Final answer:
Selegiline is an irreversible MAO-B inhibitor used as an antidepressant and in the treatment of Parkinson's disease.
Step-by-step explanation:
The irreversible MAO-B inhibitor mentioned in the question is selegiline. Monoamine oxidase inhibitors (MAOIs) are a group of medications that block the breakdown of monoamines by inhibiting the enzyme monoamine oxidase. Selegiline is known for its use as an antidepressant and in the treatment of Parkinson's disease. When designing safer covalent inhibitors, researchers aim for specificity to reduce side effects. Selegiline, as an irreversible inhibitor, forms a covalent bond with the enzyme, resulting in permanent inactivation.