The therapeutic potential of the benzimidazole nucleus has been recognized since 1944, and it is an important heterocycle system due to its presence in a wide range of bioactive compounds such as antiviral, anticancer, antibacterial, and so on, where optimization of substituents in this class of pharmacophore has resulted in many drugs. Its broad biological activity stems from physicochemical properties such as hydrogen bond donor-acceptor capability, π→π stacking interactions, coordination bonds with metals as ligands and hydrophobic interactions; properties that allow them to easily bind with a series of biomolecules, including enzymes and nucleic acids, causing a growing interest in these types of molecules. This review aims to present an overview to leading benzimidazole derivatives, as well as to show the importance of the nature and type of substituents at the N1, C2, and C5(6) positions when they are biologically evaluated, which can lead to obtaining potent drug candidate with a significant range of biological activities.

The heterocycle ring tetrazole is an important moiety relevant to medicinal chemistry since it is present in some drugs with clinical importance. Its primary biological activity is being a bioisosteric analogue of the carboxylic acid and cis-amide groups. Its metabolic stability and other physicochemical properties make it an attractive structure for designing and synthesizing new pharmaceuticals. The biological activity of tetrazoles is quite extensive and includes antiviral, antibacterial, anticancer, antifungal, and antioxidant properties; all of them are discussed in this review. The most effective way to obtain tetrazoles is by azide derivatives, either in the starting materials by the cycloaddition [3 + 2] of organic azides and nitriles or by preparing a reactive imidoyl azide intermediate. The nucleophilic behavior of the azide group is discussed when the raw materials include isocyanides. Some other methods include alternative synthetic routes like thermolysis. This review also highlights some of the developments regarding the use of different heterogeneous catalysts to synthesize several tetrazole derivatives.

Reducing the risk of the aquatic ecosystem’s contamination with organic substances such as pharmaceuticals is of great importance due to the toxicological effect of these substances on aquatic organisms. Therefore, the removal of pharmaceuticals and/or their metabolites frequently reported in industrial or municipal wastewaters require efficient processes that complement the conventional treatment systems; the constructed wetlands are an option. In this work, the removal efficiency of mixed diclofenac and naproxen was evaluated using a subsurface flow constructed wetland planted with cattail (Typha latifolia), operated during 100 days at a hydraulic residence time (HRT) of 3 days. Under these conditions, the diclofenac and naproxen removal efficiencies were 82.0% and 74.5%, respectively. The interaction between diclofenac and naproxen with cellulose, which is the major cell wall compound of higher plants, was computationally modeled at the PM6 semi-empirical level of theory and it was found that diclofenac and naproxen interact with cellulose via hydrogen bonds. Resumen. Reducir el riesgo de contaminación de los ecosistemas acuáticos con sustancias orgánicas como los fármacos es de gran importancia debido al efecto toxicológico de estas sustancias para los organismos acuáticos. Por ello, la remoción de los fármacos y/o sus metabolitos frecuentemente reportados en aguas residuales industriales o municipales requiere de procesos eficientes que complementen los sistemas convencionales de tratamiento; los humedales construidos son una opción. En este trabajo, se evaluó la eficiencia de remoción de diclofenaco y de naproxeno en mezcla utilizando un humedal construido de flujo subsuperficial con plantas de tule (Typha latifolia), operado durante 100 días con un tiempo de residencia hidráulica (TRH) de 3 días. En estas condiciones, las eficiencias de remoción de diclofenaco y de naproxeno fueron de 82.0 % y 74.5 % respectivamente. La interacción entre diclofenaco y naproxeno con celulosa, que es el componente mayoritario de la pared celular de las plantas superiores, se modeló computacionalmente al nivel de teoría semiempírico con el método PM6, y se encontró que diclofenaco y naproxeno interactúan con celulosa mediante puentes de hidrógeno.