Natural bioenhancers for dermal delivery: Mechanisms, formulation design and cosmeceutical applications

Natural bioenhancers have emerged as promising strategies for improving dermal and transdermal delivery of cosmetic and therapeutic products. Natural bioenhancers comprise diverse chemical classes, including alkaloids, fatty acids, polyphenols, polysaccharides, saponins, triterpenoids, and others, each contributing distinct structural features that influence interactions with the stratum corneum. These interactions include modulation of lipid packing, increased membrane fluidity, enhanced hydration, keratin-associated effects and changes in the microenvironment at the formulation-skin interface. Advances in molecular and biophysical studies have clarified how polarity, chain length, unsaturation, volatility and stereochemistry shape enhancer performance across hydrophilic and lipophilic actives. Alongside mechanistic insights, contemporary formulation science has adopted natural bioenhancers within nanoemulsions, lipid carriers, ethosomes, nanoemulgels, hydrogels and natural deep eutectic solvent systems. These platforms support improved solubility, stability and controlled release, while enabling targeted delivery to the stratum corneum, viable epidermis or hair follicles. Applications include anti-ageing, skin-brightening, anti-inflammatory and barrier-repairing products, and scalp-delivery formulations, with growing emphasis on biocompatibility and long-term tolerability. This review integrates current evidence on the chemistry, mechanisms and formulation strategies of natural bioenhancers and outlines their expanding role in cosmeceutical innovation.