Extracellular vesicles from microalgae as natural bioactive agents for UVB protection, anti-aging, and skin depigmentation.

The search for effective dermocosmetic treatments has recently been accompanied by the growing demand for ingredients that are both naturally derived and sustainable. In this context, microalgae have emerged as a promising biofactory, producing bioactive compounds for skin health, widely recognized for their antioxidant, anti-inflammatory, and anti-aging activities. To leverage these properties, beyond the conventional use of microalgal biomass or extracts, the isolation and application of their secretome, including the extracellular vesicles named "nanoalgosomes", emerged as a novel approach. Extracellular vesicles are membranous nanoparticles released by all cells and naturally efficient in the transport of both endogenous and exogenous bioactive molecules. Their unique biological properties make them ideal candidates for therapeutic and cosmetic applications. Here, we propose nanoalgosomes, as a sustainable and effective solution for innovative dermocosmetic treatments. In this study we exemplify the use of the microalgae Tetraselmis chuii, an edible, green and renewable bio-source of extracellular vesicles. We demonstrated the nanoalgosomes' skin-health promoting potential, by employing the human skin cells as model to evidence the nanoalgosome ability to protect the cells from ultraviolet B (UVB) radiation-related damages, by reducing both the oxidative stress, and senescence-associated phenotype in UVB-exposed skin cells. Furthermore, nanoalgosomes modulate melanogenesis in UVB-stimulated melanocytes by downregulating tyrosinase, significantly reducing melanin content, supporting their role as photoprotective and pigmentation-modulating agents. Altogether, our results provide a solid foundation for the development of nanoalgosome-based formulations in dermocosmetic applications aimed at UV protection, anti-aging, and depigmentation, supporting the transition toward natural and sustainable skincare solutions.