3‑O‑Ethyl Ascorbic Acid (3OAA) is a modified vitamin C analogue in which an ethyl group at the third carbon protects the labile 3‑hydroxyl of ascorbic acid from ionization and oxidation. This structural change gives 3OAA superior stability compared with pure L‑ascorbic acid; the derivative is water‑ and oil‑soluble and maintains integrity in elevated temperatures and diverse solvents. Because it is more lipophilic than L‑ascorbic acid, 3OAA permeates the stratum corneum more efficiently and acts as a pro‑vitamin C once inside the epidermis. Studies on cosmetic formulations show that a serum containing 30 % 3OAA and 1 % lactic acid was highly biocompatible; it enhanced collagen production in dermal fibroblasts, reduced UVB‑induced DNA damage (γ‑H2AX histone), and significantly decreased melanin content in reconstructed human pigmented epidermis. As a result, 3OAA can deliver many of the well‑established benefits of vitamin C — antioxidant defence, collagen synthesis, and tyrosinase inhibition — while being less prone to degradation. These properties make the molecule attractive for serums, lotions and eye treatments targeting hyperpigmentation, uneven tone, photoageing and loss of firmness. The slow conversion to active vitamin C and pH stability around 4 – 5.5 contribute to improved tolerability for sensitive skin.

The antioxidant and barrier‑supporting actions of 3OAA may also translate to scalp and hair care, although formal data are scarce. Oxidative stress and collagen breakdown affect follicular health; vitamin C derivatives neutralise reactive oxygen species and support collagen cross‑linking. Since 3OAA has demonstrated lipophilic transdermal delivery, formulators can incorporate it into leave‑in scalp serums or conditioning treatments to protect follicles from environmental damage, help maintain dermal collagen, and improve shine. Unlike classic L‑ascorbic acid — which is unstable and can oxidise to pro‑oxidant compounds—3OAA resists oxidation and can coexist with lipophilic ingredients, allowing integration into oils and emulsions. While human hair‑specific studies are limited, the general antioxidant, brightening and collagen‑support benefits imply potential for scalp‑conditioned products aimed at preventing dullness and supporting healthy hair growth.