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Abstract: Olive mill wastewaters (OMW) are a potential source of biophenols, but they have a complex composition with many unknown phenolics. The analysis of purified methanol extracts from two Portuguese OMW by electrospray mass spectrometry in the negative mode showed [M−H]− ions at m/z 539 and m/z 523, corresponding respectively to oleuropein and ligstroside isomers which contain the glucose unit linked to its aromatic moiety. Also, the fragmentation pathway of the [M−H]− ions at m/z 863, 685 and 847 indicated the presence of a diglucoside derivative of the oleuropein isomer and of mono- and diglucosides of the ligstroside isomer, respectively. Moreover, the two OMW samples contained an elenoic derivative of the ion at m/z 685 and a degradation product (m/z 453) of the [M−H]− ion at m/z 523. Future studies focusing on the abundance of these compounds on OMW, as well as their bioactivities, will determine their possible industrial exploitation. [Copyright &y& Elsevier]

Thymus herba-barona, Thymus pseudolanuginosus, and Thymus caespititius decoctions were screened for their phenolic constituents, along with their potential antioxidant, anti-inflammatory, and antibacterial activities. The total phenolic compounds in the extracts of the three plants ranged from 236.0 ± 26.6 mgGAE/g (T. caespititus) to 293.0 ± 30.5 mgGAE/g of extract (T. pseudolanuginosus), being particularly rich in caffeic acid derivatives, namely rosmarinic acid and its structural isomers, as well as flavones, such as luteolin-O-glucuronide. The T. pseudolanuginosus extract presented the best DPPH radical scavenging ability (EC50 = 10.9 ± 0.7 μg/mL), a high reducing power (EC50 = 32.2 ± 8.2 μg/mL), and effectively inhibited the oxidation of β-carotene (EC50 = 2.4 ± 0.2 μg/mL). The extracts also showed NO• scavenging activity close to that of ascorbic acid, and thus might be useful as anti-inflammatory agents. In addition, they exhibited antibacterial activity against gram-negative and gram-positive bacteria. Staphylococcus aureus strains were the most sensitive bacteria to thyme extracts, with minimum inhibitory concentration and minimum bactericidal concentration values in the range of 0.6-3.5 mg/mL. Overall, this work is an important contribution for the phytochemical characterization and the potential antioxidant, anti-inflammatory, and antimicrobial activities of these three Thymus species, which have been poorly explored. [ABSTRACT FROM AUTHOR]

Abstract: Bioconversions using enzymes immobilized in magnetic supports present significant advantages due to the easy separation of the enzyme from the reaction mixture and the simplicity and low cost of the support preparation. The characterization of the oligosaccharide mixture obtained by the action of β-galactosidase covalently attached, via glutaraldehyde, to a hydrazide–Dacron–magnetite composite is presented. The fractionation of the oligosaccharide mixture by high performance liquid chromatography, followed by the analysis of the purified compounds by mass spectrometry and nuclear magnetic resonance spectroscopy permitted the identification of glucose, galactose, lactose and a hexose disaccharide containing a 1→6 linkage. Also, the following GOS were identified: β-d-Galp-(1→6)-β-d-Galp-(1→4)-Glcp, β-d-Galp-(1→4)-[β-d-Galp-(1→6)]-Glcp and β-d-Galp-(1→6)-β-d-Galp-(1→6)-β-d-Galp-(1→4)-Glcp. When GOS yield (26.2%) and kinetics of biotransformation of lactose by the Dacron immobilized β-galactosidase were compared with values obtained for the enzyme immobilized in other magnetic supports, similar behaviour was observed. [ABSTRACT FROM AUTHOR]

Thymus x citriodorus is a Lamiaceae plant extensively cultivated in the Mediterranean region and used for centuries in culinary and in traditional medicine. The present work describes the detailed phenolic composition of T. x citriodorus for the first time, by means of HPLC–DAD, ESI–MS and MSn and nuclear magnetic resonance (NMR) analyses. The ethanolic extract of T. x citriodorus was analyzed by reversed phase HPLC. The method of analysis was also validated concerning its linearity, instrumental and method precision (for repeatability, immediate precision and intermediate precision) and accuracy (absolute recovery study). The technique was combined with electrospray mass spectrometry in order to identify the phenolic compounds and the structure of the main phenolics was also confirmed by NMR analysis. The in-house validated HPLC–DAD method showed good linearity for the tested reference compounds as well as satisfactory repeatability and immediate precision values, for both instrument and method. Furthermore, the satisfactory results of intermediate precision analysis and recovery assays indicated that the chromatographic method could be used to quantify the main phenolic compounds of T. x citriodorus with adequate precision and accuracy. The extract was rich in rosmarinic acid (10.4±0.6mg/g extract) that is a widespread phenolic acid in Thymus plants, but also in luteolin-7-O-α-glucuronide (12±2mg/g extract), that was herein reported in Thymus for the first time. Other novel compounds comprised one eriodictyol dihexoside with O-glycosidic linkages, two eriodictyol-O-monohexosides, one quercetagetin dimethyl ether-O-hexoside, one naringenin-O-hexoside and chrysoeriol-7-β-O-glucoside. Having in mind the health-promoting properties reported in literature for some of the main polyphenols found in T. x citriodorus, we suggest that this plant has a high potential for being used as a functional food. [ABSTRACT FROM AUTHOR]

In this study, an ethanolic extract from Portuguese propolis was prepared, fractionated by high-performance liquid chromatography, and the identification of the phenolic compounds was done by electrospray mass spectrometry in the negative mode. This technical approach allowed the identification of 37 phenolic compounds, which included not only the typical phenolic acids and flavonoids found in propolis from temperate zones but also several compounds in which its occurrence have never been referred to in the literature. Four of the novel phenolic compounds were methylated and/or esterified or hydroxylated derivatives of common poplar flavonoids, although six peculiar derivatives of pinocembrin/pinobanksin, containing a phenylpropanoic acid derivative moiety in their structure, were also identified. Furthermore, the Portuguese propolis sample was shown to contain a p-coumaric ester derivative dimer. [ABSTRACT FROM AUTHOR]

To probe the effect of 3′,8″-dimerization on antioxidant flavonoids, acacetin and its 3′,8″-dimer isoginkgetin were comparatively analyzed using three antioxidant assays, namely, the ·O2− scavenging assay, the Cu2+ reducing assay, and the 2,2′-azino bis(3-ethylbenzothiazolin-6-sulfonic acid) radical scavenging assay. In these assays, acacetin had consistently higher IC50 values than isoginkgetin. Subsequently, the acacetin was incubated with 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxy radicals (4-methoxy-TEMPO) and then analyzed by ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC−ESI−Q−TOF−MS) technology. The results of the UHPLC−ESI−Q−TOF−MS analysis suggested the presence of a dimer with m/z 565, 550, 413, 389, 374, 345, 330, and 283 peaks. By comparison, standard isoginkgetin yielded peaks at m/z 565, 533, 518, 489, 401, 389, 374, and 151 in the mass spectra. Based on these experimental data, MS interpretation, and the relevant literature, we concluded that isoginkgetin had higher electron transfer potential than its monomer because of the 3′,8″-dimerization. Additionally, acacetin can produce a dimer during its antioxidant process; however, the dimer is not isoginkgetin. [ABSTRACT FROM AUTHOR]

The rhizome of Reynoutria japonica is a well-known traditional herb (Hu zhang) used in East Asia to treat various inflammatory diseases, infections, skin diseases, scald, and hyperlipidemia. It is also one of the richest natural sources of resveratrol. Although, it has been recently included in the European Pharmacopoeia, in Europe it is still an untapped resource. Some of the therapeutic effects are likely to be influenced by its antioxidant properties and this in turn is frequently associated with a high stilbene content. However, compounds other than stilbenes may add to the total antioxidant capacity. Hence, the aim of this research was to examine rhizomes of R. japonica and the less studied but morphologically similar species, R. sachalinensis and R. x bohemica for their phytochemical composition and antioxidant activity and to clarify the relationship between the antioxidant activity and the components by statistical methods. HPLC/UV/ESI-MS studies of three Reynoutria species revealed 171 compounds, comprising stilbenes, carbohydrates, procyanidins, flavan-3-ols, anthraquinones, phenylpropanoids, lignin oligomers, hydroxycinnamic acids, naphthalenes and their derivatives. Our studies confirmed the presence of procyanidins with high degree of polymerization, up to decamers, in the rhizomes of R. japonica and provides new data on the presence of these compounds in other Reynoutria species. A procyanidin trimer digallate was described for the first time in, the studied plants. Moreover, we tentatively identified dianthrone glycosides new for these species and previously unrecorded phenylpropanoid disaccharide esters and hydroxycinnamic acid derivatives. Furthermore, compounds tentatively annotated as lignin oligomers were observed for the first time in the studied species. The rhizomes of all Reynoutria species exhibited strong antioxidant activity. Statistical analysis demonstrated that proanthocyanidins should be considered as important contributors to the total antioxidant capacity. [ABSTRACT FROM AUTHOR]

In this study, the extraction of phenolic antioxidants from red corn cob was carried out using ultrasound-assisted extraction (UAE). The solid:liquid ratio and extraction time were evaluated when obtaining these bioactive compounds. The total phenolic contents were evaluated using the Folin Ciocalteu method, while the antioxidant activity was measured by ABTS•+ and DPPH• assays. The amount of phenolic compounds ranged from 215.17 ± 33.49 to 527.33 ± 103.79 GAE mg/100 g and, overall, high solid:liquid ratios and time periods release more phenolic compounds. Moreover, the red corn cob extracts showed higher radical scavenging capacity according to the results obtained using the ABTS•+ technique compared to the DPPH• test. The coupling of liquid chromatography and mass spectrometry assay allowed the determination of 11 phenolic compounds, including phenolic acids and flavonoids. Thus, our results demonstrated for the first time the potential of red corn cob as a source of bioactive compounds, which might be included in food and pharmacological preparations. [ABSTRACT FROM AUTHOR]