Valorization of antioxidants extracted from olive mill wastewater

Antioxidants are highly important gradients used to preserve cosmetic products and reduce the effect of oxidative stress on the skin. The present work explores the possibility of using phenolic compounds of olive mill wastewater (OMW) as effective alternatives to the commercial antioxidants used in cosmetic formulations deemed by their allergic and carcinogenic effects. Esterification of tyrosol and hydroxytyrosol extracted from OMW with various fatty acids was conducted using Novozyme 435 lipase as a biocatalyst. Upon synthesis, butyrate, caprate, laurate, and palmitate tyrosyl and hydroxytyrosyl esters were isolated and evaluated for their antioxidant and antibacterial activities. Results showed that laurate derivatives are the most efficient in preventing lipid oxidation and inhibiting growth of pathogenic strains. In the prospective of industrial use, laurate tyrosyl and hydroxytyrosyl derivatives were incorporated in a formulation of moisturizer to substitute the commercial antioxidant butylated hydroxyltoluene. Oleuropein, extracted from olive leaves powder, was also tested as an antiaging ingredient in cosmetic formulations. The evaluation of physicochemical, microbiological, and sensorial properties of the new cosmetic products indicated that oleuropein and lipophilic derivatives do not affect the properties of the standard formulation. Oleuropein and lipophilic derivatives can be added as active ingredients to stabilize cosmetic preparations.