Antimicrobial activity of food-compatible plant extracts and chitosan against naturally occurring micro-organisms in tomato juice

BACKGROUND: Chitosan (AC) and five hydroalcoholic extracts from Lithospermum erythrorhizon (SE), Rheum palmatum (RE), Thymus vulgaris (AT), Lippia citriodora (PLX) and a mixture of Rosmarinus officinalis, Salvia lavandulifolia and Thymus mastichina (LA) were tested for antimicrobial activity against bacteria, yeasts and filamentous fungi using two broth dilution methods. The effects of adding single extracts on naturally occurring micro‐organisms and sensory qualities of raw tomato juice were also evaluated. RESULTS: SE extract exhibited the strongest activity, with minimum inhibitory concentrations (MICs) of 100–400 µg mL^?1 for Gram‐positive and 1600–3200 µg mL^?1 for Gram‐negative bacteria. Enterobacter aerogenes showed the greatest susceptibility to AC (MIC 1600 µg mL^?1). Lethal effects of extracts and AC were achieved at a minimum bactericidal concentration (MBC)/MIC ratio of 2 in 88% of assays. SE and RE extracts and AC also exhibited antifungal effect against yeasts, but they had no activity on filamentous fungi. Control and 100 mg L^?1 SE‐added tomato juices did not differ in acceptance, but this SE concentration was not effective in the control of microbial load throughout cold storage. CONCLUSION: Results confirm the antimicrobial potential of the plant extracts, but additional research is needed until the agents responsible for the activities have been determined in order to use them as natural constituents of multiple‐barrier food preservation systems. Copyright © 2012 Society of Chemical Industry     

Effect of Oak Chips on Evolution of Phenolic Compounds and Color Attributes of Bog Bilberry Syrup Wine During Bottle‐Aging

This study investigated the evolution of phenolic compounds of bog bilberry syrup wine during a bottle‐aging process, and further estimated the oak chip treatment on the wine color alteration. The wine was macerated with oak chips (2 or 5 g/L under light or medium toasting level) for 20 d and then bottle‐aged for 6 mo. Results showed that the oak chip treatment significantly increased the content of phenolic compounds and enhanced the copigmented anthocyanin level before aging. It also resulted in an increase on a^* and C^* but a decrease on L^*, b^*, and H^* of the wine. During aging process, a content decrease of total phenol and antioxidant capacity of the wine was observed. Phenolic acids, flavonol glycosides, and anthocyanins reduced the content, whereas flavonol increased the content. Free and copigmented anthocyanin levels decreased, whereas polymerized anthocyanins level increased. This process caused an increase on L^*, b^*, and H^*, but a decrease on a^* and C^*. The oak chip treatment delayed the wine color change and its effect was mainly depended on the addition amount. Partial least square regression revealed that flavonol glycosides, phenolic acids, and anthocyanins displayed a positive correlation with L^*, b^*, and H^*, but a negative correlation with a^* and C^*. Quercetin‐3‐O‐glucuronide, myricetin‐3‐O‐galactoside, chlorogenic acid, and quercetin exerted a more important effect on the color alteration in wine.     

Postharvest ethylene and 1-MCP treatments both affect phenols, anthocyanins, and aromatic quality of Aleatico grapes and wine

Aleatico grapes (Vitis vinifera L. cv. Aleatico) picked at 20.4–20.6^oBrix were treated with air containing 500 mg/L ethylene for 15 h, or 1 mg/L 1‐MCP (1‐methylcyclopropene) for 15 h, or 1 mg/L 1‐MCP for 15 h + 500 mg/L ethylene for further 15 h, or air (control). All treatments were imposed at 20^oC and 95–100% relative humidity. Samples undergoing treatment were then held in air at 20^oC and 85% relative humidity for 13 days. Ethylene production from ethylene‐treated grapes was very high (25 μL/kg.h) immediately after treatment, and declined progressively until day 6; 1‐MCP‐ethylene‐treated grapes showed lower ethylene production (10 μL/kg.h). This high ethylene production was mainly due to in‐out diffusion of ethylene absorbed during the treatment, but a potential effect of 1‐MCP is postulated, since 1‐MCP‐treated grapes did not show ethylene production for 2 days after treatment, whereas control grapes produced constant amounts (3–4 μL/kg.h) of ethylene. After day 6, no significant difference was observed among samples. No difference in respiration was revealed. Total phenols were increased significantly by ethylene treatment from 520 mg/L up to 710, while total anthocyanins were lost in air‐treated samples (from 175 mg/L to 120) and remained constant in ethylene and 1‐MCP‐treated grapes. HPLC analyses of anthocyanins confirmed this result: air‐treated samples lost anthocyanins rapidly while this loss was delayed in gas‐treated samples. Terpenols, esters, alcohols, and C6 compounds were increased by ethylene treatment. Conversely, 1‐MCP‐treated grapes showed a significant loss of terpenols and esters, although maintaining alcohols, especially hexan‐1‐ol. Berry pathology was also affected, with 1‐MCP and 1‐MCP‐ethylene treated grapes hosting a diffuse attack of grey mould. Wine analyses revealed higher concentrations of phenols and anthocyanins in wine from ethylene‐treated grapes, although aromatic compounds were lost, and thus the aroma profile of those wines was diminished.     

Chemical analysis and acetylcholinesterase inhibitory effect of anthocyanin-rich red leaf tea (cv. Sunrouge)

BACKGROUND: The purpose of this study was to evaluate the effects of leaf order or crop season on anthocyanins and other chemicals in the anthocyanin‐rich tea cultivar ‘Sunrouge’ (Camellia sinensis x C. taliensis) by using high‐performance liquid chromatography, and to study the effect of ‘Sunrouge’ extract on acetylcholinesterase (AChE) activity in human neuroblastoma SK‐N‐SH cells. RESULTS: The total anthocyanin content was higher in the third (3.09 mg g^?1) than in the second (2.24 mg g^?1) or first crop season (1.79 mg g^?1). The amount of anthocyanins contained in the stem was high (1.61 mg g^?1). In the third crop season, the concentrations of delphinidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside (DCGa), cyanidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside, delphinidin‐3‐O‐β‐D ‐galactopyranoside, delphinidin‐3‐O‐β‐D ‐(6‐O‐(Z)‐p‐coumaroyl)galactopyranoside, cyanidin‐3‐O‐β‐D ‐galactoside, and delphinidin‐3‐O‐β‐D ‐glucoside were 1.57 mg g^?1, 0.52 mg g^?1, 0.40 mg g^?1, 0.22 mg g^?1, 0.14 mg g^?1, and 0.11 mg g^?1, respectively. DCGa accounted for about 50% of the anthocyanins present. The suppressive effect of ‘Sunrouge’ water extract on AChE activity in human neuroblastoma SK‐N‐SH cells was the strongest among the three tea cultivars (‘Sunrouge’, ‘Yabukita’ and ‘Benifuuki’). CONCLUSION: These results suggested that ‘Sunrouge’ might protect humans from humans from AChE‐related diseases by suppressing AChE activity. To obtain sufficient amounts of anthocyanins, catechins and/or caffeine for a functional food material, ‘Sunrouge’ from the third crop season should be used. Copyright © 2012 Society of Chemical Industry     

Bioavailability of a bilberry anthocyanin extract and its impact on plasma antioxidant capacity in rats

Anthocyanins are secondary metabolites from the flavonoid family, frequently found in fruits and vegetables. They have been shown to possess beneficial health effects and various in vitro assays have highlighted their powerful antioxidant capacity. However, little is known about their metabolism after digestion and their antioxidant potency in vivo. The aim of this work was to evaluate anthocyanin bioavailability and to determine the impact of an anthocyanin‐rich diet on plasma antioxidant status in rats. Animals were fed for 8 days with a vitamin E‐deficient diet supplemented with a bilberry (Vaccinium myrtillus L.) anthocyanin extract providing daily 1.43 mmol anthocyanins kg^?1 body weight. An anthocyanin‐enriched diet significantly enhanced the plasma antioxidant capacity compared with a control diet (P < 0.0001). Moreover, anthocyanins were recovered in urine in the intact glycosidic forms in addition to unknown metabolites. Urinary excretion of bilberry anthocyanins and their metabolites was 0.71 ± 0.08 µmol per 24 h (ie 0.22% of the ingested dose). Anthocyanins and their corresponding aglycones were detected in caecal contents. After a single oral administration of the bilberry extract, native anthocyanins quickly (30 min) appeared in plasma. Hence, in spite of a low bioavailability, bilberry anthocyanin extract consumption has a positive effect on plasma antioxidant capacity. Copyright © 2005 Society of Chemical Industry     

INHIBITION OF SOME FOODBORNE BACTERIA BY ALCOHOL EXTRACT OF SUMAC (RHUS CORIARIA L.)

The inhibitory effect of alcohol extract of sumac (Rhus coriaria L.) was investigated at concentrations of 0.1, 0.5, 1.0, 2.5 and 5.0% (w/v) on the growth of 12 bacterial strains (6 Gram positives and 6 Gram negatives), mostly foodborne including pathogens. Minimal inhibitory concentration of the spice for each test organism was also studied by observing their growth on Nutrient Agar containing the spice extract at various incremental levels equivalent to 100–5000 mg/L of spice. Alcohol extract of sumac was found to be effective against all the test organisms, Gram positives being more sensitive than Gram negatives. Among the Gram positives, Bacillus species (B. cereus, B. megaterium, B. subtilis and B. thuringiensis) were found to be the most sensitive, surviving up to only 500 mg/L of the spice, followed by Staphylococcus aureus (1000 mg/L), whereas Listeria monocytogenes was found to be the most resistant, surviving up to 1500 mg/L. Of the Gram negative bacteria, Salmonella enteritidis and Escherichia coli type I were found to be more resistant, surviving up to 3000 mg/L of the spice, followed by E. coli O157:H7 (2500 mg/L), Hafnia alvei (2000 mg/L), Proteus vulgaris (1500 mg/L) and Citrobacter freundii (1000 mg/L). Significant differences (P < 0.01) were found among bacterial strains and between the extracts of unripened and ripened sumac samples, with ripened being more effective against all of the bacteria tested.     

Preparation of antibacterial chito‐oligosaccharide by altering the degree of deacetylation of β‐chitosan in a Trichoderma harzianum chitinase‐hydrolysing process

BACKGROUND: Chito‐oligosaccharide (COS) is generally known to possess many specific biological functions, especially antibacterial activity, depending on its size. To prepare a specific size range of COS, however, has proved difficult. The aim of this study was to establish a method for preparing a specific size range of antibacterially active COS by adjusting the degree of deacetylation (DD) of β‐chitosan in a Trichoderma harzianum chitinase‐hydrolysing process. RESULTS: The molecular weight spectrum, elucidated by viscosity‐average molecular weight, high‐performance liquid chromatography and thin layer chromatography, of COS in chitosan hydrolysate was significantly related to the DD of its original chitosan. Compared with the original form, COS produced at 90% DD showed superior activity against most Gram‐negative bacteria tested, with a minimum inhibition concentration (MIC) ranging from 55 ± 27 to 200 ± 122 µ g mL^?1. Conversely, most Gram‐positive strains tested were less sensitive to COS (MIC > 880 ± 438 µ g mL^?1) than to its original form. Among the Gram‐positive strains, Staphylococcus xylosus was the only exception in that it showed a high susceptibility to COS and had an MIC as low as 45 ± 11 µ g mL^?1. CONCLUSION: The results indicate that the production of a specific size range of COS product is possible by altering the DD of chitosan in the chitinase‐catalysed process. To produce various sizes of COS for versatile biological functions, as seen in this study to inhibit various types of bacteria, is made possible in this established process. Copyright © 2008 Society of Chemical Industry     

Inhibitory Effects of Red Wine on Lipid Oxidation in Fish Oil Emulsion and Angiogenesis in Zebrafish Embryo

The capabilities of red wine against lipid oxidation and angiogenesis were evaluated by using a fish oil emulsion system and an in vivo zebrafish embryos model, respectively. The red wine contained 12 different antioxidant phenolics which levels were led by anthocyanins (140.46 mg/L), catechin (55.08 mg/L), and gallic acid (46.76 mg/L). The diversity of the phenolics in red wine was greater than the tea, coffee, or white wine selected as a peer control in this study. The total phenolics concentration of red wine was 305.53 mg/L, although the levels of tea, coffee, and white wine were 85.59, 76.85, and 26.57 mg/L, respectively. The activity of red wine in scavenging DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) free radicals was approximately 4 times higher than the tea and 8 times than the coffee or white wine. The red wine showed the highest capability in preventing long chain PUFA oxidation in the fish oil emulsion. Because of the outstanding antioxidant activity of red wine, the red wine dried extract was used to monitor its inhibitory effect against angiogenesis by using transgenic zebrafish embryos (Tg[fli1:egfp]^y1) with fluorescent blood vessels. After incubated in 100 μg/mL of the extract solution for 26 h pf, each of the embryos had a lower number of intersegmental vessel than the control embryo. The inhibition rate of red wine extract against growing of angiogenic blood vessel reached 100%.     

Inhibitory effect of propolis extract on the growth of Listeria monocytogenes and the mutagenicity of 4‐nitroquinoline‐N‐oxide

Propolis originates from a resinous substance collected by honeybees from the buds and leaves of trees and plants, which is then mixed with pollen as well as enzymes secreted by the bees. In the present study, the susceptibility of Listeria monocytogenes to the ethanol extract of propolis (EEP) as influenced by EEP concentration, incubation temperature, pH, and cell age was investigated. In addition, the antimutagenic action of EEP against 4‐nitroquinoline‐N‐oxide (4‐NQO) was also examined. Results revealed that EEP at a dosage of 7.5 µg mL^?1 or higher exerted a bactericidal effect on L. monocytogenes. L. monocytogenes was most susceptible to EEP at 37 °C followed by 25 and 4 °C. At acid pH values, cells of the test organism were more sensitive to EEP than at neutral pH, while most resistant at alkaline pH values. Cell age was also found to affect the susceptibility of L. monocytogenes to EEP. Cells in the mid‐exponential phase showed the highest susceptibility, followed by cells in the late‐exponential phase and stationary phase. EEP caused cell leakage of the test organism. A marked increase in the absorbance at 260 nm, UV‐absorbing material in the supernatant of cell suspension, and irregularly shaped materials around the cell surface were noted after cells of L. monocytogenes were exposed to EEP. Furthermore, EEP at a dosage of 7.5–60.0 µg per plate was found to suppress 4‐NQO‐induced mutation by 17.6–88.8%. Copyright © 2006 Society of Chemical Industry     

Antimicrobial effect of water extract of sumac (Rhus coriaria L.) on the growth of some food borne bacteria including pathogens

The antimicrobial effect of water extracts of sumac (Rhus coriaria L.) at concentrations of 0.1%, 0.5%, 1.0%, 2.5% and 5.0% (w/v), non-neutralized and after neutralization to pH 7.2+/-0.1, was studied on the growth of 12 bacterial strains (six Gram positive strains and six Gram negative strains), mostly food borne including pathogens. It was found to be effective against all the test organisms with Gram positive strains being more sensitive than Gram negative strains. Significant differences (P<0.01) were found among the bacteria and between the non-neutralized and neutralized extracts with non-neutralized being more effective against all the bacteria. The minimal inhibitory concentration (MIC) of the extract for each bacterial strain was studied by a gradient plate method. Among the Gram positive organisms, Bacillus species (Bacillus cereus, Bacillus megaterium, Bacillus subtilis, and Bacillus thuringiensis) were found to be the most sensitive showing MICs of 0.25-0.32% (after 24 h incubation) followed by Staphylococcus aureus (0.49%), while Listeria monocytogenes was found to be the least sensitive demonstrating a MIC of 0.67%. Of the Gram negative organisms, Salmonella enteritidis was found to be the most resistant with a MIC of 0.67% followed by Escherichia coli Type I, E. coli O157:H7, Proteus vulgaris and Hafnia alvei having MICs of 0.63%, 0.60%, 0.55% and 0.45%, respectively; whereas Citrobacter freundii was found to be the least resistant surviving up to 0.42%. Some loss of antimicrobial activity was, however, observed after incubation for 3 days. Bacteriostatic/bactericidal effects of sumac, as studied by enumerating survival by the viable count technique after 1 h direct contact of each microorganism with various concentrations of sumac extract, revealed a 4-5 log cycle reduction in Bacillus spp. and 2-3 log cycle reduction in other bacteria tested with 1.0% sumac extract.     

LC‐MS identification of anthocyanins in boysenberry extract and anthocyanin metabolites in human urine following dosing

The anthocyanin composition of boysenberry (Rubusloganbaccus × baileyanus Britt) extract was determined by LC‐ESI‐MS. Four anthocyanins were identified, all comprising a cyanidin‐anthocyanidin‐type skeleton. The two major components were identified as the disaccharide cyanidin‐3‐O‐sophoroside and the monosaccharide cyanidin‐3‐O‐glucoside. The two less abundant components were identified as the rutinosides, cyanidin‐3‐O‐2^G‐glucosylrutinoside and cyanidin‐3‐O‐rutinoside, respectively. These same four anthocyanins were also detected in human urine following a dosing study with boysenberry extract indicating that glycosylated anthocyanins can be absorbed from the gut and excreted intact in the urine. Several anthocyanin metabolites were also detected in the urine and were identified by LC‐ESI‐MS as monoglucuronides of peonidin, cyanidin and pelargonidin. The results suggest that anthocyanins consumed as part of a diet are bioavailable and are present as intact or metabolized forms in the body. Copyright © 2004 Society of Chemical Industry     

Anthocyanins,Antioxidative, and Antimicrobial Properties of American Cranberry (Vaccinium macrocarpon Ait.) and their Press Cakes

ABSTRACT: Amounts of total phenolics, anthocyanins, and ascorbic acid in 4 American cranberry varieties harvested at 4 stages of maturity were measured. The larger amount of phenolic compounds was found in berries of “Black Veil” cultivar (504 mg/100 g) at II stage of maturity. Significantly larger amounts of anthocyanins were determined in the overripe berries of the cultivars “Ben Lear” and “Black Veil.” The amount of ascorbic acid in berries increased during ripening from I to III stage, and slightly decreased in the overripe berries. The biggest quantities of ascorbic acid were found in the ripe berries of “Ben Lear” cultivar (15.8 mg/100 g). The distribution of anthocyanins pigments was determined by HPLC‐UV/MS in mature berries. The composition of individual anthocyanins in berries was quite similar in all the studied cranberry cultivars. While skins of cranberries are rich in anthocyanins and other phenolic compounds, the extracts of the by‐products of cranberries juice—berry cakes, were analyzed and obtained results were compared with the properties of extracts made from whole berries. The anthocyanins and total phenolics content, radical scavenging activity, antimicrobial activity of the whole berries, and their press cakes extracts were measured. All investigated extracts from berries and their press cakes showed good radical scavenging activity and revealed antimicrobial properties. It was found that Bacillus cereus (ATCC 10876) and Micrococcus luteus (ATCC 9341) were the most sensitive among 10 tested Gram‐negative and Gram‐positive bacteria.     

Optimization extraction of anthocyanins from purple corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.) cob using tristimulus colorimetry

Optimization of the conditions for extracting anthocyanins from the cob, a byproduct of purple corn (Zea mays L.), was investigated in this paper. A full factorial design (2² × 3²) was used. The factors studied were type of solvent: ethanol or methanol; solvent/water mixture: 100, 90, 80% v/v; type of acid: citric acid or acetic acid; and concentrations of acid: 0.25, 0.5, 1% v/v. Tristimulus colorimetry was employed to evaluate the yield and quality of anthocyanins extracts. The results showed that the maximum yield (5.90 mg/g dw) was obtained with the combination of 80% (v/v) methanol and 1% (v/v) citric acid, and that the relatively high chroma (C* = 23.60) and hue angle (h = 16.63) values of the anthocyanins extract were observed under the same conditions. Eight kinds of anthocyanins in the cob were detected by HPLC–DAD, most the anthocyanins were non-acylated.     

Pomegranate (Punica granatum) juices: chemical composition, micronutrient cations, and antioxidant capacity

Abstract: Phenolics, flavonoids, anthocyanins, and tannins of pomegranate juices, obtained from 9 Tunisian ecotypes were quantified. Phenolics and flavonoids in the variety Tounsi (TN) (3299 mg gallic acid equivalents [GAE]/L and 636 mg quercetin equivalents [QE]/L of juice, respectively) were higher than in the variety Gabsi (GB) (1570 mg GAE/L and 135 mg QE/L of juice, respectively). The highest anthocyanins quantity was found in GB 2 with 156 mg cyanidin‐3‐glucoside equivalents (CGE)/L. TN 3 ecotype showed the highest tannins quantity with 2550 mg catechin equivalents (CE)/L of juice. TN 1 presented the highest radical‐scavenging activity (2, 2′‐azinobis‐3‐ethylbenzothiazoline‐6‐sulphonate [ABTS], IC₅₀ [50% inhibition concentration] = 525 mg/L), as well as the highest concentration of micronutrient cations (potassium and sodium). A high correlation (R²= 0.80) between antioxidant capacity and proanthocyanin contents was found, this suggests that proanthocyanins are the principal contributor in the antioxidant capacity of pomegranate. Our data suggest also that the high concentrations of K⁺ and Na⁺ may play a role in the adaptation of pomegranate to arid environments.     

Chemical,antioxidant and antibacterial study of Brazilian fruits

In this study, the antioxidant capability, total phenolic content and antimicrobial activity of ethanolic extracts of seven fruits from the Brazilian Atlantic Forest were evaluated. The conditions for the extraction of crude phenolics from the fruits were determined using an experimental factorial design. Total phenolic content, 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH^?) scavenging activity and β‐carotene‐linoleic acid couple oxidation assays were used to evaluate the antioxidant properties of the extracts. In addition, antimicrobial activity was screened using two Gram‐negative bacteria (Escherichia coli and Klebsiella pneumoniae) and one Gram‐positive bacterium (Staphylococcus aureus). All native fruits assayed in this study have high potential as natural antioxidant sources. Among the seven fruits evaluated, Jabuticaba and Uvaia had the highest antioxidant activity in the DPPH^? and of β‐carotene‐linoleic acid coupled oxidation assays. In the biological assay, K. pneumoniae was the most sensitive microorganism to the fruit extracts, and the Jabuticaba extract had a slight inhibitory effect against this Gram‐positive bacterium.     

Antihyperlipidaemic effect of Aegle marmelos fruit extract in streptozotocin‐induced diabetes in rats

The present study determines the effect of an aqueous extract of Aegle marmelos fruits on serum and tissue lipids in experimental diabetes. Albino Wistar rats were rendered diabetic by intraperitoneal administration of streptozotocin (45 mg kg^?1). Serum and tissue lipids such as total cholesterol, triglycerides, free fatty acids and phospholipids were elevated in diabetic rats. Oral administration of A marmelos fruit extract at doses of 125 and 250 mg kg^?1 to diabetic rats twice daily for 1 month led to a significant lowering of these lipids in diabetic rats. The effect exerted by the fruit extract at a dose of 250 mg kg^?1 was greater than that of the dose of 125 mg kg^?1 or of glibenclamide (300 µg kg^?1). The results of this study demonstrate that an aqueous A marmelos fruit extract exhibits an antihyperlipidaemic effect in streptozotocin‐induced diabetic rats. Copyright © 2004 Society of Chemical Industry     

Cherry (Prunus cerasus cv Montmorency) extract with standardised antioxidant potential as preservative for refrigerated storage of ground pork

Antioxidants occurring naturally are much sought‐after for their safety of use for human nutrition and strong preservative properties. The study was performed to determine the antioxidant potential of sour cherry extract and its effect (equivalent of 20 mg and 40 mg GAE kg^?1) on the quality of ground pork patties during 8‐day storage. The patties were analysed for antioxidant capacity, oxidation, profile of fatty acids, flavour, colour, sensory properties and aerobic bacteria count. Patties with addition of cherry extract (40 mg GAE kg^?1) showed higher antioxidant capacity of 844 ± 149 μmol TE L^‐1 on the last day of the storage than the control group where the result was 480 ± 81 μmol TE L^‐1. The addition of extract caused lower overall increase in lipid oxidation and prevented loss of redness even on the last day of the storage. Flavour changes resulted from oxidation and decrease in the amount of desirable volatile compounds in storage. The application of the extract from Prunus cerasus combined with vacuum packaging inhibited both oxidation and quality deterioration of pork patties in cold storage.     

Damage inhibition during refrigerated storage of mackerel (Scomber scombrus) fillets by a presoaking in quince (Cydonia oblonga) polyphenolic extract

The effect of quince (Cydonia oblonga Miller) polyphenolic extract on preserving mackerel (Scomber scombrus) fillets during refrigerated (4 °C) storage for 11 days was investigated. The quince extract, mainly consisted of procyanidin B dimer (50.8%) and hydroxycinnamic acids (36.62%), was found to quench 2,2‐diphenyl‐1‐picrylhydrazyl radicals by nearly 59.3%. As deduced from the lower peroxide value of the fillet fat fraction and the inhibition of thiobarbituric acid reactive substances formation, the quince extract (8.9 ± 0.4 mg phenolics mL^?1) was found to prevent fish oil from oxidative deterioration compared to control samples. Moreover, the extract was found to be active for in vitro inhibiting the growth of a range of food‐borne bacteria, including Vibrio fluvialis, a halophilic bacterium responsible for a relevant number of sporadic gastroenteritis attributed to contaminated seafood. The minimal inhibition and bactericide concentration (MIC, MBC) values were about 0.37–1.2 mg of polyphenols mL^?1. In a second experiment, following cold smoking of fillets, sensory attributes firmness, astringency, acidity, colour and odour were analysed. The use of multivariate statistical methods (cluster analysis and principal component analysis) revealed no significant differences between samples pre‐treated and non‐pre‐treated (control) with the quince‐phenolic extract.     

Temperature and storage effects on antioxidant activity of juice from red and white grapes

The effect of temperature and storage time on the phenolic composition and on the antioxidant activity of grape (Vitis vinifera L.) juices made using a red (Sangiovese, SG) and a white (Muscat of Alexandria, MA) variety was studied. Total phenolics, flavonoids, flavan‐3‐ols and hydroxycinnamoyl‐tartrates (HCT) were determined on grape extracts (GE) and juices. Total anthocyanins and anthocyanins composition were measured on GE. The antioxidant activity was assessed by means of two different in vitro tests: scavenging of the stable 2,2‐diphenyl‐1‐picrylhydrazyl radical and the inhibition of tyrosine nitration mediated by authentic peroxynitrite (ONOO^?). All the juices were analysed after 24 h and 2 weeks of storage by means of two‐way anova (factors being cultivar and temperature). Anthocyanins were not detected in MA extract, whereas in SG their content was 534 mg malvidin‐equivalent per 100 g of dry matter (d.m.) and malvidin derivatives (glycosylated and coumaroylated) were the most represented (respectively 169 and 41 malvidin‐equivalent per 100 g of d.m.). HCT content of the extracts was higher in SG (overall +33%). Also in grape juices, HCT were lower in MA and in this variety, the trans‐fertaric and cis‐coutaric acids were also undetectable. Cultivar effect proved to be highly significant, while no significant differences in the phenolic composition were observed for storage temperatures (4 and ?20 °C) and cultivar × temperature interaction. However, when statistical analysis was focused on each cultivar, MA was found to be more sensible to storage conditions and a significant reduction in total phenolics (?20%) and flavonoids (?53%) content and in the ONOO^? scavenging potential (?32%) was evident after 2 weeks at 4 °C (when compared with the same storage temperature after 24 h). On the contrary, SG juices did not show significant differences among the four storage treatments investigated. These results could be explained suggesting that anthocyanins presence in red grape plays a key role in juice stability.     

UPLC-PDA-ESI/MS metabolic profiling of dill shoots bioactive fraction; evidence of its antioxidant and hepatoprotective effects in vitro and in vivo

Hydroxyl radical (^•OH) scavenging capacity of aqueous dill (Anethum graveolens L.) shoot (ADSh) extract was assessed using electron paramagnetic resonance (EPR) spectroscopy. ADSh extract (at concentrations of 0.5 and 10 mg/ml) exerted high (OH) radical scavenging power. ADSh extract was further fractionated on Diaion HP-20 column to yield five fractions. EPR spin-trapping assay revealed fraction 4 (eluted with 75% aq. MeOH) to possess (^•OH) radical scavenging capacity over a concentration range (0.01–10 mg/ml), whereas fraction 2 (eluted with 25% aq. MeOH) appeared to be pro-oxidant at concentration 0.01 mg/ml. UPLC-PDA-ESI-MS metabolite profiling of ADSh extract revealed 87 metabolites, of which 64 compounds were identified in fraction 4, the most active fraction. Furthermore, ADSh extract demonstrated a hepatoprotective effect against acetaminophen (APAP)-induced hepatotoxicity in rats. Pretreatment of rats with ADSh extract (200 mg/kg b.wt) markedly attenuated the increased in the serum hepatic enzyme levels. It also increased free glutathione level and total antioxidant capacity in the serum of treated rats. [Correction added on May 3, 2021, after first online publication: "rates" has been changed to "rats" in the previous sentence.] Additionally, levels of (TNF-α and IL-1β) were back to almost normal levels compared to the control group. The above findings suggest that ADSh extract has a protective effect against APAP-induced liver damage.