Chemical and biological approaches on nine fruit tree leaves collected from the Mediterranean region of Turkey

The antioxidant and enzyme inhibitory activities of two extracts [methanolic and water] of nine different fruit tree leaves were assessed. The antioxidant activity of leaves was determined by ABTS (2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)), DPPH (1,1-diphenyl-2-picrylhydrazyl radical), CUPRAC (cupric ion reducing antioxidant capacity), and FRAP (ferric reducing antioxidant power)assays. The enzyme inhibitory activity was evaluated against acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and tyrosinase. Individual phenolic components were detected using HPLC-DAD (high performance liquid chromatography-diode array detector) technique. Chlorogenic acid was the most abundant compounds in the leaves. Total phenolic and flavonoid contents were determined as 22.24-274.50 milligram gallic acid equivalents (mgGAE/g) and 4.93-46.99 milligram rutin equivalents (mgRE/g), respectively. A higher antioxidant and enzyme inhibitory activity was observed in pomegranate and carob extract as compared to other leaves. This study suggested that the leaves may be beneficial for preparing novel functional food ingredients.