1,210 research outputs found
Effect of dietary bile extracts on serum response of astaxanthin in rainbow trout (Oncorhynchus mykiss): a preliminary study
Effects of porcine bile extracts added at three different dietary
concentrations 0, 10 and 20 g kg)1 were studied on
astaxanthin serum concentration in rainbow trout (mean
weight 200 ± 7 g). Astaxanthin from micro-algae Haematococcus
pluvialis and synthetic astaxanthin (CAROPHYLL
pink) were incorporated in diets of rainbow trout
at a rate of 100 mg astaxanthin kg)1 of feed. Fish were hand
fed twice a day. After 5 days of feeding there was a significant
effect of the pigment source on the ratio (total blood
astaxanthin per unit body weight to cumulative astaxanthin
intake per unit body weight). Trout receiving synthetic
astaxanthin showed a significantly (P < 0.05) higher ratio
than trout fed algal astaxanthin. Increasing dietary bile
extract did not lead to produce any effect on this ratio. The
power of the statistical analysis is discussed. Therefore, the
interaction (pigment source · dietary bile concentration)
showed no more effect
Logic of agreement: Foundations, semantic system and proof theory
AbstractIn this paper a multi-valued propositional logic — logic of agreement — in terms of its model theory and inference system is presented. This formal system is the natural consequence of a new way to approach concepts as commonsense knowledge, uncertainty and approximate reasoning — the point of view of agreement. Particularly, it is discussed a possible extension of the Classical Theory of Sets based on the idea that, instead of trying to conceptualize sets as “fuzzy” or “vague” entities, it is more adequate to define membership as the result of a partial agreement among a group of individual agents. Furthermore, it is shown that the concept of agreement provides a framework for the development of a formal and sound explanation for concepts (e.g. fuzzy sets) which lack formal semantics. According to the definition of agreement, an individual agent agrees or not with the fact that an object possesses a certain property. A clear distinction is then established, between an individual agent — to whom deciding whether an element belongs to a set is just a yes or no matter — and a commonsensical agent — the one who interprets the knowledge shared by a certain group of people. Finally, the logic of agreement is presented and discussed. As it is assumed the existence of several individual agents, the semantic system is based on the perspective that each individual agent defines her/his own conceptualization of reality. So the semantics of the logic of agreement can be seen as being similar to a semantics of possible worlds, one for each individual agent. The proof theory is an extension of a natural deduction system, using supported formulas and incorporating only inference rules. Moreover, the soundness and completeness of the logic of agreement are also presented
Receptor–drug association studies in the inhibition of the hematin aggregation process of malaria
AbstractDocking studies were performed to investigate the binding of several antimalarial compounds to the putative drug receptors involved in the hematin aggregation process. These studies reveal a binding profile that correlates with the complementarity of electrostatic potentials between the receptors and the active molecules. These results allow a possible explanation for the same molecular mechanism shown by 4-aminoquinolines, quinine, mefloquine, halofantrine and hydroxylated xanthones. The docking data presented in this work offer an interesting approach to the design of new molecules with potential antimalarial activity
Arylxanthones and arylacridones: a synthetic overview
Arylxanthones and arylacridones although not yet found in nature are becoming an important group of heterocyclic compounds due to their promising biological activities. Their central cores, xanthone and acridone, are recognized as interesting motifs for drug development mainly to be used in antitumour chemotherapy. The synthesis of this type of compounds is still scarce but several successful examples were recently published and a large variety of arylated xanthone and acridone derivatives were prepared. A systematic survey of the literature dedicated to their synthesis will be presented and discussed in this review.Thanks are due to the University of Aveiro, Polytechnic Institute of Bragança, Fundação
para a Ciência e a Tecnologia (FCT) FCT/MEC for the financial support of the QOPNA research Unit (FCT
UID/QUI/00062/2013) through national founds and, where applicable, co-financed by the FEDER, within
the PT2020 Partnership Agreement. V.L.M. Silva also acknowledges FCT for the financial support of her post-doctoral grant (SFRH/BPD/108807/2015), in the ambit of “QREN e POCH e Tipologia 4.1 e Formação Avançada”, co-sponsored by FSE and by national funds of MCTESinfo:eu-repo/semantics/publishedVersio
Evaluation of different cell disruption processes on encysted cells of Haematococcus pluvialis: effects on astaxanthin recovery and implications for bio-availability
Although Haematococcus pluvialis is one of the most importantnatural sources of the carotenoid astaxanthin as a pigmentor for theaquaculture industry, the thick sporopollenin cell wall in the cysts hindersastaxanthin extraction and its subsequent bio-availability to fish. A rangeof physical and chemical processes were tested to promote the disruptionof the encysted cells. The efficacy of these processes was evaluated interms of astaxanthin recovery, which was assessed by determining theextent of leaching of astaxanthin into an organic solvent. The processestested were: autoclave 30 min, 121 °C, 1 atm; HCl 0.1 M, 15min and 30 min; NaOH 0.1 M, 15 min and 30 min; enzymatictreatment with a mixture of 0.1% protease K and 0.5% driselase in aphosphate buffer, pH 5.8, 30 °C, for one hour; spray drying, inlet180 °C, outlet 115 °C; and mechanical disruption, with acell homogeniser developed for this purpose. The mechanical(homogenisation) and autoclave treatments were the most effective in termsof extraction and availability
Tetrahydroquinazoline-substituted chromones from Diels–Alder reaction of (E)-2-styrylchromones and pyrimidine ortho-quinodimethane
The Diels-Alder reaction of (E)-2-styrylchromones with a pyrimidine ortho-quinodimethane is reported for the first time. These cycloaddition reactions afford mixtures of two regioisomeric tetrahydroquinazoline-substituted chromones in moderate to excellent global yields. Irrespectively of the substituents on the 2-styrylchromones, the 2-(7-aryl-4-methoxy-2-methyl-5,6,7,8-tetrahydroquinazolin-6-yl)chromone derivatives are always the major isomers
AML patients lacking kir ligand for donor KIR exhibit increased overall survival in HLA-identical sibling transplants
2-Styrylchromones: novel strong scavengers of reactive oxygen and nitrogen species
http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=S2NjaL1GBbk143plPl1&page=1&doc=1&colname=WOS2-Styrylchromones are a small group of naturally occurring chromones, vinylogues of flavones (2-phenylchromones).
Natural and synthetic 2-styrylchromones have been tested in different biological systems, showing activities with potential therapeutic
applications. In particular, the potential and hitherto understudied antioxidant behavior of these compounds has been raised as a
matter of interest. Thus the present work consisted in the study of the in vitro scavenging activities for reactive oxygen species (ROS)
and reactive nitrogen species (RNS) of various 2-styrylchromone derivatives and structurally similar flavonoids. Some of the studied
2-styrylchromones proved to be extremely efficient scavengers of the different ROS and RNS, showing, in some cases, IC50s under
1 lM. The hydroxylation pattern of 2-styrylchromones, especially in the B-ring but also in the A ring, modulates the activity of these
compounds, the catecholic derivatives being the most effective scavengers. The styryl pattern also contributes to their observed outstanding
antioxidant activity. In conclusion, the scavenging activities for ROS/RNS of 2-styrylchromone derivatives, here shown for
the first time, provide novel and most promising compounds to be applied as antioxidants
Anti-inflammatory potential of 2-styrylchromones regarding their interference with arachidonic acid metabolic pathways
Cyclooxygenases (COXs) are the key enzymes in the biosynthesis of prostanoids. COX-1 is a constitutive
enzyme while the expression of COX-2 is highly stimulated in the event of inflammatory processes,
leading to the production of large amounts of prostaglandins (PGs), in particular PGE2 and PGI2, which
are pro-inflammatory mediators.
Lipoxygenases (LOXs) are enzymes that produce hydroxy acids and leukotrienes (LTs). 5-LOX
metabolizes arachidonic acid to yield, among other products, LTB4, a potent chemoattractantmediator of
inflammation.
The aim of the present work was to evaluate the anti-inflammatory potential of 2-styrylchromones
(2-SC), a chemical family of oxygen heterocyclic compounds, vinylogues of flavones (2-phenylchromones),
by studying their COX-1 and COX-2 inhibitory capacity as well as their effects on the LTB4
production by stimulated human polymorphonuclear leukocytes (PMNL).
Some of the tested 2-SC were able to inhibit both COX-1 activity and LTB4 production which makes
them dual inhibitors of the COX and 5-LOX pathways. The most effective compounds in this study were
those having structural moieties with proved antioxidant activity (30,40-catechol and 40-phenol
substituted B-rings).
This type of compounds may exhibit anti-inflammatory activity with a wider spectrum than that of
classical non-steroidal anti-inflammatory drugs (NSAIDs) by inhibiting 5-LOX product-mediated
inflammatory reactions, towards which NSAIDs are ineffective.The authors acknowledge FCT and FEDER financial support for
the project POCI/QUI/59284/2004 and the Organic Chemistry
Research Unit (no. 62; Univ. Aveiro). Ana Gomes acknowledges FCT
and FSE her PhD grant (SFRH/BD/23299/2005)
2-Styrylchromones as novel inhibitors of xanthine oxidase. A structure-activity study
The purpose of this study was the evaluation of the
xanthine oxidase (XO) inhibition produced by some
synthetic 2-styrylchromones. Ten polyhydroxylated
derivatives with several substitution patterns were
synthesised, and these and a positive control, allopurinol,
were tested for their effects on XO activity by
measuring the formation of uric acid from xanthine. The
synthesised 2-styrylchromones inhibited xanthine oxidase
in a concentration-dependent and non-competitive
manner. Some IC50 values found were as low as 0.55mM,
which, by comparison with the IC50 found for allopurinol
(5.43 mM), indicates promising new inhibitors.
Those 2-styrylchromones found to be potent XO
inhibitors should be further evaluated as potential
agents for the treatment of pathologies related to the
enzyme’s activity, as is the case of gout, ischaemia/
reperfusion damage, hypertension, hepatitis and cancer
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