Azobenzene as Antimicrobial Molecules

Azo molecules, characterized by the presence of a -N=N- double bond, are widely used in various fields due to their sensitivity to external stimuli, ch as light. The emergence of bacterial resistance has pushed research towards designing new antimicrobial molecules that are more efficient than those currently in use. Many authors have attempted to exploit the antimicrobial activity of azobenzene and to utilize their photoisomerization for selective control of the bioactivities of antimicrobial molecules, which is necessary for antibacterial therapy. This review will provide a systematic and consequential approach to coupling azobenzene moiety with active antimicrobial molecules and drugs, including small and large organic molecules, such as peptides. A selection of significant cutting-edge articles collected in recent years has been discussed, based on the structural pattern and antimicrobial performance, focusing especially on the photoactivity of azobenzene and the design of smart materials as the most targeted and desirable application.     

Metalloporphyrin receptors for bases

The review summarizes data on the reversible addition of inorganic and organic biologically active bases at the coordination sites of mixed complexes containing the porphyrin dianion as one of ligands. An analysis of the thermodynamic parameters revealed new receptors for small cyclic molecules holding promise for analytical purposes and sensorics. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 636–654, April, 2007.     

卟啉及金属卟啉的应用

卟啉和金属卟啉类化合物在仿生化学、催化、太阳能利用、特种材料、医学和分析化学等方面有着越来越重要的作用和应用。本文作一简单介绍。     

Single Amino-Acid Based Self-Assembled Biomaterials with Potent Antimicrobial Activity

The design and development of soft biomaterials based on amino acid and short-peptide have gained much attention due to their potent biomedical applications. A slight alteration in the side-chain of single amino acid in a peptide or protein sequence has a huge impact on the structure and function. Phenylalanine is one of the most studied amino acids, which contains an aromatic phenyl group connected through a flexible −CH₂− unit. In this work, we have examined whether flexibility and aromatic functionality of phenylalanine (Phe) are important in gel formation of model gelator Fmoc-Phe-OH or not. To examine this hypothesis, we synthesized Fmoc-derivatives of three analogues unnatural amino acids including cyclohexylalanine, phenylglycine, and homophenylalanine; which are slightly varied from Phe. Interestingly, all these three new analogues formed hydrogels in phosphate buffer at pH 7.0 having different gelation efficacy and kinetics. This study suggests that the presence of aromatic side-chain and flexibility are not mandatory for the gelation of this model gelator. Newly synthesized unnatural amino acid derivatives have also exhibited promising antimicrobial activity towards gram-positive bacteria by inhibiting cellular oxygen consumption. We further determined the biocompatibility of these amino acid derivatives by using a hemolysis assay on human blood cells. Overall studies described the development of single amino acid-based new injectable biomaterials with improved antimicrobial activity by the slight alteration in the side-chain of amino acid.     

Mirror‐Image Organometallic Osmium Arene Iminopyridine Halido Complexes Exhibit Similar Potent Anticancer Activity

Four chiral Os^II arene anticancer complexes have been isolated by fractional crystallization. The two iodido complexes, (S_Os,S_C)‐[Os(η⁶‐p‐cym)(ImpyMe)I]PF₆ (complex 2 , (S)‐ImpyMe: N‐(2‐pyridylmethylene)‐(S)‐1‐phenylethylamine) and (R_Os,R_C)‐[Os(η⁶‐p‐cym)(ImpyMe)I]PF₆ (complex 4 , (R)‐ImpyMe: N‐(2‐pyridylmethylene)‐(R)‐1‐phenylethylamine), showed higher anticancer activity (lower IC₅₀ values) towards A2780 human ovarian cancer cells than cisplatin and were more active than the two chlorido derivatives, (S_Os,S_C)‐[Os(η⁶‐p‐cym)(ImpyMe)Cl]PF₆, 1 , and (R_Os,R_C)‐[Os(η⁶‐p‐cym)(ImpyMe)Cl]PF₆, 3 . The two iodido complexes were evaluated in the National Cancer Institute 60‐cell‐line screen, by using the COMPARE algorithm. This showed that the two potent iodido complexes, 2 (NSC: D‐758116/1) and 4 (NSC: D‐758118/1), share surprisingly similar cancer cell selectivity patterns with the anti‐microtubule drug, vinblastine sulfate. However, no direct effect on tubulin polymerization was found for 2 and 4 , an observation that appears to indicate a novel mechanism of action. In addition, complexes 2 and 4 demonstrated potential as transfer‐hydrogenation catalysts for imine reduction.     

A New Antimicrobial Flavonol Glycoside from Alchornea Davidii

A new flavonol glycoside,isorhamnetin-3-O- β-D-xyloside,was isolated from the extract of leaves and twigs of Alchornea davidii (Euphorbiaceae).Its structure was established on the basis of the spectral analysis and chemical degradation.Antimicrobial assay showed that it moderately inhibited the growth of test bacteria (Staphylocoocu aureus,Bacillus subtilis and Pseudomonas fluorescens)and fungi (Candida albicans,Aspergillus niger and Trichophyton rubrum) with MICs at 50μg/ml.     

辽河减压渣油中卟啉的分离和分析

采用溶剂萃取－紫外可见吸收光谱法对辽河减压渣油中的卟啉进行了分离和鉴定,结果指出,乙腈能有效地将镍卟啉从辽河减压渣油中萃取分离出来,对卟啉组分进行甲烷磺酸脱金属,所得游离卟啉在可光区4个吸收峰的强度特征,表明辽河减压渣油中的卟啉以初卟啉（ETIO）为主。     

Conformational Study of Short Peptoid Models for Future Applications as Potent Antimicrobial Compounds

Development of peptides as clinically useful drugs is limited by their poor metabolic stability and low bioavailability. Recent progresses in chemical synthesis and design have led to several strategies for producing potent mimetics. This study aims to analyze sequence/structure requirements and composition for antimicrobial peptoid designs, as use of peptoids is one of the most representative approaches to meet the goal of biomimicry. Analysis of the designs showed that for maximum activity and minimum hemolysis, the plane of the aromatic residues should be at an angle between 0 and 90 ° with respect to membranes, cationic residues need not be at the terminal position, and central positions should be uniform in NIle, NLys, and NPhe residues.

     

金属卟啉核酸定位断裂剂的设计及氧化断裂研究

金属卟啉连接到一些特殊基团如寡聚核苷酸、蛋白肽链、吖啶等上时, 可达到对DNA 的定位断裂, 这在核酸探针及抗癌剂的设计中具有重要的作用。本文就近年来国内外在金属卟啉对DNA 的定位识别及在Ph IO、KHSO 5、O 2? 还原剂等存在下, 对DNA 定位氧化断裂等方面的研究进展进行了综述, 可供该方向的研究人员参考。     

A 6,11,16‐Triarylbiphenylcorrole with an adj‐CCNN Core: Stabilization of an Organocopper(III) Complex

An adj‐dicarbacorrole with CCNN in the core is achieved by replacing the bipyrrole moiety by a simple polycyclic aromatic hydrocarbon, such as biphenyl unit. Spectroscopic studies and structural analyzes confirm the absence of macrocyclic aromatization, thus leading to overall nonaromatic character. The trianionic core is effectively utilized to stabilize a copper(III) ion to form an organocopper complex.     

新型异噻唑啉酮化合物的合成和抑菌活性研究

合成了10个2-取代异噻唑啉酮化合物, 其中7个未见文献报道. 所有目标物的结构都经元素分析, ¹H NMR, MS及IR证实, 并将其中8个化合物对五种细菌进行了抑菌活性测试. 与市售农药20%三环唑、70%威尔达甲托以及三氯新的抑菌活性进行对比, 发现它们对五种有害菌种均有极强的杀菌活性.     

氨基卟啉配合物的合成、表征和催化性能研究

合成了3种5－（4－乙二胺烷氧基）苯基－10,15,20－三苯基卟啉及其锰配合物,并用UV－Vis,IR,^1H NMR和LC－MCD表征了它们的结构。考察了这3种锰卟啉配合物对空气－乙苯体系直接羟基化的催化性能。结果表明,这种氨基卟啉配合物对空气氧化乙苯体系具有良好的催化作用,其催化活性比四苯基卟啉强3倍－4倍。     

模拟天然抗菌多肽高分子抗菌药物的研究进展

由于传统抗生素类药物容易使细菌产生耐药性而成为超级细菌,新型的抗菌药物亟待开发。通过模拟天然抗菌多肽设计合成的高分子抗菌剂,具有很高的抗菌活性和生物选择性,而且由于其合成方法简单,结构易于控制,且可实现大规模工业生产,有望成为代替传统抗生素和抗菌多肽的新一代抗菌药物。本文介绍了天然抗菌多肽的抗菌机理与模拟天然抗菌多肽的...     

Amide Moieties Modulate the Antimicrobial Activities of Conjugated Oligoelectrolytes against Gram-negative Bacteria

Cationic conjugated oligoelectrolytes (COEs) are a class of compounds that can be tailored to achieve relevant in vitro antimicrobial properties with relatively low cytotoxicity against mammalian cells. Three distyrylbenzene-based COEs were designed containing amide functional groups on the side chains. Their properties were compared to two representative COEs with only quaternary ammonium groups. The optimal compound, COE2−3C−C3-Apropyl , has an antimicrobial efficacy against Escherichia coli with an MIC=2 μg mL⁻¹, even in the presence of human serum albumin low cytotoxicity (IC₅₀=740 μg mL⁻¹) and minimal hemolytic activity. Moreover, we find that amide groups increase interactions between COEs and a bacterial lipid mimic based on calcein leakage assay and allow COEs to readily permeabilize the cytoplasmic membrane of E. coli. These findings suggest that hydrogen bond forming moieties can be further applied in the molecular design of antimicrobial COEs to further improve their selectivity towards bacteria.     

Combining Topology and Sequence Design for the Discovery of Potent Antimicrobial Peptide Dendrimers against Multidrug‐Resistant Pseudomonas aeruginosa

Multidrug‐resistant opportunistic bacteria, such as Pseudomonas aeruginosa, represent a major public health threat. Antimicrobial peptides (AMPs) and related peptidomimetic systems offer an attractive opportunity to control these pathogens. AMP dendrimers (AMPDs) with high activity against multidrug‐resistant clinical isolates of P. aeruginosa and Acinetobacter baumannii were now identified by a systematic survey of the peptide sequences within the branches of a distinct type of third‐generation peptide dendrimers. Combined topology and peptide sequence design as illustrated here represents a new and general strategy to discover new antimicrobial agents to fight multidrug‐resistant bacterial pathogens.     

Molecular Dyads Comprising Metalloporphyrin and Alkynylplatinum(II) Polypyridine Terminal Groups for Use as a Sensitizer in Dye‐Sensitized Solar Cells

A new class of molecular dyads comprising metalloporphyrin‐linked alkynylplatinum(II) polypyridine complexes with carboxylic acids as anchoring groups has been designed and synthesized. These complexes can sensitize nanocrystalline TiO₂ in dye‐sensitized solar cell (DSSC) studies. The photophysical, electrochemical, and luminescence properties of the complexes were studied and their excited‐state properties were investigated by nanosecond transient absorption spectroscopy, with the charge‐separated [Por^.??{(C?C)Pt(tBu₃tpy)}^.+] state observed upon excitation. Excited‐state redox potentials were determined; the electrochemical data supports the capability of the complexes to inject an electron into the conduction band of TiO₂. The complexes sensitize nanocrystalline TiO₂ and exhibited photovoltaic properties, as characterized by current–voltage measurements under illumination of air mass 1.5 G sunlight (100 mWcm^?2). A DSSC based on one of the complexes showed a short‐circuit photocurrent of 10.1 mAcm^?2, an open‐circuit voltage of 0.64 V, and a fill factor of 0.52, giving an overall power conversion efficiency of 3.4 %.     

Isatin Bis-Indole and Bis-Imidazothiazole Hybrids: Synthesis and Antimicrobial Activity

Isatin and its derivatives are important heterocycles found in nature and present in numerous bioactive compounds which possess various biological activities. Moreover, it is an essential building block in organic synthesis. The discovery of novel compounds active against human pathogenic bacteria and fungi is an urgent need, and the isatin may represent the suitable scaffold in the design of biologically relevant antimicrobials. A small library of 18 isatin hybrids was synthetized and evaluated for their antimicrobial potential on three reference strains: S. aureus, E. coli, both important human pathogens infamous for causing community- and hospital-acquired severe systemic infections; and C. albicans, responsible for devastating invasive infections, mainly in immunocompromised individuals. The study highlighted two lead compounds, 6k and 6m, endowed with inhibitory activity against S. aureus at very low concentrations (39.12 and 24.83 µg/mL, respectively).     

BOPHY-Fullerene C60 Dyad as a Photosensitizer for Antimicrobial Photodynamic Therapy

A novel BOPHY–fullerene C₆₀ dyad ( BP-C₆₀ ) was designed as a heavy-atom-free photosensitizer (PS) with potential uses in photodynamic treatment and reactive oxygen species (ROS)-mediated applications. BP-C₆₀ consists of a BOPHY fluorophore covalently attached to a C₆₀ moiety through a pyrrolidine ring. The BOPHY core works as a visible-light-harvesting antenna, while the fullerene C₆₀ subunit elicits the photodynamic action. This fluorophore–fullerene cycloadduct, obtained by a straightforward synthetic route, was fully characterized and compared with its individual counterparts. The restricted rotation around the single bond connecting the BOPHY and pyrrolidine moieties led to the formation of two atropisomers. Spectroscopic, electrochemical, and computational studies disclose an efficient photoinduced energy/electron transfer process from BOPHY to fullerene C₆₀. Photodynamic studies indicate that BP-C₆₀ produces ROS by both photomechanisms (type I and type II). Moreover, the dyad exhibits higher ROS production efficiency than its individual constitutional components. Preliminary screening of photodynamic inactivation on bacteria models (Staphylococcus aureus and Escherichia coli) demonstrated the ability of this dyad to be used as a heavy-atom-free PS. To the best of our knowledge, this is the first time that not only a BOPHY–fullerene C₆₀ dyad is reported, but also that a BOPHY derivative is applied to photoinactivate microorganisms. This study lays the foundations for the development of new BOPHY-based PSs with plausible applications in the medical field.