Search

The information about the presence of free radicals in biological materials was given forthe first time about 70 years ago. Since then, numerous scientific studies have been conducted and thescience of free radicals was introduced. Today we know that free radicals are by-products of enzymaticreactions occurring in the organism. They are produced during endogenous processes such as cellrespiration, phagocytosis, biosynthesis, catalysis, and biotransformation. They can also be producedby exogenous processes (radiation, sunlight, heavy metals, bacteria, fungi, protozoa, and viruses). Theoverproduction of free radicals affects the aging processes, Oxidative Stress (OS) and takes part in thepathogenesis of various diseases. Among them are cancer, rheumatoid arthritis, neurodegenerativediseases: Alzheimer and Parkinson, pulmonary diseases, atherosclerosis, and DNA damage. Compoundswith antioxidant activity are very important nowadays because they allow organisms to keep abalance between the production of free radicals and the speed of their neutralization in the body. Nextto the natural antioxidants (flavonoids, carotenoids, vitamins, etc.), synthetic ones are also of greatimportance. Among synthetic compounds with antioxidant activity are 1,2,4-triazoles and their derivatives.1,2,4-Triazoles are heterocyclic compounds with three nitrogen atoms. Due to a broad spectrumof biological activities, these derivatives have been of interest to scientists for many years. Some ofthem are also used as drugs. The finding of new synthetic compounds with antioxidant features in thetriazole group has become an important problem of medicinal chemistry.

Background: Bacterial biofilms are a cause of a number of infections and are associated with specific drug resistance. In particular, dental biofilm can consist of up to 100 bacterial species and may result in the diseases in the teeth and the surrounding tissues, including dental caries and periodontal diseases. Moreover, pathogens from the dental biofilm can migrate to other organs and lead to systemic diseases. Thus, it is important to search for inhibitors of dental biofilm formation. The series of 1,4-disubstitued thiosemicarbazide derivatives were evaluated for their ability to inhibit mono-species Streptococcus mutans or Streptococcus sanguinis biofilm formation. Methods: The Minimum Biofilm Inhibitory Concentration (MBIC) is defined as the lowest concentration of an antimicrobial agent required to inhibit the formation of biofilm. MBIC was determined spectrophotometrically. Molecular docking was performed using Glide from the Schrödinger suite of software. The grid file was generated indicating acarbose as a reference ligand. The compounds were modeled using LigPrep protocol from the Schrödinger suite of software. Molecular docking was performed using the SP (standard precision) protocol of Glide. Molecular dynamics studies of ligand-receptor complexes was performed using Desmond v. 3.0.3.1.4. Results: The series of 1,4-disubstituted thiosemicarbazide derivatives were synthesized and investigated for their ability to inhibit S. mutans or S. sanguinis biofilm. The most active compounds caused inhibition of S. sanguinis and S. mutans biofilm formation in the concentration of 7.81 μg/ml- 62.5 μg/ml. We showed, that growth of S. mutans and S. sanguinis biofilm was faster and higher in presence of sucrose. Additionally it was harder to inhibit the growth of biofilm in BHIbroth with the presence of sucrose, than the biofilm growing in BHI without sucrose. It seems that colonization by tested caries bacteria depends on sucrose content in medium. Based on above in vitro anti-biofilm data, we postulated that the mechanism of antibacterial activity of the investigated compounds might be connected with the inhibition of mono-species bacteria biofilm formation. In order to demonstrate that the investigated compounds may inhibit the enzyme glucansucrase and thus, biofilm formation, we performed molecular docking and molecular dynamics of the studied compounds to glucansucrase crystal structure. The obtained results reveal that the thiosemicarbazide derivatives can be used as potential inhibitors of dental biofilm formation, acting possibly through inhibition of glucansucrase. Conclusion: In this study we showed that some of tested thiosemicarbazide derivatives can be used as potential inhibitors for mono-species cultures of S. mutans or S. sanguinis biofilm. The possible blocking mechanism of mono-species biofilm formation was proposed via molecular modelling technique. The data suggested that this mechanism may involve the glucansucrase inhibition as it was demonstrated that tested derivatives occupy the same binding pocket in this enzyme as acarbose, commonly known inhibitor of glucosylotransferases. Therefore, it is possible that tested derivatives could be used in prevention of dental caries.

In this study, we described the synthesis of the derivatives of thiosemicarbazide, dicarboximide, 1,2,4-triazole-5-thione and 4-oxo-1,3-thiazolidine. Two different dicarboxylic acid anhydrides reacted with 4-substituted-3-thiosemicarbazide, and derivatives of thiosemicarbazide and dicarboximide were obtained. Next, cyclization reaction of dicarboximide derivatives in alkaline media was used to prepare 1,2,4-triazole-5-thione. The 4-oxo-1,3-thiazolidine was synthesized by the reaction of dicarboximide with ethyl bromoacetate. All obtained derivatives were analysed by 1H and 13C NMR spectra, and for one compound, the X-ray crystallography was done. Antimicrobial, antiviral and in vitro evaluations of cytotoxicity were examined. According to the preliminary antiviral screening, compounds 3and 4presented the antiviral activity against HSV-1 and CVB3. Additionally, compound 3shows selective in vitro toxic effect against human epithelial cells FaDu, without affecting normal animal cell line (Vero). The same derivatives 3and 4also displayed a wide spectrum of antimicrobial activity against reference microorganisms and indicated both antibacterial and antifungal potential activities.

Infectious diseases are one of the most important and urgent health problems in the world. According to the World Health Organization (WHO) statistics, infectious and parasitic diseases are a cause of about 16% of all deaths worldwide and over 40% of deaths in Africa. A considerable progress that has been made during last hundred years in the fight against infectious diseases, in particular bacterial infections, can be attributed mainly to three factors: (1) the general improvement of living conditions, in particular sanitation; (2) development of vaccines and (3) development of efficient antibacterial drugs. Although considerable progress in reduction of the number of cases of bacterial infections, especially in lethal cases, has been made, continued cases and outbreaks of these diseases persist, which is caused by different contributing factors. Indeed, during last sixty years antibacterial drugs were used against various infectious diseases caused by bacterial pathogens with an undoubtable success. The most fruitful period for antibiotic development lasted from 40's to 60's of the last century and resulted in the majority of antibiotics currently on the market, which were obtained by screening actinomycetes derived from soil. Although the market for antibacterial drugs is nowadays greater than 25 billion US dollars per year, novel antibacterial drugs are still demanded due to developed resistance of many pathogenic bacteria against current antibiotics. In the last five years, one can observe a dramatic increase in cases of resistant bacteria strains (e.g. Klebsiella pneumoniae and E. coli) which are responsible for difficult to treat pneumonia and infections of urinary tract. The development of resistant bacteria strains is a side effect of antibiotic application for treatment: the infections become untreatable as a result of the existence of antibiotic-tolerant persisters. In this review, we discuss the challenges in antibacterial drug discovery, including the molecular basis of drug resistance, drug targets for novel antibacterial drugs, and new compounds (since year 2010) from different chemical classes with antibacterial activity, focusing on structure-activity relationships.

The article discusses the highlights of the Fire Toxicity Conference 2016 held at Preston in Lancashire, England. Topics covered include the evolution and measurement of toxic products from fires, short- and long-term care of fire victims, and safety and health issues for firefighters. Also mentioned are deficiencies in the regulatory framework that fails to protect fire victims from smoke inhalation, the quantification of the toxicity of effluents, and cancer in firefighters.

Here, we propose a self-assembly process to prepare hierarchical HM-SiO2@Co–Al LDH@graphene, with the purpose of combining their outstanding performance. Hollow mesoporous silica was first synthesized as the core, using a novel sonochemical method, followed by a controlled shell coating process and chemical reduction. As a result of the electrostatic potential difference among HM-SiO2, Co–Al LDH, and graphene oxide, the HM-SiO2spheres were coated by Co–Al LDH and graphene. Subsequently, the HM-SiO2@Co–Al LDH@graphene spheres were introduced into an epoxy resin (EP) matrix for investigation of their toxic effluents capture and elimination effectiveness during combustion. The amount of toxic CO and volatile organic compounds from the epoxy resin decomposition significantly suppressed after incorporating the HM-SiO2@Co–Al LDH@graphene hybrids, implying a reduced toxicity.

Hierarchical mesoporous silica@Co–Al layered double hydroxide (m-SiO2@Co–Al LDH) spheres were prepared through a layer-by-layer assembly process, in order to integrate their excellent physical and chemical functionalities. TEM results depicted that, due to the electrostatic potential difference between m-SiO2and Co–Al LDH, the synthetic m-SiO2@Co–Al LDH hybrids exhibited that m-SiO2spheres were packaged by the Co–Al LDH nanosheets. Subsequently, the m-SiO2@Co–Al LDH spheres were incorporated into epoxy resin (EP) to prepare specimens for investigation of their flame-retardant performance. Cone results indicated that m-SiO2@Co–Al LDH incorporated obviously improved fire retardant of EP. A plausible mechanism of fire retardant was hypothesized based on the analyses of thermal conductivity, char residues, and pyrolysis fragments. Labyrinth effect of m-SiO2and formation of graphitized carbon char catalyzed by Co–Al LDH play pivotal roles in the flame retardance enhancement.

Lipophilicities of 21 newly synthesized 1,2,4-triazoles, compounds of potential importance as fungicides, have been determined by micellar and reversed-phase planar chromatography. Different stationary and mobile phases were used in the measurements. Chromatographic lipophilicities (log kmand RM0) were correlated with partition coefficients log P(Alog Ps, AClog P, Alog P, Mlog P, KowWin, xlog P2and xlog P3) calculated from molecular structures. Principal component analysis allowed a more objective comparison of different lipophilicity descriptors determined from various chromatographic systems and calculated theoretically as log Pparameters.

N-Substituted amides of endo-3-(3-methylthio-1,2,4-triazol-5-yl)bicyclo[2.2.1]hept-5-ene- 2-carboxylic acid and 1-(5-methylthio-1,2,4-triazol-3-yl)cyclohexane-2-carboxylic acid were prepared by the condensation reaction of endo-S-methyl-N1-(bicyclo[2.2.1]hept-5-ene-2,3- dicarbonyl)isothiosemicarbazide and S-methyl-N1-(cyclohexane-2,3-dicarbonyl)isothiosemicarbazide with primary amines. The synthesized compounds were screened for their microbiological and pharmacological activities

The title compounds (IV) and (VI) are synthesized via two methods.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.