Nanotechnological breakthroughs in the development of topical phytocompounds-based formulations

Cosmeceuticals are a type of cosmetic products distinguished by the presence of active ingredients that, in addition to their cosmetic effects, also hold therapeutic outcomes. This review is focused on phytocompounds (PHYTOCs)-based cosmeceuticals, an established segment of cosmetic industry, due to the great demand for vitamins and plant-derived products. PHYTOCs beauty and health-related applications are due to their anti-oxidant, anti-bacterial, wound-healing, anti-aging, sun protection, cytoprotective, anticarcinogenic and anti-inflammatory activities. However, PHYTOCs present disadvantages, precisely the poor solubility, instability, reduced skin permeation and low skin retention time, which strongly restrict their topical application. Therefore, and since the cosmetic industry constantly pursues groundbreaking technological products, nanotechnology emerges as an innovative strategy to tackle the PHYTOCs recognized limitations. Nanotechnology manipulates and reduces materials size to 1 and 100 nm, creating structures able to encapsulate active ingredients, such as PHYTOCs, with the purpose of overcoming their limitations and delivering them in a controlled manner to the skin. This review highlights the potential properties of PHYTOCs loaded in several types of nanocarriers (liposomes, niosomes, ethosomes, transferosomes, cubosomes, phytosomes, nanoemulsions, nanocrystals, polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carriers, carbon nanotubes, fullerenes, and dendrimers) used to overcome PHYTOCs free form limitations and potentiate their cosmeceutical properties. An approach to the "green" chemical synthesis of metallic nanoparticles taking advantage of PHYTOCS as natural reducing agents is exposed as well. Nanocosmeceuticals toxicity concerns and regulatory aspects are also addressed.