Decoding Cyclodextrins in Skin Applications: Structure, Mechanisms, and Safety in Cosmetic and Dermatologic...

Cyclodextrins (CDs) have emerged as important encapsulation platforms in dermatologic and cosmetic sciences, addressing critical challenges related to the solubility and stability of bioactive compounds. This review (Part I) systematically explores the relationship between the molecular architecture of CDs and their functional performance at the skin interface. A comprehensive analysis of the physicochemical properties of natural and derivative cyclodextrins is presented, alongside an evaluation of their interaction mechanisms with the skin barrier and current regulatory frameworks. This study highlights how the hydrophobic cavity of CDs enables the successful encapsulation of botanical extracts, significantly enhancing their bioavailability and photostability. Furthermore, the mechanistic insights provided clarify how appropriately selected and formulated CDs can modulate skin penetration while maintaining acceptable epidermal barrier compatibility. A critical synthesis of safety data and toxicological profiles confirms the suitability of specific CD types for topical application, supported by an overview of the evolving European and international legislative landscapes. Understanding the molecular design and safety constraints of cyclodextrin-based systems is essential for developing next-generation dermocosmetics. This foundational analysis provides the necessary framework for the clinical and technological applications discussed in the subsequent part of this review.