Fusarium graminearum growth inhibition mechanism using phenolic compounds from Spirulina sp

The application of natural antifungal substances is motivated by the need for alternatives to existing methods that are not always applicable, efficient, or that do not pose risk to consumers or the environment. Furthermore, studies on the behaviour of toxigenic species in the presence of natural fungicides have enabled their safe application in the food chain In this study, Spirulina LEB-18 phenolic extract was assessed for its antifungal activity on 12 toxigenic strains of Fusarium graminearum isolated from barley and wheat. The susceptible metabolic pathways were assessed through the determination of structural compounds (glucosamine and ergosterol) and enzyme activity of the microorganisms' primary metabolism. The results indicate that phenolic extracts reduced the growth rate of the toxigenic species investigated. The IC50 was obtained by applying 3 to 8% (p/p) of phenolic compounds in relation to the culture medium. The use of this natural fungicide proved promising for the inhibition of fungal multiplication, especially in terms of the inactivation of enzymatic systems (amylase and protease) of Fusarium graminearum.

Color, phenolic and flavonoid content, and antioxidant activity of honey from Roraima, Brazil

The total phenolic and flavonoid content, color, and antioxidant activity were evaluated from ten honey samples from Apis mellifera L. collected from Roraima State, Brazil. The total phenolic content was determined using the Folin-Ciocalteu reagent and ranged from 250 to 548 mg gallic acid kg-1 of honey. The total flavonoid content was obtained using two methods: total flavones/flavonols were determined with aluminum chloride, and flavonones/dihydroflavonols were determined with 2,4-dinitrophenylhydrazine. The results ranged from 9 to 48.6 mg of quercetine kg-1 of honey and 1805 to 2606 mg of pinocembrin kg-1 of honey, respectively. Antioxidant activity was measured with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavengers, and the results of the IC50 ranged from 3.17 to 8.79 mg/mL. Statistical analysis demonstrated positive correlations between color intensity, flavone and flavonol content, and phenolic content and negative correlations with antioxidant capacity.

Nutritional quality and bioactive compounds of partially defatted baru almond flour

This study aimed to investigate the nutritional quality and bioactive potential of partially defatted baru (Dipteryx alataVog.) almond flour (BAF). The flour’s proximate and mineral compositions, total phenolic, tocopherols and carotenoids contents, antioxidant capacity, trypsin inhibitor and amino acid analyses were performed. An experiment was conducted with 24 male Wistar rats in order to evaluate the flour’s protein quality. BAF has high protein, fiber and mineral contents (iron, zinc, magnesium and copper), and it is a source of calcium. BAF presented relevant amounts of total phenolics (625 mg/100g) and good antioxidant capacity (130 µmol/Trolox eq). Autoclaved BAF showed essential amino acids profile, digestibility and protein quality better than in natura BAF. Autoclaved BAF might be used for human consumption as a source of quality protein and bioactive compounds, in healthy diets and processed foods.

Characterization of the phenolic and antioxidant profiles of selected culinary herbs and spices: caraway, turmeric, dill, marjoram and nutmeg

Culinary herbs and spices have long been considered essentially as flavor enhancers or preservatives, with little attention given to their potential health-promoting properties. Nevertheless, recent research has shown them to be significant dietary sources of bioactive phenolic compounds. Despite noteworthy efforts performed in recent years to improve our knowledge of their chemical composition, a detailed phenolic profile of these plant-based products is still lacking. In the present work, antioxidant activities and phenolic composition of five herbs and spices, namely caraway, turmeric, dill, marjoram and nutmeg, have been studied. The use of liquid chromatography coupled to LTQ-Orbitrap mass spectrometry enabled the identification of up to 42 phenolic compounds. To the best of our knowledge, two of them, apigenin-C-hexoside-C-pentoside and apigenin-C-hexoside-C-hexoside have not been previously reported in turmeric. Qualitative and quantitative differences were observed in polyphenol profiles, with the highest phenolic content found in caraway. Multivariate statistical treatment of the results allowed the detection of distinctive features among the studied herbs and spices.

Adsorption capacity of phenolic compounds onto cellulose and xylan

The interaction between three phenolic compounds (catechin, caffeic acid and ferulic acid) onto two dietary fibres (cellulose and xylan) has been evaluated to inquire possible interferences on the biodisponibility of phenolic compounds. The adsorption kinetics were performed using solutions containing 100 mg/L of phenolic compounds during a contact time ranging between 10 and 120 minutes at pH 2.0, 4.5, and 7.0. After the kinetics, isotherms were obtained using phenolic compounds concentration ranging between 10 and 80 mg/L during 60 minutes, at pH 2.0 and 7.0 and temperature of 36 °C. Results indicate that adsorbed quantities mainly changed in function of pH, however the maximum adsorption was only of 0.978 mg of caffeic acid/g of xylan at pH 2 and after 60 min. Redlich-Peterson model were able to predict the adsorption isotherms of all phenolic compounds onto cellulose, except for caffeic acid at pH 7.0. The low adsorption capacities observed suggest that both dietary fibres are unable to compromise the biodisponibility of phenolic compounds, especially in the small intestine, where they are partially absorbed.

Phenolic content and antioxidant capacity in organically and conventionally grown eggplant (Solanum melongena) fruits following thermal processing

AbstractThermal processing and production practices used in vegetables can cause changes in their phytochemical contents. Eggplant is characterized by its high antioxidant content. The objective of this work was to determine levels of anthocyanins, polyphenols, and flavonoids and antioxidant capacity in organically and conventionally grown eggplant prepared fresh or subjected to one of three thermal preparation methods: boiling, baking or steaming. The soluble and hydrolyzable polyphenols and flavonoids content were quantified by Folin-Ciocalteu and Aluminum chloride methods, respectively. Anthocyanins were quantified according to the pH differential method. Antioxidant capacity was determined by DPPH and ORAC methods. The results showed differences between organic and conventional eggplant for some variables although cultivation method did not have a consistent effect. Hydrolysable polyphenol content was greater, and soluble and hydrolysable antioxidant capacities were higher in organically grown eggplant, while anthocyanin content was greater in conventionally grown eggplant. Fresh eggplant produced under conventional cultivation had a much greater content of anthocyanins compared to that of other cultivation method-thermal treatment combination. In general, steamed eggplant contained higher total polyphenol and flavonoid levels as well as greater antioxidant capacity. Steamed eggplant from both conventional and organic systems also had high amounts of anthocyanins compared to other thermal treatments.

Effect of dietary fiber on the bioaccessibility of phenolic compounds of mango, papaya and pineapple fruits by an in vitro digestion model

The presence of dietary fiber (DF) in the food matrix of some tropical fruits plays an important role in the release and absorption of its bioactive compounds, such as phenolic compounds (PCs). The aim of this study was to evaluate the effect of the DF fractions in mango cv. ‘Ataulfo’, papaya cv. ‘Maradol’ and pineapple cv. ‘Esmeralda’, on the bioaccessibility of their PCs and antioxidant capacity (AOXC) under an in vitro digestion model. The highest PCs content and AOXC was found in mango (274.30 mg GAE/100 g FW), followed by papaya (212 mg GAE//100 g FW), and pineapple (107.63 mg GAE/100 g FW), respectively. About 50% of the total PCs in all fruits was released at gastric phase, increasing closer to 60% at intestinal phase in mango and pineapple. However, the highest content of PCs associated to DF was found in mango (2.48 mg GAE/100 g FW) compared with papaya DF fractions (0.96 GAE/100 g FW) and pineapple (0.52 GAE/100 g FW). The presence of DF in mango, papaya and pineapple did not represent a major limitation on the bioaccessibility of its PCs according to the in vitro digestion model used in this study.

Anti-quorum sensing activity of phenolic extract from Eugenia brasiliensis (Brazilian cherry)

Abstract The aim of this study was to assess the anti-quorum sensing activity of phenolic extracts from grumixama (Eugenia brasiliensis), also known as Brazilian cherry, in concentrations that did not interfere with bacterial growth. The pulp phenolic compounds were extracted by using solid phage extraction in a mini-collumn C18 and quantified by spectrophotometry. The anti-quorum sensing activity was evaluated by testing the inhibition of violacein production in Chromobacterium violaceum and by evaluating the swarming motility in Aeromonas hydrophila and Serratia marcescens, both phenotypes regulated by quorum sensing. The phenolic extract strongly inhibited the production of violacein in C. violaceum, reducing its production in comparison with a control with no extract. No inhibition of growth was observed at the concentrations tested for quorum sensing inhibition. Confirming the quorum sensing inhibition phenotype, the extract was also able to inhibit swarming motility in S. marcescens and in A. hydrophila, although in the later the effect was marginal. Overall, these results indicate that phenolic extract from E. brasiliensis presents quorum sensing inhibitory activity most likely due to the presence of fruit phenolics which have been implicated as quorum sensing inhibitors in Gram negative bacteria.

Critical levels of organic acids on seed germination and seedling growth of wheat

The objective of this study was to determine the responses of the wheat cultivars CD 108 and CD 111 for tolerance to organic acids. The effects of five concentrations of the three main acids formed in the soil were studied: acetic acid (0, 4, 8, 12 and 16 mM), propionic acid (0, 4, 8, 12 and 16 mM) and butyric acid (0, 2, 4, 8 and 12 mM). Tests included germination, shoot length, root length and dry weight of shoot and root. The variable root length is the most responsive variable for all the acids tested and the critical level of toxicity of acetic, propionic and butyric acids, which reduced root length by at least 50% was 9.0, 8.5 and 4.0 mM respectively. It was concluded that the presence of acetic, propionic and butyric acids in the germination substratum of wheat seeds of the cultivars CD 111 and CD 108 reduced seedling development, mainly by reducing the length of the radicles.

Recognition of nucleic acids by metal ion complexes

Metal-ion-mediated base-pairing of nucleic acids has attracted considerable attention during the past decade, since it offers means to expand the genetic code by artificial base-pairs, to create predesigned molecular architecture by metal-ion-mediated inter- or intra-strand cross-links, or to convert double stranded DNA to a nano-scale wire. Such applications largely depend on the presence of a modified nucleobase in both strands engaged in the duplex formation. Hybridization of metal-ion-binding oligonucleotide analogs with natural nucleic acid sequences has received much less attention in spite of obvious applications. While the natural oligonucleotides hybridize with high selectivity, their affinity for complementary sequences is inadequate for a number of applications. In the case of DNA, for example, more than 10 consecutive Watson-Crick base pairs are required for a stable duplex at room temperature, making targeting of sequences shorter than this challenging. For example, many types of cancer exhibit distinctive profiles of oncogenic miRNA, the diagnostics of which is, however, difficult owing to the presence of only short single stranded loop structures. Metallo-oligonucleotides, with their superior affinity towards their natural complements, would offer a way to overcome the low stability of short duplexes. In this study a number of metal-ion-binding surrogate nucleosides were prepared and their interaction with nucleoside 5´-monophosphates (NMPs) has been investigated by 1H NMR spectroscopy. To find metal ion complexes that could discriminate between natural nucleobases upon double helix formation, glycol nucleic acid (GNA) sequences carrying a PdII ion with vacant coordination sites at a predetermined position were synthesized and their affinity to complementary as well as mismatched counterparts quantified by UV-melting measurements.

Intramolecular carbenoid insertions : the reactions of [alpha]-diazoketones derived from furanyl, thienyl, benzofuranyl and benzothienyl acetic acids with rhodium (II) acetate /

A number of synthetically useful ring systems can be prepared via the intramolecular insertion of a metal-stabilized carbenoid into a heteroaromatic systems. The chemical outcome of these reactions are dependent not only on the nature of the heteroatom but also on the length of the aliphatic tether linking the carbenoid moiety with the aromatic fragment. Our work with furanyl and thienyl systems containing a single methylene tether have allowed for some rather atypical chemistry. For example, treatment of l-diazo-3-(2-thienyl)-2-propanone (6) with catalytic rhodium (II) acetate yields 5,6- dihydro-4^-cyclopenta[Z>]thiophen-5-one (3) while, the isomeric l-diazo-3-(3-thienyl)-2- propanone(15) gives a spiro-disulphide (20). Novel chemistry was also exhibited in the analogous furanyl systems. While treatment of l-diazo-3-(3-furanyl)-2-propanone (52) with Rh2(OAc)4 resulted in the expected 2-(4-Oxo-2-cyclopentenyliden)acetaldehyde (54), isomeric l-diazo-3-(2- furanyl)-2-propanone (8) undergoes vinylogous Wolff rearrangement to give a mixture of 6a-methyl-2,3,3a,6a-tetrahydrofuro[2,i-^>]furan-2-one (44) and 2-(2-methyl-3-furyl)acetic acid (43). Rhodium acetate catalyzed decomposition of l-diazo-3-(3-benzofuranyl)-2- propanone (84) and l-diazo-3-(2-benzofuranyl)-2-propanone (69)also allows for vinylogous Wolff rearrangement, a chemistry unseen in benzofuranyl systems with longer tethers. A number of interesting products were isolated from the trapping of intermediate ketenes. Decomposition of l-diazo-3-(3-benzothienyl)-2-propanone (100) resulted in the formation of 2,3-dihydro-l//-benzo[^]cyclopenta[^thiophen-2-one (102). However, in addition to (102), a dimer was also generated from the decomposition of l-diazo-3-(2- benzothienyl)-2-propanone (109). The insight into the mechanistic underpinnings of the above reactions are provided by molecular modeling at a PM3 level.

Skeletal muscle fibre-type comparison of whole tissue and subcellular membrane phospholipids and fatty acids

Membranes are dynamic structures that affect cell structure and function. Compositional changes ofmembranes have been shown with the application of a perturbation; however these are limited to whole tissue analysis. The purpose of this thesis was to compare the phospholipid (PL) fatty acid (FA) composition of rat whole muscle (Wm) to 1) purified and non-purified subsarcolemmal (SS) mitochondria in soleus, plantaris, and red gastrocnemius, and 2) sarcolemma, transverse-tubules, SS and intermyofibrillar (IMF) mitochondria fix)m whole hindlimb. The major findings were that 1) contamination significantly altered the PL FA composition of the SS mitochondrial membrane fraction, 2) Wm and SS mitochondria compositions differed between muscle types, and 3) Wm did not accurately reflect the PL FA composition of any isolated subcellular membranes, with each being unique from each other. As such, the relevancy of the trends reported in the literature of the effects of perturbations on Wm may be limited.

The acute effects of differential dietary fatty acids on PDHa activity in human skeletal muscle at the onset of exercise

Pyruvate dehydrogenase (PDH) is an important regulator of carbohydrate oxidation during exercise and its activity can be down-regulated by an increase in dietary fat. The purpose of this study was to determine the acute metabolic effects of differential dietary fatty acids on the activation of PDH in its active form (PDHa) at rest and at the onset of moderate-intensity exercise. University-aged male subjects (n=7) underwent 2 fat loading trials spaced at least 2 weeks apart. Subjects consumed saturated (SFA) or polyunsaturated (PUFA) fat over the course of 5 hours. Following this, participants cycled at 65% VO2 max for 15 min. Muscle biopsies were taken prior to and following fat loading and at 1 min exercise. Plasma free fatty acids increased from 0.15 ± 0.07 to 0.54 ± 0.19 mM over 5 hours with SFA and from 0.1 1 ± 0.04 to 0.35 ±0.13 mM with PUFA. PDHa activity was unchanged following fat loading, but increased at the onset of exercise in the SFA trial, from 1 .4 ± 0.4 to 2.2 ± 0.4 /xmol/min/kg wet wt. This effect was negated in the PUFA trial (1 .2 ± 0.3 to 1 .3 ± 0.3 pimol/min/kg wet wt.). PDH kinase (PDK) was unchanged in both trials, suggesting that the attenuation of PDHa activity with PUFA was a result of changes in the concentrations of intramitochondrial effectors, more specifically intramitochondrial NADH or Ca^*. Our findings suggest that attenuated PDHa activity participates in the preferential oxidation of PUFA during moderateintensity exercise.

Intramolecular carbenoid insertion : reactions of [alpha] -diazoketones derived from benzothienyl, pyrolyl and indolyl alkanoic acids with rhodium (II) acetate

Recent studies have shown that the rhodium (II) acetate decomposition chemistry observed for a-diazoketones tethered to thienyl, furanyl, and benzofuranyl moieties is dependent not only on the nature of the heteroatom but also on the length of the aliphatic tether linking the diazoketone moiety with the aromatic fragment. The present thesis expands on these results and focuses on a-diazoketones tethered to benzothiophenes, pyrroles and indoles by a methylene linker. In the case of benzothiophenes, it was shown that the rhodium catalyst decomposition of I-diazo-4-(3-benzothienyl)-2-butanone (146) and 1-diazo-4-(3benzothienyl)- 2-butanone (152) allow for the isolation of 1,2,3a,3b-tetrahydro-3Hbenzo[ b]cyclopenta[1,3]cyclopropa- [1 ,2-d]thiophen-3-one (147) and 1,2,3a,3btetrahydro- 3H-benzo[b]cyclopenta[1,3]cyclopropa[1,2-d]thiophen-3-one (153). However treatment of 1-diazo-3-(3-Benzothienyl)-2-Propanone (165) with Rh(II) acetate results in the formation of 2,3-Dihydro-1H-benzo[b]cyclopenta[d]thiophen-2-one (159), while 1diazo- 3-(2-Benzothienyl)-2-Propanone with the same condition gives 5,5-bis( 1benzothiophen- 2-ylmethyl)-2(5H)-furanone (166) along with the tricycle 159. The chemistry of the pyrrolyl and the indolyl moieties linked to terminal adiazoketone systems was also investigated. The decomposition of I-diazo-(2-pyrrolyl)-2propanone (173) results in the formation of two products; the N-H insertion product IHpyrrolizin- 2(3H)-one (176) and the alkylation product 4,6-dihydrocyclopenta[b]pyrrol5( 1 H)-one (180). When 1-Diazo-3-(3-indoly)-3-propanone (194) is treated with catalytic amount of Rh (II) 3,4-dihydrocyclopenta[b]indol-2(1H)-one (193) is isolated quantitatively. The later reaction when monitored using IH NMR the intermediate 200 can be seen whose structure was confirmed by the comparison to series of model compounds. The mechanisms underlying these reactions as well as their synthetic utility is discussed.

Investigations on the production of long chain fatty acids in Choanephora cucurbitarum (Berk. & Rav.) Thaxte

Thesis (M.Sc.)--Brock University, 1979.