Search Results

You are looking at 61 - 70 of 243 items for :

Clear All
Open access

Rado Nosáľ, Katarína Drábiková, Viera Jančinová, Tatiana Mačičková, Jana Pečivová, Tomáš Perečko and Juraj Harmatha

Abstract

In this study we investigated the effect of five therapeutically used drugs and four natural polyphenolic compounds on the mechanism of oxidative burst of human neutrophils concerning their participation in the generation of reactive oxygen species (ROS). The compounds investigated decreased the oxidative burst of whole blood in the rank order of potency: N-feruloylserotonin > quercetin > curcumin > arbutin > dithiaden > carvedilol. The generation of intracellular reactive oxygen species in isolated neutrophils decreased in the same rank order, while carvedilol was ineffective. Scavenging of extracellular oxygen radicals followed the rank order of potency: N-feruloylserotonin > curcumin > quercetin > dithiaden. Arbutin and carvedilol had no effect. All compounds tested increased the activity of caspase-3 in cell-free system indicating a positive effect on apoptosis of neutrophils. Activation of protein kinase C was significantly decreased by dithiaden, curcumin, quercetin and N-feruloylserotonin. Carvedilol, dithiaden, quercetin and arbutin reduced activated neutrophil myeloperoxidase release more significantly compared with their less pronounced effect on superoxide generation The presented results are indicative of pharmacological intervention with neutrophils in pathological processes. Of particular interest was the effect of natural compounds. Intracellular inhibition of oxidative burst in isolated neutrophils by the drugs tested and natural antioxidants has to be further analysed since ROS play an important role in immunological responses of neutrophils.

Open access

Adina Frum

Abstract

Romanian spontaneous flora provides a lot of resources for the determination of different chemical compounds. This study uses flower samples from Calendula officinalis L. extracted through maceration. The chemical compounds determined were: (+)-catechin, caffeic acid, chlorogenic acid, cinnamic acid, ferulic acid, gallic acid, rutin, resveratrol and quercetin. They were analyzed by using an optimized HPLC method. (+)-Catechin, caffeic acid, chlorogenic acid and quercetin could not be identified in the analyzed samples. The greatest amount of phenolic compound found was rutin and the smallest quantity was determined for ferulic acid. The quantified compounds have proven to have benefits regarding human health, thus they can be used as functional compounds and can be included in food products and food supplements.

Open access

Silvia Mošovská, Patrícia Petáková, Michal Kaliňák and Anna Mikulajová

Abstract

The evaluation of antioxidant potential of food has received much attention in recent years. Antioxidant compounds can scavenge free radicals and thereby can protect the human body from free radicals. This study was focused on the isolation of curcuminoids from the dried turmeric rhizome, and studying their antioxidant activity. The presence of curcuminoids was identified in turmeric sample by Nuclear Magnetic Resonance (NMR) analysis. Since neutral curcumin is known to be poorly soluble, the synthesis of curcumin-cyclodextrin and curcumin-phospholipid complexes was also performed. The antioxidant activity of isolated curcuminoids was assessed by two methods (ABTS and FRAP assay) and their scavenging activities were compared with those of prepared complexes. The ability to reduce ABTS radical cation decreased as follows: quercetin > trolox > curcuminoids > curcumin-cyclodextrin complex > curcumin-phospholipid complex. The reducing potential of tested samples in descending order was quercetin > trolox > curcumin-cyclodextrin complex > curcuminoids > curcumin-phospholipid complex.

Open access

Tahareh Gholami, Mohammad Ghadamyari, Ali Olyaie Oliaee and Maryan Ajamhasani

Abstract

The rosaceous branch borer, Ospheranteria coerulescens, is an important pest of rosaceous trees. This insect feeds on the twigs and branches of living trees and causes their death. The characterization of the insect phenoloxidase (PO) is of interest when doing comparative investigations, and so that we may be able to understand its biochemical properties. When designing new methods of insect control such as the use of PO inhibitors, an understanding of the biochemical properties is fundamental. In this study, PO from hemolymph of the rosaceous branch borer was purified using ammonium sulfate precipitation, gel-filtration, and ion-exchange chromatography. The biochemical properties were characterized using l-dihydroxyphenylalanine (L-DOPA) as the specific substrate. The apparent molecular weights of the three isoforms of PO were determined by SDS-PAGE to be 85.23, 79.45, and 66.06 kDa. Optimal pH for PO activity was pH 8, and the optimal temperature was 45°C. Phenoloxidase lost less than 50% of its relative activity after a 60 min incubation at the optimal temperature. The effects of ions and chemical materials such as K+, Ba2+, Zn2+ and EDTA on PO showed that PO activity was strongly inhibited by Zn2+. The Michaelis constant (Km) and maximum velocity (Vmax) were 88.61 mM and 0.14 μmol/min, respectively. The inhibitory effects of kojic acid, 4-hexylresorsinol, and quercetin on PO were determined, and the IC50s (inhibitory concentration) were estimated as 23.31 for kojic acid, 35.75 for 4-hexylresorcinol, and 60.8 μM for quercetin. The inhibitory potency of kojic acid was 1.54 times higher than that of 4-hexylresorcinol and 2.58 times higher than that of quercetin. Phenoloxidase was effectively inhibited by 4-hexylresorcinol, and the inhibition type was competitive. The inhibition types of PO by kojic acid and quercetin were found to be mixed.

Open access

Iwona Skrzecz, Alicja Sowińska and Wojciech Janiszewski

Abstract

The aim of the study was to evaluate the possibility of using botanic antifeedants to reduce the damage caused by Melolontha spp. grubs. To achieve the objective, the experiments were established in semi-field conditions to estimate the antifeedant activity of rutin, quercetin (flavonoids from buckwheat Fagopyrum esculentum) and an extract from black alder Alnus glutinosa leaves against Melolontha melolontha grubs. The grubs were placed individually in the pots with a soil in which 2 year old Pinus sylvestris trees were planted. The pots were put in garden pavilions placed in the open area. Then the soil in the pots were watered with the emulsions of rutin, quercetin, an extract from A. glutinosa leaves, and with pure water-comparative variant. After 4 months, the weight and mortality of grubs were compared, as well as the weight of tree roots in all pots.

There was no effect of the antifeedants on the development and extent of damage caused by M. melolontha grubs. The results do not indicate the use of botanic antifeedants in the protection of forests against the cockchafer grubs

Open access

Silvia Tsanova-Savova and Fanny Ribarova

Abstract

Flavonols and flavones are antioxidants of plant origin with a beneficial role in the prevention of different diseases. Therefore it is important for their content in various foods to be measured in order to be able to judge on their potential for disease prevention.

The aim of the study is to present precise and representative data for flavonols and flavones content of Bulgarian foods from Malvaceae and Umbiliferae plant families, based on a validated analytical HPLC procedure.

The content of flavonols and flavones was determined in one representative belonging to Malvaceae plant family used as food - okra, and four representatives of Umbiliferae plant family - dill, parsley, celery, and carrots. An HPLC method for simultaneous determination of flavonols myricetin, quercetin, kaempferol and flavones luteolin and apigenin was applied and validated.

The results showed that dill was particularly rich in the flavonol quercetin (403.0 mg/kg) followed by okra (200.3 mg/kg). The other analysed samples contained only flavones with the highest amount noted for luteolin in celery leaves (228.9 mg/kg) and for apigenin in parsley (747.9 mg/kg). Those data outlined the ranking of green leaf herbs among the greatest sources of flavonols and flavones among Bulgarian foods. They could be used to characterise various biological species and, what is more, they could be successfully applied in practice to formulate preventive antioxidant diets to be administered in case of various contemporary diseases.

Open access

Anna Mikulajová, Dominika Šedivá, Eva Hybenová and Silvia Mošovská

Abstract

Common buckwheat (Fagopyrum esculentum) and tartary buckwheat (Fagopyrum tataricum) cultivars originating in different world countries were investigated and compared for their quantitative and qualitative abundance of phenolics and flavonoids. Moreover, the antioxidant properties were tested using two different methods. The total phenolic and total flavonoid content ranged from 0.897 to 4.226 mg GAE g−1 dw and from 0.238 to 4.626 mg rutin g−1 dw, respectively. Flavonoids — rutin, quercetin, and hydroxybenzoic acids — gallic, protocatechuic, vanillic and syringic were identified and quantified. Rutin was the most abundant flavonoid and protocatechuic acid was the most abundant phenolic acid in evaluated cultivars. All cultivars showed significant antiradical properties, but their chelating activity was weak. The German cultivar of tartary buckwheat Lifago had significantly higher phenolic content and better antioxidant properties than other cultivars. The content of rutin was 24 times higher and free radicals scavenging activity about 70 % higher than the average value of other cultivars.

Open access

O T Olaru, Adriana Iuliana Anghel, Viorica Istudor and Iulia Ioana Olaru

Abstract

Introduction: Polygonum convolvulus L. (black bindweed), syn. Fallopia convolvulus (L.) Á. Löve, Polygonaceae family is a plant from the spontaneous flora, spread from the plain zone up to the subalpine zone. The objectives of our researches are the qualitative and quantitative determination of polyphenolic compounds from Polygoni convolvuli herba and the choice of the adequate solvent for obtaining an active pharmacological extract.

Method: The qualitative exam consisted of phytochemical screening and thin layer chromatography. The quantitative determination of the total polyphenols was made through the Folin-Ciocâlteu method.

Results: The flavonoids, the anthocyanins, the tannins and the phenol carboxylic acids (phytochemical screening) were emphasized and the following compounds were identified: rutin, hyperoside, isoquercitroside, quercetin, myricetin, kaempferol and caffeic acid.

Conclusions: In order to establish the technological lab process for obtaining an active pharmacological extract standardized in total polyphenols the adequate solvent is ethanol 50% (v/v).

Open access

Martin Michalík, Ján Rimarčík, Vladimír Lukeš and Erik Klein

Abstract

Very recently, a report on the antioxidant activity of flavonoids has appeared, where authors concluded that Hydrogen Atom Transfer mechanism represents the thermodynamically preferred mechanism in polar media (https://doi.org/10.1016/j.foodres.2018.11.018). Unfortunately, serious errors in the theoretical part of the paper led to incorrect conclusions. For six flavonols (galangin, kaempferol, quercetin, morin, myricetin, and fisetin), reaction enthalpies related to three mechanisms of the primary antioxidant action were computed. Based on the obtained results, the role of intramolecular hydrogen bonds (IHB) in the thermodynamics of the antioxidant effect is presented. Calculations and the role of solvation enthalpies of proton and electron in the determination of thermodynamically preferred mechanism is also briefly explained and discussed. The obtained results are in accordance with published works considering the Sequential Proton-Loss Electron-Transfer thermodynamically preferred reaction pathway.

Open access

Ouroud Fellah, Samir Hameurlaine, Noureddine Gherraf, Amar Zellagui, Tahar Ali, Abdennabi Abidi, Muhammed Altun, Ibrahim Demirtas and Ayse SahinYaglioglu

Abstract

The aerial parts of T. gallica collected from three different locations (arid, humid and semi-arid) were extracted using ethyl acetate. The crude extracts were subjected to phenolic appraisal and antiproliferative activity using ELISA and xCELLigence assays. The total phenolic and flavonoids were evaluated using appropriate techniques to give a yield of total phenolics ranging between 238.46 and 348.56 mg GAE (Gallic acid equivalent)/g dry weight extract. The flavonoids yield was found to vary from 36.6 to 103.14 mg QE (quercetin equivalent)/g dry weight extract. Moreover, the extracts were tested against rat brain tumor (C6) and human cervix carcinoma (HeLa) cell lines and displayed important differences in activity. These disparities highlighted the effect of climatic factors as quality determinants of secondary metabolites and therefore as a key control of the biological therapeutic effect.