The rate of an enzymatic reaction may be changed by a moderator. Usually, the effect is to reduce the rate, and this is called inhibition. Sometimes the rate of enzyme reaction is raised, and this is called activation. Not only enzyme activation is subject of a less detailed presentation, but also enzyme inhibition and activation are very often discussed independently in enzymology. I attempt to introduce a general model of enzyme inhibition and activation to allow one to interpret inhibition and activation from a mechanistic or physical perspective using the significance of cooperativity as a new approach. The magnitude of interaction between substrate and inhibitor binding sites is given by the a parameter and the magnitude of increasing catalytic reaction constant is given by the b parameter, which both parameter values characterize the type of inhibition and activation. The moderation of mushroom tyrosinse is described by application of the model as a typical.

In this research, novel complexes of Zn(II) were produced using amino acid Schiff bases. First, new Schiff bases were synthesized from the reaction of 3-methoxy-2-hydroxybenzaldehyde (o-vanillin) and amino acid methyl esters (isoleucine, phenylalanine, methionine). The synthesis of new complexes was carried out by the reaction of these Schiff bases and Zn(OAc)2.2H2O. The structures of the synthesized complexes were elucidated using elemental analysis, FT-IR, NMR, UV-vis spectroscopy, and thermal analysis techniques. In this research, we synthesized new complexes of Zn(II) with amino acid Schiff bases labeled as 1a-1c. We then examined their impact on specific metabolic enzymes, namely acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The results showed that the molecules exhibited potent inhibitory activities against all targets compared to the standard inhibitor as indicated by IC50 values. Ki values of the compounds for AChE and BChE enzymes were obtained in the range of 78.04±8.66-111.24±12.61 and 24.31±3.98-85.18±7.05 µM, respectively. Molecular docking calculations were performed to investigate the biological activities of the metal complexes. The Protein Ligand Interaction Profiler (PLIP) was used to study the chemical interactions of metal complexes with enzymes.

Introduction: Drymaria cordata is used traditionally against hyperglycemia. In this research the methanol (DCM), hexane (DCH), and water (DCW) extracts of D. cordata were investigated for their metabolite profiling, antioxidant, antibacterial, and carbohydrate hydrolyzing enzyme inhibitory activities. Methods: The antidiabetic activities of the extracts were investigated using the α-amylase and α-glucosidase (carbohydrate-hydrolyzing enzymes) inhibition assays and yeast glucose uptake assays. Antibacterial investigation of D. cordata extracts was done against methicillin-resistant Staphylococcus aureus (MRSA) and β-lactam-resistant Escherichia coli. The zone of inhibition and minimum inhibitory concentration (MIC) were observed. Results: GC-MS metabolite profiling revealed the presence of stearyl aldehyde, henicosanal, glycidyl palmitate, eicosane, phytol, octacosanal, and neophytadiene. The DCM extract had a higher phenolic (168. 19 ± 3. 34 mg gallic acid equivalent/g), flavonoid (843 ±11. 55 mg rutin equivalents/g), and ferric reducing potential (556. 083 ± 6. 51 mg ascorbic acid equivalent/g) than the DCH and DCW extracts. Also, DCM showed its greatest scavenging activity with a minimum IC50 value using the ABTS assay. DCM extract had the highest zone of inhibition and lowest MIC value against E. coli and S. aureus. Carbohydrate-hydrolyzing enzymes were inhibited, with DCM extract having minimum IC50 values of 714. 66 µg/ml and 508. 94 µg/ml. Yeast glucose uptake assays confirmed the highest efficacy of DCM extract for glucose uptake by yeast cells. Conclusion: Drymaria cordata, especially DCM, has the potential to be considered an effective phytopharmaceutical drug for the treatment of oxidative stress, bacterial infections, and type 2 diabetes.