Optimization of Bioactive Phenolics Extraction and Cosmeceutical Activity of Eco-Friendly Polypropylene-Glycol–Lactic-Acid-Based Extracts of Olive Leaf

Abstract

Olive leaf is a rich source of phenolic compounds with numerous activities related to skin health and appearance. In this study, a green extraction method was developed using eco-friendly solvents: polypropylene glycol (PPG), lactic acid (LA), and water. The optimal extraction conditions were established, including solvent, extraction time, technique (magnetic stirrer vs. ultrasound-assisted extraction), and herbal material/solvent ratio. The composition of the solvent mixture was optimized using a mixture design. The content of phenolic compounds, including oleuropein and verbascoside, was determined using high-performance liquid chromatography (HPLC) and spectrophotometric methods. Using different extraction conditions, three extracts were prepared and their phytochemical compositions and antioxidant and skin-related bioactivities were investigated. The extracts were excellent inhibitors of elastase, collagenase, tyrosinase, and lipoxygenase. The best activity was shown by the extract richest in phenolics and prepared using magnetic-stirrer-assisted extraction for 20 min, with 0.8 g of herbal material extracted in 10 mL of PPG/LA/water mixture (28.6/63.6/7.8, w/w/w), closely followed by the extract prepared using the same extraction conditions but with 0.42 g of herbal material. The investigated PPG/LA/water mixtures contributed to the overall enzyme-inhibitory activity of the extracts. The prepared extracts were appropriate for direct use in cosmetic products, thus saving the time and energy consumption necessary for the evaporation of conventional solvents.

Optimization of Cyclodextrin-Assisted Extraction of Phenolics from Helichrysum italicum for Preparation of Extracts with Anti-Elastase and Anti-Collagenase Properties

“…Topical application of low concentrations of LA may have a peeling effect and give skin a more youthful appearance. This is achieved by slight disruption of the cohesion of the corneocytes in the skin barrier [ 44 ]. However, applications of high concentrations of LA may result in skin irritation [ 45 ].…”

Glycerol and Natural Deep Eutectic Solvents Extraction for Preparation of Luteolin-Rich Jasione montana Extracts with Cosmeceutical Activity

“…Unlike non-toxic alcohol GL, lactic acid could have both beneficial and adverse effects depending on the concentration in the cosmetic product. Topical application of low concentrations of lactic acid may slightly disrupt the cohesion of the corneocytes in the skin barrier, and give skin a more youthful appearance, a feature widely utilized in so-called chemical peelings [ 21 ]. Still, applications of high concentrations may as well result in skin irritation [ 30 ].…”

“…Increased oxidative stress gradually increases the activity of extracellular matrix enzymes and causes DNA damage that leads to various issues such as genetic, hormonal, and metabolic changes [ 37 , 38 ]. By interfering with the proteolytic enzymes that accelerate the aging process and degradation of the skin, antioxidants prevent skin changes caused by aging and, consequently, positively affect the appearance of the skin [ 21 ]. In this work, the antioxidant activity of GL-based optimized extracts (OPT-TP, OPT-LUT and OPT-RSA) was analyzed.…”

“…Total phenolic content (TP) was determined applying the modified Folin–Ciocalteu method, by mixing 80 μL of the diluted extract with 80 μL of Folin–Ciocalteu reagent and 80 μL of 10% sodium carbonate solution [ 21 ]. After 1 h the absorbance at 700 nm was measured and TP concentration was determined from the calibration curve and expressed as μg of gallic acid per mL of extract.…”

Conventional and advanced extraction methods of some bioactive compounds with health benefits of food and plant waste: A comprehensive review

“…Olive leaf has many phenolic compounds, which have several functions in maintaining skin health and beauty (Figure 8). Marijan et al (2022) used polypropylene glycol (PPG), water, and lactic acid (LA) to develop a green extraction process. HPLC and spectrophotometric techniques were used to ascertain the phenolic component concentration, which included oleuropein and verbascoside.…”