PROGRAMME

Demand for natural and organic cosmetics is growing rapidly every year. This increases interest in herbal extracts that contain biologically active ingredients able to prevent and delay skin aging. Olive (Olea europaea L., Oleaceae) is a small tree mostly utilized for its fruit, whose oil is widely used in traditional Mediterranean cuisine. Olive leaves, rich in bioactive phenolics such as oleuropein and verbascoside, are commonly utilized as a traditional drug for numerous chronic conditions, such as diabetes and cardiovascular diseases1. In this work, eco-friendly, polypropilene glycol (PPG)-based extraction of olive leaf was optimized using a IV-optimal mixture design. Powder herbal material was subjected to extraction using different ternary solvent mixtures consisting of PPG, lactic acid and water. Ultrasound-assisted and magnetic stirrer-assisted extraction were compared in regard to their extraction efficiency. Total polyphenol (TP) content was determined spectrophotometrically, while the quantification of oleuropein and verbascoside was performed using HPLC. Cosmeceutical activity of the extracts prepared using the optimized extraction conditions was investigated through their antioxidant activity (DPPH radical scavenging activity, the activity in the -carotene linoleic acid assay) and the inhibitory activity on the selected enzymes (elastase, collagenase, tyrosinase and lipoxidase). The most appropriate solvent mixture for extraction of olive leaf phenolics was PPG:water:lactic acid (28.6:63.6:7.8 w/w/w). Magnetic stirrer-assisted extraction was shown to be more efficient, as well as economically and environmentally more acceptable option for the extraction of target phenols. Optimal time for TP, oleuropein and verbascoside extraction, determined by kinetics measurements, occurred at 20 min of extraction process (Fig. 1a.). Correlation between mass concentration (γ) of extracted phenolics against mass of the employed herbal material was determined to be linear indicating a good solubility of target compounds in the selected solvent (Fig. 1b.). The prepared extracts were efficient antioxidants and enzyme inhibitors deeming them appropriate candidates for active cosmeceutical ingredients in natural cosmetics.