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

Sepal phenolic profile during Helleborus niger flower development

Morphological changes and phenolic patterns of developing hellebore sepals and the effects of pistil removal on these parameters were studied by comparing six flower stages of Helleborus niger. Color changes were evaluated colorimetrically, chlorophyll content was measured spectrophotometrically, and anthocyanins and flavonols were identified and quantified with HPLC-MS. Pistil removal not only altered the morphological development of hellebore flower resulting in smaller flower and significant color changes but also lead to several biochemical modifications. Five cyanidin glycosides have been identified from the group of anthocyanins in hellebore. Individual and total anthocyanin content increased from bud to subsequent developmental stages. Moreover, significantly higher content levels of individual and total anthocyanins have been measured in non-pollinated flower sepals compared to sepals of pollinated flowers. From the group of flavonols eight quercetin and kaempferol compounds have been quantified in hellebore sepals. Flavonol content significantly decreased during flower development with lowest levels recorded in sepals of non-pollinated and senescent pollinated hellebore flowers. Sepals of pollinated flowers contained highest levels of chlorophyll and significantly lower amounts of chlorophyll were measured in non-pollinated flowers and in sepals of senescent stage.

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

CONTEXT

Different parts of the walnut [Juglans regia L. (Juglandaceae)] have been used in folk medicine for protection against liver injury, although its actual efficacy remains uncertain.

OBJECTIVE

The present study investigated the protective effect of walnut leaf extract against carbon tetrachloride (CCl4)-induced liver damage in rats.

MATERIALS AND METHODS

The rats were randomly divided into seven groups: control, CCl4 (i.p., 0.5 mL/kg b.w., 50% CCl4 in olive oil), walnut extract (at dose level of 0.2 g/kg b.w.) alone, walnut extract (at dose levels of 0.05, 0.1, 0.2 and 0.4 g/kg b.w.) with CCl4, and treatment was carried out accordingly. On the 28th day, rats were sacrificed and blood was withdrawn by cardiac puncture. Liver damage was assessed by serum biochemical parameters (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and albumin), antioxidant enzymes (superoxide dismutase and catalase) and histopathological observation.

RESULTS

Administration of walnut leaf extract (ranging from 0.2 to 0.4 g/kg b.w.) significantly lowered serum alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase levels in CCl4-treated rats. Walnut leaf extract increased antioxidant enzymes, including superoxide dismutase and catalase. Histopathological examination of livers showed that walnut leaves extract reduced fatty degeneration, cytoplasmic vacuolization and necrosis in CCl4-treated rats.

DISCUSSION AND CONCLUSION

These results suggest that walnut extract has a protective effect over CCl4-induced oxidative damage in rat liver. These results demonstrate that walnut extract acts as a good hepatoprotective and antioxidant agent in attenuating hepatocellular damage.

Potential of Ginkgo biloba L. leaves in the management of hyperglycemia and hypertension using in vitro models

Leaves from four different Ginkgo biloba L. trees (1 and 2--females; 3 and 4--males), grown at the same conditions, were collected during a period of 5 months (from June to October, 2007). Water and 12% ethanol extracts were analyzed for total phenolics content, antioxidant activity, phenolic profile, and the potential in vitro inhibitory effects on alpha-amylase, alpha-glucosidase, and Angiotensin I-Converting Enzyme (ACE) enzymes related to the management of diabetes and hypertension. The results indicated a significant difference among the trees in all functional benefits evaluated in the leaf extracts and also found important seasonal variation related to the same functional parameters. In general, the aqueous extracts had higher total phenolic content than the ethanolic extracts. Also, no correlation was found between total phenolics and antioxidant activity. In relation to the ACE inhibition, only ethanolic extracts had inhibitory activity.

HPLC-DAD-ESI-MS/MS analysis and antioxidant activities of nonanthocyanin phenolics in mulberry (Morus alba L.)

Qualitative analysis of the nonanthocyanin phenolics from 2 mulberry cultivars, da-10 and hongguo, was performed by the HPLC-DAD-ESI-MS/MS method. Six nonanthocyanin phenolics compounds were identified (procatechuic acid, chlorogenic acid, 4-caffeolyquinic acid, taxifolin, rutin, quercetin) and 3 others (3,5-diCQA, taxifolin-hexoside, kamepferol-hexoside) were tentatively identified. Quantification of nonanthocyanin phenolic was performed by HPLC-DAD, which revealed that rutin (111.38 and 90.79 microg/g FW) was the major nonanthocyanin phenolics in the 2 mulberry cultivars. Phenolic acids in cultivar da-10 (54.68 microg/g FW) were far more than in cultivar hongguo (14.93 microg/g FW). CQA and its isomers (40.02 microg/g FW) were the major phenolic acid in cultivar da-10. The nonanthocyanin phenolics in the 2 cultivars of mulberry had higher antiradical activities in superoxide anion and DPPH radical and antioxidant activity in beta-CLAMS assay than the Trolox. These results were relevant to not only the control of color stability and organoleptic characteristics of mulberry juice and wine but also the exploitation of the functional foods made from mulberry.

Do cultivar, geographical location and crop season influence phenolic profile of walnut leaves?

Walnut leaves from nine different cultivars (Arco, Franquette, Hartley, Lara, Marbot, Mayette, Meylannaise, Parisienne and Rego) were studied for their phenolic compounds. Samples were harvested along three consecutive years, at two different geographical locations, in order to evaluate if significant differences in the phenolics composition can be related with genetic, climatic or geographical factors. Nine compounds (3-caffeoylquinic, 3-p-coumaroylquinic and 4-p-coumaroylquinic acids, quercetin 3-galactoside, quercetin 3-arabinoside, quercetin 3-xyloside, quercetin 3-rhamnoside, a quercetin 3-pentoside derivative and a kaempferol 3-pentoside derivative) were quantified using an HPLC-DAD methodology. The qualitative profiles were identical for all samples, but differences were observed in terms of individual compounds’ contents. Multivariate statistical analysis was carried out, showing that significant differences exist among production years, which can be related to climatic reasons.

Total phenols, antioxidant potential and antimicrobial activity of walnut (Juglans regia L.) green husks

The total phenols content and antioxidant and antimicrobial activities were studied in walnut (Juglans regia L.) green husks aqueous extracts of five different cultivars (Franquette, Mayette, Marbot, Mellanaise and Parisienne). Total phenols content was determined by colorimetric assay and their amount ranged from 32.61 mg/g of GAE (cv. Mellanaise) to 74.08 mg/g of GAE t (cv. Franquette). The antioxidant capacity of aqueous extracts was assessed through reducing power assay, scavenging effects on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and beta-carotene linoleate model system. A concentration-dependent antioxidative capacity was verified in reducing power and DPPH assays, with EC50 values lower than 1 mg/mL for all the tested extracts. The antimicrobial capacity was screened against Gram positive and Gram negative bacteria, and fungi. All the extracts inhibited the growth of Gram positive bacteria, being Staphylococcus aureus the most susceptible one with MIC of 0.1 mg/mL for all the extracts. The results obtained indicate that walnut green husks may become important in the obtainment of a noticeable source of compounds with health protective potential and antimicrobial activity.

Antibacterial activity of tannin constituents from Phaseolus vulgaris, Fagoypyrum esculentum, Corylus avellana and Juglans nigra

Tannins were fractionated from acetonic extract preparations of phenolic compounds from Phaseolus vulgaris, Fagoypyrum esculentum, Corylus avellana and Juglans nigra. Wide variations in antibacterial activities ranging from MICs of 62.5 to 500 microg/ml were apparent. Of particular note was a relatively high level of activity (62.5 to 125 microg/ml) for all extracts against Listeria monocytogenes.

Characterization of cyanidin- and quercetin-derived flavonoids and other phenolics in mature saskatoon fruits (Amelanchier alnifolia Nutt.)

In order to further characterize the anthocyanins, flavonols, and other phenolics present in mature saskatoon ( Amelanchier alnifolia Nutt.) fruit, extracts were characterized using high-performance liquid chromatography, gas chromatography, and liquid chromatography-mass spectrometry. Cyanidin 3-O-galactoside, cyanidin 3-O-glucoside, cyanidin 3-O-arabinoside, and cyanidin 3-O-xyloside were identified as the four major anthocyanins in the mature fruit. The quercetin-derived flavonols, quercetin 3-O-glucoside, quercetin 3-O-galactoside, quercetin 3-O-arabinoside, quercetin 3-O-xyloside, quercetin 3-O-arabinoglucoside, quercetin 3-O-robinobioside, and quercetin 3-O-rutinoside were also identified in mature fruit extracts. In addition, two chlorogenic acid isomers (hydroxycinnamates), 3-O-caffeoylquinic acid and 5-O-caffeoylquinic acid were detected. The total content of the anthocyanin-, flavonol-, and hydroxycinnamate-type phenolics detected in mature 'Smoky' saskatoon fruit was 140, 25, and 96 mg/100 g fresh weight, respectively. These data further our knowledge of the phenolic composition of mature saskatoon fruit, and as anthocyanins, flavonols, and hydroxycinnamates exhibit antioxidant activities, the presence and levels of these classes of phenolics will aid in the understanding of the potential health-beneficial effects of saskatoon fruits in the human diet.

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/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 0.1mg/mL). Gram negative bacteria and fungi were resistant to the extracts at 100mg/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 beta-carotene linoleate model system. In a general way, all of the studied walnut leaves cultivars presented high antioxidant activity (EC(50) values lower than 1mg/mL), being Cv. Lara the most effective one.

Phenolic acids, syringaldehyde, and juglone in fruits of different cultivars of Juglans regia L

Phenolic acids (chlorogenic, caffeic, p-coumaric, ferulic, sinapic, ellagic, and syringic acid) as well as syringaldehyde and juglone were identified in ripe fruits of 10 walnut cultivars: Adams, Cisco, Chandler, Franquette, Lara, Fernor, Fernette, Alsoszentivani 117 (A-117), Rasna, and Elit. Analyses were done using a high-performance liquid chromatograph equipped with a diode array detector. Significant differences in the contents of identified phenolics were observed among cultivars. Phenolics were determined separately in the kernel and in the thin skin of the walnut, termed the pellicle. Not only in the kernel but also in the pellicle did syringic acid, juglone, and ellagic acid predominate (average values of 33.83, 11.75, and 5.90 mg/100 g of kernel; and 1003.24, 317.90, and 128.98 mg/100 g of pellicle, respectively), and the contents of ferulic and sinapic acid (average values of 0.06 and 0.05 mg/100 g of kernel and 2.93 and 2.17 mg/100 g of pellicle, respectively) were the lowest in all cultivars. The highest differences in the sum of all identified phenolics were observed between Rasna and Fernette fruits; in Rasna there were >2-fold higher contents of identified phenolics in both kernel and pellicle. It was found that the walnut pellicle is the most important source of walnut phenolics. The ratio between the contents in pellicle and kernel varied by at least 14.8-fold for caffeic acid (cv. Adams) and by up to 752.0-fold for p-coumaric acid (cv. Elit).

Phenolic compounds in external leaves of tronchuda cabbage (Brassica oleracea L. var. costata DC)

Glycosylated kaempferol derivatives from the external leaves of tronchuda cabbage (Brassica oleracea L. var. costata DC) characterized by reversed-phase HPLC-DAD-MS/MS-ESI were kaempferol 3-O-sophorotrioside-7-O-glucoside, kaempferol 3-O- (methoxycaffeoyl/caffeoyl)sophoroside-7-O-glucoside, kaempferol 3-O-sophoroside-7-O-glucoside, kaempferol 3-O-sophorotrioside-7-O-sophoroside, kaempferol 3-O-sophoroside-7-O-sophoroside, kaempferol 3-O-tetraglucoside-7-O-sophoroside, kaempferol 3-O-(sinapoyl/caffeoyl)sophoroside-7-O-glucoside, kaempferol 3-O-(feruloyl/caffeoyl)sophoroside-7-O-glucoside, kaempferol 3-O-sophorotrioside, kaempferol 3-O-(sinapoyl)sophoroside, kaempferol 3-O-(feruloyl)sophorotrioside, kaempferol 3-O-(feruloyl)sophoroside, kaempferol 3-O-sophoroside, and kaempferol 3-O-glucoside. These acylated derivatives are reported for the first time in nature, with the exception of kaempferol 3-O-(sinapoyl)sophoroside. Quantification of the identified compounds was achieved by HPLC-DAD and carried out in samples cultivated under conventional or organic practices and collected at different times. In general, samples from organic production exhibited higher total phenolics content than those from conventional practices collected in the same period.