Hydroxypropyl-ß-cyclodextrin-containing hydrogel enhances skin formononetin permeation/retention.

OBJECTIVES: This study was aimed to investigate the in vitro permeation potential of hydrogel formulations containing the isoflavones formononetin and biochanin A and cyclodextrins in different combinations. METHODS: The permeation assay was performed using porcine skin discs on Franz diffusion cells model. The isoflavone contents of the formulations were quantified in the different layers of the skin using a validated HPLC-PDA method. KEY FINDINGS: The isoflavones individually incorporated into the formulations showed high permeation potential, especially formononetin, after the incorporation of hydroxypropyl-ß-cyclodextrin that enhanced its permeation in the epidermis and dermis. Biochanin A showed 2.7 times of permeation capacity in the epidermis and dermis mainly after incorporation of cyclodextrins in the formulations. Formononetin showed reduction in its permeation when incorporated in the formulations together to biochanin A, showing the absence of synergism. CONCLUSIONS: Our results indicated a noticeable skin permeation promoting effect of HPßCD in formononetin formulation. Furthermore, formononetin and biochanin A can permeate the skin being mostly retained in the epidermis and dermis, revealing its potential use in cosmetic preparations intended to prevent skin aging.