Acylated Forms Research Articles

Authenticity Markers of Aged Red Wines from Aglianico, Uva di Troia, Negroamaro and Primitivo Grapes.

The wide ampelographic treasure of Italian wine grape varieties is driving research towards suitable approaches for the varietal authenticity control of wine. In this paper, Aglianico, Negroamaro, Primitivo and Uva di Troia red wines, which were produced experimentally by single-grape winemaking from non-aromatic grapes native to southern Italy, were analyzed with respect to berry markers, namely anthocyanins, hydroxycinnamic acids (HPLC-DAD), shikimic acid (HPLC-UV) and glycosidic aroma precursors (GC-MS). The study confirms that, just as for the berries, useful varietal authenticity markers for red wine, even after aging, turn out to be hydroxycinnamic acids, relative amounts of acylated forms of anthocyanins, and shikimic acid, together with some grape glycosidic precursors from terpenes and C13- norisoprenoids. Principal Component Analysis was used as a valuable tool to highlight the results.

Flavonoid Glycosides in Leaves of Plants of the Genus Nigella L.

Phenolic compounds in plants of the genus Nigella are represented by various groups of flavonoids, gallocatechins, and derivatives of cinnamic and caffeic acids. The content of flavonoid glycosides in the leaves of Nigella damascena L., N. sativa L., and N. orientalis L. was established by the HPLC-MS method. Species-specific dependence of accumulation of flavonoid glycosides has been established. It was shown that the main flavonoids in the leaves of the studied objects were glycosides of quercetin and kaempferol, while quercetin glycosides were 1.40–1.97 times more than kaempferol in the studied extracts. N. sativa leaves had an increased composition of flavonoid glycosides compared to other studied species. The qualitative composition of N. damascena flavonoid glycosides was like N. sativa, whereas it is close to N. orientalis in terms of the total content of this group of compounds. Total amount of flavonoid glycosides in N. sativa leaf extracts was four times higher than in extracts of other types of Nigella. It is worth noting that the types N. sativa and N. damascena have the greatest phenotypic similarity and are more resistant to growing conditions in Belarus, while the species N. orientalis is different in appearance and more demanding on cultivation conditions. It was found that the variety of flavonoids glycosides in N. orientalis leaves is less in the absence of high molecular weight and acylated forms. The possible absence of acylated derivatives and less variety of flavonoids glycosides affects the low stability N. orientalis to abiotic factors and reduces its adaptive potential.

Oxygen Exposure and Tolerance Shapes the Cell Wall-Associated Lipids of the Skin Commensal Cutibacterium acnes.

Cutibacterium acnes is one of the most abundant bacteria on the skin. Being exposed to oxygen and oxic stress, the secretion of the bacterial antioxidant protein RoxP ensures an endogenous antioxidant system for the preservation of skin health. To investigate the impact of the antioxidant RoxP on oxidation of the bacteria, wildtype and an isogenic roxp mutant were cultured in anaerobic and oxic conditions. The carbonylated status of proteins were recorded, as were the most significant modifications in a relative intensity of free fatty acids (FFA) and lipids containing fatty acids (FA), such as di- (DG) and triglycerides (TG), di- (DGDG) and sulfoquinozyldiacylglycerol (SQDG) and ceramides. Concerning the fatty acid types, it was observed that the free fatty acids contained mainly C12:0-C26:0 in hydroxy and acylated forms, the DG contained mainly C29:0-C37:0, the TG contained mainly C19:0-C33:0, and the DGDG/SQDGs contained very long fatty acids (C29:0-C37:0) demonstrating the interdependence of de novo synthesis of lipids and RoxP. The area of DGDG peaks (924.52, 929.56 and 930.58) were affected by bacterial growth conditions, with the exception of m/z 910.61. Moreover, the FFA unsaturation is wider in the SQDG species (C30:0 to C36:6) than in DG, TG or free FFA species. It could be concluded that both environmental oxidative statuses, as well as the prevalence of bacterial antioxidant systems, significantly shape the lipidome of C. acnes.

Green Fractionation and Structural Characterization of Lignin Nanoparticles via Carboxylic-Acid-Based Deep Eutectic Solvent (DES) Pretreatment

Green fractionation and a comprehensive overview of lignin molecular structures during the DES (deep eutectic solvent) pretreatment are very important for lignin valorization and the whole biorefinery process. Herein, intractable woody biomass (poplar wood) was pretreated with five types of carboxylic-acid-based DESs (acetamide served as an HBA (hydrogen bond acceptor), propanedioic acid, tartaric acid, malic acid, glutaric acid, and succinic acid served as HBDs (hydrogen bond donors)) under the optimized pretreatment conditions. Results showed that the optimal delignification ratio was achieved for tartaric-acid-based DES at 140 °C for 20 min under microwave-assisted heating. Two-dimensional HSQC NMR data demonstrated that the isolated poplar DES lignin consisted mainly of β-β, β-O-4 (normal and acylated forms), β-5, and esterified p-hydroxybenzoates (PBs) in different contents. Especially, the contents of β-O-4 in the isolated DES lignin fractions varied based on the pretreatment temperature and different chemical compositions of the DES. The antioxidant activity (2,2-diphenyl-1-picrylhydrazyl, DPPH analysis), microstructure (scanning electron microscope, SEM), and molecular weights (gel permeation chromatography, GPC) of the DES lignin fractions demonstrated that the DES delignification promoted the rapid assembly of lignin nanoparticles (LNPs) and could yield homogeneous lignin (1.23 < PDI < 1.58) with controlled nanometer size (30–170 nm) and good antioxidant activity. This study will improve the knowledge of structural changes of lignin during the different carboxylic-acid-based DES pretreatments and maximize the lignin valorization.

Sphingolipid Long-Chain Base Signaling in Compatible and Non-Compatible Plant–Pathogen Interactions in Arabidopsis

The chemical diversity of sphingolipids in plants allows the assignment of specific roles to special molecular species. These roles include NaCl receptors for glycosylinositolphosphoceramides or second messengers for long-chain bases (LCBs), free or in their acylated forms. Such signaling function has been associated with plant immunity, with an apparent connection to mitogen-activated protein kinase 6 (MPK6) and reactive oxygen species (ROS). This work used in planta assays with mutants and fumonisin B1 (FB1) to generate varying levels of endogenous sphingolipids. This was complemented with in planta pathogenicity tests using virulent and avirulent Pseudomonas syringae strains. Our results indicate that the surge of specific free LCBs and ceramides induced by FB1 or an avirulent strain trigger a biphasic ROS production. The first transient phase is partially produced by NADPH oxidase, and the second is sustained and is related to programmed cell death. MPK6 acts downstream of LCB buildup and upstream of late ROS and is required to selectively inhibit the growth of the avirulent but not the virulent strain. Altogether, these results provide evidence that a LCB- MPK6- ROS signaling pathway contributes differentially to the two forms of immunity described in plants, upregulating the defense scheme of a non-compatible interaction.

Non-acylated and acylated anthocynins in red wines of different ages: Color contribution and evaluation

This study investigated the non-acylated and acylated anthocyanins and chromatic characteristics of 108 red wines with a range of ages. The K-means cluster analysis showed that the evolution pattern of cyanidin-3-O-glucoside (Cy) differed among non-acylated anthocyanins and the pattern of malvidin-3-O-(6-O-acetyl)-glucoside (Mv-ac) differed among acylated anthocyanins. Partial least squares regression (PLS) showed that non-acylated anthocyanins, especially Cy, contributed to the red-violet color. Wine age, tawny characteristics, and color density strongly negatively correlated with anthocyanins. Wine age played an essential role in chromatic characteristics and anthocyanins, especially more than 4 years. A prediction model of wine age was established using the chosen variables of color parameters and anthocyanins employing PLS. This model showed good performance in predicting the wine age. Besides malvidin-3-O-glucoside (Mv), other anthocyanins and acylated forms with low content were demonstrated to be promising and practical chemical parameters for predicting the age of dry red wine.

The K218 capsular polysaccharide produced by Acinetobacter baumannii isolate 52-249 includes 5,7-di-N-acetylpseudaminic acid linked by a KpsS3 glycosyltransferase

Two acylated forms of the higher sugar, 5,7-diamino-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid called pseudaminic acid, Pse5Ac7Ac and Pse5Ac7RHb where R indicates (R)-3-hydroxybutanoyl, have been found to occur in many capsular polysaccharide (CPS) types produced by isolates of an important human pathogen, Acinetobacter baumannii. The presence of either a psaABCEDF or psaABCGHF gene module at the K locus (KL) for CPS biosynthesis determines the type of the variant produced. Here, an A. baumannii clinical isolate 52-249, recovered in 2015 in Moscow, Russia, was found to include a novel psaABCIJF gene module in the KL218 sequence at the K locus. The CPS from 52‐249 was extracted and studied by sugar analysis and partial acid hydrolysis along with one- and two-dimensional 1H and 13C NMR spectroscopy. A branched tetrasaccharide repeating unit was identified, which included a →3)-α-d-Galp-(1→6)-α-d-GlcpNAc-(1→3)-β-d-GalpNAc-(1→ main chain and Pse5Ac7Ac attached as a side branch, indicating that the psaABCIJF gene module is associated with synthesis of this variant. The K218 CPS was found to be structurally related to the K46 CPS of A. baumannii, and a comparison of the two structures enabled the assignment of glycosyltransferases. A KpsS3 protein for the α-(2→6) linkage of the Pse5Ac7Ac residue to D-Galp in K218 was identified.

Grapevine row orientation mediated temporal and cumulative microclimatic effects on grape berry temperature and composition

Ambient radiation and temperature are global drivers of grapevine growth, grape yield and composition, and wine quality. Knowledge of the implications of vineyard row orientation/microclimate is required for decision-making in current and future macro- and mesoclimates. Temporal and cumulative microclimatic changes, induced by vine row orientation (NS; EW; NE-SW; NW-SE) of vertically trellised Shiraz grapevines, on berry pulp temperature and composition at different ripeness levels were investigated. Berries dynamically gained heat energy relative to: ambient climate/weather; direct canopy wall/bunch irradiance; and berry skin colour development. Berries exposed to direct solar radiation during the morning, leading to higher pulp temperatures than ambient, but having a cooling profile after that, resulted in slightly advanced sugar ripening and generally higher skin total anthocyanins and phenols, without significant effects on pH and titratable acidity, at the respective ripeness levels. In contrast, excessive exposure of bunches and those that built up heat, reaching highest temperatures during late afternoon, seemed not conducive to grape composition associated with higher quality. The S, SE, E and NE canopy sides showed consistently higher skin total anthocyanin and phenol contents than their counter sides. Except for acylated forms of peonidin-glucoside, anthocyanin (mono-, acetyl- and coumaroyl-glucosides) accumulation was mostly favoured in berries exposed to exterior canopy sides, but differences in acylated anthocyanins between exterior-facing and interior-facing berries were less than for mono-glucoside anthocyanins. Over-exposure and heat peaking during late afternoon seemed detrimental. Novel information on berry pulp temperature variation in a developing composite grape bunch, exposed to weather and microclimate fluctuation, is provided. An ostensibly homogeneous bunch in reality represents a dynamic berry pulp thermal range at any point in time. Cumulative thermal and radiation impact was evident. This is the first comprehensive attestation on the role of grapevine row orientation (or any viticulture practice) in the management of seasonal nocturnal- and diurnal berry temperature and concomitant composition.

Nitrogen Fertilization Influences the Quantity, Composition, and Tissue Association of Foliar Phenolics in Strawberries

Unlike quantitative changes, the compositional changes of plant phenolics and changes in their tissue association as influenced by the nutrient supply are less well understood. We evaluated the quantity, composition, and tissue association of phenolics in leaves of two Fragaria ananassa cultivars in response to different levels of nitrogen (N) fertilization using global metabolomic approaches. Influence of N supply on phenolic content in both cultivars was similar, but the magnitude of this response was compound specific. Ellagitannins, the most abundant class of phenolic oligomers, were less responsive to the applied N treatments, whereas proanthocyanidins, the less abundant class of phenolic oligomers, exhibited higher fold change. Within mono-phenolics, the hydroxycinnamates were more abundant but showed lower fold change than the hydroxybenzoates. Among flavonoids, the hydroxylated flavonols showed higher abundances than the flavones, with a preferential accumulation of dihydroxylated flavonol at lower N levels. Furthermore, glycosylated flavonols were higher than the acylated forms. The extractable fraction of phenolics was more influenced by the N treatment than the fiber-bound fraction. The extensive compositional modification of phenolics and a greater response of non-bound fractions in response to N rates highlight the potential to use precise management of N supply as an effective strategy to enhance the bioactive compounds in crops.

Identification and quantification of phenolic composition from different species of Jabuticaba (Plinia spp.) by HPLC-DAD-ESI/MSn

The aim of this study was to investigate phenolic compounds in peel, pulp and seeds of five different jabuticabas - Plinia trunciflora, “cabinho”, P. cauliflora, cultivars “paulista” and “canaã-açu”, P. jaboticaba, “sabará” and P. phitrantha, “branca-vinho”. In addition to the commonly reported cyanidin-3-glucoside and delphinidin3-glucoside, it was also found the unreported cyanidin-3-coumaroylglucoside in the peels. Flavonols derived from quercetin and myricetin were also detected in jaboticaba peels, along with a wide variety of derivatives of ellagic acid and methyl ellagic acid. The latter derivatives occurred in acylated forms, which were not usually found in jabuticabas. The pulps and seeds of jabuticabas contained large amounts of ellagitannins vescalagin and castalagin, as well as gallic and ellagic acids. The jabuticabas showed small amounts of catechin and gallocatechin. P. jaboticaba showed the highest levels of anthocyanins and flavonols derived from myricetin, and P. phitrantha presented the highest concentration of ellagitannins and flavan-3-ols.

Characterization of Isoflavone Conjugated Metabolites in Human Plasma and Urine by Dietary Soybean Meals

Abstract Objectives Soy isoflavones are one of the best studied secondary plant metabolites for the last 30 years and associated with potential health benefits such as prevention of cancer, cardiovascular diseases, and menopausal symptoms. The study aimed to identify isoflavone conjugated metabolites from human plasma and urine after dietary soybean meals using a targeted metabolomic approach and to investigate the effect of fermentation on bioavailability of soy isoflavones. Methods In the cross-over intervention design with 10 candidates (6 women and 4 men), standardized meals with fermented soybean (FS, Cheonggukjang, by Bacillus subtilis) and non-fermented soybean (NFS) were served over two weeks in two randomized groups. Flavonoid derivatives in each freeze-dried tested meal and isoflavone conjugated metabolites in plasma and urine collected before and after the consumption of each meal were evaluated by UPLC-DAD-QToF/MS. Results Twenty-two isoflavones, including genistein, daidzein, glycitein, and its glycosides, were identified in both tested meals. In particular, 6”-O-succinoyldadizin and 6”-O-succinoylgenistin produced newly as acylated forms with succinic acid in fermented process. Also, in levels of simple glycosidic forms (e.g., daidzin and genistin), the FS meal showed higher than NFS meal, which might be explained by the degradation of malonylglucosides during the fermentation. Fourteen metabolites conjugated with glucuronic acid and sulfuric acid were identified in plasma and urine, among them, genistein 4’,7-di-O-glucuronide and daidzein 7-O-glucuronide were confirmed as major metabolites in plasma and urine, respectively. The bioavailability was differentiated by personal characteristics after intake soy isoflavones, and it was considered that genistein class was more excellent as well as FS meal was more effective when compared to NFS meal on bioavailability. Conclusions The results may contribute to not only understanding the potential health effects of fermented foods by modifying the bioavailability of soybean bioactive components but also application of other traditional foods related with fermentation. Funding Sources This work was supported by the National Institute of Agricultural Science of Rural Development Administration, Republic of Korea.

A natural colorant system from corn: Flavone-anthocyanin copigmentation for altered hues and improved shelf life

Anthocyanins are a major source of natural red colorants but currently face difficulties matching the hue range, stability, and affordability of synthetic options. Purple corn offers an FDA and EFSA-approved economical source of anthocyanin-based colorants. A C-glycosyl flavone and anthocyanin copigmentation system consisting of a flavone-rich anthocyanin-poor line and two anthocyanin-rich flavone-poor lines containing either pelargonidin or cyanidin-derived anthocyanins is described. This system offers a broad hue range and can improve stability. Cyanidin-rich model beverages had better stability than pelargonidin-rich beverages over time, but the addition of flavone-rich extract to both resulted in significantly longer half-lives (up to 50% longer). Flavone copigments produced hyperchromic and bathochromic shifts in both. A protective effect from flavone copigmentation was observed for glycosides. In contrast acylated forms displayed significantly shorter half-lives. Results suggest that corn C-glycosyl flavone-rich extracts could serve as a color enhancing and stabilizing agent for anthocyanin colorants.

Relationship of phenolic composition of selected purple maize (Zea mays L.) genotypes with their anti-inflammatory, anti-adipogenic and anti-diabetic potential

This study aimed to investigate the associations between phenolic composition of selected purple maize genotypes and their anti-inflammatory, anti-adipogenic and anti-diabetic properties in vitro. Anthocyanin-rich water extracts (PMWs) from 20 purple maize genotypes were evaluated in RAW 264.7 macrophages and 3T3-L1 adipocytes under different conditions. Cyanidin-3-O-glucoside (C3G), pelargonidin-3-O-glucoside (Pr3G), peonidin-3-O-glucoside (P3G) and corresponding acylated forms were major anthocyanins in PMW, accompanied by ten tentatively identified non-anthocyanin phenolics. Correlation studies showed that C3G, P3G, and derivatives, but not Pr3G and its acylated form contributed to the biological properties of PMW. Besides anthocyanins, quercetin, luteolin, and rutin were the dominant anti-inflammatory and anti-diabetic components, in terms of down-regulating pro-inflammatory mediator production in inflamed macrophages and adipocytes, modulating diabetes-related key enzymes and improving insulin sensitivity in insulin-resistant adipocytes. Quercetin and phenolic acids, especially vanillic acid and protocatechuic acid, were closely associated with anti-adipogenic properties of PMW via inhibition of the preadipocyte-adipocyte transition.

Comparative Study on the Chemical Structure and In Vitro Antiproliferative Activity of Anthocyanins in Purple Root Tubers and Leaves of Sweet Potato ( Ipomoea batatas).

The structure and in vitro antiproliferative activity of anthocyanins in the root tubers of a sweet potato variety cv. Bhu Krishna and the purple leaves of a promising accession S-1467 were studied with the objectives of understanding the structure-activity relationship and comparing the leaf and tuber anthocyanins. The chemical structure of anthocyanins was determined by high-resolution electrospray ionization mass spectrometry analysis. A fluorescence-resonance-energy-transfer-based caspase sensor probe had been used to study the antiproliferative property, and analysis of the cell cycle was performed after staining with propidium iodide and subsequent fluorescence-activated cell sorting. Structurally, the anthocyanins in root tubers were identical to those in leaves, but there was a difference in the proportion of various aglycones present in both. This has led to distinguishable differences in the antiproliferative activity of leaf and tuber anthocyanins to various cancer cells. All nine anthocyanins were found in acylated forms in both tubers and leaves. However, peonidin derivatives were major anthocyanins in tubers (33.98 ± 1.41 mg) as well as leaves (27.68 ± 1.07 mg). The cyanidin derivatives were comparatively higher in leaves (20.55 ± 0.91 mg) than tubers (9.44 ± 0.94 mg). The tuber and leaf anthocyanins exhibited potential antiproliferative properties to MCF-7, HCT-116, and HeLa cancer cells, and the structure of anthocyanins had a critical role in it. The leaf anthocyanins exhibited significantly higher activity against colon and cervical cancer cells, whereas tuber anthocyanins had a slightly greater effect against breast cancer cells.

Anthocyanin profile of wild grape Vitis vinifera in the eastern Adriatic region

Wild grapevine (Vitis vinifera L., subsp. sylvestris) was found recently along the rivers in the karst landscape of the eastern Adriatic region, which includes Croatia and Bosnia and Herzegovina. The wild grapevine is almost extinct and grows in a restricted habitat in Europe. The anthocyanin profile of red grape berries from naturally growing populations of female wild var. sylvestris were characterized in two consecutive years and compared to the domesticated cultivars ‘Plavac mali’, ‘Merlot’ and ‘Xinomavro’. Five anthocyanidin-3-monoglucosides and their corresponding five 3-(6-O-acetyl) and five 3-(6-O-coumaryl) derivatives were identified and quantified using HPLC-DAD. Most wild grape samples had both acylated and non-acylated anthocyanin monoglucosides, although two individuals lacked acylated forms. DpGl were a greater percentage of the total in wild grape than in ‘Plavac mali’, ‘Merlot’ or ‘Xinomavro’. Principal component analysis showed differentiation of sylvestris from vinifera by anthocyanin profile. The anthocyanin profiles of sylvestris genotypes from the eastern Adriatic region, here presented for the first time, suggest genetic diversity within sylvestris in anthocyanin synthesis.

A Targeted, Differential Top-Down Proteomic Methodology for Comparison of ApoA-I Proteoforms in Individuals with High and Low HDL Efflux Capacity.

Top-down proteomics (TDP) allows precise determination/characterization of the different proteoforms derived from the expression of a single gene. In this study, we targeted apolipoprotein A-I (ApoA-I), a mediator of high-density-lipoprotein cholesterol efflux (HDL-E), which is inversely associated with coronary heart disease risk. Absolute ApoA-I concentration and allelic variation only partially explain interindividual HDL-E variation. Therefore, we hypothesize that differences in HDL-E are associated with the abundances of different ApoA-I proteoforms. Here, we present a targeted TDP methodology to characterize ApoA-I proteoforms in serum samples and compare their abundances between individuals. We characterized 18 ApoA-I proteoforms using selected-ion monitoring coupled to electron-transfer dissociation mass spectrometry. We then compared the abundances of these proteoforms between two groups of four participants, representing the individuals with highest and lowest HDL-E values within the Chicago Healthy Aging Study ( n = 420). Six proteoforms showed significantly ( p < 0.0005) higher intensity in high HDL-E individuals: canonical ApoA-I [fold difference (fd) = 1.17], carboxymethylated ApoA-I (fd = 1.24) and, with highest difference, four fatty acylated forms: palmitoylated (fd = 2.16), oleoylated (fd = 2.08), arachidonoylated (fd = 2.31) and one bearing two modifications: palmitoylation and truncation (fd = 2.13). These results demonstrate translational potential for targeted TDP in revealing, with high sensitivity, associations between interindividual proteoform variation and physiological differences underlying disease risk.

High resolution LC-MS characterization of phenolic compounds and the evaluation of antioxidant properties of a tropical purple radish genotype

This study reports qualitative profiling of the phenolic compounds in an indigenously developed purple radish genotype VRRAD-151 using ultra performance liquid chromatography with quadrupole time of flight mass spectrometry. The root and leaf samples were harvested at the horticultural maturity stage of the genotype. Roots were divided into the periderm, and xylem, and the leaf samples were divided into petiole, and lamina, and these were separately extracted with methanol before the LC-MS analysis. A total of 66 compounds, including 23 flavonols, 1 dihydroflavonols, 4 flavonones, 4 flavones, 28 anthocyanins, 2 isoflavonoids, 3 phenolic acids, and 1 hydroxybenzaldehyde were putatively identified based on high resolution accurate mass analysis with the data processing through UNIFI®, which is a comprehensive compound identification software solution. An in-house developed database comprising the secondary metabolites of polyphenols was used for the screening purpose, and each phenolic compound was identified based on the detection of the precursor ion, and at least one characteristic fragment ion, each with less than 5 ppm of mass error. Anthocyanins were the most abundant type of phenolics exhibiting 59% in leaf petiole, 80% in root periderm, and 90% in root xylem. The relative concentration of anthocyanins was lower (11%) in the leaf lamina. Cyanidins were the most predominant anthocyanins accounting for 54, 100, 90 and 65%, in leaf lamina, leaf petiole, root periderm and root xylem, respectively. Eight anthocyanins and 25 flavonols (except kaempferol-3-O-p-coumaryl-shophoroside-7-O-glucoside) are tentatively new identifications and reported for the first time in radish. Flavonols were found to be the predominant group of phenolic compounds in the leaf lamina, and interestingly, the gradient of antioxidant activity followed the (relative) concentration gradient of flavonols in the samples. The relative antioxidant activity of various fractions when compared with each other, followed the trend: leaf lamina > root periderm > leaf petiole ≈ root xylem. Based on the results it can be reflected that this genotype can be utilized as a functional food for management of various human and animal diseases. Since the detected anthocyanins were mostly present in acylated forms, this genotype can function as a potential source of stable natural colorants.

The rare sugar N-acetylated viosamine is a major component of Mimivirus fibers

The giant virus Mimivirus encodes an autonomous glycosylation system that is thought to be responsible for the formation of complex and unusual glycans composing the fibers surrounding its icosahedral capsid, including the dideoxyhexose viosamine. Previous studies have identified a gene cluster in the virus genome, encoding enzymes involved in nucleotide-sugar production and glycan formation, but the functional characterization of these enzymes and the full identification of the glycans found in viral fibers remain incomplete. Because viosamine is typically found in acylated forms, we suspected that one of the genes might encode an acyltransferase, providing directions to our functional annotations. Bioinformatic analyses indicated that the L142 protein contains an N-terminal acyltransferase domain and a predicted C-terminal glycosyltransferase. Sequence analysis of the structural model of the L142 N-terminal domain indicated significant homology with some characterized sugar acetyltransferases that modify the C-4 amino group in the bacillosamine or perosamine biosynthetic pathways. Using mass spectrometry and NMR analyses, we confirmed that the L142 N-terminal domain is a sugar acetyltransferase, catalyzing the transfer of an acetyl moiety from acetyl-CoA to the C-4 amino group of UDP-d-viosamine. The presence of acetylated viosamine in vivo has also been confirmed on the glycosylated viral fibers, using GC-MS and NMR. This study represents the first report of a virally encoded sugar acetyltransferase.

Comparative analysis of antioxidant, antimicrobiological and cytotoxic activities of native and fermented chamomile ligulate flower extracts.

The work investigated differences in apigenin content, as well as in other compounds, and examined the chemical profiles, antioxidant, antimicrobial and cytotoxic effects of extracts obtained from native and fermented chamomile ligulate flowers. Chamomile (Chamomilla recutita L.) has a long history of being used as a medicinal plant due to many health benefits, including antiinflammatory, anticancer, antispasmodic, radical-scavenging effects and others. Apigenin is recognized as one of the most bioactive phenolic compounds in chamomile. In comparison to its bound forms, which include mostly apigenin-7-O-β-glucoside and various acylated forms, the aglycone is attributed with much higher bioactivity. Due to this fact, in this work ligulate florets of chamomile anthodium were subjected to a fermentation process using native chamomile enzymes to hydrolyze bound forms of apigenin to free aglycone. The contents of apigenin and apigenin-7-O-β-glucoside were determined in both fermented and nonfermented samples by UHPLC-MS-MS analysis to define the efficiency of conversion. After defining their chemical profiles, the extracts of fermented and nonfermented chamomile samples were also compared with respect to their antioxidant, antimicrobial and cytotoxic effects. The antioxidant effects of the obtained extracts were defined by electron spin resonance analysis for hydroxyl and superoxide radicals. The antimicrobial activity was defined for eight microbial strains, whereas cytotoxic activity was evaluated using two human cell lines (human cervix carcinoma and human rhabdomyosarcoma) and murine fibroblasts.

Structural basis of activity against aztreonam and extended spectrum cephalosporins for two carbapenem-hydrolyzing class D β-lactamases from Acinetobacter baumannii.

The carbapenem-hydrolyzing class D β-lactamases OXA-23 and OXA-24/40 have emerged worldwide as causative agents for β-lactam antibiotic resistance in Acinetobacter species. Many variants of these enzymes have appeared clinically, including OXA-160 and OXA-225, which both contain a P → S substitution at homologous positions in the OXA-24/40 and OXA-23 backgrounds, respectively. We purified OXA-160 and OXA-225 and used steady-state kinetic analysis to compare the substrate profiles of these variants to their parental enzymes, OXA-24/40 and OXA-23. OXA-160 and OXA-225 possess greatly enhanced hydrolytic activities against aztreonam, ceftazidime, cefotaxime, and ceftriaxone when compared to OXA-24/40 and OXA-23. These enhanced activities are the result of much lower Km values, suggesting that the P → S substitution enhances the binding affinity of these drugs. We have determined the structures of the acylated forms of OXA-160 (with ceftazidime and aztreonam) and OXA-225 (ceftazidime). These structures show that the R1 oxyimino side-chain of these drugs occupies a space near the β5-β6 loop and the omega loop of the enzymes. The P → S substitution found in OXA-160 and OXA-225 results in a deviation of the β5-β6 loop, relieving the steric clash with the R1 side-chain carboxypropyl group of aztreonam and ceftazidime. These results reveal worrying trends in the enhancement of substrate spectrum of class D β-lactamases but may also provide a map for β-lactam improvement.