Search Results (10)

Benzazoles, such as benzoxazoles and benzothiazoles, are compounds with important biological and pharmacological activities and important intermediaries in synthesis. This report presents the synthesis of a butanamide derived from linking 5-chloro-2-aminobenzoxazole and 2-aminobenzothiazole via 4-chlorobutanoyl chloride. The corresponding compound N-(benzothiazol-2-yl)-4-((5-chlorobenzoxazol-2-yl)aminobutanamide was obtained at a 76% global yield using accessible starting materials and a methodology in two reaction steps. Furthermore, we conducted docking studies of this compound on 3-TOP protein to explore its potential as an antidiabetic agent. Full article

Benzoxazole and benzothiazole have a broad spectrum of agricultural biological activities, such as antibacterial, antiviral, and herbicidal activities, which are important fused heterocyclic scaffold structures in agrochemical discovery. In recent years, great progress has been made in the research of benzoxazoles and benzothiazoles, especially in the development of herbicides and insecticides. With the widespread use of benzoxazoles and benzothiazoles, there may be more new products containing benzoxazoles and benzothiazoles in the future. We systematically reviewed the application of benzoxazoles and benzothiazoles in discovering new agrochemicals in the past two decades and summarized the antibacterial, fungicidal, antiviral, herbicidal, and insecticidal activities of the active compounds. We also discussed the structural–activity relationship and mechanism of the active compounds. This work aims to provide inspiration and ideas for the discovery of new agrochemicals based on benzoxazole and benzothiazole. Full article

In the search for new bioactive compounds, a methodology based on combining two molecules with biological properties into a new hybrid molecule was used to design and synthesize of a series of ten indole derivatives bearing imidazole, benzothiazole-2-thione, or benzoxazole-2-thione moieties at the C-3 position. The compounds were spectroscopically characterized and tested for their antioxidant, antibacterial, and fungicidal activities. The crystal structures were determined for five of them. Comparison of the closely related structures containing either benzothiazole-2-thione or benzoxazole-2-thione clearly shows that the replacement of -S- and -O- ring atoms modify molecular conformation in the crystal, changes intermolecular interactions, and has a severe impact on biological activity. The results indicate that indole-imidazole derivatives with alkyl substituent exhibit an excellent cytoprotective effect against AAPH-induced oxidative hemolysis and act as effective ferrous ion chelating agents. The indole-imidazole compound with chlorine atoms inhibited the growth of fungal strains: Coriolus versicolor (Cv), Poria placenta (Pp), Coniophora puteana (Cp), and Gloeophyllum trabeum (Gt). The indole-imidazole derivatives showed the highest antibacterial activity, for which the largest growth-inhibition zones were noted in M. luteus and P. fluorescens cultures. The obtained results may be helpful in the development of selective indole derivatives as effective antioxidants and/or antimicrobial agents. Full article

Fluorescent biopolymer derivatives are increasingly used in biology and medicine, but their resistance to heat and UV radiation, which are sterilizing agents, is relatively unknown. In this work, chitosan (CS) modified by three different heterocyclic aromatic dyes based on benzimidazole, benzothiazole, and benzoxazole (assigned as IBm, BTh, and BOx) has been studied. The thermal properties of these CS derivatives have been determined using the Thermogravimetric Analysis coupled with the Fourier Transform Infrared spectroscopy of volatile degradation products. The influence of UV radiation on the thermal resistance of modified, fluorescent chitosan samples was also investigated. Based on the temperature onset as well as the decomposition temperatures at a maximal rate, IBm was found to be more thermally stable than BOx and BTh. However, this dye gave off the most volatile products (mainly water, ammonia, carbon oxides, and carbonyl/ether compounds). The substitution of dyes for chitosan changes its thermal stability slightly. Characteristic decomposition temperatures in modified CS vary by a few degrees (<10 °C) from the virgin sample. Considering the temperatures of the main decomposition stage, CS-BOx turned out to be the most stable. The UV irradiation of chitosan derivatives leads to minor changes in the thermal parameters and a decrease in the number of volatile degradation products. It was concluded that the obtained CS derivatives are characterized by good resistance to heat and UV irradiation, which extends the possibilities of using these innovative materials. Full article

Chitosan is a valuable, functional, and biodegradable polysaccharide that can be modified to expand its applications. This work aimed to obtain chitosan derivatives with fluorescent properties. Three heterocyclic aromatic dyes (based on benzimidazole, benzoxazole, and benzothiazole) were synthesized and used for the chemical modification of chitosan. Emission spectroscopy revealed the strong fluorescent properties of the obtained chitosan derivatives even at a low N-substitution degree of the dye. The effect of high-energy ultraviolet radiation (UV–C) on modified chitosan samples was studied in solution with UV–Vis spectroscopy and in the solid state with FTIR spectroscopy. Moreover, cytotoxicity towards three different cell types was evaluated to estimate the possibilities of biomedical applications of such fluorescent chitosan-based materials. It was found that the three new derivatives of chitosan were characterized by good resistance to UV–C, which suggests the possibility of using these materials in medicine and various industrial sectors. Full article

A simple, economical and metal-free approach to the synthesis of 2-substituted benzoxazoles and 2-substituted benzothiazoles from 2-aminophenols, 2-aminothiophenols and DMF derivatives, only using imidazolium chloride (50% mmol) as promoter without any other additive, was reported. Various 2-substituted benzoxazoles and 2-substituted benzothiazoles were thus prepared in moderate to excellent yields. Full article

Based on benzoxazole and benzothiazole scaffold as an important pharmacophore, two series of 2-(aryloxymethyl) benzoxazole and benzothiazole derivatives were synthesized and their antifungal effects against eight phytopathogenic fungi were evaluated. Compounds 5a, 5b, 5h, and 5i exhibited significant antifungal activities against most of the pathogens tested. Especially 5a, 5b, 5h, 5i, 5j, and 6h inhibited the growth of F. solani with IC₅₀ of 4.34–17.61 μg/mL, which were stronger than that of the positive control, hymexazol (IC₅₀ of 38.92 μg/mL). 5h was the most potent inhibitor (IC₅₀ of 4.34 μg/mL) against F. Solani, which was about nine times more potent than hymexazol. Most of the test compounds displayed significant antifungal effects against B. cinerea (IC₅₀ of 19.92–77.41 μg/mL), among them, 5a was the best one (IC₅₀ of 19.92 μg/mL). The structure-activity relationships (SARs) were compared and analyzed. The result indicates that the electron-drawing ability and position of the substituents have a significant impact on biological activities. Furthermore, docking studies were carried out on the lipid transfer protein sec14p from S. cerevisiae, and preliminarily verified the antifungal activities. Taken together, these results provide 2-(phenoxymethyl)benzo[d]oxazole as an encouraging framework that could lead to the development of potent novel antifungal agents. Full article

Compounds possessing benzimidazole system exhibit significant antituberculous activity. In order to examine how structure modifications affect tuberculostatic activity, a series of benzazole derivatives were synthesized and screened for their antitubercular activity. The compounds 1–20 were obtained by the reaction between o-diamine, o-aminophenol, or o-aminothiophenol with carboxylic acids or thioamides. The newly synthesized compounds were characterized by IR, ¹H-NMR, ¹³C-NMR spectra, and elemental analysis. Synthesized benzazoles were evaluated for their tuberculostatic activity toward Mycobacterium tuberculosis strains. Quantum chemical calculations were performed to study the molecular geometry and the electronic structure of benzimidazoles GK-151B, 4, 6, and benzoxazole 11, using the Gaussian 03W software (Gaussian, Inc., Wallingford, CT, USA). Three-dimensional structure of benzimidazoles 1–3, MC-9, and GK-151B was determined by ab initio calculation using Gamess-US software. The activity of the received benzimidazoles was moderate or good. All of the benzoxazoles and benzothiazoles demonstrated much lower activity. Benzoxazoles were less active by about 50 times, and benzothiazole by 100 times than the benzimidazole analogs. Quantum chemical calculations showed differences in the distribution of electrostatic potential in the benzazole system of benzimidazoles and benzoxazoles. Three-dimensional structure calculations revealed how the parity of the alkyl substituent at the C2 position impacts the activity. Benzimidazole system is essential for the antituberculosis activity that is associated with the presence of the imine nitrogen atom in N-1 position. Its replacement by an oxygen or sulfur atom results in a decrease of the activity. The parity of the alkyl substituent at the C-2 position also modifies the activity. Full article

In a previous hit-to-lead research program targeting anticancer agents, two promising lead compounds, 1a and 1b, were found. However, the poor solubility of 1a and 1b made difficult further in vivo studies. To solve this problem, a lead optimization was conducted through introducing N-methyl-piperazine groups at the 2-position and 6-position. To our delight, the optimized analogue 1d showed comparable antiproliferative activity in vitro with better solubility, compared with 1a. Based on this result, the replacement of the benzothiazole scaffold with benzimidazole and benzoxazole moieties afforded 1f and 1g, whose activities were fundamentally retained. In the preliminary in vitro biological evaluation, the immunofluorescence staining of HCT116 cells indicated that 1d, 1f and 1g led to cytosolic vacuolization which was not induced by 1a at low micromolecular concentrations. These results suggest that these optimized compounds might potentially constitute a novel class of anticancer agents, which merit further studies. Full article

The synthesis and spectroscopic characterisation of some representative N-alkylsubstituted quaternary ammonium salts derived from benzothiazole, benzoxazole, benzoselenazole, indole and quinoline are described. These heterocyclic salts, bearing an activated methyl group in the 2-position in relation to the nitrogen atom and N-methyl, -pentyl, -hexyl and -decyl chains, are typical precursors of cyanine dyes. Full article