Walnut Bark Research Articles

Antibacterial, anticandidal and antioxidant activities of Salvadora persica and Juglans regia L. extracts

Salvadora persica and Juglans regia L. are traditionally used for the treatment of oral infections. The anticandidal; antibacterial and antioxidant activities of diluted acetone extract of S. persica (dry stems) and ethyl acetate extract of Tunisian Juglans regia L. bark were tested. The chemical composition of the volatile oil of the stems of S. persica was also investigated. The essential oil of S. persica stems was rich on benzyl isothiocyanate (52.5%) and benzyl nitrile (38.3%). Comparatively to the diluted acetone extract of S. persica , ethyl acetate extract of walnut’s bark was more effective against Gram positive and Gram negative bacteria and the different species of Candida tested in the present work. Similarly, the walnut extract was rich on phenols (34.833 mg GAE.g -1 DW) and tannins (16.167 mg EC.g -1 DW) comparatively to the arak extract (0.443 mg GAE.g -1 DW and 0.39 mg EC.g -1 DW, respectively). The walnut extract displayed the highest DPPH scavenging ability with the lowest IC 50 value (IC 50 , 3 µg/ml), a high capacity to quench superoxide (IC 50 : 70 μg.ml -1 ), the greater reducing power and bleaching of βcarotene (EC 50 , 99 μg.ml -1 and IC 50 , 280 µg.ml -1 , respectively) as compared to S. persica extract. These findings support the interest of S. persica and especially walnut bark and their possible use in the developing countries due to their inexpensive cost in order to maintain oral hygiene and as a source of new antioxidant compounds.

Investigation of the phenotypic and genetic properties of Brenneria nigrifluens strains, the causal agent of walnut bark canker in Kurdistan province, Iran

SummaryPhenotypic and genetic properties of Brenneria nigrifluens, the causal agent of walnut bark canker disease were studied using a combination of key biochemical tests, analysis of whole‐cell protein extracts and genetic fingerprints based on DNA primers corresponding to conserved motifs in bacterial repetitive (repetitive extragenic palindromic, enterobacterial repetitive intergenic consensus and BOX) elements and to the 16s rRNA gene. Phenotypic properties indicated that 11 strains showed a high degree of similarity and <5% of isolates showed different properties such as utilization of dulcitol and inositol. A majority of isolates produced rep‐PCR profiles similar (>80%) to a B. nigrifluens reference strain. This study showed that the majority of strains had 0–3 plasmids with estimated sizes ranging 9–32 Kb. Strains were clustered into two and three groups by whole‐cell protein analysis and rep‐PCR, respectively.

Detection and Identification of Brenneria nigrifluens, the Causal Agent of the Shallow Bark Canker of Walnut by, PCR Amplification

AbstractA 1 kb DNA band from strains of Brenneria nigrifluens, as shown by amplification of their genomic DNA by polymerase chain reaction (PCR) using minisatellite primer designed on the minisatellite sequence of the M13 phage, was isolated, cloned and sequenced. Specific oligonucleotides (F1–C3) were selected into this 1 kb DNA sequence and used in a PCR assay to detect and identify strains of B. nigrifluens. Several strains of B. nigrifluens were assessed with F1–C3 primers producing a specific band of approximately 250 bp pairs in length. This target was successfully amplified from purified genomic DNA, from bacterial culture and directly from infected walnut bark tissue. No amplification was obtained when the PCR assay was performed on other plant‐pathogenic species from the following genera Brenneria, Erwinia, Agrobacterium, Pseudomonas, Ralstonia, Pectobacterium, Xanthomonas and from walnut‐associated bacteria, indicating the specificity of these primers. The PCR assay with the primers described here provides a rapid, specific and sensitive diagnostic method for B. nigrifluens and a useful tool for epidemiological studies.

In vitro antioxidant activity of Juglans regia L. bark extract and its protective effect on cyclophosphamide-induced urotoxicity in mice

Walnut (Juglans regia L.) bark has been claimed to possess anti-inflammatory, blood purifying, anticancer, depurative, diuretic and laxative activities. It contains several therapeutically active constituents, especially polyphenols. We studied the antioxidant potential of aqueous extract of walnut bark and its modulatory effect on cyclophosphamide (CP)-induced urotoxicity in Swiss albino male mice. Free radical-scavenging activity of extract was assessed in four in vitro assays. The phenolic and flavonolic contents of the extract were also measured. Walnut bark extract treatment (150 mg/kg p.o. × 10 days) resulted in protective restoration of decreased antioxidants in CP-treated (18 mg/kg i.p. × 10 days) animals. CP treatment caused decreases in the activities of catalase (CAT), glutathione peroxidase (GP), glutathione reductase (GR) and glutathione S-transferase (GST) and in the glutathione (GSH) content in urinary bladder and a significant concomitant increase in lipid peroxidation (LPO). Administration of extract restored all the antioxidants significantly and lowered the elevated LPO in the bladder. A correlation between radical scavenging capacities of the extract with phenolic content was observed thus justifying its antioxidant potential against oxidative stress-mediated urotoxicity in mice. Walnut is reported to possess antiproliferative activity. Its protective effect on CP-induced toxicity in bladder is a promising activity, which warrants possible clinical investigations on this medicinal plant.

Morphactin transport and metabolism in tree bark tissues: comparative studies in vitro

AbstractBark banding of morphaction is an effective means of controling stem elongation in Pinus radiata D. Don (Monterey pine) but not Juglans regia L. (English walnut). Diffusion coefficients of 14C‐labeled morphactin across excised disks of tree bark, measured in specially designed diffusion chambers, were 11 to 85 fold greater in pine than walnut. In seedlings of comparable age, the suberin layer of walnut bark is much thicker than that of pine; if the layer is removed, diffusion of 14C‐morphactin is enhanced 39‐fold in pine and 285‐fold in walnut.Morphactin applied to the bark as an ester is rapidly hydrolyzed to its carboxylic acid derivative in both pine and walnut. This conversion occurs rapidly in the bark of both species and does not appear to limit the rate of morphactin movement across the bark.These results suggest that diffusion across the suberin layer and not metabolism limits morphactin transport across the bark.