Retinol, topical application

Topical application of Cathepsin D-like enzyme from mushroom extract (Actizyme) has also been shown to be beneficial for the treatment of xerosis.47 In dry skin SC turnover is reduced. This parameter can be measured in vivo using the dansyl chloride test. Addition of this enzyme to a formulation increased SC turnover by about 30%. This was of similar order to the effect of hydroxyacids, retinol, and mechanical scrubbing. In contrast to these treatments use of the enzyme did not impair barrier function nor increase stinging scores. 

Kang et al. [23] compared the clinical, histologic, and molecular responses of normal human skin to topical retinol with that of retinoic acid. Application of retinol and retinoic acid produced epidermal thickening. However, retinol produced less erythema compared with retinoic acid. The authors suggest that these data are compatible with the idea that retinol may he a pro-hormone of retinoic acid. 

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