allowed comparison of the magnitude of Dym under the different experimental conditions. Leukotrienes play important roles in immune responses. Leukotriene B4 recruits neutrophils to damaged tissue and induces the production of inflammatory cytokines. Cysteinyl LTs are involved in endothelial cell adherence and chemokine production. They also increase muscle contractions to reduce airflow in asthma, and anti-LTs are used to treat asthma. Leukotriene A4 is produced by two consecutive steps of dioxygenation from arachidonic acid by 5-lipoxygenase. LTA4 is then converted to LTB4 by LTA4 hydrolase, or to cysteinyl LTs by LTC4 synthase and other related enzymes. Because 5-LO plays an essential role in the production of various LTs, its inhibition is expected to be the most effective in treating diseases caused by overproduction of LTs, such as asthma, arthritis, pulmonary hypertension, atherosclerosis, osteoporosis, and prostate cancer. Many 5-LO inhibitors have been developed to treat inflammation- related diseases. Depending on their actions at the ferric iron, which is at the center of the 5-LO active site, they are conventionally classified into three categories: redox inhibitor, iron (R,S)-Ivosidenib ligand inhibitor, and non-redox inhibitor. During the process of enzyme activation, lipid peroxide converts inactive 5- LO with ferrous iron into active 5-LO with ferric iron. Redox inhibitors reduce ferric iron to inactive ferrous iron. Iron ligand inhibitors have binding affinity to the ferric iron and block the binding ability of substrates without changing the iron state. Nonredox inhibitors compete with substrates for binding to 5-LO. Estimating the redox characteristics of an inhibitor is important in understanding its actions in various diseases. Redox-active inhibitors are usually lipophilic-reducing agents, and poor selectivity can cause side effects, such as methemoglobinemia, through actions on other redox systems that utilize ferric irons in the body. On the other hand, non-redox 5-LO inhibitors are highly potent in the low nanomolar ranges of IC50; however, they show impaired potency in a condition with elevated peroxide levels. Thus, elucidating the mechanisms of each class of inhibitors requires additional NKL 22 distributor experiments. Substrate specificity is more important for r
