Search

This preliminary report shows eight complexes of triorganotin(IV): Ph3SnOH and (CH3)3SnOH with four chelating imines on new synthesis. Of these ligands, two are salen-like (four coordination sites, two imidic, two phenoxidic) [1], one is a tetradentate pyrrole derivative [2] while the fourth, a vita- min B6 derivative, is pentadentate [3]. Ligands have been characterized by means of FT-IR, UV-Vis, Fluorescence, 1H- and 13C-NMR, LC-MS ESI triple quadrupole; complexes by means FT-IR, 1H- and 119Sn-NMR, LC-MS ESI, using the isotopic distribution pattern as a discriminant [4]. Geometry and nature of coordination complexes have been also evaluated using the 119Sn chemical shifts. Solid-state synthesis of the complexes (with a ball mill [5]) was also explored; such method reduces both solvent consumption and time – from 8-10 h under controlled atmosphere to about 1 h, with results identical to the wet synthesis. Antitumoral and antibacterial activities of the triorganotin (IV) complexes (BS01M, BS01P, BS02M, BS02P, BS03M, BS03P, BS04M, BS04P) were tested in vitro. In both analyses, the Shiff bases alone showed no biological activity. Antimicrobial activity was evaluated by Kirby-Bauer method against the Gram-negative Escherichia coli, and the two Gram-positive Kocuria rizophila and Staphylococcus aureus strains. All the ML2 complexes were active in inhibiting bacterial growth, with BS02P and BS03P showing the best antibacterial performance. Among the ML complexes, BS01M was not active, BS02M showed a weak antibacterial activity only against the Gram-positive bacteria, BS04M was mainly active against the Gram-negative E. coli and BS03M was active against all the tested strains. Antitumor activity was evaluated by MTT assay against cervical (HeLa), colon adenocarcinoma (HT- 29) and breast (MDA-MB231) cancer cell lines. Results showed that ML2 complexes are more active than ML ones, with HeLa cells more sensitive to treatments. These complexes (especially the ML2) showed promising results; their mechanism of action is under investigation. References 1. K. Tayade, S.K. Sahoo, S. Chopra, N. Singh, Inorganica Chimica Acta, 421, 538-543 (2014); https://doi.org/10.1016/j. ica.2014.05.014 2. S. Meghdadi, M. Amirnasr, K. Mereiter, Polyhedron, 30, 1651-1656 (2011); https://doi.org/10.1016/j.poly.2011.03.041 3. D. Sharma, S.K. Sahoo, S. Chaudhary, R. Kanta Bera, J.F. Callan, Analyst, 138, 3646-3650 (2013); https://doi.org/10.1039/ C3AN00199G 4. G. Lawson, R.H. Dahm, N. Ostah, E.D. Woodland, Applied Organometallic Chemistry, 10, 125-133 (1996); https://doi. org/10.1002/(SICI)1099-0739(199603)10:23.0.CO;2-1 5. G.A. Bowmaker, Chemical Communications, 49, 334-348 (2013); http://doi.org/10.1039/C2CC35694E 6. R. Di Stefano, M. Scopelliti, C. Pellerito, G. Casella, T. Fiore, G.C. Stocco, R. Vitturi, L. Ronconi, I.D. Sciacca, L. Pellerito, Journal of Inorganic Biochemistry, 98, 534-546 (2004); https://doi.org/10.1016/j.jinorgbio.2003.12.013 7. C. Pellerito, L. Nagy, L. Pellerito, A. Szorcsik, Journal of Organometallic Chemistry, 691, 1733-1747 (2006); https://doi. org/10.1016/j.jorganchem.2005.12.025

DNA methylation is an epigenetic modification regulating many aspects of biological processes. DNA cytosine methylation plays mainly a regulatory role in chromatin organization, genome maintenance and gene expression in eukaryotes, while its role has not been deeply investigated in prokaryotes. Differently, DNA adenine methylation regulates chromosome replication, DNA repair, transposition of insertion elements in prokaryotes, while it is supposed to have exclusively a role in regulating gene expression and DNA replication in mitochondria. Streptomyces coelicolor is a soil-dwelling Gram-positive bacterium that exhibits a complex life cycle, with three different cell types (unigenomic spores, aerial and vegetative hyphae) and two events of programmed cell death, and produces three antibiotics. The aim of this project is to correlate DNA methylation with morphological and physiological differentiation of S. coelicolor. Dot blot analysis revealed that the global level of methylated cytosines and adenines changes during growth in liquid medium. The characterization of cytosine methylome, by Bisulphite-sequencing, revealed that 30% of S. coelicolor genes contain a AAGCCmCG or TGGCmCGGC motif in their upstream regions. Among these, genes related to differentiation, DNA repair and condensation were found. Treatment with 5-aza-2’-deoxycytidine, a hypomethylating agent, showed that DNA methylation influences growth and antibiotic production both in liquid and on solid culture. These results suggest a role for DNA cytosine methylation in morphological and physiological differentiation of S. coelicolor. Further experiments are ongoing to demonstrate if it has a role in regulating gene expression and/or in activating cell death events.

Lo scopo di questo studio è la realizzazione e lo studio di sistemi a rilascio controllato costituiti da silice mesoporosa MCM-41 e biocidi commerciali e di nuova generazione. Tali materiali possono essere utilizzati in ambito conservativo per risolvere alcuni problemi di biodeterioramento che interessano i manufatti di interesse storico-artistico e a scopo preventivo per ridurre il numero e la frequenza di interventi conservativi. La MCM-41 è stata preparata in ambiente alcalino mediante il metodo sol-gel utilizzando dei tensioattivi come templanti1. Al fine di creare un’interazione favorevole biocida-superficie, sulla superficie dei pori sono stati ancorati gruppi amminici. L’incapsulamento del biocida è stato effettuato mediante immersione ed è stato studiato il suo rilascio in acqua o in altri solventi utilizzati in ambito conservativo. La caratterizzazione dei materiali è stata effettuata mediante diffrattometria a raggi X e spettroscopia NMR. Il rilascio del biocida è stato seguito mediante spettroscopia Uvvis.