Phenolic profile in the quality control of walnut (Juglans regia L.) leaves

Abstract

Qualitative and quantitative determinations of phenolic compounds were carried out on walnut leaves samples from six different cultivars, with the same agricultural, geographical and climatic conditions. The evolution of major phenolic compounds amounts was monitored from May to September. Two extractive procedures were assayed and best results were obtained using acidified water and a solid phase extraction column purification step. Qualitative analysis was performed by HPLC-DAD/MS and, in all samples, seven phenolic compounds were identified (3-caffeoylquinic, 3-p-coumaroylquinic and 4-p-coumaroylquinic acids, quercetin 3-galactoside, quercetin 3-arabinoside, quercetin 3-xyloside, quercetin 3-rhamnoside) and two other partially identified phenolics (quercetin 3-pentoside and kaempferol 3-pentoside derivatives) were also detected. 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. The highest content of phenolics was found in May and July.

Juglone Content in Leaf and Green Husk of Five Walnut (Juglans regia L.) Cultivars

“…In accordance with literature Amaral et al, 2004), juglone was identified in all cultivars, but there were differences among cultivars regarding content and between materials showed. In general juglone content is higher in green husk of walnut fruits.…”

Hepatoprotective effects of Juglans regia extract against CCl4-induced oxidative damage in rats

“…Nevertheless, because of polymerization phenomena, juglone only occurs in dry leaves at vestigial amounts (Wichtl & Anton, 1999). Several hydroxycinnamic acids (3-caffeoylquinic, 3-p-coumaroylquinic and 4-p-coumaroylquinic acids) and flavonoids (quercetin 3-galactoside, quercetin 3-arabinoside, quercetin 3-xyloside, quercetin 3-rhamnoside and two other partially identified quercetin 3-pentoside and kaempferol 3-pentoside derivatives) of different walnut cultivars collected at different times were detected (Amaral et al, 2004). In addition, the existence of 5-caffeoylquinic acid was also reported (Wichtl & Anton, 1999).…”

“…Amaral et al (2004) determined the phenolic profile of walnut leaves of several cultivars. This variety was characterized by the presence of at least nine phenolic compounds: three hydroxycinnamic acid derivatives, the 3-O-caffeoylquinic, 3-O-p-coumaroylquinic and 4-O-p-coumaroylquinic acids, and six flavonol heterosides, the quercetin 3-O-galactoside (its major compound), a quercetin 3-O-pentoside derivative, quercetin 3-O-arabinoside, quercetin 3-Oxyloside, quercetin 3-O-ramnoside and a kaempferol 3-Opentoside (Amaral et al, 2004). Pereira et al (2007) identified another two hydroxycinnamic acid derivatives, the 5-Ocaffeoylquinic and p-coumaric acids.…”

Sunflower Oil Stabilization by Persian Walnut Leaves Extract during Oven Storage Test

“…Phenolic acids and flavanoids, two main groups of compounds in walnut leaf extract (Amaral et al, 2004), have been the subject of several studied due to their antioxidant potential and their capability of free radical scavenging (Pereira et al, 2007). In total flavonoid determination, we used quercetin as a standard compound because it is one of the widely spread flavonoids in walnut leaves extract (Amaral were irradiated by microwaves (1000 W, Butan, Iran) as the follows: 2 min 10% full power on (heating to the desired temperature, lower than 40℃ and 3 min power off and then 1 min 10% full power on (for heating) and 3 min power off (for cooling) and so on to the pre-set extraction time (4 min).…”