Walnut ( Juglans regia L.) leaves: Phenolic compounds, antibacterial activity and antioxidant potential of different cultivars

Different cultivars of walnut ( Juglans regia L.) leaves ( Cv. Lara, Franquette, Mayette, Marbot, Mellanaise and Parisienne) grown in Portugal, were investigated in what concerns phenolic compounds and antimicrobial and antioxidant properties. Phenolics analysis was performed by reversed-phase HPLC/...

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Published in:Food and chemical toxicology 2007-11, Vol.45 (11), p.2287-2295
Main Authors: Pereira, José Alberto, Oliveira, Ivo, Sousa, Anabela, Valentão, Patrícia, Andrade, Paula B., Ferreira, Isabel C.F.R., Ferreres, Federico, Bento, Albino, Seabra, Rosa, Estevinho, Letícia
Format: Article
Language:English
Subjects:
Anti-Bacterial Agents - chemistry
Anti-Bacterial Agents - pharmacology
Antifungal Agents - chemistry
Antifungal Agents - pharmacology
Antimicrobial activity
antioxidant activity
Antioxidant properties
antioxidants
Antioxidants - chemistry
Antioxidants - pharmacology
Bacillus cereus
Bacteria - drug effects
Biological and medical sciences
Biphenyl Compounds - chemistry
Candida albicans
Candida albicans - drug effects
Cryptococcus neoformans
Cryptococcus neoformans - drug effects
cultivars
Escherichia coli
free radical scavengers
free radicals
Hydrazines - chemistry
Juglans - chemistry
Juglans - classification
Juglans regia
Klebsiella pneumoniae
Lara
leaves
Medical sciences
minimum inhibitory concentration
Molecular Biology
nuts
Oxidation-Reduction
phenolic compounds
Phenolics
Phenols - analysis
Picrates
plant extracts
Plant Extracts - chemistry
Plant Extracts - pharmacology
Plant Leaves - chemistry
Plant poisons toxicology
Pseudomonas aeruginosa
quantitative structure-activity relationships
Staphylococcus aureus
Toxicology
Walnut leaves
walnuts
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Summary:Different cultivars of walnut ( Juglans regia L.) leaves ( Cv. Lara, Franquette, Mayette, Marbot, Mellanaise and Parisienne) grown in Portugal, were investigated in what concerns phenolic compounds and antimicrobial and antioxidant properties. Phenolics analysis was performed by reversed-phase HPLC/DAD and 10 compounds were identified and quantified: 3- and 5-caffeoylquinic acids, 3- and 4- p-coumaroylquinic acids, p-coumaric acid, quercetin 3-galactoside, quercetin 3-pentoside derivative, quercetin 3-arabinoside, quercetin 3-xyloside and quercetin 3-rhamnoside. The antimicrobial capacity was screened against Gram positive ( Bacillus cereus, B. subtilis, Staphylococcus aureus) and Gram negative bacteria ( Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae) and fungi ( Candida albicans, Cryptococcus neoformans). Walnut leaves selectively inhibited the growth of Gram positive bacteria, being B. cereus the most susceptible one (MIC 0.1 mg/mL). Gram negative bacteria and fungi were resistant to the extracts at 100 mg/mL. Lara walnut leaves were also submitted to antibacterial assays using 18 clinical isolates of Staphylococcus sp. Antioxidant activity was accessed by the reducing power assay, the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and β-carotene linoleate model system. In a general way, all of the studied walnut leaves cultivars presented high antioxidant activity (EC 50 values lower than 1 mg/mL), being Cv. Lara the most effective one.
ISSN:0278-6915
1873-6351
DOI:10.1016/j.fct.2007.06.004