Pyridine, a compound with a heterocyclic structure, is a key player in medicinal chemistry and drug design. It is widely used as a framework for the design of biologically active molecules and is the second most common heterocycle in FDA-approved drugs. Pyridine is known for its diverse biological activity, including antituberculosis, antitumor, anticoagulant, antiviral, antimalarial, antileishmania, anti-inflammatory, anti-Alzheimer’s, antitrypanosomal, antimalarial, vasodilatory, antioxidant, antimicrobial, and antiproliferative effects. This review, spanning from 2022 to 2012, involved the meticulous identification of pyridine derivatives with antiproliferative activity, as indicated by their minimum inhibitory concentration values (IC50) against various cancerous cell lines. The aim was to determine the most favorable structural characteristics for their antiproliferative activity. Using computer programs, we constructed and calculated the molecular descriptors and analyzed the electrostatic potential maps of the selected pyridine derivatives. The study found that the presence and positions of the -OMe, -OH, -C=O, and NH2 groups in the pyridine derivatives enhanced their antiproliferative activity over the cancerous cellular lines studied. Conversely, pyridine derivatives with halogen atoms or bulky groups in their structures exhibited lower antiproliferative activity.

Molecular weights of trypsin, chymotrypsin, and lipase from anterior intestine and pyloric caeca of Totoaba macdonaldi were evaluated, as well as optimum temperature and pH for activity of the proteases. Trypsin was 24.1 kDa and effectively hydrolyzed Nα-benzoyl-DL-arginine 4-nitroanilide hydrochloride at optimum pH and temperature of 8 and 65°C, respectively. Chymotrypsin was 25.9 kDa and showed higher hydrolytic activity for N-benzoyl-L-tyrosine ethyl ester at pH 8 and 45°C, with a wider range of statistically similar activity values. Two pancreatic lipases of 70.2 and 47.5 kDa were detected, which could be the uncleaved and the final form of a colipase-dependent pancreatic lipase, since enzyme activity was detected without supplementation of bile salts and supplementing them inhibited activity.

Lipids are one of the main macronutrients that constitute balanced feeds used in aquaculture. Adequate utilization of dietary lipid is influenced by the activity of pancreatic lipase, one of the enzymes that promotes digestion of dietary lipids in the gastrointestinal tract of fish. The culture of Totoaba macdonaldi is quite recent; its nutritional requirements have been partially established. Knowing the characteristics of pancreatic lipase for this species could help optimize the dietary lipids included in balanced feeds for its culture. Therefore, the aim of this work is to partially characterize and evaluate the enzymatic activity of pancreatic lipase for T. macdonaldi. Biological indices showed that experimental organisms had a good nutritional status. Pancreatic lipase molecular weight was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and its activity was evaluated in crude enzymatic extracts from different gastrointestinal tract regions. The molecular weight of lipase was estimated to be 70.4 kDa; the highest lipolytic activity was observed at 45?C and at a pH optimum of 8.0 in the anterior intestine and pyloric caeca, where the concentration and activity of the enzyme was significantly higher (P=0.004) compared to the distal parts of the intestine. Biochemical characteristics observed for the pancreatic lipase of T. macdonaldi are quite similar to other lipases of fish cultured worldwide; results provided in this study will help understand the role this lipolytic enzyme plays in the digestive process of this species.