Search results for "Phenolic"
showing 10 items of 200 documents
The influence of two different pH levels on the antioxidant properties of flavonols, flavan-3-ols, phenolic acids and aldehyde compounds analysed in …
2011
Abstract The aim of this study is evaluate either the antioxidant or pro-oxidant behaviour of some typical polyphenolic compounds of red wine, to investigate the influence of two different pH levels on the antioxidant properties and to clarify their activity–structure relationship. The antioxidant activity of compounds in hydrophilic solutions at pH 3.5 and pH 7.4 were measured by a competition kinetic test, based on the crocin bleaching. The position and the number of substitution groups influence the magnitude of the antioxidant activity of the polyphenolic compounds, but their antioxidant properties are also strongly influenced by the pH conditions. Increasing the pH, a considerable incr…
Inactivation of PadR, the repressor of the phenolic acid stress response, by molecular interaction with Usp1, a universal stress protein from Lactoba…
2009
ABSTRACT The phenolic acid decarboxylase gene padA is involved in the phenolic acid stress response (PASR) in gram-positive bacteria. In Lactobacillus plantarum , the padR gene encodes the negative transcriptional regulator of padA and is cotranscribed with a downstream gene, usp1 , which encodes a putative universal stress protein (USP), Usp1, of unknown function. The usp1 gene is overexpressed during the PASR. However, the role and the mechanism of action of the USPs are unknown in gram-positive bacteria. Therefore, to gain insights into the role of USPs in the PASR; (i) a usp1 deletion mutant was constructed; (ii) the two genes padR and usp1 were coexpressed with padA under its own promo…
Allelopatyczne właściwości metabolitów wtórnych roślin uprawnych
2009
Allelopathy has been defined by the International Allelopathy Society as "any process involving secondary metabolites produced by plants, microorganisms, viruses and fungi that influence the growth and development of agricultural and biological systems, including positive and negative effects [1]". Allelochemicals can be released into the environment and despite what effect they evoke towards living organisms this kind of specific chemical interactions is known as "allelopathy". Allelopathic phenomena have been observed and studied from ancient times. Theophrastus from Eresos, a disciple of Aristotle, reported an inhibitory effect of pigweed Polygonum spp. on alfalfa in ca. 350 B.C., wherea…
A study of the chemical composition and biological activity of extracts from wild carrot (Daucus carota l.) seeds waste
2015
Waste (wild carrot seeds, Daucus carota L.) formed after the industrial extraction of 96% ethanol were re-extracted with 40% and 70% ethanol in order to recover of valuable substances for potential use as a safe food additives and functional food ingredients or nutraceuticals. In this study we compared chemical composition and activity of two obtained extracts (70% EtOH and 40% EtOH). The results indicated that the 70% EtOH extract has a higher total phenol and flavonoid content than 40% EtOH extract. The antioxidant activity of 70% EtOH extract was 86.88 % ± 3.018, whereas of 40% EtOH extract scavenging activity was 78.72% ± 3.276. The extracts were also active against bacteria with MIC ag…
Inspired by nature: Fiber networks functionalized with tannic acid and condensed tannin-rich extracts of Norway spruce bark show antimicrobial effica…
2023
This study demonstrated the antibacterial and antiviral potential of condensed tannins and tannic acid when incorporated into fiber networks tested for functional material purposes. Condensed tannins were extracted from industrial bark of Norway spruce by using pressurized hot water extraction (PHWE), followed by purification of extracts by using XADHP7 treatment to obtain sugar-free extract. The chemical composition of the extracts was analyzed by using HPLC, GC‒MS and UHPLC after thiolytic degradation. The test matrices, i.e., lignocellulosic handsheets, were produced and impregnated with tannin-rich extracts, and tannic acid was used as a commercial reference. The antibacterial and antiv…
Field-Grown and In Vitro Propagated Round-Leaved Sundew (Drosera rotundifolia L.) Show Differences in Metabolic Profiles and Biological Activities
2021
Drosera rotundifolia L. is a carnivorous plant used in traditional medicine for its therapeutic properties. Because of its small size, its collection in nature is laborious and different cultivation methods have been studied to ensure availability. However, only a few studies exist where the lab-grown sundew tissue and field-grown sundew would have been compared in their functionality or metabolic profiles. In this study, the antioxidant and antiviral activities of lab-grown and field-grown sundew extracts and their metabolic profiles are examined. The effect of drying methods on the chromatographic profile of the extracts is also shown. Antioxidant activity was significantly higher (5–6 ti…
Antioxidant Activity and Release Kinetics of Caffeic and p-Coumaric Acids from Hydrocolloid-Based Active Films for Healthy Packaged Food
2017
International audience; Sustainable hydrocolloid-based films containing natural antioxidants, caffeic and p-coumaric acids at different concentrations of 0.5%, 1%, 5%, and 10% w/w of polymers, were designed for packing fatty foods. Antioxidant activities and kinetics for all film formulations were assessed using radical scavenging activity (DPPH), reducing power, and iron chelating ability. Release kinetics of the antioxidants from the films into a food simulant (96% ethanol) were analyzed. The intermolecular interactions between antioxidants and polymers chains were assessed by Fourier transform infrared attenuated total reflectance (FTIR-ATR) and related to the film properties. Antioxidan…
Species-Specific Antioxidant Power and Bioactive Properties of the Extracts Obtained from Wild Mediterranean Calendula Spp. (Asteraceae)
2019
In this study we focused on four taxa of the genus Calendula (C. maritima, C. suffruticosa subsp. fulgida, C. arvensis, and the hybrid between the first two ones), collected in Mediterranean area (Sicily). Six extracts for each species were obtained using solvents with increasing polarity (hexane, ethanol 80%, acetone 70%, and water) and through extraction by supercritical fluids (SFE). It has been observed that the solvent with the highest extraction efficiency was ethanol 80% for all species. However, SFE extracts showed high antioxidant activity comparable to the ethanol 80% extract (polyphenol, DPPH, and reducing power method). These findings were confirmed by in vitro analysis (MTT ass…
Effects of phenolic-like intercalated layered double hydroxides on poly(lactic acid) based nanocomposites
2015
Two phenolic-like antioxidants (AOs), 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate and 6-hydroxy-2,5,7,8-tetrametilcromano-2-carboxylate anions, were intercalated by anion exchange in layered double hydroxides (LDHs). The two AO-LDHs were dispersed by ultrasound-assisted solution mixing in poly(lactic acid) (PLA) and the thermal oxidation stability of the composites was evaluated following the variation of the molecular weight by SEC, after a controlled aging process, and determining the oxidation induction time (OIT) by DSC. The results evidenced that the intercalation of both the AO molecules within the LDH galleries prevent their own thermal and thermo-oxidative degradation as well a…
Variability of sensory profile and quality characteristics for ‘Pesca di Bivona’ and ‘Pesca di Leonforte’ peach (Prunus persica Batsch) fresh-cut sli…
2015
Abstract Peach genotypes in Southern Italy include the white-flesh ‘Pesca di Bivona’ (‘Murtiddara’, ‘Bianca’, ‘Agostina’ and ‘Settembrina’) and the yellow-flesh ‘Pesca di Leonforte’ (‘Settembrina’, ‘Giallone’ and ‘Ottobrina’ ) landraces, with non-melting clingstone fruit, characterized by a persistent aroma and an excellent flavor that is highly appreciated by consumers. The aim of this work was to assess the suitability of these white- and yellow-flesh landraces to be processed as fresh-cut product with regard to the persistence of their quality and sensory profiles. Fruit of ‘Pesca di Bivona’ and ‘Pesca di Leonforte’ landraces were cut into slices and stored at 5 °C for 3, 5, 7, 12 d. Fre…