Olive leaf as a functional cosmetic ingredient and analysis of the principal component

Abstract

The present study aims to present a novel and environmentally sustainable method for extraction of phenolic antioxidants from olive leaves using a deep eutectic solvent (DES) composed of urea and glycerol. These components were selected due to their availability and compatibility with cosmetic formulations. The homogenizer-assisted extraction (HAE) system was designed, modelled and optimized by 3-factor and 3-level central composite design (CCD) of Response Surface method (RSM). The optimal HAE conditions (30 s of homogenizing, 70 % (v/v) water content in the DES and 0.1 g of leaf sample) provided the highest yields of total phenolic content (28.448 mg-GAE/g-DL) and antioxidant activity (26.263 mg-TEAC/g-DL), which were verified by satisfactory validation findings (the error<2 %). The application of the best DES-based olive leaf extract was investigated through the Rancimat test in order to provide a measure of stability against oxidation. Principal component analysis (PCA) of the Rancimat data indicated significant correlations among the quality characteristics (phenolic content and antioxidant activity) of the samples. These findings demonstrates the cosmetic relevance of olive leaf metabolites as a sustainable bioactive ingredient in cream-based cosmetic products. The use of glycerol and urea in DES offers a practical approach for the introducing natural antioxidants into skin-care formulations.