Antimicrobial activity and composition profile of grape (Vitis vinifera) pomace extracts obtained by supercritical fluids

Effect of Raw and Fermented Grape Pomace on the Growth Performance, Antioxidant Status, Intestinal Morphology, and Selected Bacterial Species in Broiler Chicks

The effects of raw (GP) and fermented grape pomace (FGP) on the growth performance, some carcass parameters, antioxidant status, intestinal morphology, and selected bacterial species in broiler chicken were investigated in this study. Grape pomace was fermented with Aspergillus niger for 7 d. In total, 140 one-day-old male chicks (Ross 308) were randomly assigned to four treatment groups, with five replicates and seven birds each. Chickens were fed either a basal diet (CON) or the basal diet supplemented with 0.25 g/kg synthetic antioxidants (5% butylated hydroxytoluene, 1% butylated hydroxyanisole, and 11% ethoxyquin) (AO), or 15 g/kg GP (GP), or 15 g/kg FGP (FGP) for 42 d. Dietary GP raised serum glutathione peroxidase (p = 0.031) and superoxide dismutase (p = 0.021) levels, increased ileum lamina muscularis thickness (p = 0.016), and did not affect selected bacterial species in the cecum of broiler chickens. Dietary FGP improved body weight (p = 0.003), increased the serum catalase level (p = 0.032), and decreased the cecal Clostridium perfringens count (p = 0.033) but did not affect the ileal morphology of broiler chickens. The carcass parameters, malondialdehyde level, pH, and color of the breast meat of chickens were not changed by either GP or FGP supplementation. Chickens fed with the synthetic antioxidants had similar growth performance with the chickens fed with FGP but had better body weight (p = 0.003) and feed conversion ratio (p = 0.045) compared with the chickens fed with GP. The obtained results showed that FGP can be used as an alternative to synthetic antioxidants in broiler diets.

Polymeric nanoparticles as oral delivery systems for a grape pomace extract towards the improvement of biological activities

Grape pomace (GP) is a major by-product from the wine industry, known for its bioactive compounds and their impact upon gastrointestinal (GI) health. However, bioaccessibility is often poor due to their degradation during digestion. This work aimed to encapsulate bioactive GP extract (GPE) into chitosan (CS) and alginate (Alg) nanoparticles (NPs) to mitigate degradation in the GI tract. Alg and CS NPs were optimized using a rotatable central composite design and NPs were characterized for their size, polydispersity, zeta potential and total phenolics (TP) association efficiency. The best formulations showed sizes ranging 523-853 nm, polydispersity indexes of 0.11-0.36, zeta potential of -15.0-14.9 mV and TP association efficiencies of 68 and 65%. FTIR confirmed that there was no formation of new chemical groups after association of the polymers with GPE. Both formulations improved the bioaccessibility of different phenolics following in vitro GI digestion, leading to increased antioxidant and antimicrobial activities. Moreover, the permeability of bioactive compounds through a Caco-2/HT29-MTX co-culture was reduced, suggesting a higher residence time in the intestine. Cy5.5 was used for tracking the CS NPs, which did not affect the metabolic activity of Caco-2 and HT29-MTX cells. Confocal microscopy images confirmed the adsorption of NPs to the cellular layer and suggested a reduction of the tight junction protein occludin when cells were incubated with Cy5.5-CS in solution. This study suggests that encapsulation of GPE can offer protection against along the GI tract and improve its biological activity with significant impact for oral delivery applications, including functional foods.

Curcumin-Loaded Bacterial Cellulose/Alginate/Gelatin as A Multifunctional Biopolymer Composite Film

Multifunctional biopolymer composites comprising mechanically-disintegrated bacterial cellulose, alginate, gelatin and curcumin plasticized with glycerol were successfully fabricated through a simple, facile, cost-effective mechanical blending and casting method. SEM images indicate a well-distributed structure of the composites. The water contact angles existed in the range of 50-70°. Measured water vapor permeability values were 300-800 g/m2/24 h, which were comparable with those of commercial dressing products. No release of curcumin from the films was observed during the immersion in PBS and artificial saliva, and the fluid uptakes were in the range of 100-700%. Films were stretchable and provided appropriate stiffness and enduring deformation. Hydrated films adhered firmly onto the skin. In vitro mucoadhesion time was found in the range of 0.5-6 h with porcine mucosa as model membrane under artificial saliva medium. The curcumin-loaded films had substantial antibacterial activity against E. coli and S. aureus. The films showed non-cytotoxicity to human keratinocytes and human gingival fibroblasts but exhibited potent anticancer activity in oral cancer cells. Therefore, these curcumin-loaded films showed their potential for use as leave-on skin applications. These versatile films can be further developed to achieve desirable characteristics for local topical patches for wound care, periodontitis and oral cancer treatment.

Antifungal Activity of Phenolic and Polyphenolic Compounds from Different Matrices of Vitis vinifera L. against Human Pathogens

Phenolic compounds, the most widely distributed class of natural products in the plants, show several biological properties including antifungal activity. Phenolics contained in grapes can be classified in two main groups, flavonoids and non-flavonoids compounds. Variability and yield extraction of phenolic and polyphenolic compounds from different matrices of Vitis vinifera depends of cultivar, climate, soil condition and process technology. Unripe grapes, berry skins and seeds, leaves, canes and stems and not-fermented and fermented pomaces represent large reusable and valuable wastes from agricultural and agro-industrial processes. This review summarizes studies that examine the extraction method, chemical characterization, and antifungal activity of phenolic and polyphenolic compounds from edible and non-edible V. vinifera matrices against human fungal pathogens. In the world, around one billion people have fungal diseases related to skin, nail or hair and around 150 million have systemic diseases caused by fungi. Few studies on antifungal activity of plant extracts have been performed. This review provides useful information for the application of V. vinifera phenolics in the field of antifungals for human use.

Potential of grape byproducts as functional ingredients in baked goods and pasta

Wine making industry generates high quantities of valuable byproducts that can be used to enhance foods in order to diminish the environmental impact and to obtain more economic benefits. Grape byproducts are rich in phenolic compounds and dietary fiber, which make them suitable to improve the nutritional value of bakery, pastry, and pasta products. The viscoelastic behavior of dough and the textural and the sensory characteristics of baked goods and pasta containing grape byproducts depend on the addition level and particle size. Thus, an optimal dose of a finer grape byproducts flour must be found in order to minimize the negative effects such as low loaf volume and undesirable sensory and textural characteristics they may have on the final product quality. In the same time, an enrichment of the nutritional and functional value of the product by increasing the fiber and antioxidant compounds contents is desired. The aim of this review was to summarize the effects of the chemical components of grape byproducts on the nutritional, functional, rheological, textural, physical, and sensory characteristics of the baked goods and pasta. Further researches about the impact of foods enriched with grape byproducts on the human health, about molecular interactions between components, and about the effects of grape pomace compounds on the shelf life of baked goods and pasta are recommended.

Research Advances in the Use of Bioactive Compounds from Vitis vinifera By-Products in Oral Care

Oral health is considered an important factor of general health and it contributes to the quality of life. Despite the raising awareness of preventive measures, the prevalence of oral health conditions continues to increase. In this context, a growing interest in investigating natural resources like Vitis vinifera (V. vinifera) phenolic compounds (PhCs) as oral health promoters has emerged. This paper aims to review the evidence about the bioactivities of V. vinifera by-products in oral health. Up to date, a high number of studies have thoroughly reported the antimicrobial and antiplaque activity of V. vinifera extracts against S. mutans or in multi-species biofilms. Moreover, the bioactive compounds from V. vinifera by-products have been shown to modulate the periodontal inflammatory response and the underlying oxidative stress imbalance induced by the pathogenic bacteria. Considering these beneficial effects, the utility of V. vinifera by-products in the maintaining of oral health and the necessary steps towards the development of oral care products were emphasized. In conclusion, the high potential of V. vinifera by-products could be valorized in the development of oral hygiene products with multi-target actions in the prevention and progression of several oral conditions.

Integrated biorefinery approach to valorize winery waste: A review from waste to energy perspectives

The ever-increasing environmental crisis, depleting natural resources, and uncertainties in fossil fuel availability have rekindled researchers' attention to develop green and environmentally friendlier strategies. In this context, a biorefinery approach with a zero-waste theme has stepped-up as the method of choice for sustainable production of an array of industrially important products to address bio-economy challenges. Grape winery results in substantial quantities of solid organic and effluent waste, which epitomizes an increasing concentration of pollution problems with direct damage to human health, economy and nature. From the perspective of integrated biorefinery and circular economy, winery waste could be exploited for multiple purpose value-added products before using the biomass for energy security. This review covers state-of-the-art biorefinery opportunities beyond traditional methods as a solution to overcome many current challenges such as waste minimization in grape leaves, stems, seeds, pomace, wine lees, vinasse etc. and the biosynthesis of various high-value bioproducts viz., phenolic compounds, hydroxybenzoic acids, hydroxycinnamic acids, flavonoids, tartaric acids, lignocellulosic substrates etc.. The critical discussion on the valorization of winery waste (solid, liquid, or gaseous) and life cycle assessment was deployed to find a sustainable solution with value added energy products in an integrated biorefinery approach, keeping the environment and circular economy in the background.

Composition and Antibacterial Activity of Aronia melanocarpa (Michx.) Elliot, Cornus mas L. and Chaenomeles superba Lindl. Leaf Extracts

The purpose of this study was to investigate the composition of leaf extracts from Aronia melanocarpa, Chaenomeles superba, and Cornus mas, and their antimicrobial activity against typical spoilage-causing and pathogenic bacteria found in meat and meat products. The highest total phenolic content (TPC) was detected in C. superba extract, followed by C. mas and A. melanocarpa extracts. The antioxidant capacity of the extracts was measured by DPPH and ABTS assays. The lowest IC₅₀ values were found for C. superba extract, followed by C. mas and A. melanocarpa extracts. LC-MS and HPLC analysis revealed that A. melanocarpa and C. superba extracts contained hydroxycinnamic acid derivatives and flavonoids (mainly flavonols). Hydroxycinnamic acid derivatives were detected in the C. mas extract, as well as flavonols, ellagitannins, and iridoids. The antibacterial activity of the plant extracts was tested against Gram-negative bacteria (Moraxella osloensis, Pseudomonas fragi, Acinetobacter baumanii, Escherichia coli, Enterobacter aerogenes, Salmonella enterica) and Gram-positive bacteria (Enterococcus faecium, Staphylococcus aureus, Brochothrix thermosphacta, Lactobacillus sakei, Listeria monocytogenes) using the microculture method. The extracts acted as bacteriostatic agents, decreasing the growth rate (µ_max) and extending the lag phase (t_lag). C. mas showed most potent antibacterial activity, as confirmed by principal component analysis (PCA).

Effects of grape seed extract on performance, immunity, antioxidant capacity, and meat quality in Pekin ducks

This study was conducted to evaluate the effects of grape seed extract (GSE) on growth performance, immunity, antioxidant capacity, relative organ weight, jejunum morphology, ileal microflora, and meat quality in Pekin ducks. A total of 1,500 female 1-day-old Pekin ducklings (52.0 ± 0.2 g) were blocked based on body weight (BW) and randomly allocated into 3 treatments with 10 replicates of 50 birds each. The experiment lasted for 6 wk, and dietary treatments included corn-soybean meal-based diet supplemented with 0, 0.01, and 0.02% GSE. The supplementation of GSE increased (P < 0.05) body weight gain (BWG) and final BW linearly but decreased (P < 0.05) feed-to-gain ratio (F/G) linearly during day (D) 22 to 42 and the entire experiment. The inclusion of GSE increased (P < 0.05) serum superoxide dismutase, glutathione peroxidase, total antioxidative capacity, catalase, complement4, immunoglobin G, interleukin-2, and interferon-γ linearly but decreased (P < 0.05) serum malondialdehyde linearly. The relative weight of carcass, breast meat, and spleen in GSE treatments was increased (P < 0.05) linearly, whereas the relative weight of abdominal fat was decreased linearly (P < 0.05). Birds fed GSE1 and GSE2 diets had lower (P < 0.05) cook loss, 2-thiobarbituric acid reactive substances, and drip loss on day 3 and 5 linearly but higher (P < 0.05) pH24h and water-holding capacity. The addition of GSE decreased (P < 0.05) jejunum crypt depth and ileal Escherichia coli counts linearly but increased (P < 0.05) jejunum villus height: crypt depth ratio and ileal Lactobacilli linearly. Taken together, the inclusion of GSE increased final BW and BWG, decreased F/G during day 22 to 42 and day 1 to 42, partially improved antioxidant activities, immunity, meat quality, and gut health in Pekin ducks.

Recovery of bioactive compounds from white grape (Vitis vinifera L.) stems as potential antimicrobial agents for human health

The grape is a matrix rich in bioactive compounds and its production generates large quantities of by-products, such as grape stems, which, to date, present low commercial value. However, there is a growing interest in the application of this material as a source of phenolic compounds. Therefore, the present study aims at assessing the phytochemical profile of (poly)phenolic extracts of white Portuguese grape stem varieties produced in the Região Demarcada do Douro (Portugal). The antioxidant activity determined by several assays, as well as the antimicrobial activity using the disc diffusion method against human gastrointestinal pathogenic bacteria of the hydromethanolic extracts, were evaluated. This work presents very positive results as the rich composition in phenolic compounds (94.71–123.09 mg GA⁻¹ and 0.02–73.79 mg g⁻¹ for the total phenol content and for individual phenolics, respectively) presented by grape stems can explain the high antioxidant (0.37–1.17 mmol Trolox g⁻¹) and antimicrobial activities against, essentially, Gram-positive bacteria, and in some cases with higher efficacy than commercial antibiotics. Thus, demonstrating that this wine by-product should deserve greater attention from the pharmaceutical industries due to its excellent biological properties and characteristics not yet applied.

Plant extracts rich in polyphenols: antibacterial agents and natural preservatives for meat and meat products

Plant extracts contain large amounts of bioactive compounds, mainly polyphenols. Polyphenols inhibit the growth of microorganisms, especially bacteria. Their mechanism of action is still not fully understood but may be related to their chemical structure. They can cause morphological changes in microorganisms, damage bacterial cell walls and influence biofilm formation. Polyphenols also influence protein biosynthesis, change metabolic processes in bacteria cells and inhibit ATP and DNA synthesis (suppressing DNA gyrase). Due to the antioxidant and antibacterial activity of phenolic compounds, plant extracts offer an alternative to chemical preservatives used in the meat industry, especially nitrates (III). They can inhibit the growth of spoilage and pathogenic microflora, suppress oxidation of meat ingredients (lipids and proteins) and prevent discoloration. In this paper, we describe the factors that influence the content of polyphenols in plants and plant extracts. We present the antimicrobial activities of plant extracts and their mechanisms of action, and discuss the effects of plant extracts on the shelf-life of meat and meat products.

In-situ extraction and impregnation of black walnut husk into polyethylene film using supercritical carbon dioxide with an ethanol modifier

Walnuts are commonly cultivated for their kernel, which is a rich source of antioxidant phenolic compounds. The husk likewise contains antioxidant and antimicrobial compounds, but is typically discarded without further processing. Antioxidant compounds are useful in creating active packaging films, but typically decompose at melt extrusion temperatures in polymer processing. Due to carbon dioxide's low critical point and ability to swell polymer films, supercritical carbon dioxide may be used to impregnate phenolic compounds into polymers. For this study, a novel technique is used to simultaneously produce walnut husk extracts and impregnate the extract into polymer films in the same batch extractor using supercritical carbon dioxide with a 15 wt-% ethanol modifier at 60°C at 19.4 MPa. The effect of varying the loading of walnut husk in the extractor upon impregnation mass was evaluated with the impregnation mass of the film increasing with walnut husk loading. It was determined by FTIR, as well as the reduction of the protein cytochrome c, that antioxidant compounds may be extracted from walnut husks and impregnated into low-density polyethylene film (LDPE) by this technique.

Agriculture waste valorisation as a source of antioxidant phenolic compounds within a circular and sustainable bioeconomy

Agro-food industrial waste is currently being accumulated, pushing scientists to find recovery strategies to obtain bioactive compounds within a circular bioeconomy. Target phenolic compounds have shown market potential by means of optimization extraction techniques.

Grape Pomace as a Promising Antimicrobial Alternative in Feed: A Critical Review

Antimicrobial resistance is among the most urgent global challenges facing sustainable animal production systems. The use of antibiotics as growth promoters and for infectious disease prevention in intensive animal-farming practices has translated into the selection and spread of antimicrobial resistance genes in an unprecedented fashion. Several multi-resistant bacterial strains have been isolated from food-producing animals, thus constituting an alarming food-safety issue. Many industrial byproducts with potential antimicrobial properties are currently being investigated to identify empirical and affordable solutions/alternatives that can potentially be used in feed for animals. Grape pomace is among such byproducts that gained the attention as a result of its low cost, abundance, and, most importantly, its bioactive and antibacterial properties. This review discusses the recently reported studies with regard to exploring the use of grape pomace (and its extracts) in animal production to control pathogens, along with the promotion of beneficial bacterial species in the gut to ultimately alleviate antibacterial resistance. The review further summarizes realistic expectations connected with grape pomace usage and lists the still-to-be-addressed concerns about its application in animal agriculture.

Impact of in vitro gastrointestinal digestion on the chemical composition, bioactive properties, and cytotoxicity of Vitis vinifera L. cv. Syrah grape pomace extract

Grape pomace (GP) is a major byproduct worldwide, and it is well known for its bioactive compounds, such as fibers and phenolic compounds, that are popular for their impact upon human health, including gastrointestinal health. The objective of this work was to evaluate the chemical composition and biological activities of an enzymatic GP extract, as well as to investigate how gastrointestinal digestion (GID) modulates these properties. GP extract was previously produced using an enzymatic cocktail with xylanase activity and was then exposed to simulated conditions of GID, characterized for its chemical composition, and screened for antimicrobial, prebiotic, and antioxidant activities. The safety of this ingredient after GID was also assessed. GP extract presented high contents of dietary fiber and other carbohydrates, including xylooligosaccharides, in addition to minerals and phenolic compounds. In vitro simulated GID revealed that xylobiose was resistant to gastric conditions, unlike phenolic compounds. The use of 2% (w/v) of this ingredient proved to be a potential carbon source that could be fermented by Lactobacillus and Bifidobacterium spp, even after digestion. The extract also exhibited strong antioxidant and antimicrobial activities against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa; however, after GID, the antioxidant capacity decreased, and the antimicrobial capacity was strongly reduced or lost. Furthermore, the extract safety was also guaranteed on Caco-2 intestinal cells. This novel and green GP extract proved to be composed of relevant bioactive molecules, including xylooligosaccharides, polyphenols, organic acids, and minerals, which provided different biological properties; it has potential applications in the food industry such that it can be used as an ingredient in the development of new functional foods.

Grape Infusions: The Flavor of Grapes and Health-Promoting Compounds in Your Tea Cup

Traditionally, tea, a beverage made from the processed leaves of the tea plant, Camellia sinensis, and herbal infusions have been primarily consumed for their pleasant taste. Nowadays, they are also consumed because they contain nutraceutical compounds, such as polyphenols. Grapes and grape/wine sub-products such as non-fermented/semi-fermented or fermented grapes, skins, and seeds are a rich source of health-promoting compounds, presenting a great potential for the development of new beverages. Therefore, these grape/wine sub-products are used in the beverage sector for the preparation of infusions, tisanes, and decoctions. Besides polyphenols, fermented grapes, skins, and seeds, usually discarded as waste, are enriched with other health-promoting/nutraceutical compounds, such as melatonin, glutathione, and trehalose, among others, which are produced by yeasts during alcoholic fermentation. In this review, we summarize the benefits of drinking herbal infusions and discuss the potential application of some grapevine fermentation waste products in the production of healthy beverages that we can call grape infusions.

Phytochemical Evaluation, Antimicrobial and Anticancer Properties of New “Oligo Grapes” Supplement

This research presents complete data about phytochemical analysis and biological activities of a new dietary supplement for commercial use “Oligo Grapes” (OG), and its individual constituents: lyophilized pomace (LP), clay supplemented with red wine extract, lyophilized pomace ethanolic extract (PE), and red wine extract. OG, as a commercially available food supplement, has not been previously tested for its biological activity. Now we want to present new data about its phytochemical screening, antioxidant and antibacterial activities, and anticancer properties with respect to its cytotoxicity and effects on redox status in colon cancer cell lines. The tested extracts expressed strong antibacterial activity against Proteus mirabilis and Proteus mirabilis ATCC 12453, where the synergy of contents inside the supplement demonstrated a higher influence on the bacteria than its separately tested constituents. Among the investigated extracts, PE, as the extract with the highest phenolics concentration, had remarkable cytotoxic activity on HCT-116 and SW-480 colon cancer cells. Also, the treatments modulated redox status in the investigated cancer cells, by inducing oxidative and nitrosative stress, which could be one of the preferred mechanisms of the anticancer action. Based on the achieved antimicrobial and anticancer properties, there is a need for producing different food supplements and nutritional products originating from grapes. In this respect, the food supplement OG and its health benefits deserve scientific attention and further research.

Grape juice by-products extracted by ultrasound and microwave-assisted with different solvents: a rich chemical composition

By-products of the grape juice industry contain valuable compounds. The current work produced bioactive-enriched extracts from by-products of the grape juice, through three different extraction methods. Yields and chemical compositions varied, according to the extraction method (ultrasound, microwave, liquid-liquid). High-efficiency liquid chromatography with UV-Vis and high-resolution mass spectrometry characterised were used for chemical characterization, with glycosylated flavonoids evident. The crude extract was fractionated by open column, which has possibility carried-out fraction rich in resveratrol. The inhibition of DPPH radicals ranged from 14.2 to 74.2%, and the total phenolic content ranged from 0.1 to 107.0 mg gallic acid equivalents/100 g. Microwave-assisted extraction of grape juice by-products using polar solvents, such as ethanol and water, provided the best yield and chemical composition, obtaining extracts rich in flavonoids. In this way, this work has demonstrated the industrial grape by-products importances, which are a rich source of antioxidants if properly extracted.

Food Preservative Capabilities of Grape (Vitis vinifera) and Clementine Mandarin (Citrus reticulata) By-products Extracts in South Africa

The drive towards sustainable food systems coupled with increased consumer sophistication have prompted innovation in waste valorization. Grape and citrus processing by-products, abundant in the Mediterranean and tropical regions, respectively, are expanding and are sustainable sources of bioactive phytochemicals that can be used as natural preservatives for foods. Phytochemical composition, antioxidant, and antimicrobial properties of extracts from grape pomace (GPE), seeds (GSE), and clementine mandarin peel and pulp (MPE) grown in South Africa were analyzed. Total phenols and carotenoids were highest in GPE followed by GSE and MPE (p ≤ 0.05). Flavonoids and anthocyanins were higher (p ≤ 0.05) in GPE and GSE compared to MPE. The GSE had the highest proanthocyanidins content followed by GPE and MPE (p ≤ 0.05). Ascorbic acid was only detected in MPE, which also had the highest titratable acidity and lowest pH values (p ≤ 0.05). The GSE had the highest antioxidant potency composite index followed by GPE and MPE (p ≤ 0.05). The order of antimicrobial activity of the extracts was MPE > GSE > GPE (p ≤ 0.05). Current findings show that GSE is a potential antioxidant while MPE holds promise as an antimicrobial for the food industry.

Essential Oil, Extracts, and Sesquiterpenes Obtained From the Heartwood of Pilgerodendron uviferum Act as Potential Inhibitors of the Staphylococcus aureus NorA Multidrug Efflux Pump

Staphylococcus aureus is a serious human pathogen that is highly adaptive to environmental conditions and rapidly develops antibiotic resistance. The use of efflux pumps to reduce antibiotic concentrations at the intracellular level is one of the main mechanisms by which bacteria develop antibiotic resistance. The management of efflux pumps, specifically NorA, which is expressed by S. aureus strains, is a valuable strategy for restoring susceptibility in strains resistant to antibacterial agents. In recent years, many studies have focused on searching for natural substances that can reverse efflux pump-mediated resistance in S. aureus. Extracts and compounds obtained from plants can be efficient efflux pump inhibitors (EPIs) and represent a potentially patient-friendly strategy for controlling S. aureus. In the present study, we evaluated the ability of essential oils, petroleum ether extracts, dichloromethane extract (DCME) and six compounds isolated from the heartwood of Pilgerodendron uviferum (Cupressaceae) and two synthetic derivatives to inhibit efflux in NorA pumps in the following three S. aureus strains: K2378, which overexpressed the norA gene (norA++), K1902 (norA-deleted, ΔnorA) and the parental strain, NCTC 8325-4. Efflux activity was evaluated using a fluorometric method that measured the accumulation of the universal efflux pump substrate ethidium bromide (EtBr). Only DCME and the compounds 15-copaenol and epi-cubenol inhibited EtBr efflux by K2378. Even the lowest concentration of 15-copaenol exhibited a stronger inhibitory effect than carbonyl cyanide m-chlorophenyl hydrazone on EtBr efflux by K2378. 15-copaenal only showed inhibition of EtBr efflux in K2378 cells at 125 μg/mL, but not superior to the control inhibitor and 15-copaenyl acetate exerted no intrinsic EPI activity against K2378. Fractional inhibitory concentration index (FICI) values obtained in the checkerboard assays, indicated that all combinations between DCME, epi-cubenol and 15-copaenol, and tested antibiotics showed a synergistic effect in wild type, norA ++ and ΔnorA strains. Moreover, those were not toxic for the HeLa cell line at concentrations in which the synergistic effect and inhibitory activity of efflux pumps was determined. Other extracts and compounds obtained from P. uviferum did not display EtBr efflux-inhibiting activity against the evaluated S. aureus strains.

Influence of pH and ionic strength on the color parameters and antioxidant properties of an ethanolic red grape marc extract

The aim of present study was to investigate the influences of pH and several salts on the antioxidant activity and color of an ethanolic grape marc extract. Furthermore, the phenolic content of the extract was analyzed using HPLC and spectrophotometric methods while the total antioxidant activity was assessed by the reaction with ABTS radical. Gallic acid, procyanidins B1, B2, polydatin, catechin, epicatechin, hyperoside, ferulic, chlorogenic, and salicylic acids were among the main identified polyphenols. Different pH values had slight influence on the antioxidant activity, the highest value being determined for pH 3.7. The redness, chroma, and hue were significantly enhanced at pH 3.7 and 2.6. The chromaticity decreased at pH = 5.5 and pH = 7.4, so the extract should be used with care in products with such media. The presence of salts did not noticeably affect the antioxidant activity, except the higher concentrations of CaCl₂ , which decreased the antioxidant activity but enhanced the color intensity. PRACTICAL APPLICATION: The data presented in this paper could be used for the development of a new food dye with antioxidant properties of natural origin. The optimal medium conditions (i.e., pH and ionic strength) for the use of an ethanolic red grape marc extract have been identified. The information could be used in product development and product formulation, especially when functional foodstuffs are envisaged. Consequently, this paper would be of significant interest for food chemists, food technologists, food manufacturers, and especially manufacturers of food dyes and all those using natural substances in their production process.

Preservative effect of Chinese cabbage (Brassica rapa subsp. pekinensis) extract on their molecular docking, antioxidant and antimicrobial properties

This study aimed at investigating the antimicrobial activity of different solvent extracts of Chinese cabbage Brassica rapa subsp. pekinensis (BRARP) and their antioxidant and cytotoxicity properties. Of the different solvents extracts, the chloroform extracts (CE) were significantly inhibited the bacterial pathogens at minimum inhibitory concentration (MIC) of 16.5 mg.mL^-1. Biochemical analysis revealed that total phenol (62.6 ± 0.05 mg GAE.g^-1) and flavonoids (27.6 ± 0.04 mg QE.g^-1) were higher in the extracts of BRARP, which resulted in enhanced antioxidant activity in CE. A total of eight dominant compounds were detected in the potent antimicrobial extract from BRARP based on GC-MS analysis. The molecular interactions study revealed that, among the screened compounds the 1,2-benzenedicarboxylic acid and 2,3-dicyanopropionamide interacted with the active site of pathogenicity and survival related protein with lipopolysaccharide (LpxC) with higer binding energy. This work concluded that the 1, 2-Benzenedicarboxylic acid and 2, 3-Dicyanopropionamide from BRARP was reported to be good non-cytotoxic and antioxidant antimicrobials against bacterial pathogens.

Chemical profile and antioxidant potential of four table grape (Vitis vinifera) cultivars grown in Douro region, Portugal

The aim of this work was to improve the knowledge about the potential of Douro region (North of Portugal) to produce table grapes of superior quality. Skin, pulp, and seeds of four table grapes ‘Alphonse Lavallée’, ‘Cardinal’, ‘Dona Maria’ and ‘Muscat Hamburgo’ produced in Dour region, collected at commercial maturity stage, were evaluated. Phenolic compounds, organic acids and sugars were determined in each cultivar and in the different parts of the grape by HPLC-DAD, while the antioxidant properties were evaluated by DPPH, Cuprac and lipid peroxidation assays. Phenolics from different classes were found: four anthocyanins (delphynidin, cyanidin, petunidin and malvidin), two hydroxibenzoic acids (gallic acid and protocatechuic acid), three hydroxycinnamic acids (caffeic, chlorogenic and coumaric acids), one flavonol (rutin), three flavan-3-ols ((+)-catechin, (-)-epicatechin, and (-)-epicagallocatechin)), one oligomer (procyanidin B2) and one stilbene (resveratrol). In addition, three organic acids (tartaric, malic and citric acids) and two types of sugars (glucose and fructose) were detected in all samples. Differences were found between cultivars (p<0.001) and sample material type (p<0.001). Skins presented the higher content in anthocyanins, seeds in flavan-3-ols and pulps in phenolic acids, organic acids and free-sugars. The cultivar ‘Cardinal’ showed the highest content in phytochemicals, while ‘Dona Maria’ was the cultivar with the lowest content. Nonetheless, the content of flavan-3-ols and organic acids in ‘Dona Maria’, associated with its higher antioxidant capacity, makes it an interesting choice as table grape from healthier point of view. According to our results, Douro region have proper environmental conditions to produce these table grapes.

Equisetum telmateia extracts: Chemical compositions, antioxidant activity and antimicrobial effect on the growth of some pathogenic strain causing poisoning and infection

The aerial parts of Equisetum telmateia have been used as a source of biologically active compounds to treat inflammatory, diarrhea, stomach-ache, eczema and mouth infections in traditional medicine. The aim of this work is to evaluate the extraction yield, chemical compositions, antioxidant activity and antimicrobial activity of E. telmateia extracts on Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella typhi and Candida albicans. Chemical compositions E. telmateia was analyzed by high performance liquid chromatography (HPLC) using a C18 column. Analysis of E. telmateia extract by HPLC allowed the identification of Kaempferol 3-O-(6″-O-acetylglucoside) as major compound. The antioxidant activity of extracts was examined by measuring their ability to sequestrate 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. The results showed that the DPPH (IC₅₀ = 70.83 ± 0.2 μg/ml) were obtained in the case of supercritical fluid extraction (SFE) extract. MIC microdilution assay were used to determine the antimicrobial activities. Contrary to lower extraction yield (9.6 ± 0.5), the SFE extract exhibited the highest antimicrobial potency with MIC and MBC values of 32 mg/ml against S. aureus compared to the other extracts. The results suggest that SFE method is more appropriate for extraction of E. telmateia biologically active substances with antimicrobial and antioxidant activity than conventional solvent extraction methods.

Antibacterial and antioxidant properties of grape stem extract applied as disinfectant in fresh leafy vegetables

In the present study total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity and antimicrobial properties of grape (Vitis vinifera var. Red Globe) stem extract is reported. Also, the identification of main phenolic compounds was carried out by UPLC-PAD analysis. TPC and TFC of extract were 37.25 g GAE kg^-1 and 98.07 g QE kg^-1, respectively. Extract showed an antioxidant capacity of 132.60 and 317 g TE kg^-1 for DPPH and ABTS radical scavenging capacity, respectively. The main phenolic compounds identified were rutin, gallic acid, chlorogenic acid, caffeic acid, catechin and ferulic acid. Extract inhibited the growth of Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica subsp. enterica serovar Typhimurium, and Escherichia coli O157: H7 at MIC range 16-18 g L^-1. Extract affected the different phases of bacterial growth. In addition, application of Extract (25 g L^-1) as a sanitizer was effective to reduce the populations of all bacteria inoculated in lettuce (0.859-1.884 log reduction) and spinach (0.843-2.605 log reduction). This study emphasizes the potential of grape processing byproducts as an emergent and attractive source of bioactive compounds with antioxidant properties and antimicrobial activity against important foodborne pathogens. The study demonstrated that stem extract could be used to control the presence of human pathogenic bacteria in fresh leafy vegetables.

Effect of grape pomace on fermentation quality and aerobic stability of sweet sorghum silage

The objective of this study was to evaluate the effect of grape pomace (GP) with different adding levels (0%, 5%, 10% and 15%, fresh matter basis), alone (GP-LAB) or in combine with an inoculant LAB (GP+LAB), on the fermentation quality and aerobic stability of sweet sorghum silage. After 90 days of ensiling in vacuumized mini-silos, silages were subject to a 7-day aerobic stability test, in which chemical, microbial and polyphenol composition were measured. In the GP-LAB group, adding GP decreased (P < 0.05) concentrations of water-soluble carbohydrate (WSC) and butyric acid in silage. In the GP+LAB group, adding GP increased (P < 0.05) concentrations of lactic acid, WSC and crude protein, decreased (P < 0.05) final pH value, NH₃ -N ratio and butyric acid concentration in silage. Polyphenol level was reduced (P < 0.05) after silage fermentation. During aerobic exposure, the fungi count, pH value and silage temperature increased (P < 0.05), the levels of lactic acid, acetic acid and polyphenols (quercetin 3-O-glucoside and quercetin 3-O-glucuronid) decreased (P < 0.05) in silage. GP+LAB treated silage had a lag phase for aerobic spoilage. When the fermentation products, microbial counts, chemical and polyphenol composition were considered, the use of 10% GP+LAB at ensiling could provide a valuable source for improved fermentation quality and aerobic stability of sweet sorghum silage.

Grape by-product extracts against microbial proliferation and lipid oxidation: a review

The wine industry is responsible for the production of million tons of waste, such as grape skin, stalk, sludge and seeds, which can be considered inexpensive sources of phenolic compound owing to incomplete extraction during wine production. Phenolic compounds, also called polyphenols, comprise the most abundant bioactive compounds in grape and are recognized by their antioxidant and antimicrobial potential. Because of their functional properties, extracts obtained from grape wastes, which are rich in phenolic compounds, can be employed in the development of many products, ranging from medical to food applications, decreasing the growth of spoilage and pathogenic microorganisms and inhibiting lipid oxidation. These characteristics are motivating the research for alternative sources of natural antioxidant and antimicrobial agents, aimed at decreasing the use of artificial additives, which have been associated with some toxic effects. This article provides a review of the use of grape by-product extracts and their bioactive compounds as natural antioxidant and antimicrobial agents in food products. © 2016 Society of Chemical Industry.