Ampyrone Identified as Potential Treatment for Hypopigmentation Disorders

Understanding Hypopigmentation and the Role of Melanin

Hypopigmentation disorders are characterized by abnormally low or absent levels of melanin within cells. These conditions include severe genetic forms like oculocutaneous albinism (OCA), as well as patches of skin that lose pigmentation due to inflammation. Melanin functions as an ultraviolet-absorbing antioxidant, and its absence can lead to significant health and social challenges, including an increased risk of skin cancer and vision impairments resulting from improper retinal development.

Dr. Jonathan Zippin, an associate professor of dermatology at Weill Cornell Medicine, noted that the pharmacologic enhancement of human pigmentation is a promising strategy to protect skin, improve visual function, and enhance the quality of life for affected patients. Dr. Brian Brooks, chief of the Ophthalmic Genetics and Visual Function Branch at the National Eye Institute, added that improving melanin pigmentation in the eyes of people with OCA could potentially help mitigate issues such as glare sensitivity and, if treatment is initiated early, support the development of better vision.

Overcoming Technical Barriers in Drug Discovery

While tyrosinase inhibitors are commonly utilized in skin-lightening products, identifying effective tyrosinase activators has historically proven difficult.

To address this, Dr. Brooks and his team developed a soluble, catalytically active form of human tyrosinase. This advancement allowed for the purification of large quantities of the functional enzyme and the creation of a high-throughput, chemical-optical assay. Using this platform, the researchers screened more than 34,000 compounds to identify modulators of tyrosinase activity. The screen resulted in the identification of seven potential activators and 65 potential inhibitors.

Ampyrone as a Lead Compound

Intensive follow-up testing revealed that ampyrone was the most promising activator among the candidates. The compound significantly increased the catalytic activity of both normal tyrosinase and mutant versions of the enzyme associated with albinism. Furthermore, ampyrone demonstrated the ability to rapidly boost melanin production in both cell models and a 3D human skin model.

Researchers highlighted several key findings regarding the compound’s potential:

• Safety Profile: No signs of toxicity were observed during testing, even after three weeks of exposure, which is consistent with ampyrone’s status as a derivative of the NSAID-type analgesic aminopyrine.
• Potency: Utilizing a new liquid chromatography-mass spectrometry (LC-MS)-based method, investigators found that ampyrone induced new melanin synthesis within one hour.
• Methodological Impact: The success of the LC-MS-based method suggests it could be a valuable tool for future in-cell screenings of other pigment-altering drugs.

Future Directions

The research team is currently utilizing ampyrone as a “lead compound” to guide the next phase of drug development. By serving as a starting point, ampyrone provides a pathway toward creating a therapeutic tyrosinase activator. The research was supported by the National Institutes of Health, the National Eye Institute, the National Center for Advancing Translational Sciences, and the National Institute for Arthritis and Musculoskeletal and Skin Diseases, with additional support from the Vision for Children Foundation and the National Organization for Albinism and Hypopigmentation.