Comparative phenolic profile of Persian walnut (Juglans regia L.) leaves cultivars grown in Iran

Abstract

In this study Walnut leaves from 11 different cultivars (Mayette, Fernor, Mellanaise, Elit, Orientis, Lara, Hartley, Franquette, Parisienne, Arco and Marbot) were studied for their phenolic compounds. The evolution of major phenolic compounds amounts was monitored from May to September. Two extractive procedures were assayed and the best results were obtained using acidified water (pH 2) and a solid phase extraction column purification step. Qualitative analysis was performed by HPLC-DAD/MS and, in all samples; nine phenolic compounds (3-caffeoylquinic, 3-p-coumaroylquinic and 4-p-coumaroylquinic acids, quercetin 3-galactoside, quercetin 3-arabinoside, quercetin 3-xyloside, quercetin 3-rhamnoside, quercetin 3-pentoside and kaempferol 3-pentoside) were identified. Quantification of phenolic compounds was performed by HPLC-DAD, which revealed that quercetin 3-galactoside was always the major compound while 4-p-coumaroylquinic acid was the minor one. All cultivars presented slightly higher values of total phenolic compounds in May and July. Key words: Juglans regia L., phenolic profile, walnut leaf, high performance liquid chromatography -diode array detector (HPLC-DAD), high performance liquid chromatography/ diode array detector-electrospray ionization- mass spectrometry (HPLC/DAD/ESI-MS).