Idebenone

Idebenone is a synthetic analog of coenzyme Q10 originally developed as a pharmaceutical for neurodegenerative conditions (Friedreich's ataxia), then repositioned for topical antioxidant use after Allergan-funded research showed it scored highest on the Environmental Protection Factor (EPF) test — a composite measure of antioxidant potency that ranks idebenone above vitamin C, vitamin E, alpha-lipoic acid, kinetin, and CoQ10 itself. The skincare launch (Elizabeth Arden Prevage in 2005, formulated by Allergan and licensed to Arden) was a genuine event — first independent test data on a serum-form antioxidant that beat the L-ascorbic acid + ferulic acid + vitamin E benchmark. Idebenone protects mitochondrial function specifically, which is increasingly understood as the cellular bottleneck in skin aging. The catch: it can sting, especially on sensitive skin, and it's expensive to manufacture, which is why most premium antioxidant serums (Mary & May Idebenone serum, COSRX RX, several K-beauty premium lines) keep it to PM-only positioning. Worth the trouble if you tolerate it.