols were noted. The highest radical-scavenging ability was recorded for the BUE against DPPH (IC50 = 59.38 ± 0.72 µg/mL), galvinoxyl (IC50 = 36.25 ± 0.42 µg/mL), ABTS (IC50 = 49.52 ± 1.54 µg/mL) and superoxide (IC50 = 13.61 ± 0.38 µg/mL). The BUE had the best reducing power according to the CUPRAC (A0.5 = 71.80 ± 1.22 µg/mL), phenanthroline test (A0.5 = 20.29 ± 1.16 µg/mL) and FRAP (A0.5 = 119.17 ± 0.29 µg/mL). The LC-MS analysis of BUE allowed us to identify eight compounds including six phenolic acids and two flavonoids: quinic acid, five chlorogenic acid derivatives, rutin and quercetin 3-o-glucoside. This preliminary investigation revealed that the extracts of C. parviflora have a good biopharmaceutical activity. The BUE possesses an interesting potential for pharmaceutical/nutraceutical applications.

Two Ligands of Interest in Recovering Uranium from the Oceans: The Correct Formation Constants of the Uranyl(VI) Cation with 2,2'-Bipyridyl-6,6'-dicarboxylic Acid and 1,10-Phenanthroline-2,9-dicarboxylic Acid.

The ligands BDA (2,2'-bipyridyl-6,6'-dicarboxylic acid) and PDA (1,10-phenanthroline-2,9-dicarboxylic acid) are of interest as functional group types for ion-exchange materials for extracting uranium from the oceans, reported in a previous paper for PDA Lashley, M. A. ( Inorg. Chem. 2016 55 10818 10829). Yang, Y. ( Inorg. Chem. 2019, 58, 6064 6074) have published what they claim to be a more accurate result for the formation of the UO22+/PDA complex of log K1 = 22.84 compared with our reported value of log K1 = 16.5, as well as log K1 = 21.52 for the BDA complex. The determination of log K1 for the PDA and BDA complexes with the UO22+ cation was carried out by Yang et al. using a competition reaction between DTPA (diethylenetriamine pentaacetic acid) and BDA or PDA, monitoring the absorbance due to the BDA and PDA ligands. This competition method using absorbance versus pH titrations was developed for determining the formation constants of the complexes of several polypyridyl ligands plus PDA complexes of metal ions, which were too stable for log K determination by competition with protons. A key feature of such titrations is that in the competition reaction, the displacement of the pyridyl donor ligand (e.g., PDA) by the competing ligand (e.g., DTPA), the absorbance spectrum of the displaced pyridyl donor ligand should be observed. Competing ligands used to date have been EDTA (ethylenediamine tetraacetic acid), DTPA, or the hydroxide ion. In the study of Yang et al., no such displaced PDA or BDA was apparent in the absorbance spectra in their titrations so that their reported log K1 values have no validity. Their log K1 values are so much higher than log K1 for the uranyl DTPA complex (∼13.6) that DTPA could not possibly displace BDA or PDA from the uranyl cation, and a competition reaction could not possibly occur. We report the correct value of log K1 = 15.4 (ionic strength = zero) for the uranyl BDA complex, to illustrate the correct determination of such a constant by a competition reaction between BDA and hydroxide, showing how the characteristic absorbance spectrum for a BDA complex, here the UO22+ complex, disappears, and the distinctive absorbance spectrum of the free nonprotonated BDA ligand appears as the pH is increased, and BDA is displaced by the hydroxide ion.

Synthesis of Hemiprotonic Phenanthroline-Phenanthroline+ Compounds with both Antitumor and Antimicrobial Activity.

Currently, cancer patients with microbial infection are a severe challenge in clinical treatment. To address the problem, we synthesized hemiprotonic compounds based on the unique structure of hemiprotonic nucleotide base pairs in a DNA i-motif. These compounds were produced from phenanthroline (ph) dimerization with phenanthroline as a proton receptor and ammonium as a donor. The biological activity shows that the compounds have a selective antitumor effect through inducing cell apoptosis. The molecular mechanism could be related to specific inhibition of transcription factor PLAGL2 of tumor cells, assessed by transcriptomic analysis. Moreover, results show that the hemiprotonic ph-ph+ has broad-spectrum antibacterial and antifungal activities, and drug-resistant bacteria, including methicillin-resistant Staphylococcus aureus, are sensitive to the compound. In animal models of liver cancer with fungal infection, the ph-ph+ retards proliferation of hepatoma cells in tumor-bearing mice and remedies pneumonia and encephalitis caused by Cryptococcus neoformans. The study provides a novel therapeutic candidate for cancer patients accompanied by infection.

Hydrazine Hydrate Accelerates Neocuproine-Copper Complex Generation and Utilization in Alkyne Reduction, a Significant Supplement Method for Catalytic Hydrogenation.

Diimine (HN═NH) is a strong reducing agent, but the efficiency of diimine oxidized from hydrazine hydrate or its derivatives is still not good enough. Herein, we report an in situ neocuproine-copper complex formation method. The redox potential of this complex enable it can serve as an ideal redox catalyst in the synthesis of diimine by oxidation of hydrazine hydrate, and we successfully applied this technique in the reduction of alkynes. This reduction method displays a broad functional group tolerance and substrate adaptability as well as the advantages of safety and high efficiency. Especially, nitro, benzyl, boc, and sulfur containing alkynes can be reduced to the corresponding alkanes directly, which provides a useful complementary method to traditional catalytic hydrogenation. Besides, we applied this method in the preparation of the Alzheimer's disease drug CT-1812 and studied the mechanism.

Zinc(II) niflumato complex effects on MMP activity and gene expression in human endometrial cell lines.

Endometriosis is a chronic inflammatory disease which increasingly affects young women under 35 years of age and leads to subfertility even infertility. Analysis of the cytotoxic effect of zinc(II) niflumato complex with neocuproine ([Zn(neo)(nif)2] or Zn-Nif) on immortalized human endometriotic cell line (12Z) and on control immortalized human endometrial stromal cell line (hTERT) was performed using xCELLigence technology for approximately 72 h following the treatment with Zn-Nif as well as cell viability Trypan Blue Assay. 12Z cell line proliferated more slowly compared to unaffected cells, whereas hTERT cells did not show similar behavior after treatment. The complex probably reduces the effect of pro-inflammatory pathways due to the effect of NSAID, while presence of zinc might reduce the level of ROS and regulate ER2 levels and MMP activity. The observed effects and high selectivity for rapidly proliferating cells with increased inflammatory activity suggest a good prognosis of successful decrease of endometriosis stage with this complex.

JTP-117968, a novel selective glucocorticoid receptor modulator, exhibits significant anti-inflammatory effect while maintaining bone mineral density in mice.

Classic glucocorticoids have been prescribed for various inflammatory diseases, such as rheumatoid arthritis, due to their outstanding anti-inflammatory effects. However, glucocorticoids cause numerous unwanted side effects, including osteoporosis and diabetes. Hence, selective glucocorticoid receptor modulators (SGRMs), which retain anti-inflammatory effects with minimized side effects, are among the most anticipated drugs in the clinical field. The assumption is that there are two major mechanisms of action via glucocorticoid receptors, transrepression (TR) and transactivation (TA). In general, anti-inflammatory effects of glucocorticoids are largely due to TR, while the side effects associated with glucocorticoids are mostly mediated through TA. We previously reported that JTP-117968, a novel SGRM, maintained partial TR activity while remarkably reducing the TA activity. In this study, we investigated the anti-inflammatory effect of JTP-117968 on a lipopolysaccharide (LPS) challenge model and collagen-induced arthritis (CIA) model in mice. Meanwhile, we tested the effect of JTP-117968 on the bone mineral density (BMD) in mouse femur to evaluate the side effect. Based on the evaluation, JTP-117968 reduced the plasma levels of tumor necrosis factor α induced by LPS challenge in mice significantly. Remarkably, CIA development was suppressed by JTP-117968 comparably with prednisolone and PF-802, an active form of fosdagrocorat that has been developed clinically as an orally available SGRM. Strikingly, the side effect of JTP-117968 on mouse femoral BMD was much lower than those of PF-802 and prednisolone. Therefore, JTP-117968 has attractive potential as a new therapeutic option against inflammatory diseases with minimized side effects compared to classic glucocorticoids.

Comparative differential cuproproteomes of Rhodobacter capsulatus reveal novel copper homeostasis related proteins.

Copper (Cu) is an essential, but toxic, micronutrient for living organisms and cells have developed sophisticated response mechanisms towards both the lack and the excess of Cu in their environments. In this study, we achieved a global view of Cu-responsive changes in the prokaryotic model organism Rhodobacter capsulatus using label-free quantitative differential proteomics. Semi-aerobically grown cells under heterotrophic conditions in minimal medium (∼0.3 µM Cu) were compared with cells supplemented with either 5 µM Cu or with 5 mM of the Cu-chelator bathocuproine sulfonate. Mass spectrometry based bottom-up proteomics of unfractionated cell lysates identified 2430 of the 3632 putative proteins encoded by the genome, producing a robust proteome dataset for R. capsulatus. Use of biological and technical replicates for each growth condition yielded high reproducibility and reliable quantification for 1926 of the identified proteins. Comparison of cells grown under Cu-excess or Cu-depleted conditions to those grown under minimal Cu-sufficient conditions revealed that 75 proteins exhibited statistically significant (p < 0.05) abundance changes, ranging from 2- to 300-fold. A subset of the highly Cu-responsive proteins was orthogonally probed using molecular genetics, validating that several of them were indeed involved in cellular Cu homeostasis.

Screening of Phenanthroquinolizidine Alkaloid Derivatives for Inducing Cell Death of L1210 Leukemia Cells with Negative and Positive P-glycoprotein Expression.

We describe the screening of a set of cryptopleurine derivatives, namely thienoquinolizidine derivatives and (epi-)benzo analogs with bioactive phenanthroquinolizidine alkaloids that induce cytotoxic effects in the mouse lymphocytic leukemia cell line L1210. We used three variants of L1210 cells: i) parental cells (S) negative for P-glycoprotein (P-gp) expression; ii) P-glycoprotein positive cells (R), obtained by selection with vincristine; iii) P-glycoprotein positive cells (T), obtained by stable transfection with a human gene encoding P-glycoprotein. We identified the most effective derivative 11 with a median lethal concentration of ≈13 µM in all three L1210 cell variants. The analysis of the apoptosis/necrosis induced by derivative 11 revealed that cell death was the result of apoptosis with late apoptosis characteristics. Derivative 11 did not induce a strong alteration in the proportion of cells in the G1, S or G2/M phase of the cell cycle, but a strong increase in the number of S, R and T cells in the subG1 phase was detected. These findings indicated that we identified the most effective inducer of cell death, derivative 11, and this derivative effectively induced cell death in S, R and T cells at similar inhibitory concentrations independent of P-gp expression.

Multifunctional mesoporous curcumin encapsulated iron-phenanthroline nanocluster: A new Anti-HIV agent.

A new strategy to encapsulating the drug curcumin into the hydrophobic core of the iron-phenanthroline nanocomplex (NIP) and eventually its release is signified. NIP was prepared via coordinate interaction between Fe2+ and the lone pairs present on the N atoms of the bidentate phenanthroline ligand (spherical morphology, diameter 18.8 nm, mesoporous with pore size 2.443 nm, amorphous). Thereafter, curcumin was successfully encapsulated (NCIP) in NIP, resulting in its enhanced stability (spherical morphology, diameter 46.8 nm). The nanocomplex NIP was used for drug delivery applications. We evaluated the anti-HIV effects of NCIP in vitro on cultures of HIV infected human microglia. The treatment of HIV-1 infected microglia with NCIP significantly decreased the expression of HIV-p24 by 41% and pro-inflammatory mediators TNF-α, IL-8 and NO by 61.2%, 41% and 50.2%, respectively, compared to NIP. Flow cytometry data also support the decrease in TNF-α and IL-8 expression in case of NCIP. NCIP induced antioxidative effects by increasing the gene expression of catalase (CAT) and simulatenously decreasing hemeoxygenase-1 (HMOX-1) gene expression, thereby maintaining homeostasis which reduces neuroinflammation. These results support our premise that NCIP may be a significant adjuvant when used with traditional anti-retroviral regimens and may ameliorate HIV-1 associated neurotoxicity.

Silver(I) complexes with 4,7-phenanthroline efficient in rescuing the zebrafish embryos of lethal Candida albicans infection.

Five novel silver(I) complexes with 4,7-phenanthroline (4,7-phen), [Ag(NO3-O)(4,7-phen-µ-N4,N7)]n (1), [Ag(ClO4-О)(4,7-phen-µ-N4,N7)]n (2), [Ag(CF3COO-O)(4,7-phen-µ-N4,N7)]n (3), [Ag2(H2O)0.58(4,7-phen)3](SbF6)2 (4) and {[Ag2(H2O)(4,7-phen-µ-N4,N7)2](BF4)2}n (5) were synthesized, structurally elucidated and biologically evaluated. These complexes showed selectivity towards Candida spp. in comparison to the tested bacteria and effectively inhibited the growth of four different Candida species, particularly of C. albicans strains, with minimal inhibitory concentrations (MICs) in the range of 2.0-10.0 µM. In order to evaluate the therapeutic potential of 1-5, in vivo toxicity studies were conducted in the zebrafish model. Based on the favorable therapeutic profiles, complexes 1, 3 and 5 were selected for the evaluation of their antifungal efficacy in vivo using the zebrafish model of lethal disseminated candidiasis. Complexes 1 and 3 efficiently controlled and prevented fungal filamentation even at sub-MIC doses, while drastically increased the survival of the infected embryos. Moreover, at the MIC doses, both complexes totally prevented C. albicans filamentation and rescued almost all infected fish of the fatal infection outcome. On the other side, complex 5, which demonstrated the highest antifungal activity in vitro, affected the neutrophils occurrence of the infected host, failed to inhibit the C. albicans cells filamentation and showed a poor potential to cure candidal infection, highlighting the importance of the in vivo activity evaluation early in the therapeutic design and development process. The mechanism of action of the investigated silver(I) complexes was related to the induction of reactive oxygen species (ROS) response in C. albicans, with DNA being one of the possible target biomolecules.

DNA binding, prominent photonuclease activity and antibacterial PDT of cobalt(II) complexes of phenanthroline based photosensitizers.

The chemistry of Co(II) complexes showing efficient light induced DNA cleavage activity, binding propensity to calf thymus DNA and antibacterial PDT is summarized in this article. Complexes of formulation [Co(mqt)(B)2]ClO4 1-3 where mqt is 4-methylquinoline-2-thiol and B is N,N-donor heterocyclic base, viz. 1,10-phenanthroline (phen 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq 2) and dipyrido[3,2-a:2',3'-c]phenazine (dppz 3) have been prepared and characterized. The DNA-binding behaviors of these three complexes were explored by absorption spectra, viscosity measurements and thermal denaturation studies. The DNA binding constants for complexes 1, 2 and 3 were determined to be 1.6 × 103 M-1, 1.1 × 104 M-1 and 6.4 × 104 M-1 respectively. The experimental results suggest that these complexes interact with DNA through groove binding mode. The complexes show significant photocleavage of supercoiled (SC) DNA proceeds via a type-II process forming singlet oxygen as the reactive species. Antimicrobial photodynamic therapy was studied using photodynamic antimicrobial chemotherapy (PACT) assay against E. coli and all complexes exhibited significant reduction in bacterial growth on photoirradiation.

Gas-Phase Ion/Ion Reactions Involving Tris-Phenanthroline Alkaline Earth Metal Complexes as Charge Inversion Reagents for the Identification of Fatty Acids.

Fatty acids (FA) play vital biological roles as energy sources, signaling molecules and key building blocks of complex lipids in cell membranes. Modifications to FA structure and composition are associated with the onset and progression of a number of chronic diseases. Consequently, the sensitive detection and unambiguous structure elucidation of FA is integral to the advancement of biomedical sciences. Recent advances in FA analysis have taken advantage of wet chemical derivatization to enhance detection and drive unique fragmentation in tandem mass spectrometry protocols. Here, we significantly further this approach through demonstrating gas-phase charge inversion of singly deprotonated FA ions, [M - H]-, using doubly charged tris-phenanthroline alkaline earth metal complexes, [Cat(Phen)3]2+ (Cat = Mg2+, Ca2+, Sr2+, or Ba2+). Metal cationized FA, [M - H + Cat]+ are obtained after the gas-phase ion/ion reaction. Low-energy collision-induced dissociation (CID) of the [M - H + Cat]+ cations facilitates double bond localization for a variety of monounsaturated and polyunsaturated FAs. Ultimately, detailed characterization presented unambiguous distinction among FA double bond positional isomers, such as n-3 and n-6 isomers. The method was successfully used to identify the FA profile of corn oil, including double bond localization for unsaturated FAs present.

Heparin-stabilized gold nanoparticles-based CUPRAC colorimetric sensor for antioxidant capacity measurement.

Sensing of total antioxidant capacity (TAC) as an integrated parameter showing the collective action of various antioxidants is an important challenge in food, biochemical and drug analysis. A novel heparin-stabilized gold nanoparticles (AuNPs)-based 'cupric reducing antioxidant capacity' (CUPRAC) colorimetric sensor was designed for TAC measurement. Heparin, a sulfated polysaccharide, was both the reducing and stabilizing agent for distinct negatively-charged AuNPs synthesis. The stabilized AuNPs were added to the copper(I)-neocuproine (Cu(I)-Nc) solution formed from the reaction of Cu(II)-Nc with antioxidants, and the absorbance of the resulting Cu(I)-Nc-AuNPs (Cu(I)-Nc cationic chelate electrostatically adsorbed on gold nanoparticles) was measured at 455 nm. As opposed to other similar AuNPs-based sensors, the proposed nano-sensor exhibited excellent (1000-fold) tolerance toward inert electrolytes without aggregation. The linear range was wider than that of conventional CUPRAC, with lower LOD (0.2 µM for trolox) and higher molar absorptivity (8.36â€¯× 104 M-1 cm-1 for quercetin). The 'trolox equivalent antioxidant capacity' (TEAC) values and activity order for a number of antioxidants were in accordance with those of the reference CUPRAC assay. Antioxidant additions to black tea extract gave recoveries of 93-97% and RSD 2-6%. This green sensor significantly reduced reagent consumption, and operated in complex food samples with a simple, reliable and robust methodology.

Comparisons of the spectroscopic and microbiological activities among coumarin-3-carboxylate, o-phenanthroline and zinc(II) complexes.

Coumarins (2H-chromen-2-one) are oxygen-containing heterocyclic compounds that belong to the benzopyranones family. In this work we have synthesized different coordination complexes with coumarin-3-carboxylic acid (HCCA), o-phenanthroline (phen) and zinc(II). In the reported [Zn(CCA)2(H2O)2] complex, coumarin-3-carboxylate (CCA) is acting as a bidentate ligand while in the two prepared complexes, [Zn(phen)3]CCA(NO3) (obtained as a single crystal) and [Zn(CCA)2phen].4H2O, CCA is acting as a counterion of the complex cation [Zn(phen)3]+2 or coordinated to the metal center along with phen, respectively. These compounds were characterized on the basis of elemental analysis and thermogravimetry. NMR, FTIR and Raman spectroscopies of the compounds and the CCA potassium salt (KCCA) allow to determine several similarities and differences among them. Finally, their behavior against alkaline phosphatase enzyme and their antimicrobial activities were also measured.

Analysis of phenolic acids by ionic liquid-in-water microemulsion liquid chromatography coupled with ultraviolet and electrochemical detector.

An environmentally friendly ionic liquid-in-water (IL/W) microemulsion was established and applied as mobile phase in microemulsion liquid chromatography (MELC) with ultraviolet (UV) detection or electrochemical detector (ECD) for analysis of phenolic compounds in real samples. The optimal condition of the method was using the best composition of microemulsion (0.2% w/v [HMIM]PF6, 1.0% w/v SDS, 3.0% w/v n-butanol, 95.8% v/v water, pH 2.5) with UV detection. The validation results indicated that the method provided high degree of sensitivity, precision and accuracy with the low limit of detections ranged from 17.9-238ng/mL, satisfactory mean recovery values in the range of 80.1-105% and good linearity (r2>0.9994). Additionally, this method exhibited high selectivity and resolution for the analytes and was more eco-friendly compared with traditional MELC method. Consequently, the established IL/W MELC method was successfully applied to simultaneously separate and determine target compounds in Danshen sample and its preparation.

Probing the Interactions of Cytotoxic [Pt(1S,2S-DACH)(5,6-dimethyl-1,10-phenanthroline)] and Its PtIV Derivatives with Human Serum.

The discrepancy between the in vitro cytotoxic results and the in vivo performance of Pt56MeSS prompted us to look into its interactions and those of its PtIV derivatives with human serum (HS), human serum albumin (HSA), lipoproteins, and serum-supplemented cell culture media. The PtII complex, Pt56MeSS, binds noncovalently and reversibly to slow-tumbling proteins in HS and in cell culture media and interacts through the phenanthroline group with HSA, with a Kd value of ∼1.5×10-6 m. All PtIV complexes were found to be stable toward reduction in HS, but those with axial carboxylate ligands, cct-[Pt(1S,2S-DACH)(5,6-dimethyl-1,10-phenantroline)(acetato)2 ](TFA)2 (Pt56MeSS(OAc)2 ) and cct-[Pt(1S,2S-DACH)(5,6-dimehtyl-1,10-phenantroline)(phenylbutyrato)2 ](TFA)2 (Pt56MeSS(PhB)2 ), were spontaneously reduced at pH 7 or higher in phosphate buffer, but not in Tris buffer (pH 8). HS also decreased the rate of reduction by ascorbate of the PtIV complexes relative to the reduction rates in phosphate buffer, suggesting that for this compound class, phosphate buffer is not a good model for HS.

Zn2+-dependent autocatalytic activity of the Bordetella pertussis CyaA-hemolysin.

Proteolytic degradation of the ∼100-kDa isolated RTX (Repeat-in-ToXin) subdomain (CyaA-RTX) of the Bordetella pertussis CyaA-hemolysin (CyaA-Hly) was evidently detected upon solely-prolonged incubation. Here, a truncated CyaA-Hly fragment (CyaA-HP/BI) containing hydrophobic and acylation regions connected with the first RTX block (BI1015-1088) was constructed as a putative precursor for investigating its potential autocatalysis. The 70-kDa His-tagged CyaA-HP/BI fragment which was over-expressed in Escherichia coli as insoluble aggregate was entirely solubilized with 4 M urea. After re-naturation in a Ni2+-NTA affinity column, the purified-refolded CyaA-HP/BI fragment in HEPES buffer (pH 7.4) supplemented with 2 mM CaCl2 was completely degraded upon incubation at 37 °C for 3 h. Addition of 1,10-phenanthroline‒an inhibitor of Zn2+-dependent metalloproteases markedly reduced the extent of degradation for CyaA-HP/BI and CyaA-RTX, but the degradative effect was clearly enhanced by addition of 100 mM ZnCl2. Structural analysis of a plausible CyaA-HP/BI model revealed a potential Zn2+-binding His-Asp cluster located between the acylation region and RTX-BI1015-1088. Moreover, Arg997‒one of the identified cleavage sites of the CyaA-RTX fragment was located in close proximity to the Zn2+-binding catalytic site. Overall results demonstrated for the first time that the observed proteolysis of CyaA-HP/BI and CyaA-RTX fragments is conceivably due to their Zn2+-dependent autocatalytic activity.

Copper-mediated DNA damage by the neurotransmitter dopamine and L-DOPA: A pro-oxidant mechanism.

Oxidative DNA damage has been implicated in the pathogenesis of neurological disorders, cancer and ageing. Owing to the established link between labile copper concentrations and neurological diseases, it is critical to explore the interactions of neurotransmitters and drug supplements with copper. Herein, we investigate the pro-oxidant DNA damage induced by the interaction of L-DOPA and dopamine (DA) with copper. The DNA binding affinity order of the compounds has been determined by in silico molecular docking. Agarose gel electrophoresis reveals that L-DOPA and DA are able to induce strand scission in plasmid pcDNA3.1 (+/-) in a copper dependent reaction. These metabolites also cause cellular DNA breakage in human lymphocytes by mobilizing endogenous copper, as assessed by comet assay. Further, L-DOPA and DA-mediated DNA breaks were detected by the appearance of post-DNA damage sensitive marker γH2AX in cancer cell lines accumulating high copper. Immunofluorescence demonstrated the co-localization of downstream repair factor 53BP1 at the damaged induced γH2AX foci in cancer cells. The present study corroborates and provides a mechanism to the hypothesis that suggests metal-mediated oxidation of catecholamines contributes to the pathogenesis of neurodegenerative diseases.