Different coordination abilities of 1,7- and 4,7-phenanthroline in the reactions with copper(II) salts: Structural characterization and biological evaluation of the reaction products

The reactions between equimolar amounts of CuX2 (X = NO3− and CF3SO3−) and two aromatic nitrogen-containing heterocycles differing in the position of nitrogen atoms, 1,7- and 4,7-phenanthroline (1,7- and 4,7-phen), were performed in ethanol/methanol at room temperature. When CuX2 salts were mixed with 4,7-phen, two copper(II) complexes, [Cu(NO3)2(4,7-Hphen)2](NO3)2 (1) and [Cu(CF3SO3)(4,7- phen)2(H2O)2]CF3SO3 (2), were formed. On the other hand, in the reaction of CuX2 salts with 1,7-phen, only 1,7-HphenNO3 (3a/b) and 1,7-HphenCF3SO3 (4) were obtained as the final products. The obtained products 1–4 were characterized by spectroscopic and X-ray diffraction techniques. In the copper(II) complexes 1 and 2, the coordination geometry around the Cu(II) ion is distorted octahedral and square pyramidal, respectively. The antimicrobial potential of the copper(II) complexes 1 and 2 and corresponding compounds used for their synthesis were assessed against four different bacterial species and Candida albicans, displaying moderate growth inhibiting activity. The cytotoxic properties of the investigated complexes were also evaluated against the normal human lung fibroblast cell line (MRC-5) indicating moderate, yet more pronounced cytotoxicity than antimicrobial properties

Genomics-Based Insights Into the Biosynthesis and Unusually High Accumulation of Free Fatty Acids by Streptomyces sp NP10

Schneider O, Ilic-Tomic T, Rückert C, et al. Genomics-Based Insights Into the Biosynthesis and Unusually High Accumulation of Free Fatty Acids by Streptomyces sp NP10. FRONTIERS IN MICROBIOLOGY. 2018;9: 10.Streptomyces sp. NP10 was previously shown to synthesize large amounts of free fatty acids (FFAs). In this work, we report the first insights into the biosynthesis of these fatty acids (FAs) gained after genome sequencing and identification of the genes involved. Analysis of the Streptomyces sp. NP10 draft genome revealed that it is closely related to several strains of Streptomyces griseus. Comparative analyses of secondary metabolite biosynthetic gene clusters, as well as those presumably involved in FA biosynthesis, allowed identification of an unusual cluster C12-2, which could be identified in only one other S. griseus-related streptomycete. To prove the involvement of identified cluster in FFA biosynthesis, one of its three ketosynthase genes was insertionally inactivated to generate mutant strain mNP10. Accumulation of FFAs in mNP10 was almost completely abolished, reaching less than 0.01% compared to the wild-type strain. Cloning and transfer of the C12-2 cluster to the mNP10 mutant partially restored FFA production, albeit to a low level. The discovery of this rare FFA biosynthesis cluster opens possibilities for detailed characterization of the roles of individual genes and their products in the biosynthesis of FFAs in NP10

Antiplasmodial activity and in vivo bio-distribution of chloroquine molecules released with a 4-(4-ethynylphenyl)-triazole moiety from organometallo-cobalamins

We have explored the possibility of using organometallic derivatives of cobalamin as a scaffold for the delivery of the same antimalarial drug to both erythro- and hepatocytes. This hybrid molecule approach, intended as a possible tool for the development of multi-stage antimalarial agents, pivots on the preparation of azide- functionalized drugs which, after coupling to the vitamin, are released with a 4-(4- ethynylphenyl)-triazole functionality. Three chloroquine and one imidazolopiperazine derivative (based on the KAF156 structure) were selected as model drugs. One hybrid chloroquine conjugate was extensively studied via fluorescent labelling for in vitro and in vivo bio-distribution studies and gave proof-of-concept for the design. It showed no toxicity in vivo (zebrafish model) as well as no hepatotoxicity, no cardiotoxicity or developmental toxicity of the embryos. All 4-(4-ethynylphenyl)-triazole derivatives of chloroquine were equally active against chloroquine-resistant (CQR) and chloroquine- sensitive (CQS) Plasmodium falciparum strains

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

Mononuclear silver(I) complexes with 1,7-phenanthroline as potent inhibitors of Candida growth

Mononuclear silver(I) complexes with 1,7-phenanthroline (1,7-phen), [Ag(NO3-O,O′) (1,7-phen-N7)2] (1) and [Ag(1,7-phen-N7)2]X, X = ClO4− (2), CF3SO3− (3), BF4− (4) and SbF6− (5) were synthesized and structurally characterized by NMR (1H and 13C), IR and UV–Vis spectroscopy and ESI mass spectrometry. The crystal structures of 1, 3 and 4 were determined by single-crystal X-ray diffraction analysis. In all these complexes, 1,7-phen coordinates to the Ag(I) ion in a monodentate fashion via the less sterically hindered N7 nitrogen atom. The investigation of the solution stability of 1–5 in DMSO revealed that they are sufficiently stable in this solvent at room temperature. Complexes 1–5 showed selectivity towards Candida spp. in comparison to bacteria, effectively inhibiting the growth of four different Candida species with minimal inhibitory concentrations (MIC) between 1.2 and 11.3 μM. Based on the lowest MIC values and the lowest cytotoxicity against healthy human fibroblasts with selectivity index of more than 30, the antifungal potential was examined in detail for the complex 1. It had the ability to attenuate C. albicans virulence and to reduce epithelial cell damage in the cell infection model. Induction of reactive oxygen species (ROS) response has been detected in C. albicans, with fungal DNA being one of the possible target biomolecules. The toxicity profile of 1 in the zebrafish model (Danio rerio) revealed improved safety and activity in comparison to that of clinically utilized silver(I) sulfadiazine

Special Issue on Environmental Biocatalysis

Biocatalysis has developed new molecular tools for the improvement of a wide range of bioprocesses that diminish raw material and energy consumption, while reducing or eliminating the formation of byproducts that might be hazardous to human health and the environment [...

High frequency transformation of the Amphotericin-producing bacterium Streptomyces nodosus

This study has investigated DNA transformation in the Amphotericin-producing organism Streptomyces nodosus. Amphotericin B is an antifungal drug with severe side effects in humans and the availability of structural variants would aid investigations into the mode of action and cytotoxity of the drug. Analogs of related polyketide drugs have been rapidly made by genetic engineering of biosynthetic genes; however, this requires the introduction of foreign DNA into the host. Protocols for protoplast formation and regeneration were established; however, preparations were recalcitrant to DNA uptake. Electroporation-mediated methodologies also were not successful. Intergeneric conjugal transfer of DNA from E. coli demonstrated transformation efficiencies of 5Ã10−5 exconjugants generated per recipient. Use of DNA methylation-impaired E. coli donor strains resulted in 100-fold higher transformation efficiencies, indicating that DNA methylation recognition systems are operable in the organism. This methodology will enable genetic and biochemical analysis of the gene cluster responsible for making Amphotericin B

High yield preparation of genomic DNA from Streptomyces

Streptomyces species produce important drugs such as antibiotics, immunosuppressants, and antitumor compounds.The isolation of genomic DNA is imperative for the understanding of the biosynthesis of these compounds and has led to the rational design of new analogs (1−5). Streptomyces are Gram-positive bacteria, making DNA isolation difficult due to their resistance to cell lysis (6,7). Most methods use lysozyme and sodium docecyl sulfate (SDS) for cell disruption. To further increase lysis, glycine is often incorporated into media to minimize peptidoglycan cross-linking; muramidases such as mutanolysin or grinding of mycelia are also commonly used (1,8−10). Compared with DNA isolation methods for Escherichia coli, most methods are time-consuming or low yielding, or give low-quality DNA (1). This report details an improved method for DNA isolation from Streptomyces species using achromopeptidase, lysozyme, and SDS for cell lysis that results in higher yield compared with current standard methods

FadD from Pseudomonas putida CA-3 Is a True Long-Chain Fatty Acyl Coenzyme A Synthetase That Activates Phenylalkanoic and Alkanoic Acids▿ †

A fatty acyl coenzyme A synthetase (FadD) from Pseudomonas putida CA-3 is capable of activating a wide range of phenylalkanoic and alkanoic acids. It exhibits the highest rates of reaction and catalytic efficiency with long-chain aromatic and aliphatic substrates. FadD exhibits higher kcat and Km values for aromatic substrates than for the aliphatic equivalents (e.g., 15-phenylpentadecanoic acid versus pentadecanoic acid). FadD is inhibited noncompetitively by both acrylic acid and 2-bromooctanoic acid. The deletion of the fadD gene from P. putida CA-3 resulted in no detectable growth or polyhydroxyalkanoate (PHA) accumulation with 10-phenyldecanoic acid, decanoic acid, and longer-chain substrates. The results suggest that FadD is solely responsible for the activation of long-chain phenylalkanoic and alkanoic acids. While the CA-3ΔfadD mutant could grow on medium-chain substrates, a decrease in growth yield and PHA accumulation was observed. The PHA accumulated by CA-3ΔfadD contained a greater proportion of short-chain monomers than did wild-type PHA. Growth of CA-3ΔfadD was unaffected, but PHA accumulation decreased modestly with shorter-chain substrates. The complemented mutant regained 70% to 90% of the growth and PHA-accumulating ability of the wild-type strain depending on the substrate. The expression of an extra copy of fadD in P. putida CA-3 resulted in increased levels of PHA accumulation (up to 1.6-fold) and an increase in the incorporation of longer-monomer units into the PHA polymer