Eco-friendly intracellular biosynthesis of CdS quantum dots using Pseudomonas aeruginosa: Evaluation of antimicrobial effects and DNA cleavage activities

Background: Intracellular biosynthesis of quantum dots (QDs) based on microorganisms offers a green alternative and eco-friendly for the production of nanocrystals with superior properties. This study focused on the production of intracellular CdS QDs by stimulating the detoxification metabolism of Pseudomonas aeruginosa. Methods: For this aim, Pseudomonas aeruginosa ATCC 27853 strain was incubated in a solution of 1mM cadmium sulphate (CdSO4) to manipulate the detoxification mechanism. The intracellularly formed Cd-based material was extracted, and its characterization was carried out by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and dynamic light scattering (DLS) analyses and absorption-emission spectra. Results: The obtained material showed absorption peaks at 385 nm and a luminescence peak at 411 nm, and the particle sizes were measured in the range 4.63-17.54 nm. It was determined that the material was sphere-shaped, with a cubic crystalline structure, including Cd and S elements. The agar disk diffusion method investigated the antibacterial and antifungal activities of CdS QDs against eleven bacterial (four Gram-positive and seven Gram-negative) and one fungal strain. It was revealed that the obtained material has antibacterial effects on both Gram-positive and Gram-negative bacteria. However, cleavage activity of CdS QDs on pBR322 DNA was not detected. Conclusion: As a result, it has been proposed that the stimulation of the detoxification mechanism can be an easy and effective way of producing green and cheap luminescent QDs or nanomaterial.

Σύμπλοκες ενώσεις του ουρανυλίου και του κοβαλτίου με μη-στεροειδή αντιφλεγμονώδη φάρμακα

Στην παρούσα διδακτορική διατριβή περιγράφεται η σύνθεση, ο δομικός χαρακτηρισμός και η μελέτη της βιολογικής δραστικότητας τριανταπέντε συμπλόκων ενώσεων του ουρανυλίου(II) και του κοβαλτίου με ligand μια σειρά από μη-στεροειδή αντιφλεγμονώδη φάρμακα παρουσία ή απουσία co-ligand ως δότες ατόμων Ν. Ο χαρακτηρισμός των συμπλόκων έγινε µε μετρήσεις µοριακής αγωγιµότητας, μαγνητικές μετρήσεις σε θερμοκρασία περιβάλλοντος, µε φασµατοσκοπία ΙR, UV-vis και (για τα σύμπλοκα του ουρανυλίου(II)) 1Η NMR και µε κρυσταλλογραφία ακτίνων–Χ.Η μελέτη της βιολογικής δράσης των συμπλόκων περιελάμβανε την αλληλεπίδρασή τους με το CT DNA, με το pBR322 πλασμιδιακό DNA, με τις αλβουμίνες του ορού BSA και HSA και τη διερεύνηση της αντιοξειδωτικής τους δράσης. Η μελέτη της αλληλεπίδρασης με το CT DNA πραγματοποιήθηκε με φασματοσκοπία UV-vis, ιξωδομετρία, ανταγωνιστική δράση με το ΕΒ και κυκλική βολταμμετρία για τα σύμπλοκα του κοβαλτίου. Η ικανότητα διάσπασης του pBR322 DNA εξετάστηκε με ηλεκτροφόρηση σε πηκτή αγαρόζης. Η αλληλεπίδραση με τις αλβουμίνες του ορού έλαβε χώρα με φασματοσκοπία φθορισμού όπου εξετάστηκε η ισχύς σύνδεσης των ενώσεων, και προσδιορίστηκε η πιθανή θέση σύνδεσης στα μόρια των αλβουμινών. Τα αποτελέσματα έδειξαν ισχυρή σύνδεση των ενώσεων στο CT DNA και στις αλβουμίνες ενώ μεταξύ των συμπλόκων της παρούσας διατριβής υπολογίστηκε και η υψηλότερη σταθερά σύνδεσης στο DNA από όλα τα σύμπλοκα Co-ΜΣΑΦ της βιβλιογραφίας. Η ικανότητα διάσπασης του υπερελικωμένου pBR322 DNA ήταν χαμηλή έως μέτρια ενώ τα σύμπλοκα της εργασίας έδειξαν εκλεκτικότητα ως προς την δέσμευση της ρίζας ABTS και αναγωγής του Η2Ο2 έναντι της ρίζας DPPH. Οι in silico μοριακές μελέτες πρόσδεσης έδειξαν εσωτερική συναρμογή των συμπλόκων στην διπλή έλικα του CT DNA και σύνδεση τους σε μια θέση στο μόριο των αλβουμινών, η οποία βρίσκεται κοντά στη θέση δέσμευσης του ibuprofen χωρίς όμως να ταυτίζονται οι θεωρητικά υπολογισμένες ενέργειες δέσμευσης με τις σταθερές σύνδεσης που υπολογίστηκαν από τα in vitro πειράματα.

Synthesis, Biomacromolecular Interactions, Photodynamic NO Releasing and Cellular Imaging of Two [RuCl(qn)(Lbpy)(NO)]X Complexes

Two light-activated NO donors [RuCl(qn)(Lbpy)(NO)]X with 8-hydroxyquinoline (qn) and 2,2′-bipyridine derivatives (Lbpy) as co-ligands were synthesized (Lbpy1 = 4,4′-dicarboxyl-2,2′-dipyridine, X = Cl− and Lbpy2 = 4,4′-dimethoxycarbonyl-2,2′-dipyridine, X = NO3−), and characterized using ultraviolet–visible (UV-vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (1H NMR), elemental analysis and electrospray ionization mass spectrometry (ESI-MS) spectra. The [RuCl(qn)(Lbpy2)(NO)]NO3 complex was crystallized and exhibited distorted octahedral geometry, in which the Ru–N(O) bond length was 1.752(6) Å and the Ru–N–O angle was 177.6(6)°. Time-resolved FT-IR and electron paramagnetic resonance (EPR) spectra were used to confirm the photoactivated NO release of the complexes. The binding constant (Kb) of two complexes with human serum albumin (HSA) and DNA were quantitatively evaluated using fluorescence spectroscopy, Ru-Lbpy1 (Kb~106 with HSA and ~104 with DNA) had higher affinity than Ru-Lbpy2. The interactions between the complexes and HSA were investigated using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) and EPR spectra. HSA can be used as a carrier to facilitate the release of NO from the complexes upon photoirradiation. The confocal imaging of photo-induced NO release in living cells was successfully observed with a fluorescent NO probe. Moreover, the photocleavage of pBR322 DNA for the complexes and the effect of different Lbpy substituted groups in the complexes on their reactivity were analyzed.

Yb/chitosan catalyzed synthesis of highly substituted piperidine derivatives for potential nuclease activity and DNA binding study

Background: Herein, a new chitosan supported ytterbium nano-catalyst has been prepared and used for mild, efficient, and expeditious method for the synthesis of substituted piperidine derivatives via three component condensation of substituted anilines, formaldehyde and different cyclic/acyclic active methylene compounds at room temperature. Methods: The catalyst was characterized by FTIR, XRD, SEM, EDX, TEM, ICP-AES and the stability of catalyst was evaluated by TG analysis. The synthesized compound 3,3,11,11-Tetramethyl-15-(phenyl)-15- azadispiro[5.1.5.3]hexadecane-1,5,9,13-tetrone (3a) was explored for pBR322 DNA cleavage activity and genotoxicity for the first time. Further, the interaction study of 3a with CT-DNA was investigated through UV-vis, Fluorescence and Viscosity method. Results: The successful preparation of Yb/chitosan nano-catalyst was proved using various techniques and the catalyst was found effective towards substituted piperidine formations with the catalyst reusability. Further, compound 3a was successfully tested for DNA cleavage activity. In addition, Fluorescence results revealed that compound 3a interacts with DNA having a binding affinity of 4.84 x 104 M-1 . Conclusion: Hence, it could be suggested that compounds bearing spiro-piperidine scaffold synthesized using reusable nano-catalyst would be an effective biological agent.

Novel Benzimidazole Derived Imine-Based Ligand and its Co(III), Ni(II), Cu(II) and Pt(II) Complexes: Chemical Synthesis, Structure, Antimicrobial, DNA Interaction Studies and Nuclease Activity

Herein, we report the synthesis of a Schiff base ligand, 2-((E)-((1H-benzo[d]imidazol-2-yl)methylimino)methyl)-4,6-dichlorophenol (BMDC) and its Co(III), Ni(II), Cu(II) and Pt(II) coordinated compounds (henceforth named as M1, M2, M3, and M4, respectively). The synthesized compounds were subjected to various analytical and physical characterization techniques to confirm their molecular structures. Further, the DNA binding and cleavage propensity of the as-prepared metal complexes were evaluated using calf thymus DNA (CT-DNA) and supercoiled plasmid DNA (pBR322). The DNA interaction results revealed that the tested metal complexes bind with DNA through the covalent and non-covalent mode of interaction, which is investigated using absorption and fluorescence spectral studies followed by viscosity measurement. The scission of supercoiled plasmid DNA by the metal complexes suggested the potentiality of the molecules toward the cleavage of pBR322 DNA. Furthermore, the compounds were screened for in vitro antiproliferative activity, tested against the various cell lines such as A549, EAC, SIHA, and NIH3T3. Results revealed that compound M4 exhibited marked anti-proliferative activity against EAC cell line with a significant IC50 value of 10 µm compared to its parent ligand, BMDC, and other metal transition complexes under study. In addition, various hematological parameters (alkaline phosphate, creatinine, urea, RBC, and WBC) were studied, and significant results are obtained from the experiments.

Equilibrium, DNA Cleavage and Antimicrobial Studies of Cu(II) and Zn(II) Complexes with Novel 1-Propionyl-4-methyl-3-thiosemicarbazide

Cu(II) and Zn(II) metal complexes with novel Schiff base 1-propionyl-4-methyl-3-thiosemicarbazide (PMTSC) were synthesized and characterized by LC-MS, IR, 1H NMR (D2O exchangeable), 13C NMR and UV-visible spectra, ESR, TGA, molar conductance and magnetic susceptibility measurements. The spectro-analytical studies revealed the composition of complexes as ML2 for Cu(II)-PMTSC and Zn(II)-PMTSC complex. The proton-ligand dissociation constant and metal-ligand formation constants of PMTSC with Zn(II) have been determined in 70 % (v/v) DMF-water medium at 0.1M (KNO3) ionic strength and 303 K using potentiometric Irving-Rossotti titration technique. The results revealed that PMTSC acts as monobasic ligand by releasing proton from amide via enol form and forms 1:2 (Zn-L) complex in solution. The cleavage of plasmid pBR322 DNA without any additives was monitored by gel electrophoresis and these complexes exhibited hydrolytic cleavage of plasmid DNA. The antibacterial activity of the Schiff base and its Cu(II) and Zn(II) complexes were tested against Gram-positive and Gram-negative bacteria.

DNA Cleavage Properties, Antimicrobial and Cytotoxic Activity and 4D-QSAR Analysis of Some Pyrazole Derivatives

Background:An extensive study of 19 pyrazole derivatives were carried out based on the evaluation of DNA cleavage properties, antimicrobial and cytotoxic activities and 4D-QSAR analysis including pharmacophore modelling and bioactivity prediction by the Electron Conformational-Genetic Algorithm (EC-GA) method.Methods:The pyrazole derivatives were tested for their antimicrobial activity against certain human pathogenic organisms using the agar diffusion procedure. Binding of compounds with DNA was studied by gel electrophoresis using plasmid pBR322 DNA. The compounds were investigated for their properties as cytotoxic agents by brine shrimp lethality bioassay. To identify the pharmacophoric elements and find out the most important molecular properties which govern cytotoxic activity, multiple conformations of the compounds were used.Results:The urea derivatives of pyrazole had higher antibacterial activities against Gram-negative bacteria than against Gram-positive bacteria. Many of the compounds were found to cleave plasmid pBR322 DNA from the supercoiled form to the nicked circular. The cytotoxicity values of the compounds ranged from 13.87 to 84.1 µg/mL. The generated QSAR model was evaluated through the use of the Leave-One-Out Cross Validation (LOO-CV) method. A statistically significant and considerably predictive QSAR model was obtained with 4- descriptors resulting in R2 training =0.8223, R2 test =0.9346, q2=0.6201, q2 ext1=0.8672, q2 ext2= 0.8662 and q2 ext3=0.9511.Discussion:The generated model demonstrates that geometrical parameters are more correlated with cytotoxic activity. The resulting EC-GA model would provide benefits to design novel bioactive pyrazole derivatives which are more potent and have less side effects.Conclusion:It is believed that the generated QSAR model gives insight into developing new more potent pyrazole derivative drugs.

Evaluation of Nitrobenzyl Derivatives of Camptothecin as Anti-Cancer Agents and Potential Hypoxia Targeting Prodrugs

As part of our initial efforts into developing a tumor-targeting therapy, C-10 substituted derivatives of a camptothecin analog (SN-38) have been synthesized (2-, 3- and 4-nitrobenzyl) for use as potential hypoxia-activated prodrugs and evaluated for their cytotoxicity, topoisomerase I inhibition and electrochemical (reductive) properties. All three derivatives were found to possess reduced toxicity towards human leukemia K562 cells compared to SN-38, validating a condition for prodrug action. Using an MTS assay, IC50’s were found to be 3.0, 25.9, 12.2 and 58.0 nM for SN-38, 2-nitro-, 3-nitro- and 4-nitrobenzyl-C10-substituted-SN-38, respectively, representing an 8-, 4- and 19-fold decrease in cytotoxicity. Using a topoisomerase I assay, one of the analogs (4-nitrobenzyl) was shown to inhibit the ability of this enzyme to relax supercoiled pBR322 DNA, at a similar concentration to the clinically-approved active metabolite SN-38. Cyclic voltammetry detailed the reductive nature of the analogs, and was used to infer the potential of these compounds to serve as hypoxia-targeting prodrugs. The electrochemical results also validated the quasi-reversible nature of the first reduction step, and served as a proof-of-principle that hypoxia-targeting prodrugs of SN-38 can participate in a redox-futile cycle, the proposed mechanism of activation and targeting. Chemical reduction of the 4-nitrobenzyl analog led to the formation/release of SN-38 and validated the prodrug ability of the C-10 substituted derivative.