Ascomycin is primarily used in the development of immunosuppressive drugs, especially in preventing organ transplant rejection. It acts by inhibiting T-cell activation through binding to immunophilins, thereby suppressing the immune response. Due to this mechanism, it serves as a key precursor in synthesizing derivatives like pimecrolimus, which is used topically to treat inflammatory skin conditions such as atopic dermatitis. Its potent anti-inflammatory properties make it valuable in dermatology for managing immune-mediated skin disorders without the side effects associated with corticosteroids. Additionally, ascomycin and its analogs are being investigated for potential applications in treating autoimmune diseases and neurodegenerative conditions due to their neuroprotective and immunomodulatory effects.