944 resultados para High performance liquid chromatography (HPLC)
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The aim of this study was to incorporate astaxanthin to yogurts with different fat content to match apricot (Prunus armeniaca L.) color. The samples containing astaxanthin were stored at 5 3 C, and color stability and astaxanthin content were determined by colorimetry and high performance liquid chromatography (HPLC), respectively. Yogurt samples were analyzed in triplicate every 24 hours for one week and subsequently every week for 3 more weeks There were no significant differences (p < 0.05) between astaxanthin concentration values at 0 and 28 days for both samples; therefore, it can be said that the fat content in the yogurt had not effect on the stability of pigment. The low dispersion of the data showed uniformity in the three chromaticity coordinates L*, a*, b* throughout the storage period for both types of yogurt. Values of ∆E ≥ 5.0 were not obtained at any time during storage, indicating high stability of the pigment.
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The goal of this thesis was to study factors related to the development of Brassica juncea as a sustainable nematicide. Brassica juncea is characterized by the glycoside (glucosinolate) sinigrin. Various methods were developed for the determination of sinigrin in Brassica juncea tissue extracts. Sinigrin concentrations in plant tissues at various stages of growth were monitored. Sinigrin enzymatically breaks down into allylisothiocyanate (AITC). AITC is unstable in aqueous solution and degradation was studied in water and in soil. Finally, the toxicity of AITC against the root-lesion nematode (Pratylenchus penetrans) was determined. A method was developed to extract sinigrin from whole Brassica j uncea tissues. The optimal time of extraction wi th boiling phosphate buffer (0.7mM, pH=6.38) and methanol/water (70:30 v/v) solutions were both 25 minutes. Methanol/water extracted 13% greater amount of sinigrin than phosphate buffer solution. Degradation of sinigrin in boiling phosphate buffer solution (0.13%/minute) was similar to the loss of sinigrin during the extraction procedure. The loss of sinigrin from boiling methanol/water was estimated to be O.Ol%/minute. Brassica juncea extract clean up was accomplished by an ion-pair solid phase extraction (SPE) method. The recovery of sinigrin was 92.6% and coextractive impurities were not detected in the cleaned up extract. Several high performance liquid chromatography (HPLC) methods were developed for the determination of sinigrin. All the developed methods employed an isocratic mobile phase system wi th a low concentration of phosphate buffer solution, ammonium acetate solution or an ion-pair reagent solution. A step gradient system was also developed. The method involved preconditioning the analytical column with phosphate buffer solution and then switching the mobile phase to 100% water after sample injection.Sinigrin and benzyl-glucosinolate were both studied by HPLC particle beam negative chemical ionization mass spectrometry (HPLCPB- NCI-MS). Comparison of the mass spectra revealed the presence of fragments arising from the ~hioglucose moiety and glucosinolate side-chain. Variation in the slnlgrin concentration within Brassica juncea plants was studied (Domo and Cutlass cuItivars). The sinigrin concentration in the top three leaves was studied during growth of each cultivar. For Cutlass, the minimum (200~100~g/g) and maximum (1300~200~g/g) concentrations were observed at the third and seventh week after planting, respectively. For Domo, the minimum (190~70~g/g) and maximum (1100~400~g/g) concentrations were observed at the fourth and eighth week after planting, respectively. The highest sinigrin concentration was observed in flower tissues 205090~g/g and 2300100~g/g for Cutlass and Domo cultivars, respectively. Physical properties of AITC were studied. The solubility of AITC in water was determined to be approximately 1290~g/ml at 24C. An HPLC method was developed for the separation of degradation compounds from aqueous AITC sample solutions. Some of the degradation compounds identified have not been reported in the literature: allyl-thiourea, allyl-thiocyanate and diallyl-sulfide. In water, AITC degradation to' diallyl-thiourea was favored at basic pH (9.07) and degradation to diallyl-sulfide was favored at acidic pH (4 . 97). It wap necessary to amend the aqueous AITC sample solution with acetonitrile ?efore injection into the HPLC system. The acetonitrile amendment considerably improved AITC recovery and the reproducibility of the results. The half-life of aqueous AITC degradation at room temperature did not follow first-order kinetics. Beginning with a 1084~g/ml solution, the half-life was 633 hours. Wi th an ini tial AITC concentration of 335~g/ml the half-life was 865 hours. At 35C the half-life AITC was 76+4 hours essentially independent of the iiisolution pH over the range of pH=4.97 to 9.07 (1000~g/ml). AITC degradation was also studied in soil at 35C; after 24 hours approximately 75% of the initial AITC addition was unrecoverable by water extraction. The ECso of aqueous AITC against the root-lesion nematode (Pratylenchus penetrans) was determined to be approximately 20~g/ml at one hour exposure of the nematode to the test solution. The toxicological study was also performed with a myrosinase treated Brassica juncea extract. Myrosinase treatment of the Brassica juncea extract gave nearly quantitative conversion of sinigrin into AITC. The myrosinase treated extract was of the same efficacy as an aqueous AITC solution of equivalent concentration. The work of this thesis was focused upon understanding parameters relevant to the development of Brassica juncea as a sustainable nematicide. The broad range of experiments were undertaken in support of a research priority at Agriculture and Agri-Food Canada.
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La cartographie peptidique est une mthode qui permet entre autre didentifier les modifications post-traductionnelles des protines. Elle comprend trois tapes : 1) la protolyse enzymatique, 2) la sparation par lectrophorse capillaire (CE) ou chromatographie en phase liquide haute performance (HPLC) des fragments peptidiques et 3) lidentification de ces derniers. Cette dernire tape peut se faire par des mthodes photomtriques ou par spectromtrie de masse (MS). Au cours de la dernire dcennie, les enzymes protolytiques immobilises ont acquis une grande popularit parce quelles peuvent tre rutilises et permettent une digestion rapide des protines due un rapport lev denzyme/substrat. Pour tudier les nouvelles techniques dimmobilisation qui ont t dveloppes dans le laboratoire du Professeur Waldron, la cartographie peptidique par CE est souvent utilise pour dterminer le nombre total de peptides dtects et leurs abondances. La CE nous permet davoir des sparations trs efficaces et lorsque couple la fluorescence induite par laser (LIF), elle donne des limites de dtection qui sont 1000 fois plus basses que celles obtenues avec labsorbance UV-Vis. Dans la mthode typique, les peptides venant de ltape 1) sont marqus avec un fluorophore avant lanalyse par CE-LIF. Bien que la sensibilit de dtection LIF puisse approcher 10-12 M pour un fluorophore, la raction de marquage ncessite un analyte dont la concentration est dau moins 10-7 M, ce qui reprsente son principal dsavantage. Donc, il nest pas facile dtudier les enzymes des peptides drivs aprs la protolyse en utilisant la technique CE-LIF si la concentration du substrat protique initial est infrieure 10-7 M. Ceci est attribu la dilution supplmentaire lors de la protolyse. Alors, afin dutiliser le CE-LIF pour valuer lefficacit de la digestion par enzyme immobilise faible concentration de substrat,nous proposons dutiliser des substrats protiques marqus de fluorophores pouvant tre purifis et dilus. Trois mthodes de marquage fluorescent de protine sont dcrites dans ce mmoire pour tudier les enzymes solubles et immobilises. Les fluorophores tudis pour le marquage de protine standard incluent le naphtalne-2,3-dicarboxaldhyde (NDA), la fluorescine-5-isothiocyanate (FITC) et lester de 6-carboxyfluorescine N-succinimidyl (FAMSE). Le FAMSE est un excellent ractif puisquil se conjugue rapidement avec les amines primaires des peptides. Aussi, le substrat marqu est stable dans le temps. Les protines tudies taient l-lactalbumine (LACT), lanhydrase carbonique (CA) et linsuline chane B (INB). Les protines sont digres laide de la trypsine (T), la chymotrypsine (CT) ou la pepsine (PEP) dans leurs formes solubles ou insolubles. La forme soluble est plus active que celle immobilise. Cela nous a permis de vrifier que les protines marques sont encore reconnues par chaque enzyme. Nous avons compar les digestions des protines par diffrentes enzymes telles la chymotrypsine libre (i.e., soluble), la chymotrypsine immobilise (i.e., insoluble) par rticulation avec le glutaraldhyde (GACT) et la chymotrypsine immobilise sur billes dagarose en gel (GELCT). Cette dernire tait disponible sur le march. Selon la chymotrypsine utilise, nos tudes ont dmontr que les cartes peptidiques avaient des diffrences significatives selon le nombre de pics et leurs intensits correspondantes. De plus, ces tudes nous ont permis de constater que les digestions effectues avec lenzyme immobilise avaient une bonne reproductibilit. Plusieurs paramtres quantitatifs ont t tudis afin dvaluer lefficacit des mthodes dveloppes. La limite de dtection par CE-LIF obtenue tait de 3,010-10 M (S/N = 2,7) pour la CA-FAM digre par GACT et de 2,010-10 M (S/N = 4,3) pour la CA-FAM digre par la chymotrypsine libre. Nos tudes ont aussi dmontres que la courbe dtalonnage tait linaire dans la rgion de travail (1,010-9-1,010-6 M) avec un coefficient de corrlation (R2) de 0,9991.
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La prclampsie est responsable du quart des mortalits maternelles et est la deuxime cause de dcs maternels associs la grossesse au Canada et dans le monde. Lidentification dune stratgie efficace pour la prvention de la prclampsie est une priorit et un dfi primordial dans les milieux de recherche en obsttrique. Le rle des lments nutritifs dans le dveloppement de la prclampsie a rcemment reu davantage dattention. Plusieurs tudes cliniques et pidmiologiques ont t menes pour dterminer les facteurs de risque alimentaires potentiels et examiner les effets dune supplmentation nutritive dans le dveloppement de troubles hypertensifs de la grossesse. Pour dterminer les effets de supplments antioxydants pris pendant la grossesse sur le risque dhypertension gestationnelle (HG) et de prclampsie, un essai multicentrique contrl double insu a t men au Canada et au Mexique (An International Trial of Antioxidants in the Prevention of Preeclampsia INTAPP). Les femmes, stratifies par risque, taient assignes au traitement exprimental quotidien (1 gramme de vitamine C et 400 UI de vitamine E) ou au placebo. En raison des effets secondaires potentiels, le recrutement pour lessai a t arrt avant que lchantillon complet ait t constitu. Au total, 2640 femmes ligibles ont accept dtre recrutes, dont 2363 (89.5%) furent incluses dans les analyses finales. Nous navons retrouv aucune vidence quune supplmentation prnatale de vitamines C et E rduisait le risque dHG et de ses effets secondaires (RR 0,99; IC 95% 0,78-1,26), HG (RR 1,04; IC 95% 0,89-1,22) et prclampsie (RR 1,04; IC 95% 0,75-1,44). Toutefois, une analyse secondaire a rvl que les vitamines C et E augmentaient le risque de perte ftale ou de dcs prinatal (une mesure non spcifie au pralable) ainsi quune rupture prmature des membranes avant terme. Nous avons men une tude de cohorte prospective chez les femmes enceintes recrutes dans lINTAPP afin dvaluer les relations entre le rgime alimentaire maternel en dbut et fin de grossesse et le risque de prclampsie et dHG. Un questionnaire de frquence alimentaire valid tait administr deux fois pendant la grossesse (12-18 semaines, 32-34 semaines). Les analyses furent faites sparment pour les 1537 Canadiennes et les 799 Mexicaines en raison de lhtrognit des rgimes alimentaires des deux pays. Parmi les canadiennes, aprs ajustement pour lindice de masse corporelle (IMC) prcdant la grossesse, le groupe de traitement, le niveau de risque (lev versus faible) et les autres facteurs de base, nous avons constat une association significative entre un faible apport alimentaire (quartile infrieur) de potassium (OR 1,79; IC 95% 1,03-3,11) et de zinc (OR 1,90; IC 95% 1,07-3,39) et un risque augment de prclampsie. Toujours chez les Canadiennes, le quartile infrieur de consommation dacides gras polyinsaturs tait associ un risque augment dHG (OR 1,49; IC 95% 1,09-2,02). Aucun des nutriments analyss naffectait les risques dHG ou de prclampsie chez les Mexicaines. Nous avons entrepris une tude cas-tmoins lintrieur de la cohorte de lINTAPP pour tablir le lien entre la concentration srique de vitamines antioxydantes et le risque de prclampsie. Un total de 115 cas de prclampsie et 229 tmoins ont t inclus. Les concentrations de vitamine E ont t mesures de faon longitudinale 12-18 semaines (avant la prise de supplments), 24-26 semaines et 32-34 semaines de grossesse en utilisant la chromatographie liquide de haute performance. Lorsquexamine en tant que variable continue et aprs ajustement multivari, une concentration de base leve de gamma-tocophrol tait associe un risque augment de prclampsie (quartile suprieur vs quartile infrieur 24-26 semaines : OR 2,99, IC 95% 1,13-7,89; 32-34 semaines : OR 4,37, IC 95% 1,35-14,15). Nous navons pas trouv de lien entre les concentrations de alpha-tocophrol et le risque de prclampsie. En rsum, nous navons pas trouv deffets de la supplmentation en vitamines C et E sur le risque de prclampsie dans lINTAPP. Nous avons toutefois trouv, dans la cohorte canadienne, quune faible prise de potassium et de zinc, tel questime par les questionnaires de frquence alimentaire, tait associe un risque augment de prclampsie. Aussi, une plus grande concentration srique de gamma-tocophrol pendant la grossesse tait associe un risque augment de prclampsie.
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Mmoire numris par la Division de la gestion de documents et des archives de l'Universit de Montral
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Dans cette tude, la stabilit de prparations intraveineuses de cyclosporine (0.2 et 2.5 mg/mL dans NaCl 0.9% ou dextrose 5%) entreposes dans des seringues de polypropylne, des sacs de polypropylne-polyolfine et des sacs de vinyle actate dthylne a t value. Une mthode HPLC indicatrice de la stabilit base de mthanol a t dveloppe et valide suite a des tudes de dgradation force. Les solutions values ont t prpares de faon aseptique, puis entreposes 25C. La stabilit chimique a t value par HPLC et la stabilit physique a t value par inspection visuelle et aussi par diffusion dynamique de la lumire (DLS). Tous les chantillons sont demeurs stables chimiquement et physiquement dans des sacs de polypropylne-polyolfine (>98% de cyclosporine rcupre aprs 14 jours). Lorsquentreposs dans des seringues de polypropylne, des contaminants ont t extraits des composantes de la seringue. Toutefois, aucune contamination na t observe aprs 10 min de contact entre la prparation de cyclosporine non-dilue et ces mmes seringues. Les prparations de 2.5 mg/mL entreposes dans des sacs de vinyle actate dthylne sont demeurs stables chimiquement et physiquement (>98% de cyclosporine rcupre aprs 14 jours). Toutefois, une adsorption significative a t observe avec les chantillons 0.2 mg/mL entreposs dans des sacs de vinyle actate dthylne (<90% de cyclosporine rcupr aprs 14 jours). Une tude cintique a dmontr une bonne corrlation linaire entre la quantit adsorbe et la racine carre du temps de contact (r2 > 0.97). Un nouveou modle de diffusion a t tabli. En conclusion, les sacs de polypropylne-polyolfine sont le meilleur choix; les seringues de polypropylne prsentent un risque de contamination, mais sont acceptables pour un transfert rapide. Les sacs de vinyle actate dthylne ne peuvent tre recommands cause dun problme dadsorption.
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La rduction de la taille des particules jusqu lobtention de nanocristaux est lune des approches utilises afin damliorer la pntration cutane des mdicaments usage topique. Nous proposons que la fabrication dune formulation semi solide (hydrogel) base de nanosuspension de docosanol, aboutira une diffusion du principe actif suprieure celle du produit commercial Abreva, travers des membranes synthtiques de polycarbonates. Le broyage humide est la technique propose pour la production des nanoparticules de docosanol. Nous proposons aussi la prparation dune formulation semi-solide (hydrogel) usage topique partir de la nanosuspension de docosanol. La nanosuspension de docosanol est obtenue par dispersion du docosanol en solution aqueuse en prsence du polymre stabilisant hydroxypropylcellulose (HPC) et du surfactant laurylsulfate de sodium (SDS) suivi dun broyage humide faible ou haute nergie. Lhydrogel de docosanol nanoformul est prpar laide de la nanosuspension de docosanol qui subit une glification par le carbopol Ultrez 21 sous agitation mcanique suivie dune neutralisation au trithanolamine TEA. La taille des particules de la nanosuspension et de lhydrogel a t dtermine par diffusion dynamique de la lumire (DLS). Une mthode analytique de chromatographie liquide haute performance (HPLC) munie dun dtecteur vaporatif (ELSD) a t dveloppe et valide pour valuer la teneur de docosanol dans les prparations liquides, dans les diffrentes nanosuspensions et dans les hydrogels de docosanol. Ltat de cristallinit des nanocristaux dans la nanosuspension et dans lhydrogel a t tudi par calorimtrie diffrentielle balayage. La morphologie de la nanosuspension et de lhydrogel de docosanol a t examine par microscopie lectronique balayage (MEB). Les proprits rhologiques et de stabilit physique diffrentes tempratures ont t aussi tudies pour la formulation semi-solide (hydrogel). De mme, la libration in vitro du docosanol contenu dans lhydrogel et dans le produit commercial Abreva a t tudie travers deux membranes de polycarbonates de taille de pores 400 et 800 nm. Dans le cas de nanosuspensions, des cristaux de docosanol de taille nanomtrique ont t produits avec succs par broyage humide. Les nanoparticules de tailles variant de 197 nm 312 nm ont t produites pour des pourcentages diffrents en docosanol, en polymre HPC et en surfactant SDS. Aprs lyophilisation, une augmentation de la taille dpendant de la composition de la formulation a t observe tout en restant dans la gamme nanomtrique pour la totalit presque des formulations tudies. Dans le cas des hydrogels examins, la taille moyenne des particules de docosanol est maintenue dans la gamme nanomtrique avant et aprs lyophilisation. Lanalyse thermique des mlanges physiques, des nanosuspensions et des hydrogels de docosanol a rvl la conservation de ltat de cristallinit des nanocristaux de docosanol aprs broyage et aussi aprs glification. Lexamen par microscopie lectronique balayage (MEB) a montr que la nanosuspension et lhydrogel ont tous deux une morphologie rgulire et les nanoparticules ont une forme sphrique. De plus les nanoparticules de la nanosuspension ont presque la mme taille infrieure 300 nm en accord avec le rsultat obtenu par diffusion dynamique de la lumire (DLS). Les nanoparticules de lhydrogel ont une lgre augmentation de taille par rapport celle de la nanosuspension, ce qui est en accord avec les mesures de DLS. Daprs les mesures rhologiques, lhydrogel de docosanol a un comportement pseudoplastique et un faible degr de thixotropie. Ltude de stabilit physique a montr que les formulations dhydrogel sont stables basse temprature (5C) et temprature ambiante (21C) pendant une priode dincubation de 13 semaines et instable au-del de 30C aprs deux semaines. La mthode HPLC-ELSD a rvl des teneurs en docosanol comprises entre 90% et 110% dans le cas des nanosuspensions et aux alentours de 100% dans le cas de lhydrogel. Lessai de diffusion in vitro a montr quil y a diffusion de docosanol de lhydrogel travers les membranes de polycarbonates, qui est plus marque pour celle de pore 800 nm, tandis que celui du produit commercial Abreva ne diffuse pas. Le broyage humide est une technique bien adapte pour la prparation des nanosuspensions docosanol. Ces nanosuspensions peuvent tre utilise comme base pour la prparation de lhydrogel de docosanol nanoformul.
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In the present study we assessed plasma and platelet monoamine content using high performance liquid chromatography (HPLC). The study included 22 subjects consisting of 12 freshly-detected male diabetic patients and 10 age and sex-matched healthy controls. The same parameters were measured in streptozotocin -induced diabetic rat models consisting of controls , diabetic and insulin - treated diabetic rats. The platelet counts were significantly reduced (P < 0.05) in rat models as well as human diabetic samples. The plasma norepinephrine (NE) and epinephrine (EPI) concentrations were significantly increased (P < 0.05). The platelet showed a significant increase (P < 0.01) in NE, EPI and serotonin content. Increase in the plasma and platelet content of neurotransmitters may be due to increased sympathetic function, which is an adaptation for the decreased platelet count observed in our study . The results indicate that changes in the neurotransmitter content of the platelet may be a good index to assess the neurotransmitter status in pathological condition such as diabetes mellitus.
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The mechanism of devulcanization of sulfur-vulcanized natural rubber with aromatic disulfides and aliphatic amines has been studied using 23-dimethyl-2-butene (C5H1,) as a low-molecular weight model compound. First C6H12 was vulcanized with a mixture of sulfur, zinc stearate and N-cyclohexyl-2-benzothiazylsulfenamide (CBS) as accelerator at 140 C, resulting in a mixture of addition products (C(,H 1 i-S,-C5H 1 i ). The compounds were isolated and identified by High Performance Liquid Chromatography (HPLC) with respect to their various sulfur ranks. In it second stage, the vulcanized products were devulcanized using the agents mentioned above at 200 C. The kinetics and chemistry of the breakdown of the sulfur-hridges were monitored. Both devulcanization agents decompose sulfidic vulcanization products with sulfur ranks equal or higher than 3 quite effectively and with comparable speed. Di phenyldisulfide as devulcanization agent gives rise to a high amount of mono- and disulfidic compounds formed during the devulcanization, hexadecylamine, as devulcanization agent, prevents these lower sulfur ranks from being formed.
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El present treball es centra en l'estudi a diferents nivells dels carotenoides de les espcies marrons de Bacteris Verds del Sofre (GSB, de l'angls Green Sulfur Bacteria). L'objectiu global ha estat el d'esbrinar quina s la funci d'aquests pigments dins l'aparell fotosinttic d'aquests microorganismes i aprofundir en el coneixement de la seva estructura i interaccions amb els altres pigments de l'aparell fotosinttic. En primer lloc es va dissenyar un nou mtode de cromatografia lquida d'alta resoluci (HPLC) per analitzar de manera ms rpida i precisa els carotenoides de diferents soques de GSB (Captol 3). Aquest mtode es basa en una purificaci prvia dels extractes pigmentaris amb columnes d'almina per eliminar les bacterioclorofilles (BCls). Aix va permetre analitzar amb una elevada resoluci i en tan sols 45 min de carrera cromatogrfica els diferents carotenoides i els seus precursors, aix com les configuracions trans i cis dels seus ismers. El segon mtode utilitzat va consistir en una modificaci del mtode de Borrego i Garcia-Gil (1994) i va permetre la separaci precisa de tot tipus de pigments, procedents tant de cultius purs com de mostres de carcter complex. Un exemple concret foren uns paleosediments de la zona lacustre de Banyoles. En aquests sediments (0,7-1,5 milions d'anys d'antiguitat) es van detectar, entre d'altres pigments, carotenoides especfics de les espcies marrons de GSB, la qual cosa va permetre confirmar la presncia d'aquests bacteris a la zona lacustre de Banyoles ja des del Pleistoc inferior. En aquest primer captol tamb es van analitzar els carotenoides de Chlorobium (Chl.) phaeobacteroides CL1401 mitjanant cromatografia lquida acoblada a espectrometria de masses (LC-MS/MS), amb l'objectiu de confirmar la seva identificaci i el seu pes molecular. A ms, tamb es va avaluar l'efecte de la temperatura, la llum i diferents agents oxidants i reductors en la composici quantitativa i qualitativa dels carotenoides i les BCls d'aquesta espcie. Aix va permetre confirmar el carcter fotosensible de les BCls i que els ismers trans/cis dels diferents carotenoides no sn artefactes produts durant la manipulaci de les mostres, sin que sn constitutius de l'aparell fotosinttic d'aquests microorganismes. El Captol 4 inclou els experiments de fisiologia duts a terme amb algunes espcies de GSB, a partir dels quals es va intentar esbrinar la dinmica de sntesi dels diferents pigments de l'aparell fotosinttic (BCl antena, BCl a i carotenoides) durant el creixement d'aquestes espcies. Aquestes investigacions van permetre monitoritzar tamb els canvis en el nombre de centres de reacci (CR) durant el procs d'adaptaci lumnica. La determinaci experimental del nombre de CR es va realitzar a partir de la quantificaci de la BCl663, l'acceptor primari en la cadena de transport d'electrons dels GSB. L'estimaci del nombre de CR/clorosoma es va realitzar tant a partir de dades estequiomtriques i biomtriques presents a la bibliografia, com a partir de les dades experimentals obtingudes en el present treball. El bon ajust obtingut entre les diferents estimacions va donar solidesa al valor estequiomtric calculat, que fou, com a promig, d'uns 70 CR per clorosoma. En aquest captol de fisiologia tamb es van estudiar les variacions en les relacions trans/cis pels principals carotenoides de les espcies marrons de GSB. Aquestes es van determinar a partir de cultius purs de laboratori i de poblacions naturals de GSB. Pel que fa als valors trobats en cultius de laboratori no es van observar diferncies destacades entre el valor calculat a alta intensitat de llum i el calculat a baixa intensitat, essent en ambds casos proper a 2. En els clorosomes allats de diferents soques marrons aquest quocient prengu un valor similar tant pels ismers de l'isorenierat (Isr) com pels del -isorenierat (-Isr). En poblacions naturals de Chl. phaeobacteroides aquesta relaci va ser tamb de 2 ismers trans per cada ismer cis, mantenint-se constant tant en fondria com al llarg del temps. Finalment, en el Captol 5 es presenta un marcador molecular que permet la identificaci especfica d'espcies marrons de GSB. Malgrat que inicialment aquest marcador fou dissenyat a partir d'un gen implicat en la sntesi de carotenoides (crtY, el qual codifica per a una licop ciclasa) la seqncia final a partir de la qual s'han aconseguit els encebadors selectius est relacionada amb la famlia de protenes de les Polictid-ceto-sintases (PKT). Tot i aix, l'eina dissenyada pot ser de gran utilitat per a la discriminaci d'espcies marrons de GSB respecte les verdes en poblacions mixtes com les que es troben en ambients naturals i obre la porta a futurs experiments d'ecologia microbiana utilitzant tcniques com la PCR en temps real, que permetria la monitoritzaci selectiva de les poblacions d'espcies marrons de GSB en ecosistemes naturals.
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Study objectives: There is a possibility that lower air, moisture and light protection could impact on physico-chemical stability of medicines inside multi-compartment compliance aids (MCCAs), although this has not yet been proved. The objectives of the study were to examine the physico-chemical stability of atenolol tablets stored in a compliance aid at room temperature, and at elevated temperature and humidity to simulate practice conditions. Methods: Atenolol 100 mg tablets in 28-chamber, plastic compliance aids with transparent lids were stored for four weeks at room temperature and at 40C with 75% relative humidity. Tablets were also stored at room temperature in original packaging and Petri dishes. Physical tests were conducted to standards as laid down in the British Pharmacopoeia 2005, and dissolution to those of the United States Pharmacopoeia volume 24. Chemical stability was assessed by a validated high-performance liquid chromatography (HPLC) method. Results: Tablets at room temperature in original packaging, in compliance aids and Petri dishes remained the same in appearance and passed physico-chemical tests. Tablets exposed to 40C with 75% relative humidity in compliance aids passed tests for uniformity of weight, friability and chemical stability but became pale and moist, softer (82 newtons 4; p< 0.0001) than tablets in the original packaging (118 newtons 6), more friable (0.14% loss of mass) compared with other tablets (0.005%), and failed the tests for disintegration (>15 minutes) and dissolution (only 15% atenolol released at 30 minutes). Conclusion: Although chemical stability was unaffected, storage in compliance aids at 40C with 75% relative humidity softened atenolol tablets, prolonged disintegration time and hindered dissolution which could significantly reduce bioavailability. This formulation could be suitable for storage in compliance aids at 25C, but not in hotter, humid weather.
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BACKGROUND: Flavonoid metabolites remain in blood for periods of time potentially long enough to allow interactions with cellular components of this tissue. It is well-established that flavonoids are metabolised within the intestine and liver into methylated, sulphated and glucuronidated counterparts, which inhibit platelet function. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrate evidence suggesting platelets which contain metabolic enzymes, as an alternative location for flavonoid metabolism. Quercetin and a plasma metabolite of this compound, 4'-O-methyl quercetin (tamarixetin) were shown to gain access to the cytosolic compartment of platelets, using confocal microscopy. High performance liquid chromatography (HPLC) and mass spectrometry (MS) showed that quercetin was transformed into a compound with a mass identical to tamarixetin, suggesting that the flavonoid was methylated by catechol-O-methyl transferase (COMT) within platelets. CONCLUSIONS/SIGNIFICANCE: Platelets potentially mediate a third phase of flavonoid metabolism, which may impact on the regulation of the function of these cells by metabolites of these dietary compounds.
Resumo:
Capillary electrophoresis (CE) offers the analyst a number of key advantages for the analysis of the components of foods. CE offers better resolution than, say, high-performance liquid chromatography (HPLC), and is more adept at the simultaneous separation of a number of components of different chemistries within a single matrix. In addition, CE requires less rigorous sample cleanup procedures than HPLC, while offering the same degree of automation. However, despite these advantages, CE remains under-utilized by food analysts. Therefore, this review consolidates and discusses the currently reported applications of CE that are relevant to the analysis of foods. Some discussion is also devoted to the development of these reported methods and to the advantages/disadvantages compared with the more usual methods for each particular analysis. It is the aim of this review to give practicing food analysts an overview of the current scope of CE.
Resumo:
Red leaf lettuce (Lollo Rosso) was grown under three types of plastic films that varied in transparency to UV radiation (designated as UV block, UV low, and UV window). Flavonoid composition was determined by high-performance liquid chromatography (HPLC), total phenolics by the Folin-Ciocalteu assay, and antioxiclant capacity by the oxygen radical absorbance capacity (ORAC) assay. Exposure to increased levels of UV radiation during cultivation caused the leaves to redden and increased concentrations of total phenols and the main flavonoids, quercetin and cyanidin glycosides, as well as luteolin conjugates and phenolic acids. The total phenol content increased from 1.6 mg of gallic acid equivalents (GAE)/g of fresh weight (FW) for lettuce grown under UV block film to 2.9 and 3.5 mg of GAE/g of FW for lettuce grown under the UV low and UV window films. The antioxiclant activity was also higher in lettuce exposed to higher levels of UV radiation with ORAC values of 25.4 and 55.1 mu mol of Trolox equivalents/g of FW for lettuce grown under the UV block and UV window films, respectively. The content of phenolic acids, quantified as caffeic acid, was also different, ranging from 6.2 to 11.1 mu mol/g of FW for lettuce cultivated under the lowest and highest UV exposure plastic films, respectively. Higher concentrations of the flavonoid glycosides were observed with increased exposure to UV radiation, as demonstrated by the concentrations of aglycones after hydrolysis, which were cyanidin (ranging from 165 to 793 mu g/g), quercetin (ranging from 196 to 880,mu g/g), and luteolin (ranging from 19 to 152 mu g/g). The results demonstrate the potential of the use of UV-transparent plastic as a means of increasing beneficial flavonoid content of red leaf lettuce when the crop is grown in polytunnels.
Resumo:
Red leaf lettuce (Lollo Rosso) was grown under three types of plastic films that varied in transparency to UV radiation (designated as UV block, UV low, and UV window). Flavonoid composition was determined by high-performance liquid chromatography (HPLC), total phenolics by the Folin-Ciocalteu assay, and antioxiclant capacity by the oxygen radical absorbance capacity (ORAC) assay. Exposure to increased levels of UV radiation during cultivation caused the leaves to redden and increased concentrations of total phenols and the main flavonoids, quercetin and cyanidin glycosides, as well as luteolin conjugates and phenolic acids. The total phenol content increased from 1.6 mg of gallic acid equivalents (GAE)/g of fresh weight (FW) for lettuce grown under UV block film to 2.9 and 3.5 mg of GAE/g of FW for lettuce grown under the UV low and UV window films. The antioxiclant activity was also higher in lettuce exposed to higher levels of UV radiation with ORAC values of 25.4 and 55.1 mu mol of Trolox equivalents/g of FW for lettuce grown under the UV block and UV window films, respectively. The content of phenolic acids, quantified as caffeic acid, was also different, ranging from 6.2 to 11.1 mu mol/g of FW for lettuce cultivated under the lowest and highest UV exposure plastic films, respectively. Higher concentrations of the flavonoid glycosides were observed with increased exposure to UV radiation, as demonstrated by the concentrations of aglycones after hydrolysis, which were cyanidin (ranging from 165 to 793 mu g/g), quercetin (ranging from 196 to 880,mu g/g), and luteolin (ranging from 19 to 152 mu g/g). The results demonstrate the potential of the use of UV-transparent plastic as a means of increasing beneficial flavonoid content of red leaf lettuce when the crop is grown in polytunnels.
