Browsing by Author "Pinto, Diana"
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- 2-Styrylchromones as novel inhibitors of xanthine oxidase. A structure-activity studyPublication . Fernandes, Eduarda; Carvalho, Félix; Silva, Artur; Santos, Clementina M.M.; Pinto, Diana; Cavaleiro, José; Bastos, Maria de LourdesThe 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.
- 2-Styrylchromones: novel strong scavengers of reactive oxygen and nitrogen speciesPublication . Gomes, Ana Sara; Fernandes, Eduarda; Silva, Artur; Pinto, Diana; Santos, Clementina M.M.; Cavaleiro, José; Lima, José Costa2-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 potencial of 2-Styrylchromones regarding their interference with arachidonic acid metabolic pathwaysPublication . Gomes, Ana Sara; Fernandes, Eduarda; Silva, Artur; Santos, Clementina M.M.; Pinto, Diana; Cavaleiro, José; Lima, José Costa
- Anti-inflammatory potential of 2-styrylchromones regarding their interference with arachidonic acid metabolic pathwaysPublication . Gomes, Ana Sara; Fernandes, Eduarda; Silva, Artur; Pinto, Diana; Santos, Clementina M.M.; Cavaleiro, José; Lima, José CostaCyclooxygenases (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.
- Antioxidant adjustments of olive trees (Olea europaea) under field stress conditionsPublication . Araújo, Márcia; Prada, João; Mariz-Ponte, Nuno; Santos, Conceição; Pereira, J.A.; Pinto, Diana; Silva, Artur; Dias, Maria CelesteExtreme climate events are increasingly frequent, and the 2017 summer was particularly critical in the Mediterranean region. Olive is one of the most important species of this region, and these climatic events represent a threat to this culture. However, it remains unclear how olive trees adjust the antioxidant enzymatic system and modulate the metabolite profile under field stress con-ditions. Leaves from two distinct adjacent areas of an olive orchard, one dry and the other hydrated, were harvested. Tree water status, oxidative stress, antioxidant enzymes, and phenolic and lipo-philic metabolite profiles were analyzed. The environmental conditions of the 2017 summer caused a water deficit in olive trees of the dry area, and this low leaf water availability was correlated with the reduction of long†chain alkanes and fatty acids. Hydrogen peroxide (H2O2) and superoxide radical (O2•–) levels increased in the trees collected from the dry area, but lipid peroxidation did not augment. The antioxidant response was predominantly marked by guaiacol peroxidase (GPOX) activity that regulates the H2O2 harmful effect and by the action of flavonoids (luteolin†7†O†glucu-ronide) that may act as reactive oxygen species scavengers. Secoiridoids adjustments may also con-tribute to stress regulation. This work highlights for the first time the protective role of some metabolite in olive trees under field drought conditions.
- Arylxanthones and arylacridones: a synthetic overviewPublication . Santos, Clementina M.M.; Pinto, Diana; Silva, Vera L.M.; Silva, ArturArylxanthones 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.
- A comparison between a manual and automatic method to characterize red blood cell trajectoriesPublication . Pinto, Diana; Gayubo, Fernando; Pereira, Ana I.; Lima, Rui A.The current study proposes an automatic method for the segmentation and tracking of red blood cells (RBCs) flowing through a 100 u m glass capillary. The measurements obtained with the proposed automatic method are compared with a manual tracking method using nonlinear optimization techniques.
- Cyclic voltammetric analysis of 2-styrylchromonesPublication . Gomes, Ana Sara; Fernandes, Eduarda; Garcia, M. Beatriz; Silva, Artur; Pinto, Diana; Santos, Clementina M.M.; Cavaleiro, José; Lima, José Costa
- Cyclic voltammetric analysis of 2-styrylchromones: Relationship with the antioxidant activityPublication . Gomes, Ana Sara; Fernandes, Eduarda; Garcia, M. Beatriz; Silva, Artur; Pinto, Diana; Santos, Clementina M.M.; Cavaleiro, José; Lima, José Costa2-Styrylchromones (2-SC) are a chemical family of oxygen heterocyclic compounds, vinylogues of flavones (2-phenylchromones), whose occurrence in nature has been reported. Recently, several 2-SC derivatives were demonstrated to have antioxidant properties, namely, xanthine oxidase inhibition, hepatoprotection against pro-oxidant agents in cellular and non-cellular systems and scavenging activity against reactive oxygen and reactive nitrogen species (ROS and RNS). Considering these antioxidant properties, it may be hypothesised that the electrochemical redox behaviour of 2-SC contributes significantly to their activity. To test this hypothesis, the electrochemical behaviour of different 2-SC was studied, together with a number of flavonoids with well-known antioxidant activities, by cyclic voltammetry, and the results correlated to their ability to scavenge ROS and RNS. The results obtained showed that 2-SC with a catecholic B-ring have a low oxidation peak potential corresponding to the oxidation of the 30,40-OH (catechol) moiety. The compounds with a phenolic B-ring have a common peak, with oxidation potential values of about +0.4/+0.5 V versus Ag/AgCl, corresponding to the oxidation of the 40-OH. The oxidation of the hydroxyl substituents in the A-ring generated peaks of higher potentials (+0.7/+0.8 V vs Ag/AgCl). The results from the scavenging assays were in agreement with those obtained from the cyclic voltammetry, that is, higher scavenging effects corresponded to lower values of oxidation potentials, with significant correlation coefficients. The values obtained for the studied flavonoids are in accordance with the literature, and reflect their relative antioxidant activity, when compared to the studied 2-SC. Thus, in this family of compounds, oxidation potentials obtained by cyclic voltammetry seem to be applicable as a general indicator of radical scavenging activity.
- Effects of Summer Water Deficit Stress on Olive Fruits and Oil QualityPublication . Araújo, Márcia; Rodrigues, Nuno; Santos, Conceição; Pinto, Diana; Pereira, J.A.; Silva, Artur; Dias, Maria CelesteThe Mediterranean basin is the leading worldwide region for olive production. Extreme weather is increasingly frequent in this region, and how these climate extremes will affect olive products and quality remains unknown. We aim to study the effects of the water deficit stress, which occurred in the summer of 2017, on olive fruit and oil quality from a 30-year-old orchard. Fruits from olive trees standing on (i) one hydrated and (ii) one dry area of an orchard at the north of Portugal were harvested. Fruits’ water content, oil yield and quality, fruit carbohydrates, and fruit and oil phenolic metabolite profiles were analyzed. Fruits from the dry area presented low water availability and increased carbohydrates, oleuropein, oleoside, and elenolic acid glucoside abundance. Oil yield was lower in the dry area, but the abundance of oleacein increased, together with traits of some sensory sensations. Climate stress events can reduce oil yield but stimulate the accumulation of bioactive compounds that improve oil quality and nutritional value.
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