The Preparation,Characterization,antibacterial Activity And Mechanism Of A Polypyridyl Ruthenium Complex

The invention of antibiotics is a great achievement for mankind, which open the gate of antibiotic era with the emergence of penicillin. Which means a boom of many kinds of antibiotics. However with these antibiotics became more easy and cheaper to get, the bacterial drug resistance that caused by abuse of antibiotics has become even more severe. Thus the research and development of new antibacterial compounds is severely emergency to mankind. salvarsan and cisplatin as early metal antibacterial and anticancer drugs were made a big success. Yet its still exist some problems such like the side effects. By contrast, ruthenium compounds have better bioactivity and less side effects. Thus in respect of DNA binding ability and anticancer activities attracts lots of attention. The potential of its antibacterial activity and mechanisms are yet to be developed.This article mainly formed by two aspects. At first:three kinds of rutheniu m compounds [(Phen)2Ru(dppz)]2+, 2.2’-polypyridyl ruthenium and 1.10’-phenanthr oline ruthenium complexes were synthetic and measured. Mean while the antiba cterial activity of each kind of compound was studied and compared by MIC v alue. Secondly:take advantage of the florescent characteristic of these ruthenium compounds, then analyzed the metabolic status and the combination situation b etween compounds and DNA. a comparison of DNA combination ability betwee n two kinds of compounds were made. We used all these data in order to anal ysis and study the reason that cause the difference about the antibacterial activity of these two kind of compounds.In the first aspect compounds 2.2’-polypyridyl ruthenium complex, 1.10-phe nanthroline ruthenium complex, [(Phen)2Ru(dppz)]2+ were synthetic. Then these compounds were analyzed for a MIC assay on gram negative bacteria(Escheric hia coli, salmonella, pseudomonas aeruginosa) gram positive bacteria(staphyloco ccus aureus) drug-resistant bacteria(methicillin-resistant staphylococcus aureus) a nd fungi(Monilia albican, Saccharomyces cerevisiae). From the data of absorban ce analysis we found out that the antibacterial ability of 1.10-phenanthroline rut henium complex and [(Phen)2Ru(dppz)]2+ was much better than 2.2’-polypyridyl r uthenium complex, what’s more both those two complexes showed a broad-spe ctr um antibacterial activity for all kinds of microbial(gram-positive bacteria, gra m-negative bacteria and fungi)and an activity towards drug-resistance bacteria(me thicillin-resistant staphylococcus aureus).In the second aspect. The genomic DNA were extracted from Escherichia c oli then combine with these compounds separately. We found out that each kind of compound showed a good activity to combine with DNA,while the trend o f each compound were different because of the different structure. What’s more these compounds were used for a competitive inhibition with nucleic acid dye,still there were high activity which means they all have good DNA combination ability. At last gel electrophoresis were used to determined the DNA degradatio n ability of each kind of compound after incubation with Escherichia coli DNA in different concentration. As a result only 2.2’-polypyridyl ruthenium and [(Ph en)2Ru(dppz)]2+complex showed a activity of DNA degradation which means a b etter DNA combination ability.Then the etabolic rate of these three compounds i nside the bacteria were determined by fluorescence spectrophotometer instrument,and then validation by fluorescence microscope observation. Because of better l iposolubility 1.10-phenanthroline and [(Phen)2Ru(dppz)]2+ ruthenium complexcan get through the cell wall of bacteria more easily than 2.2’-polypyridyl ruthenium complex. In conclusion each compound have a good activity to combine with DNA. The [(Phen)2Ru(dppz)]2+ruthenium complex even showed the highest activi ty and the highest antibacterial activity correspondly. However 2.2’-polypyridyl r uthenium complex can’t get through the cell wall of bacteria because of poor li posolubility, which means a lowest antibacterial activity, even if it has a better DNA combination than 1.10-phenanthroline ruthenium complex.From this research both [(Phen)2Ru(dppz)]2+ and 2.2’-polypyridyl ruthenium complex showed a better DNA combination ability. However antibacterial activit y: [(Phen)2Ru(dppz)]2+>1.10-phenanthroline>2.2’-polypyridyl ruthenium. The reas on of this phenomenon comes from several aspects. Because of its higher DNA combination activity [(Phen)2Ru(dppz)]2+has the highest antibacterial activity. Wh ile because of poor liposolubility of 2.2’-polypyridyl ruthenium, which means it can’t through the cell wall of each kind of bacteria(include fungi)turns out to be a poor antibacterial activity. These studies provide a theoretical support of an tibacterial mechanism and designing strategy of antibacterial ruthenium complex.