Flavonoid Antioxidant Activity Research Articles

Bridging the gap in antioxidant activity of flavonoids: Correlating the oxidation of human plasma with chemical and cellular assays

Traditional antioxidant screening relies on chemical assays to assess compounds' potential in combating oxidative processes. However, translating chemical antioxidant activity to complex biological systems poses challenges. In this study, the antioxidant potential of fruit-derived phenolic compounds, hyperoside (HP), epicatechin (EC), and phlorizin (PZ), and their combinations in a specific ratio were investigated using a simplex-centroid design of experiments. The research included in vitro antioxidant assays, plasma protection against oxidation tests, and cytotoxicity assessments in human cell lines. The results revealed the complex relationship between chemical antioxidant activity and its relevance to cellular oxidative and antioxidative processes. HP and EC exhibited significant antioxidant activity, with HP outperforming EC in multiple assessments. Cytotoxicity assay confirmed that these compounds did not induce cell death or hinder proliferation, even at higher concentrations (>100 μmol/mL). In the cell antioxidant activity (CAA) test, HP and EC exhibited higher CAA, while PZ displayed lower antioxidant activity. In conclusion, a synergistic effect emerged when HP, EC, and PZ were combined, particularly in plasma protection, suggesting protective effects and potential health benefits. This research emphasized the need for a nuanced understanding of the interplay between chemical assays and cellular behavior in comprehending the relationship between chemical-based, human plasma oxidation, and CAA.

Exploring the Molecular Mechanism of the Antioxidant Activity of Medicine and Food Homology Licorice Flavonoids Based on Pharmacophore Theory and Quantum Calculations

Licorice flavonoids are a kind of flavonoids extracted from the root of licorice, which have good antioxidant activity and are widely used in the food industry. In the early research of the research group, it has been found that the antioxidant activity of licorice flavonoids can be altered by solvent mediation. However, the molecular mechanism underlying the antioxidant properties of licorice flavonoids is still not fully understood. Therefore, this study aims to explore the molecular mechanism underlying the antioxidant activity of licorice flavonoids based on the principles of pharmacophore theory and quantum computing. Firstly, network pharmacology will be employed to study the antioxidant properties of licorice flavonoids. The major active components and key structural features responsible for the antioxidant activity in licorice flavonoids will be screened using pharmacophore theory and further validated through molecular docking. Lastly, quantum computing will be utilized to uncover the potential mechanism underlying their antioxidant activity. Pharmacophore studies have shown that licochalcone B, retrochalcone, isoliquiritin, and isoliquiritigenin exhibit low predicted IC50 values, indicating that these compounds are key components of licorice flavonoids in the antioxidant process. Molecular electrostatic potential (MEP) and frontier molecular orbital studies have shown that licochalcone B, retrochalcone, isoliquiritin, and isoliquiritigenin all exhibit certain chemical reactivity. Quantum computing studies have found that the para-phenol hydroxyl group on the core structure of licochalcone B, isoliquiritigenin, retrochalcone, and isoliquiritin is a crucial functional group for the antioxidant activity of flavonoid compounds. In general, this study successfully elucidated the mode of action of licorice flavonoids in the antioxidant process, providing some guidance for the synthesis of new antioxidant compounds.

A DFT-Based Mechanism Analysis of the Cyclodextrin Inclusion on the Radical Scavenging Activity of Apigenin.

Natural flavonoids are renowned for their exceptional antioxidant properties, but their limited water solubility hampers their bioavailability. One approach to enhancing their water solubility and antioxidant activity involves the use of cyclodextrin (CD) inclusion. This study investigated the impact of CD inclusion on the three primary radical scavenging mechanisms associated with flavonoid antioxidant activity, utilizing apigenin as a representative flavonoid and employing density functional theory (DFT) calculations. Initially, the optimized geometries of CD-apigenin inclusion complexes were analyzed, revealing the formation of hydrogen bonds between CD and apigenin. In less polar environments, the inclusion complex strengthened the bond dissociation enthalpies of hydroxyl groups, thereby reducing antioxidant activity. Conversely, in polar environments, the inclusion complex had the opposite effect by lowering proton affinity. These findings align with experimental results demonstrating that CD inclusion complexation enhances flavonoid antioxidant activity in aqueous ethanol solutions.

Extraction of phenolic and flavonoid compounds and evaluation of their antioxidant activity in saffron anthers (Crocus sativus L.)

Saffron (Crocus sativus L.) is the most expensive spice in the world and rich in a variety of bioactive compounds including phenolic acids, flavonoids, and vitamins. Saffron is used in food, cosmetics, perfumery, and dye industries due to its color, taste, aroma, and medicinal properties. The extraction of bioactive compounds imposes a constant search for economically and environmentally viable extraction strategies for higher yields including the solvent type. The research was carried out to evaluate total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of C. sativus L. anthers using different extraction solvents including ethanol, methanol, and distilled water. The results showed that ethanol was the most effective extraction solvent type exhibiting the highest TPC (7.29 mg GAE g-1 DW), TFC (3.77 mg QE g-1 DW), and antioxidant activity of flavonoids (88%) and ascorbic acid (76.07%). Flavonoids proved to be stronger antioxidants than ascorbic acid, irrespective of solvent type, however the ethanolic extracts showed significantly higher antioxidant activity. A Reverse Phase High-Performance Liquid Chromatography method revealed that gallic acid (3.1 mg g-1), syringic acid (0.2 mg g-1), and vanillic acid (0.13 mg g-1) were the main phenolic compounds detected in the dried anther ethanolic extracts, while quercetin (2.13 mg g-1), pyrogallol (1.73 mg g-1), kaempferol (1.2 mg g-1), rutin (0.2 mg g-1), and tricin (0.1 mg g-1) the main flavonoid compounds. Thus, apart from the spice, constituted by the red stigmas, the production of other flower parts such as the anthers, so far considered agricultural waste can constitute a rich source of bioactive compounds of high antioxidant potential by setting quality standards for new products’ development and ensuring better valorization of saffron’s bioresidues in Mashhad region of Iran.

Establishment and Optimization of Flavonoid Extraction and Detection System for Hemerocallis

Hemerocallis is a characteristic vegetable with outstanding edible and medicinal value. Flavonoids are important bioactive components of Hemerocallis. To improve the extraction efficiency and detection accuracy of flavonoids from Hemerocallis, we established a high-performance liquid chromatography (HPLC) detection system, which can simultaneously detect multiple flavonoids. In addition to the previously developed organic solvent extraction method, an ultrasonic-assisted extraction technique that uses fewer samples was established to extract flavonoids from Hemerocallis. The extraction conditions of the ultrasonic-assisted extraction were optimized via a single-factor experiment and a response surface experiment. The HPLC system detected and determined the contents of rutin, isoquercetin, myricetin, quercetin, apigenin, and diosmetin from 70 Hemerocallis germplasm resources. In addition, we evaluated the antioxidant activity of flavonoids in Hemerocallis using DPPH free radical scavenging capacity with ascorbic acid (Vc) as a positive control. The results showed that the optimum conditions for the ultrasonic extraction process were as follows: sample weight of 0.25 g, ethanol volume fraction of 72%, ethanol volume of 2.5 mL, and ultrasonic extraction time of 17 min. Under these conditions, flavonoid extraction had a strong scavenging effect on DPPH. With the increase in the sample solutions’ concentrations, its antioxidant capacity was gradually enhanced, and the DPPH scavenging rate reached 70.2%. The optimized ultrasonic-assisted extraction technology can increase the total content of six flavonoids in day lily bud by 59.01%, especially the content of rutin (increased by 64.41%) in Hemerocallis flower buds. Among 70 Hemerocallis plant resources, we selected materials H0087 and H0059 with high and stable flavonoid content, with the total content of six substances being 4390.54 ug/g and 3777.13 ug/g. Thus, this study provides a reference for extracting and determining flavonoid contents in Hemerocallis materials. It also provides a theoretical basis for high-quality individual plant breeding.

Antibacterial, Antibiofilm, Antiswarming, and Antioxidant Activities of Flavonoids Isolated from Allium colchicifolium Leaves

Allium (A.) species are one of the most widespread plants in the world, which have played a special role in terms of nutrition, treatment, and economy since long ago. This study is the first report on the phytochemical and biological activities of A. colchicifolium. Five flavonoids, including isorhamnetin (compound 1), quercetin (compound 2), morin (compound 3), isorhamnetin-3-O-glucoside (compound 4), and quercetin 3-O-glucoside (compound 5), were isolated and purified for the first time from A. colchicifolium leaves. All isolated flavonoids showed antibacterial and antibiofilm activities. Compound 3 revealed prominent antibacterial activities against Staphylococcus (S.) aureus and Proteus (P.) mirabilis. Also, compounds 3 and 5 showed the highest antibiofilm activities on S. aureus and P. mirabilis, respectively. The docking study results showed that compounds 3, 4, and 5 had the most robust interactions with two critical proteins in biofilm formation, including staphylococcal accessory regulator A (SarA) and mannose-resistant Proteus-like fimbriae H (MrpH). Besides, compounds 2 and 3 revealed significant antioxidant activities in 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and ferric (Fe3+)-reducing antioxidant power (FRAP) tests compared to the other compounds and positive controls. Also, the ADMET (absorption, distribution, metabolism, excretion, and toxicity) prediction assay showed that compounds 1, 2, and 3 have suitable physicochemical and pharmacokinetic properties. The results of this study confirm that the flavonoids isolated from the leaves of A. colchicifolium can be promising candidates for use in the pharmaceutical and food industries.

Flavonoids mitigation of typical food thermal processing contaminants: Potential mechanisms and analytical strategies.

Due to unique chemical structure, flavonoids are secondary metabolites with numerous biological activities. Thermal processing of food usually produces some chemical contaminants, which cause an adverse effect on food quality and nutrition. Therefore, it is vital to reduce these contaminants in food processing. In this study, current researches around the inhibitory effect of flavonoids on acrylamide, furans, α-dicarbonyl compounds and heterocyclic amines (HAs) were summarized. It has been shown that flavonoids inhibited the formation of these contaminants to varying degrees in chemical or food models. The mechanism was mainly associated with natural chemical structure and partly with antioxidant activity of flavonoids. Additionally, methods and tools of analyzing interactions between flavonoids and contaminants were discussed. In summary, this review demonstrated potential mechanisms and analytical strategies of flavonoids in food thermal processing, providing new insight of flavonoids applying on the food engineering.

Antioxidant Activity of Flavonoids and Phenolic Acids from Dodonaea angustifolia Flower: HPLC Profile and PASS Prediction

Background. Dodonaea angustifolia is a known medicinal plant across East Arica. The flower of D. angustifolia is not well investigated in terms of phytochemistry and biological activities. This study aims to investigate the presence of flavonoids and phenolic acids in the flower of D. angustifolia and its antioxidant activity. Methods. Preliminary phytochemical screening was carried out using the standard protocols. Antioxidant activity evaluation using DPPH assay and total phenol content (TPC) and total flavonoid content (TFC) determinations in the flower extract were compared with the values of the leaf extract. UHPLC-DAD analysis was managed to develop the profile of the flower extract. Prediction of biological activity spectra for substances (PASS) was done using an online server for antioxidant and related activities. Results. Preliminary phytochemical screening and TPC and TFC values confirmed the presence of flavonoids and phenolic acids. From the HPLC analysis of flavonoids, quercetin, myricetin, rutin, and phenolic acids such as chlorogenic acid, gallic acid, and syringic acid were detected and quantified. The biological activity spectrum was predicted for the detected and quantified polyphenols. Conclusions. D. angustifolia flower is a rich source of flavonoids and phenolic acids, which are extractable and can be checked for further biological activity. It was possible to identify and quantify phenolic compounds through HPLC analysis in the methanol extract of D. angustifolia flower. The PASS biological activity prediction results showed that there were stronger antioxidant activities for the identified flavonoids. Future work will emphasize the isolation and characterization of active principles responsible for bioactivity.

Study on Ultrasonic Enzyme-Assisted Extraction Process and Antioxidant Activity of Flavonoids from Sedum spectabile boreau flowers

Using Sedum spectabile boreau flowers as raw material, single factor and Box-Behnken response surface test were used to optimize the extraction conditions of Sedum spectabile boreau flavone assisted by ultrasonic enzymatic method, and the antioxidant activity of Sedum spectabile boreau flavone was analyzed in vitro. The results showed that the optimal extraction conditions of total Sedum spectabile boreau flavonoids were ultrasonic action time of 60 min, ethanol concentration of 35%, liquid-solid ratio (ml /g) was 20:1, and the amount of enzyme (cellulase: pectinase =1:1) was 3.2g.The study on the antioxidant activity of total flavonoids of Sedum spectabile boreau flower showed that its antioxidant capacity was gradually enhanced with the increase of the mass concentration of the test, which had a certain dose-effect relationship.

ERRATUM: Stability and antioxidant activity of flavonoids from Lycium barbarum L. leaves during digestion in vivo

ERRATUM: Stability and antioxidant activity of flavonoids from Lycium barbarum L. leaves during digestion in vivo

Optimization of enzymatic-assisted ultrasonic extraction process of total flavonoids from Sedum aizoon L. and its antioxidant activity

In order to optimize the enzymatic-assisted ultrasonic extraction method of total flavonoids from Sedum aizoon L., the effects of solid-liquid ratio, ethanol concentration, extraction temperature, extraction time, and ultrasound power on the extraction rate were investigated by single factor experiment. The optimum technological conditions for enzymatic-assisted ultrasonic extraction of total flavonoids from Sedum aizoon L. were as follows: solid-liquid ratio 1:55 (g/mL), ethanol volume fraction 60%, extraction temperature 45°C, extraction time 2 5 min, and ultrasound power 150 W. Under these conditions, the extraction rate of total flavonoids from Sedum aizoon L. could reach 10.77%. The antioxidant activity of flavonoids from Sedum aizoon L. was positively correlated with the concentration, and the greater the concentration, the stronger the antioxidant capacity. At a concentration of 0.96 mg/mL, the scavenging rate of the DPPH• radical reached 67.5%. The scavenging rate of the ABTs+• radical reached 55.8% at a concentration of 1.92 mg/mL.

Revealing and predicting the relationship between the molecular structure and antioxidant activity of flavonoids

Flavonoids have potential antioxidant activity and commercial value. Exploration of the relationship between the properties of flavonoids and their molecular structure provides the theoretical basis for screening and synthesizing flavonoids with more efficient antioxidant activities. In this article, the quantitative structure-activity relationships (QSAR) of 20 flavonoids with cellular antioxidant activity (CAA) were investigated by support vector regression. Planarity is introduced into the QSAR model as a molecular descriptor. The correlation coefficient (R2) and root mean square error (RMSE) are calculated for the training and test datasets. For the training dataset, the R2train and RMSEtrain are 0.85 and 0.090, respectively, showing that our model fits well. For the test dataset, R2test and RMSEtest are 0.61 and 0.095, indicating that our model has great predictive ability. Furthermore, the effect of different glycoside substitutions on antioxidant activity was also revealed. The atomic dipole corrected Hirshfeld charge (ADCH) distribution and bond dissociation enthalpy (BDE) values show that the addition of glycoside can significantly decrease the activity of H on the phenolic hydroxyl group of the B ring, further reducing the antioxidant activity. Moreover, the formation of intramolecular hydrogen bonds is not conducive to the improvement of antioxidant activity.

Flavonoidi i njihova antioksidativna, antimikrobna i antitumorna svojstva i kapacitet

The goal of the paper is to analyze the results of the research and present the general characteristics of flavonoids, including their biosynthetic pathway and peculiarities of secondary metabolism, through a review of available published works. Also, the work follows the antioxidant, antimicrobial and antitumor properties, and capacity of flavonoids. Flavonoids including flavones, isoflavones and anthocyanidins are formed by the condensation of phenylpropanoids with the participation of three molecules of malonyl coenzyme A. Flavonoid synthesis begins with phenylalanine, using the enzyme phenylalanine ammonium lyase (PAL) which catalyzes the release of phenylalanine and phenylalanine. Various experimental studies have shown that phenylalanine is a precursor of a large product of the secondary metabolism of phenolic compounds. The professional literature points out that o-dihydroxylation of the B-ring contributes to the antioxidant activity of flavonoids, while its antimicrobial properties are determined by the presence of (+) - catechin and quercetin against gram-positive and gram-negative bacteria. When it comes to antitumor properties, antioxidant activity, regulation of p53 protein, inhibition of protein kinase activity and apoptosis have an impact.

In Vitro-In Vivo Study of the Impact of Excipient Emulsions on the Bioavailability and Antioxidant Activity of Flavonoids: Influence of the Carrier Oil Type.

The influence of the carrier oil type on the bioavailability and bioactivity of flavonoids (quercetin, kaempferol, and apigenin) was examined using in vitro digestion, in situ intestinal perfusion, and pharmacokinetic studies. Here, medium-chain triglycerides (MCTs), long-chain triglycerides (LCTs), or MCT/LCT mixtures (1:1, w/w) served as the oil phase of excipient emulsions. Overall, the bioavailability and antioxidant activity of flavonoids increased when they were coingested with excipient emulsions. The in vitro bioaccessibility of flavonoids was affected by the carrier oil: LCT (17.9-22.8%) > MCT/LCT (12.1-13.7%) > MCT (9.2-12.6%). These differences were mainly attributed to the fact that the mixed micelles formed after the digestion of LCTs had larger hydrophobic domains to solubilize more flavonoids. However, in vivo pharmacokinetic experiments showed that the flavonoid concentrations in rat serum were comparable for all carrier oils (p > 0.05). Our results assist in formulating excipient emulsions to enhance the efficacy of flavonoids.

A gut microbial metabolite of dietary polyphenols reverses obesity-driven hepatic steatosis

The molecular mechanisms by which dietary fruits and vegetables confer cardiometabolic benefits remain poorly understood. Historically, these beneficial properties have been attributed to the antioxidant activity of flavonoids. Here, we reveal that the host metabolic benefits associated with flavonoid consumption hinge, in part, on gut microbial metabolism. Specifically, we show that a single gut microbial flavonoid catabolite, 4-hydroxyphenylacetic acid (4-HPAA), is sufficient to reduce diet-induced cardiometabolic disease (CMD) burden in mice. The addition of flavonoids to a high fat diet heightened the levels of 4-HPAA within the portal plasma and attenuated obesity, and continuous delivery of 4-HPAA was sufficient to reverse hepatic steatosis. The antisteatotic effect was shown to be associated with the activation of AMP-activated protein kinase α (AMPKα). In a large survey of healthy human gut metagenomes, just over one percent contained homologs of all four characterized bacterial genes required to catabolize flavonols into 4-HPAA. Our results demonstrate the gut microbial contribution to the metabolic benefits associated with flavonoid consumption and underscore the rarity of this process in human gut microbial communities.

Extraction, Composition, and Antioxidant Activity of Flavonoids from Xanthoceras sorbifolium Bunge Leaves.

Xanthoceras sorbifolium Bunge leaves (XLs) are valuable resources rich in phytochemicals, especially in flavonoids, but they are rarely exploited and utilized. The purpose of this paper is to reduce the waste of XLs resources (usually used as agricultural waste) and extract the high added value of active ingredients from XLs. The extraction of flavonoids from XLs using ultrasonic-assisted extraction (UAE) was reported. Response surface methodology (RSM) was used to adopt different ultrasonic conditions such as ethanol concentration, liquid:solid ratio, and ultrasonic power. In addition, the chemical structures were identified using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and HPLC. Response surface analysis indicated the optimal level of ethanol concentration, liquid:solid ratio, and ultrasonic power as 71.49%, 13.87 mL/g, and 157.49 W respectively for the maximum response of total flavonoids (5.52 ± 0.23%), which fitted well with the predicted value (5.68 ± 0.17%). In addition, the extracts from XLs exhibited potent antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) ammonium salt (ABTS). The potent antioxidant activity of flavonoids from XLs is beneficial for their application in the food and drug industry, which will facilitate the rise of the added value of the flavonoids from XLs. Myricetin, rutin, and epicatechin, which may be responsible for the antioxidant activity of the extracts from XLs, were confirmed by UPLC-MS/MS and HPLC analysis. The extracted flavonoids can be used as a natural antioxidant additive to food products.

A study from structural insight to the antiamyloidogenic and antioxidant activities of flavonoids: scaffold for future therapeutics of Alzheimer’s disease

A study from structural insight to the antiamyloidogenic and antioxidant activities of flavonoids: scaffold for future therapeutics of Alzheimer’s disease

Protective Effect of Flavonoids from Mulberry Leaf on AAPH-Induced Oxidative Damage in Sheep Erythrocytes.

To evaluate the antioxidant activity of flavonoids extracted from Chinese herb mulberry leaves (ML), flavonoids from mulberry leaves (FML) were extracted and purified by using ultrasonic-assisted enzymatic extraction and D101 macroporous resin. Using LC-MS/MS-Liquid Chromatography with tandem mass spectrometry analysis, hesperidin, rutoside, hyperoside, cyanidin-3-o-glucoside, myricitrin, cyanidin, and quercetin were identified, and NMR and UV were consistent with the verification of IR flavonoid characteristics. The antioxidant activity of FML has also been evaluated as well as the protective effect on 2,2 0-azobis (2-amidinopropane) dihydrochloride (AAPH)-induced oxidative stress. The results showed that FML exhibited powerful antioxidant activity. Moreover, FML showed dose-dependent protection against AAPH-induced sheep erythrocytes' oxidative hemolysis. In the enzymatic antioxidant system, pretreatment with high FML maintained the balance of SOD, CAT, and GSH-Px; in the non-enzymatic antioxidant system, the content of MDA can be effectively reduced after FML treatment. This study provides a research basis for the development of natural products from mulberry leaves.

Different Effects of Quercetin Glycosides and Quercetin on Kidney Mitochondrial Function-Uncoupling, Cytochrome C Reducing and Antioxidant Activity.

Flavonols are found in plants as aglycones and as glycosides. Antioxidant activity of flavonols may occur via several mechanisms within the cell, and mitochondria as a target may play an important role. There is a lack of information about the influence of the sugar moiety on biological activity of flavonoid glycosides. The aims of study were to investigate the effects of quercetin and its glycosides on mitochondrial respiration rates at various metabolic states, and to evaluate their antioxidant potential using chemical and biological approaches. Mitochondrial function was measured using an oxygraphic method, cytochrome c reduction spectrophotometrically, H2O2 generation in mitochondria fluorimetrically, and antioxidant activity of flavonoids using an HPLC-post column system. Our data revealed that quercetin and its glycosides isoquercitrin, rutin, and hyperoside uncouple kidney mitochondrial respiration (increasing the State 2 respiration rate) and significantly reduce cytochrome c. Moreover, quercetin, and its glycosides decrease the production of mitochondrial H2O2 and possess radical scavenging and ferric reducing capacities. The highest activity was characteristic for quercetin, showing that the sugar moiety significantly diminishes its activity. In conclusion, our results show the efficient radical scavenging, ferric and cytochrome c reducing capacities, and uncoupling properties of quercetin and its glycosides, as well as the importance of the sugar residue and its structure in the regulation of kidney mitochondrial function.

Effects of Extraction Technique on the Content and Antioxidant Activity of Flavonoids from Gossypium Hirsutum linn. Flowers

Cotton is one of the Uyghur medical materials in China and is rich in flavonoids. Flavonoids have important pharmacological effects. The yield of flavonoids in traditional extraction methods is low, which affects the development of flavonoids. Therefore, it is urgent to optimize the extraction techniques. The yield of flavonoids in cotton flowers was effectively improved by response surface methodology, and the highest yield of flavonoids reached 5.66%, and the optimal extraction process conditions were obtained. The DPPH free radical scavenging rate, hydroxyl free radical scavenging rate, superoxide anion free radical scavenging rate, and reducing ability were tested to reflect the antioxidant capacity of flavonoids. The flavonoids had an excellent antioxidant effect. Cell experiments suggested that the flavonoids had the effect of protecting glutamate-induced damage to HT-22 cells. The results of this study provide a theoretical basis for the extraction of cotton flowers flavonoids and the comprehensive evaluation of antioxidant products, as well as the extraction of other plant flavonoids.