Ultrasound‐assisted efficient synthesis of polyfunctional 1,2,4‐triazoles as novel antibacterial and antioxidant agents

Synthesis, characterization and antifungal activity of imidazole chitosan derivatives

Five novel imidazole-functionalized chitosan derivatives 3a-3e were synthesized via addition reactions of chitosan with imidazole derivatives. The partial incorporation of imidazole moiety in chitosan were confirmed by FTIR, UV, 1H NMR, XRD, SEM and GPC. Meanwhile, the antifungal activity against three common plant pathogenic fungi: Phytophthora nicotianae (P. nicotianae), Fusarium graminearum (F. graminearum) and Rhizoctonia solani (R. solani), was assayed in vitro at 0.5 and 1.0 mg/mL by hyphal measurement, and the introduction of imidazole group can influence the antifungal activity. At 0.5 mg/mL, 3e inhibited P. nicotianae growth by 42 % and had an inhibitory index against R. solani of 50 %. Derivative 3e was more effective than unmodified chitosan whose antifungal index was 17 % against P. nicotianae and 22 % against R. solani. To our surprise, at 1.0 mg/mL, the inhibition rate of 3e against R. solani can reach 99 %, while the inhibition rate of chitosan is only 38 %. These results indicated that some imidazole chitosan derivatives with enhanced antifungal activities could serve as potential biomaterial for antifungal application.

Synthesis of Imidazole-Based Molecules under Ultrasonic Irradiation Approaches

Imidazole-based compounds are a series of heterocyclic compounds that exhibit a wide range of biological and pharmaceutical activities. However, those extant syntheses using conventional protocols can be time-costly, require harsh conditions, and result in low yields. As a novel and green technique, sonochemistry has emerged as a promising method for organic synthesis with several advantages over conventional methods, including enhancing reaction rates, improving yields, and reducing the use of hazardous solvents. Contemporarily, a growing body of ultrasound-assisted reactions have been applied in the preparation of imidazole derivatives, which demonstrated greater benefits and provided a new strategy. Herein, we introduce the brief history of sonochemistry and focus on the discussion of the multifarious approaches for the synthesis of imidazole-based compounds under ultrasonic irradiation and its advantages in comparison with conventional protocols, including typical name-reactions and various sorts of catalysts in those reactions.

Antioxidant Activity of 1,2,4-Triazole and Its Derivatives: A Mini Review

The information about the presence of free radicals in biological materials was given for the first time about 70 years ago. Since then, numerous scientific studies have been conducted and the science of free radicals was born. Today we know that free radicals are by-products of enzymatic reactions occurring in the organism. They are produced during endogenous processes such as: cell respiration, phagocytosis, biosynthesis, catalysis, and biotransformation. They can also be produced by exogenous processes (radiation, sunlight, heavy metals, bacteria, fungi, protozoa and viruses). The overproduction of free radicals affects the aging processes, oxidative stress (OS) and takes part in the pathogenesis of various diseases. Among them are cancer, rheumatoid arthritis, neurodegenerative diseases: Alzheimer and Parkinson, pulmonary diseases, atherosclerosis and DNA damage. Compounds with antioxidant activity are very important nowadays because they allow organisms to keep a balance between the production of free radicals and the speed of their neutralization in the body. Next to the natural antioxidants (flavonoids, carotenoids, vitamins, etc.), synthetic ones are also of great importance. Among synthetic compounds with antioxidant activity are 1,2,4-triazoles and its derivatives. 1,2,4-Triazoles are heterocyclic compounds with three nitrogen atoms. Due to a broad spectrum of biological activities, these derivatives have been of interest to scientists for many years. Some of them are also used as drugs. The finding of new synthetic compounds with antioxidant features in the triazole group has become important problem of medicinal chemistry.