Ascorbyl Tetraisopalmitate

What is ascorbyl tetraisopalmitate?

Ascorbyl tetraisopalmitate is a precursor of vitamin C that is increasingly replacing the use of free vitamin C (ascorbic acid) in cosmetic formulations (R). It was introduced by Japanese researchers in 2006, who synthesized it to overcome the limitations of ascorbic acid (R).

Is ascorbyl tetraisopalmitate stable?

1 of the reasons ascorbyl tetraisopalmitate is preferred over ascorbic acid in cosmetic formulations is because of its greater stability (R). Cosmetic products containing ascorbyl tetraisopalmitate have been estimated to have shelf lives of between 6 to 12 months, possibly because the tetra substitution provides steric protection against degradation (R). This is also better than ascorbyl palmitate, which has been shown to degrade by about 80% after 6 months of storage (R). The addition of vitamin E improves the stability of ascorbyl tetraisopalmitate even further, extending its shelf life to 12 months or more (R).

Ascorbyl tetraisopalmitate may not be stable in formulations where the pH exceeds 5.0 however, with the degree of discolouration observed proportional to the degree of its degradation (R).

Does ascorbyl tetraisopalmitate get absorbed?

Ascorbyl tetraisopalmitate was also developed in order to improve upon the poor skin penetration of ascorbic acid (R). This is because unlike ascorbic acid, which is inherently hydrophilic, ascorbyl tetraisopalmitate is lipophilic, like the stratum corneum that makes up the skin barrier. Indeed, a formulation containing 1% ascorbyl tetraisopalmitate has been shown to penetrate to the deeper layers of the stratum corneum (R). A separate study found that ascorbyl tetraisopalmitate penetrates the skin more efficiently through the stratum corneum rather than through the hair follicles, and that a higher concentration speeds up the process of penetration (R).

What happens after ascorbyl tetraisopalmitate is absorbed?

Experiments using reconstructed skin models have shown that 2 days after ascorbyl tetraisopalmitate is applied, 84% was converted to ascorbic acid, presumably by esterase enzymes in the cytosol of skin cells (R).