3.4.2 Representative Target Enzymes and Assay Methods

Acetylcholinesterase (AChE) inhibition, of central relevance to Alzheimer's disease and cognition research, is measured using Ellman's reagent (DTNB), which...

Acetylcholinesterase (AChE) inhibition, of central relevance to Alzheimer's disease and cognition research, is measured using Ellman's reagent (DTNB), which generates a yellow chromophore read at 412 nm; galantamine typically serves as the reference inhibitor. Cyclooxygenase (COX-1/COX-2) inhibition, relevant to anti-inflammatory drug development and NSAID selectivity profiling, is assessed via colourimetric prostaglandin E2 ELISA or oxygen-consumption methods, with COX-2 selectivity generally preferred to minimise gastrointestinal toxicity. Alpha-glucosidase inhibition, an antidiabetic mechanism exemplified by acarbose, uses the pNPG substrate, which liberates yellow p-nitrophenol measured at 405 nm. Xanthine oxidase inhibition, relevant to antigout therapy (allopurinol being the reference standard), is measured via uric acid production at 295 nm. Urease inhibition, of interest in antibacterial research against Helicobacter pylori and in phytochemical screening, uses the phenol-hypochlorite (indophenol) colour reaction at 625 nm. Monoamine oxidase (MAO-A/B) inhibition, relevant to antidepressant and anti-Parkinsonian drug development, is measured fluorometrically using the Amplex Red hydrogen peroxide detection system, with clorgyline and selegiline serving as isoform-selective reference inhibitors.