The search for new and efficient pharmaceuticals is a constant struggle for medicinal chemists. New substances are needed in order to treat different pathologies affecting the health of humans and animals, and these new compounds should be safe, effective and have the fewest side effects possible. Some functional groups are known for having biological activity; in this matter, the nitro group (NO₂) is an efficient scaffold when synthesizing new bioactive molecules. Nitro compounds display a wide spectrum of activities that include antineoplastic, antibiotic, antihypertensive, antiparasitic, tranquilizers and even herbicides, among many others. Most nitro molecules exhibit antimicrobial activity, and several of the compounds mentioned in this review may be further studied as lead compounds for the treatment of H. pylori, P. aeruginosa, M. tuberculosis and S. mutans infections, among others. The NO₂ moiety triggers redox reactions within cells causing toxicity and the posterior death of microorganisms, not only bacteria but also multicellular organisms such as parasites. The same effect may be present in humans as well, so the nitro groups can be considered both a pharmacophore and a toxicophore at the same time. The role of the nitro group itself also has a deep effect on the polarity and electronic properties of the resulting molecules, and hence favors interactions with some amino acids in proteins. For these reasons, it is fundamental to analyze the recently synthesized nitro molecules that show any potential activity in order to develop new pharmacological treatments that enhance human health.

Lead (Pb) is a toxic metal associated with several health disorders. The mining and Pb battery industry are related to Pb increase in air, water, and soil. Mexico is an important worldwide Pb producer; however, reviews on environmental Pb contamination in Mexico are insufficient. Since Pb remains stable in soil and its concentration is an indicator of Pb exposure, this systematic review focused on reports of Pb concentrations in soil from Mexico published in 2010–2023. The retrieved reports were ordered, and contamination grade and health risk were estimated for location. From 36 retrieved reports, 24 were associated with mining Pb pollution, while a unique report mentioned the battery industry. The publications evaluated mining (13), agricultural (11), and residential (16) soils. Pb concentrations in soil were higher than the allowed limits in more than half of the reports. According to the Pb concentrations in soil, the locations evaluated in Mexico presented a contamination grade from heavily contaminated to extremely contaminated and health risks results suggested severe hazards, particularly for children. This work can guide other researchers to identify potentially contaminated but understudied Mexican locations.

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.

Background: Fluoroquinolones are widely prescribed synthetic antimicrobial agents. Quinolones act by converting their targets, gyrase and topoisomerase IV, into toxic enzymes that fragment the bacterial chromosome; the irreversible DNA damage eventually causes the killing of bacteria. Thorough knowledge of the structure-activity relationship of quinolones is essential for the development of new drugs with improved activity against resistant strains. Methods: The compounds were screened for their antibacterial activity against 4 representing strains using the Kirby-Bauer disk diffusion method. Minimal inhibitory concentration (MIC) was determined by measuring the diameter of the inhibition zone using concentrations between 250 and 0.004 μg/mL. Results: MIC of derivatives 2, 3, and 4 showed potent antimicrobial activity against gram-positive and gram-negative bacteria. The effective concentrations were 0.860 μg/mL or lower. MIC for compounds 5-11 were between 120 and 515 μg/mL against Escherichia coli and Staphylococcus aureus, and substituted hydrazinoquinolones 7-10 showed poor antibacterial activity against gram-positive and gram-negative bacteria compared with other quinolones. Conclusion: Compounds obtained by modifications on C-7 of norfloxacin with the acetylated piperazinyl, halogen atoms, and substituted hydrazinyl showed good in vitro activity - some even better than the original compound.