Study on Optimum Extraction Conditions for Olive Leaf Extracts Rich in Polyphenol and Flavonoid

Ultrasound-assisted extraction (UAE) of polyphenols and flavonoids from olive leaves was investigated. The effects of temperature (27-37 degrees C), solvent concentration (10-70% ethanol (EtOH), v/v) and time (30-60 min) were determined by both experimental and Response Surface Methodology (RSM) techniques. Free radical scavenging activity for the antioxidant capacity was tested by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical. For total phenolic content (TPC), 43.8252 mg-GAE/g dried leaf was predicted at the optimum conditions (34.18 degrees C, 43.61% (v/v) of EtOH, and 59.99 min). In case of total flavonoid content (TFC), 31.9920 mg-CE/g dried leaf was calculated at the optimum conditions (34.44 degrees C, 70% (v/v) of EtOH, and 60 min).