scholarly journals Recent Developments in Effective Antioxidants: The Structure and Antioxidant Properties

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1984
Author(s):  
Monika Parcheta ◽  
Renata Świsłocka ◽  
Sylwia Orzechowska ◽  
Monika Akimowicz ◽  
Renata Choińska ◽  
...  
Keyword(s):  
Free Radicals ◽  
Antioxidant Properties ◽  
Hydroxyl Group ◽  
Electronic Charge ◽  
Experimental Literature ◽  
Hydroxyl Groups ◽  
Food Ingredients ◽  
Group Position ◽  
Oxidative Damages ◽  
Recent Developments

Since the last few years, the growing interest in the use of natural and synthetic antioxidants as functional food ingredients and dietary supplements, is observed. The imbalance between the number of antioxidants and free radicals is the cause of oxidative damages of proteins, lipids, and DNA. The aim of the study was the review of recent developments in antioxidants. One of the crucial issues in food technology, medicine, and biotechnology is the excess free radicals reduction to obtain healthy food. The major problem is receiving more effective antioxidants. The study aimed to analyze the properties of efficient antioxidants and a better understanding of the molecular mechanism of antioxidant processes. Our researches and sparing literature data prove that the ligand antioxidant properties complexed by selected metals may significantly affect the free radical neutralization. According to our preliminary observation, this efficiency is improved mainly by the metals of high ion potential, e.g., Fe(III), Cr(III), Ln(III), Y(III). The complexes of delocalized electronic charge are better antioxidants. Experimental literature results of antioxidant assays, such as diphenylpicrylhydrazyl (DPPH) and ferric reducing activity power assay (FRAP), were compared to thermodynamic parameters obtained with computational methods. The mechanisms of free radicals creation were described based on the experimental literature data. Changes in HOMO energy distribution in phenolic acids with an increasing number of hydroxyl groups were observed. The antioxidant properties of flavonoids are strongly dependent on the hydroxyl group position and the catechol moiety. The number of methoxy groups in the phenolic acid molecules influences antioxidant activity. The use of synchrotron techniques in the antioxidants electronic structure analysis was proposed.

scholarly journals Synthesis and Evaluation of Antioxidant Properties of 2-Substituted Quinazolin-4(3H)-ones

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6585
Author(s):  
Janez Mravljak ◽  
Lara Slavec ◽  
Martina Hrast ◽  
Matej Sova
Keyword(s):  
Antioxidant Activity ◽  
Phenyl Ring ◽  
Biological Activities ◽  
Antioxidant Properties ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Ortho Position ◽  
Dpph Assay ◽  
Metal Chelating ◽  
Methoxy Substituent

Quinazolinones represent an important scaffold in medicinal chemistry with diverse biological activities. Here, two series of 2-substituted quinazolin-4(3H)-ones were synthesized and evaluated for their antioxidant properties using three different methods, namely DPPH, ABTS and TEACCUPRAC, to obtain key information about the structure–antioxidant activity relationships of a diverse set of substituents at position 2 of the main quinazolinone scaffold. Regarding the antioxidant activity, ABTS and TEACCUPRAC assays were more sensitive and gave more reliable results than the DPPH assay. To obtain antioxidant activity of 2-phenylquinazolin-4(3H)-one, the presence of at least one hydroxyl group in addition to the methoxy substituent or the second hydroxyl on the phenyl ring in the ortho or para positions is required. An additional ethylene linker between quinazolinone ring and phenolic substituent, present in the second series (compounds 25a and 25b), leads to increased antioxidant activity. Furthermore, in addition to antioxidant activity, the derivatives with two hydroxyl groups in the ortho position on the phenyl ring exhibited metal-chelating properties. Our study represents a successful use of three different antioxidant activity evaluation methods to define 2-(2,3-dihydroxyphenyl)quinazolin-4(3H)-one 21e as a potent antioxidant with promising metal-chelating properties.

Antioxidant activity of the hazelnut plant determination by computational chemistry methods

2021 ◽  
Vol 19 (4) ◽  
pp. 273-282
Author(s):  
Vildan Enisoğlu Atalay ◽  
İbrahim Barış Ölüç
Keyword(s):  
Antioxidant Activity ◽  
Free Radicals ◽  
Digestive System ◽  
Single Point ◽  
Antioxidant Properties ◽  
Hydroxyl Groups ◽  
Point Energy ◽  
Drinking Habits ◽  
Oxidative Balance ◽  
Cell Tissue

Nowadays, it is known that the species defined as free radicals in our body increase due to the change in our eating / drinking habits, physical activities and environmental conditions. Free radicals cause especially canser and diseases affecting many systems such as nervous system, cardiovascular system and digestive system. The formation of free radicals causes cell / tissue damage or cell deaths that occur as a result of oxidative balance disruption due to the insufficient antioxidants defined as oxidative stress. The purpose of this study is to determine the activity ranking of the compounds that give antioxidant properties to hazelnut plants by using quantum chemistry methods and to determine which hydroxyl groups cause the activity. In the antioxidant activity calculations, HAT, SET-PT and SPLET mechanisms are optimized with DFT//M062X/6-311++G(d,p) method, and single point energy as well as the EHOMO-ELUMO values were obtained with the Gaussian09 program in three different phases: gas, ethanol and water. According to the results, Riboflavin compound has been found to have the highest antioxidant potential and it was found that the antioxidant capacity of the compound originated from OH group at O4 position.

scholarly journals Spectroscopic studies on lipoprotein structure modification under oxidative stress

2011 ◽  
Vol 26 (3) ◽  
pp. 167-178 ◽  
Author(s):  
Andreia Tache ◽  
Simona-Carmen Litescu ◽  
Gabriel-Lucian Radu
Keyword(s):  
Free Radicals ◽  
Metal Ion ◽  
Structural Changes ◽  
Oxidation Process ◽  
Spectroscopic Studies ◽  
Oxidative Modification ◽  
Hydroxyl Groups ◽  
Oxidative Damages ◽  
Endogenous Antioxidant

Matrix assisted laser desorption–ionization time of flight (MALDI-ToF) and infrared techniques were used to study oxidative modification of low density lipoproteins (LDL), considered to have the key role in biological process that initiates and accelerates the development of cardiovascular disease. The early identification of lipoperoxidation products creates the opportunity of the efficient prevention of eventual oxidative damages. MALDI analysis of LDL subjected toin vitrooxidation process initiated by 2,2-azobis(2-amidinopropane) dihydrochloride revealed that some fragments of lipoprotein changed the molecular weight by 16 and 32 Da due to the oxygen or hydroxyl groups attachment, and peroxide or hydroperoxide formation, while Fourier Transformed Infrared studies proved that lipoprotein changes its protein secondary conformation from predominantlyα-helix in predominantlyβ-turn. The increase in free radicals concentration correlated to structural changes, and the presence of transitional metal ion, copper (II), in the oxidation process lead to an enhancing of the damaging effects of free radicals on lipoprotein substrate. It was shown that the toxic effects of oxidants are delayed by the presence of glutathione (10 mM), an endogenous antioxidant.

scholarly journals Inhibition of Lipoxygenase and Peroxidase Reaction by Some Flavonols and Flavones: The Structure-Activity Relationship

2017 ◽  
Vol 12 (11) ◽  
pp. 1934578X1701201
Author(s):  
Zbigniew Sroka ◽  
Alina Sowa ◽  
Andrzej Dryś
Keyword(s):  
Correlation Coefficient ◽  
Antioxidant Properties ◽  
Structure Activity Relationship ◽  
Methoxyl Group ◽  
Activity Relationship ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Peroxidase Reaction ◽  
Structure Activity ◽  
Reducing Properties

Some flavonoids were investigated for their effects on lipoxygenase and peroxidase. The strongest inhibitor of lipoxygenase was kaempferol with one hydroxyl group situated at the 4’ position in the B ring, with activity of 21.2±2.03 calculated per μmole of compound. The weakest inhibition was observed for diosmetin with a hydroxyl group at the 3′ position and a methoxyl group at 4′ in the B ring, with activity of 1.17±0.77 per μmole. Peroxidase was most strongly inhibited by quercetin (22.7±0.05) with two hydroxyl groups in the B ring at 3′ and 4′. The weakest inhibitor of peroxidase was genkwanin (0±0.16) with one hydroxyl group at position 4′ in the B ring and methoxyl at position 7 in the A ring. The correlation coefficient between reduction of Fe3+ by flavonoids and inhibition of lipoxygenase by these compounds was 0.72 and the reduction of Fe3+ and inhibition of peroxidase was 0.24. The results show that inhibition of peroxidase is weakly associated with reducing properties of phenols and inhibition of lipoxygenase may be associated with antioxidant properties of flavonoids.

scholarly journals Antioxidant and other health promoting properties of herbs

2018 ◽  
Vol 116 (3) ◽  
pp. 23-33
Author(s):  
Małgorzata Dula ◽  
Jan Matras ◽  
Eugeniusz R. Grela ◽  
Ignacy Niedziółka
Keyword(s):  
Free Radicals ◽  
Fruits And Vegetables ◽  
Antioxidant Properties ◽  
The Body ◽  
Antioxidant Potential ◽  
Natural Food ◽  
Oxidation Reactions ◽  
Food Ingredients ◽  
Health Promoting ◽  
The One

Many component contained in the plants we usually eat are characterized by antioxidant properties, for example polyphenols effectively neutralize free radicals and other reactive oxygen species. The antioxidant potential of some herbal plants is many times higher than that of fruits and vegetables and therefore there has been a growing interest in the active substances contained therein. An improper diet, such as the one rich in lipids, adversely affects the level of free radicals in the body; so it is very important to choose to eat foods with a high antioxidant potential. The oxidation reactions that occur in food products have a detrimental impact on their nutritional value and sensory properties, such as taste, smell, color and texture. Antioxidants added to food can effectively counteract those changes, therefore there are sought natural food ingredients with antioxidant properties to replace synthetic antioxidants, such as BHA, BHT, which are often used in food. Some herbal spices have an anti-inflammatory and antibacterial effect. Moreover, they can stimulate appetite, increase the secretion of digestive juices and improve the absorption of nutrients. A diet enriched with suitable herbs or preparations obtained from them, mainly owing to the antioxidants contained therein, improves the functioning of the organism and prevents the development of certain diseases, such as cancer or atherosclerosis of blood vessels.

scholarly journals Chemical Profile and Antioxidant Activity of the Oil from Peony Seeds (Paeonia suffruticosa Andr.)

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Xin Yang ◽  
Di Zhang ◽  
Li-min Song ◽  
Qian Xu ◽  
Hong Li ◽  
...  
Keyword(s):  
Antioxidant Activities ◽  
Virgin Olive Oil ◽  
Antioxidant Properties ◽  
Extra Virgin Olive Oil ◽  
Chemical Profile ◽  
Paeonia Suffruticosa ◽  
Oxidative Damages ◽  
Development And Utilization ◽  
Key Indicators

Peony seed oil (PSO) is a novel vegetable oil developed from the seeds of Paeonia suffruticosa Andr. The present study aimed to make an overall investigation on the chemical profile and antioxidant activities of PSO for reasonable development and utilization of this new resource food. Chemical analysis revealed that PSO was characterized by an uncommon high portion of α-linolenic acid (>38%), fairly low ratio of n-6 to n-3 polyunsaturated fatty acids (0.69), and much higher content of γ-tocopherol than various conventional seed oils. In vitro assay indicated that PSO is a more potent scavenger of free radicals than extra virgin olive oil. Moderate intake of PSO exhibited obvious protection against various oxidative damages such as tetrachloromethane-induced acute liver injury in mice and diet-induced hyperlipidemia in rats. The changes in the key indicators of oxidative injury and fatty acid composition in the liver caused by PSO administration were measured, and the results demonstrated that antioxidant properties of PSO are closely related to their characteristic chemical composition. Consequently, the present study provided new evidence for the health implications of PSO, which deserves further development for medical and nutritional use against oxidative damages that are associated with various diseases.

scholarly journals Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2131
Author(s):  
Leonardo Dalseno Antonino ◽  
Júlia Rocha Gouveia ◽  
Rogério Ramos de Sousa Júnior ◽  
Guilherme Elias Saltarelli Garcia ◽  
Luara Carneiro Gobbo ◽  
...  
Keyword(s):  
Experimental Work ◽  
Chemical Structure ◽  
31P Nmr ◽  
Kraft Lignin ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Diphenylmethane Diisocyanate ◽  
Complex Chemical ◽  
Heterogeneous Reactivity ◽  
Phenolic Hydroxyl Groups

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers.

scholarly journals Flavonoids improve drought tolerance of maize seedlings by regulating the homeostasis of reactive oxygen species

2021 ◽  
Author(s):  
Baozhu Li ◽  
Ruonan Fan ◽  
Guiling Sun ◽  
Ting Sun ◽  
Yanting Fan ◽  
...  
Keyword(s):  
Free Radicals ◽  
Drought Stress ◽  
Drought Tolerance ◽  
Infrared Imaging ◽  
Oxygen Free Radicals ◽  
Transcriptome Profiling ◽  
Far Infrared ◽  
Drought Treatment ◽  
Physiological Characterization ◽  
Oxidative Damages

Abstract Background and aims As drought threatens the yield and quality of maize (Zea mays L.), it is important to dissect the molecular basis of maize drought tolerance. Flavonoids, participate in the scavenging of oxygen free radicals and alleviate stress-induced oxidative damages. This study aims to dissect the function of flavonoids in the improvement of maize drought tolerance. Methods Using far-infrared imaging screening, we previously isolated a drought overly insensitivity (doi) mutant from an ethyl methanesulfonate (EMS)-mutagenized maize library and designated it as doi57. In this study, we performed a physiological characterization and transcriptome profiling of doi57 in comparison to corresponding wild-type B73 under drought stress. Results Under drought stress, doi57 seedlings displayed lower leaf-surface temperature (LST), faster water loss, and better performance in growth than B73. Transcriptome analysis reveals that key genes involved in flavonoid biosynthesis are enriched among differentially expressed genes in doi57. In line with these results, more flavonols and less hydrogen peroxide (H2O2) were accumulated in guard cells of doi57 than in those of B73 with the decrease of soil water content (SWC). Moreover, the capacity determined from doi57 seedling extracts to scavenge oxygen free radicals was more effective than that of B73 under the drought treatment. Additionally, doi57 seedlings had higher photosynthetic rates, stomatal conductance, transpiration rates, and water use efficiency than B73 exposed to drought stress, resulting in high biomass and greater root/shoot ratios in doi57 mutant plants. Conclusion Flavonoids may facilitate maize seedling drought tolerance by lowering drought-induced oxidative damage as well regulating stomatal movement.

scholarly journals Flavonoids from the Genus Euphorbia: Isolation, Structure, Pharmacological Activities and Structure–Activity Relationships

2021 ◽  
Vol 14 (5) ◽  
pp. 428
Author(s):  
Douglas Kemboi Magozwi ◽  
Mmabatho Dinala ◽  
Nthabiseng Mokwana ◽  
Xavier Siwe-Noundou ◽  
Rui W. M. Krause ◽  
...  
Keyword(s):  
Therapeutic Potential ◽  
Antioxidant Properties ◽  
Structure Activity Relationship ◽  
Biological Properties ◽  
Therapeutic Agents ◽  
Skeletal Structure ◽  
Activity Relationship ◽  
Hydroxyl Groups ◽  
Structure Activity ◽  
Review Reports

Plants of the genus Euphorbia are widely distributed across temperate, tropical and subtropical regions of South America, Asia and Africa with established Ayurvedic, Chinese and Malay ethnomedical records. The present review reports the isolation, occurrence, phytochemistry, biological properties, therapeutic potential and structure–activity relationship of Euphorbia flavonoids for the period covering 2000–2020, while identifying potential areas for future studies aimed at development of new therapeutic agents from these plants. The findings suggest that the extracts and isolated flavonoids possess anticancer, antiproliferative, antimalarial, antibacterial, anti-venom, anti-inflammatory, anti-hepatitis and antioxidant properties and have different mechanisms of action against cancer cells. Of the investigated species, over 80 different types of flavonoids have been isolated to date. Most of the isolated flavonoids were flavonols and comprised simple O-substitution patterns, C-methylation and prenylation. Others had a glycoside, glycosidic linkages and a carbohydrate attached at either C-3 or C-7, and were designated as d-glucose, l-rhamnose or glucorhamnose. The structure–activity relationship studies showed that methylation of the hydroxyl groups on C-3 or C-7 reduces the activities while glycosylation loses the activity and that the parent skeletal structure is essential in retaining the activity. These constituents can therefore offer potential alternative scaffolds towards development of new Euphorbia-based therapeutic agents.

scholarly journals Enhancement of Antioxidant and Hydrophobic Properties of Alginate via Aromatic Derivatization: Preparation, Characterization, and Evaluation

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2575
Author(s):  
Smaher M. Elbayomi ◽  
Haili Wang ◽  
Tamer M. Tamer ◽  
Yezi You
Keyword(s):  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Benzoyl Group ◽  
Antioxidant Evaluation ◽  
Thermo Stability

The preparation of bioactive polymeric molecules requires the attention of scientists as it has a potential function in biomedical applications. In the current study, functional substitution of alginate with a benzoyl group was prepared via coupling its hydroxyl group with benzoyl chloride. Fourier transform infrared spectroscopy indicated the characteristic peaks of aromatic C=C in alginate derivative at 1431 cm−1. HNMR analysis demonstrated the aromatic protons at 7.5 ppm assigned to benzoyl groups attached to alginate hydroxyl groups. Wetting analysis showed a decrease in hydrophilicity in the new alginate derivative. Differential scanning calorimetry and thermal gravimetric analysis showed that the designed aromatic alginate derivative demonstrated higher thermo-stability than alginates. The aromatic alginate derivative displayed high anti-inflammatory properties compared to alginate. Finally, the in vitro antioxidant evaluation of the aromatic alginate derivative showed a significant increase in free radical scavenging activity compared to neat alginate against DPPH (2,2-diphenyll-picrylhydrazyl) and ABTS free radicals. The obtained results proposed that the new alginate derivative could be employed for gene and drug delivery applications.

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