Flavonoid Antioxidant Activity Research Articles

Green extraction using deep eutectic solvents and antioxidant activities of flavonoids from two fruits of Rubia species

Natural deep eutectic solvents (DESs) were investigated as potential green extraction solvents in the ultrasound-assisted extraction (UAE) of flavonoids from Rubia truppeliana and R. cordifolia fruit. Lactic acid was selected as the optimal hydrogen bond donor for five solvents in the screening of DESs. To optimize the extraction of Rubia fruit flavonoids using DES and UAE, a Box–Behnken experimental design was developed. The optimal conditions were: liquid–solid ratio, 30; extraction temperature, 70 °C; and extraction time, 40 min. The corresponding yields were 49.41 mg/g for total flavonoids from Rubia truppeliana (TFT) and 55.15 mg/g for that of Rubia cordifolia (TFC). The extracts obtained under the optimum extraction conditions showed excellent antioxidant activities in DPPH, ABTS, and FRAP assays. The results demonstrated that the extraction using DES and UAE is an eco-friendly method for the extraction of flavonoids from Rubia fruit.

Antimicrobial and antioxidant activities of flavonoids isolated from wood of sweet cherry tree (Prunus avium L.)

Sweet cherry (Prunus avium L.) is a tree widely cultivated in temperate regions for its tasty and healing fruits. Pruning works on the tree give each year considerable amounts of woody wastes that hardly have any utility. The aims of this work were to detect the most active antioxidants present in a cherry pruning wood sample, to isolate and characterize them, and study the antimicrobial and antibiofilm activities of components found in the wood ethyl acetate extract against a selection of foodborne microorganisms. The online HPLC–DPPH technique allowed the detection of two active antioxidant peaks that, after being isolated by a combination of countercurrent chromatography (FCPC) and conventional preparative techniques, and subsequent structural characterization by NMR, MS and polarimetry, resulted to be (‒)-catechin (1) and (‒)-taxifolin (4). Other components of the cherry wood extract were also isolated, among which compounds 1, 4, and (+)-dihydrowogonin (12) have never been reported in P. avium. A selection of the isolated flavonoids was submitted to antimicrobial and antibiofilm activity evaluations against strains from type culture collections, as well as on multi-resistant strains previously isolated in our laboratory. Those compounds with antimicrobial activity detected in preliminary screenings by standard agar diffusion tests ‒the flavan-3-ol 1, the flavanonols 4 and (+)-aromadendrin (5), the flavanone (+)-pinocembrin (15), and the flavone tectochrysin (17)‒ were subjected to the minimal inhibitory concentration (MIC) test, showing all of them MIC values of 100 μg/mL. Compound 4 also induced a significative inhibition on the formation of biofilms by Enterobacter sp. UJA37p at a concentration of 1 μg/mL and a significative disruption of preformed biofilm by this strain at 0.1 µg/mL. Similar results on biofilm disruption were observed with compound 17.

Antioxidants Such as Flavonoids and Carotenoids in the Diet of Bogor, Indonesia Residents

Due to the strong antioxidant activity of flavonoids and carotenoids, daily consumption of these bioactive compounds has the potential for reducing the risk of many chronic and degenerative diseases caused by or contributed to by oxidative stress. Currently, the available research results related to the flavonoid and carotenoid intake in Asian countries are very limited, especially for Indonesian population. The present study was conducted in Bogor City and Bogor District, West Java, Indonesia. Food consumption data was obtained through the food frequency questionnaire (FFQ) method, involving 200 respondents aged 25–65 years old. Flavonoids and carotenoids contents of the consumed food items were determined by referring to the databases developed by the United States Department of Agriculture (USDA), scientific journals, and calculation based on the recipes recorded in the survey. The total flavonoid intake of Bogor adults was estimated as 149.5 mg/day, consisting of 49.4% isoflavones, 24.0% flavonols, 9.4% flavanones, 7.0% flavan-3-ols, 6.0% flavones, and 4.2% anthocyanidins, and was contributed to mainly by legumes (70.7%), vegetables (10.1%), and fruits (7.3%). At the same time, the estimated total carotenoid intake reached 7.6 mg/day, and was contributed to mainly by vegetables (53.9%), fruits (20.2%), and snacks (14.4%), with β-carotene consumed in the highest proportion (49.9%), followed by lycopene (19.9%), lutein and zeaxanthin (13.5%), α-carotene (6.9%), and β-cryptoxanthin (2.6%). The effects of different respondents’ characteristics, such as area of residence (city vs. district), gender (male vs. female), and age (25–40, 41–55, and 56–65 years old) on the flavonoid and carotenoid intake varied widely, due to the differences in the overall consumption patterns of the respective respondents’ groups.

Analysis of Conformational, Structural, Magnetic, and Electronic Properties Related to Antioxidant Activity: Revisiting Flavan, Anthocyanidin, Flavanone, Flavonol, Isoflavone, Flavone, and Flavan-3-ol.

Understanding the antioxidant activity of flavonoids is important to investigate their biological activities as well as to design novel molecules with low toxicity and high activity. Aromaticity is a chemical property found in cyclic structures that plays an important role in their stability and reactivity, and its investigation can help us to understand the antioxidant activity of some heterocyclic compounds. In the present study, we applied the density functional theory (DFT) to investigate the properties of seven flavonoid structures with well-reported antioxidant activity: flavan, anthocyanidin, flavanone, flavonol, isoflavone, flavone, and flavan-3-ol. Conformational, structural, magnetic, and electronic analyses were performed using nuclear magnetic resonance, ionization potentials, electron affinity, bond dissociation energy, proton affinity, frontier molecular orbitals (highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO)), and aromaticity through nucleus-independent chemical shifts to analyze these seven flavonoid structures. We revised the influence of hydroxyl groups on the properties of flavonoids and also investigated the influence of the aromaticity of these seven flavonoids on the antioxidant activity.

The Equifinal Achievement of the Total Antioxidant Activity of Flavonoids by Plants in Various Habitats

The most important nonspecific stress-protecting function of flavonoids is antioxidant, which is associated with blocking the spread of free radicals in cells. Moreover, the effectiveness of individual classes of flavonoids as antioxidants is different; in particular, substances can differ by three or more times. The accumulation of flavonoids by individual plants is exceptionally high in plasticity. To estimate the total potential antioxidant activity, we proposed an indicator – the antioxidant status of flavonoids, taking into account the qualitative and quantitative composition of the identified flavonoids. It has been shown that relatively close values of this indicator can be formed due to different quantitative ratios of flavonoids – either a relatively large number of low-efficiency flavonoids or a much smaller number of high-efficiency ones can accumulate in plants. It has been established that this is characteristic of various species of plants that live in a variety of conditions – from horse marshes to the steppe zone and salt marshes.

Antioxidant Activity of Flavonoids in LPS-Treated IPEC-J2 Porcine Intestinal Epithelial Cells and Their Antibacterial Effect against Bacteria of Swine Origin

Beneficial effects of flavonoids are widely known in human medicine, but less information is available about their veterinary usage. Based on their antioxidant and antibacterial activity, proanthocyanidins (PAs) and luteolin (LUT) might be used in the prevention and treatment of gastrointestinal infections in swine. In this study, in vitro beneficial effects of grape seed oligomeric proanthocyanidins (GSOPs) and LUT were investigated against bacterial endotoxin (LPS)-induced oxidative stress in IPEC-J2 porcine epithelial intestinal cells. Furthermore, antibacterial effects of GSOP and LUT were assessed against field isolates of Escherichia coli and Salmonella enterica ser. Typhimurium. Both GSOP and LUT were found to possess potent in vitro antioxidant activity in LPS-treated IPEC-J2 cells; furthermore, they showed a bacteriostatic effect against the tested bacterial strains of porcine origin. Both flavonoids seem to be effective in the protection of porcine intestinal epithelial cells against Gram-negative bacteria in vitro, but further in vivo studies are necessary to confirm these activities and to establish their optimal dosage regimen for future usage in veterinary practice.

Indonesian plants with potential as an anti-diabetes mellitus agent

Diabetes Mellitus (DM) is a degenerative disease that continues to increase in numberin Indonesia and is a disease that is spread throughout the world due to unbalancednutritional conditions. Treatment of diabetes mellitus is a chronic and lifelongtreatment. Treatment of diabetes mellitus, such as the use of insulin and oralantihyperglycemia drugs, is relatively expensive, is used for a long time and can causeunwanted side effects. There are many plants that have potential as antihyperglycemiadrugs. One of the active compounds that act as antihyperglycemia isflavonoids.Flavonoids derived from various types of plants studied are thought to actas antihyperglycemic agents. Flavonoids are known to have the ability to scavenge freeradicals or act as natural antioxidants. The antioxidant activity of flavonoids is relatedto phenolic –OH groups which can capture or neutralize free radicals (such as ROS orRNS). Flavonoids can play a role in pancreatic tissue damage caused by DNA alkylationdue to alloxan induction as a result of improving the morphology of the rat pancreas(Prameswari and Widjanarko, 2014).

Assessment of HOCl Production in Human blood: Experimental Optimization and Proof of Concept for the Antioxidant Activity of Flavonoids in this Complex Matrix

Assessment of HOCl Production in Human blood: Experimental Optimization and Proof of Concept for the Antioxidant Activity of Flavonoids in this Complex Matrix

Potensi Ekstrak Bunga Telang (Clitoria ternatea) Sebagai Pencegah Acute Kidney Injury (AKI)

Introduction: Butterfly pea (Clitoria ternatea) is a vine that has various colors such as pink, light blue, white, and purple. This plant is commonly used as a food coloring and ornamental plants. Butterfly pea has pharmacological potential, among others, as high antioxidants. The antioxidants of the butterfly pea show much higher activity than other flowers. Antioxidants are substances that can prevent the occurrence of Acute Kidney Injury (AKI), which is currently increasing in incidence and mortality due to AKI reaching 23.9% in adults and 13.8% in children. Aim of study: This article aims to discuss the potential of butterfly pea extract (Clitoria ternatea) as a preventative for Acute Kidney Injury (AKI). Method: The research method used is the literature search technique on 20 articles from the Google Scholar database. Results and Discussion: The results of the literature search show that the butterfly pea (Clitoria ternatea) has antioxidant compounds that have the potential to prevent the occurrence of acute kidney injury (AKI). Butterfly pea extract has the potential to reduce levels of urea, serum creatinine, reduce levels of malondialdehyde (MDA) and increase levels of glutathione, catalase, and superoxide dismutase (SOD). The antioxidant activity of flavonoids and tannins in butterfly pea extract was found to have a nephroprotective effect against exposure to toxic substances. Conclusion: The conclusion from this literature search is that the antioxidant content contained in butterfly pea extract can be a good alternative as a nephroprotector to prevent AKI.

The effects of solid-state fermentation on the content, composition and in vitro antioxidant activity of flavonoids from dandelion.

Dandelion (Taraxacum officinale), a common plant worldwide, is used as both a medicine and food. Fermentation is a food processing technology that has many advantages, such as low energy cost, changes in product characteristics, and enhanced product quality. The purpose of this study was to investigate the effect of solid-state fermentation (SSF) on the content, composition and antioxidant activity of dandelion flavonoids. Response surface methodology was used to optimize dandelion fermentation conditions. Under optimized conditions, the maximum flavone concentration was 66.05 ± 1.89 mg/g. The flavonoid content of the crude extract from fermented dandelion (FDF) was 183.72 ± 2.24 mg/g. The flavonoid compounds in the crude extracts were further identified by UPLC-ESI-MS/MS. A total of 229 flavonoid compounds were identified, and 57 differential flavonoids (including 27 upregulated and 30 downregulated flavonoids) between FDF and the crude extract of unfermented dandelion (DF) were observed, of which 25 were annotated to metabolic pathways. FDF displayed superior antioxidant activity to that of DF in in vitro DPPH radical-scavenging and reducing power assays. The favorable results of our investigation could provide a new way for the exploitation and utilization of dandelion, which could be promising for its application as an antioxidant and functional food additive with flavonoids as ingredients.

Effect of Heat Treatment and Light Exposure on the Antioxidant Activity of Flavonoids

The application of food processes can lead to a modification of both the structure and the activities of flavonoids. In this article, the effect of heat treatment and exposure to light on the antioxidant activity of 6 model flavonoid solutions (rutin, naringin, eriodictyol, mesquitol, luteolin, and luteolin 7-O-glucoside) was studied. The evolution of the antioxidant activity measured after heat treatment of 130 °C at 2 h and an exposure to visible light for 2 weeks is measured by the ABTS (2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) method and represented by a new parameter called ΔTEAC. The model solution of Mesquitol showed the highest increase in ΔTEAC after a heat treatment, a value of 200 mM was obtained. The increase in ΔTEAC is always greater with thermal treatment than with light exposure. Thus, temperature and light lead to different degradation pathways of the flavonoid. In vivo measurements were carried out with solutions of naringin, erodictyol, and luteolin 7-O-glucoside. Heated solutions of flavonoids do not exhibit toxicity on cells. The specific activities of superoxide dismutase and glutathione peroxide have been determined and have shown an increased impact on the potential anti-cancer of these solutions by enhancing their cellular antioxidant activity, as well as modulation of the oxidative stress.

Purification and Antioxidant Activity of Flavonoids from Chromolaena Odorata

To purify the flavonoids from Chromolaena odorata (COF) and evaluate its antioxidant activities in vitro. Methods: The COF were purified by macroporous adsorption resin with optimal purification process, and its antioxidant activities were evaluated by scavenging rate of DPPH free radical, ABTS free radical and superoxide anion radical. Results: The COF were obtained using with AB-8 macroporous adsorption resin washed by 60 % ethanol at the flow rate of 2.0 mL/min, and the purity was 74.22 %. After purification, the scavenging activities of COF on DPPH free radical, ABTS free radical and superoxide anion radical, were 91.36 %, 90.13 % and 93.17%, repectively. The purified COF also showed a certain reducing power. Conclusions: The COF showed strong antioxidant activity in vitro.

The Flow of the Redox Energy in Quercetin during Its Antioxidant Activity in Water.

Most studies on the antioxidant activity of flavonoids like Quercetin (Q) do not consider that it comprises a series of sequential reactions. Therefore, the present study examines how the redox energy flows through the molecule during Q’s antioxidant activity, by combining experimental data with quantum calculations. It appears that several main pathways are possible. Pivotal are subsequently: deprotonation of the 7-OH group; intramolecular hydrogen transfer from the 3-OH group to the 4-Oxygen atom; electron transfer leading to two conformers of the Q radical; deprotonation of the OH groups in the B-ring, leading to three different deprotonated Q radicals; and finally electron transfer of each deprotonated Q radical to form the corresponding quercetin quinones. The quinone in which the carbonyl groups are the most separated has the lowest energy content, and is the most abundant quinone. The pathways are also intertwined. The calculations show that Q can pick up redox energy at various sites of the molecule which explains Q’s ability to scavenge all sorts of reactive oxidizing species. In the described pathways, Q picked up, e.g., two hydroxyl radicals, which can be processed and softened by forming quercetin quinone.

Extraction of flavonoids from Cyclocarya paliurus (Juglandaceae) leaves using ethanol/salt aqueous two‐phase system coupled with ultrasonic

An aqueous two phase system (ATPS) coupled with ultrasonic was employed to extract flavonoids from Cyclocarya paliurus (Batalin) Iljinskaja leaves first time. The optimal conditions were determined by Response Surface Methodology(RSM) of ethanol concentration 33%; salt concentration 15%; extraction time 52 min; liquid-solid ratio 33:1, while the flavonoids extraction yield obtained the maximum of 3.00 ± 0.1%. The antioxidant activity of flavonoids was evaluated by vitro antioxidant assays under the optimal conditions, which indicated that the extract has strong DPPH, ABTS + and superoxide anion radical-scavenging activity (IC50 value of 0.0013 mg/ml, 0.0296 mg/ml and 0.126 mg/ml) which were close to and even better than Vc (extremely close to 0, 0.0291 mg/ml and 0.433 mg/ml). The study showed that the ATPS-ultrasonic was a commendable approach for the extraction of flavonoids from C. paliurus and the flavonoids may serve as new natural antioxidant for functional food ingredients and additives. Practical applications In this study, ethanol and inorganic salt are selected as the extraction and separation solvent, which is simpler than the traditional method, environmental friendly, while reducing the process cost, and has great application value. Furthermore, through the analysis of the extraction components of the edible plant Cyclocarya paliurus, it was found that the flavonoids contained in C paliurus had antioxidant activity close to vitamin C. Combined with the above research, C. paliurus has the potential to develop into functional food and additives with antioxidant function.

Constituents of flavonoids from Tridax procumbens L. and antioxidant activity

Background: To study the chemical constituents and antioxidant activities of flavonoids in Tridax procumbens L. Materials and Methods: Diaion HP-20, MCI-Gel CHP-20, Sephadex LH-20, and silica gel column chromatography were used to isolate and purify the chemical components of T. procumbens L., and the structures of the compounds were identified by physical and chemical properties and spectral techniques (1H-nuclear magnetic resonance [NMR] and 13C-NMR). The antioxidant activities of five flavonoids were evaluated by 2,2-diphenyl-1-picryl-hydrazyl method. Results: Six compounds were isolated and identified as luteolin-7-O-β-D-glucoside (1), 5,7,3'-trimethyl-4'-methoxyl-3-O-β-D-flavonoid glucoside (2), 8,3'-dihydroxyl-3,7,4'-trimethoxy-6-O-β-D-flavonoid glucoside (3), 4,2',4'-trihydroxy-6'-methoxyl-3'-isopentenyl chalcone (4), quercetin-7-O-β-D-glucopyranosyl-(2→1)-α-L-rhamnose (5), and nodakenin (6). Conclusions: All compounds except compound 3 were isolated from the plant for the first time. It was found that compounds 1–5 had significant antioxidant and free radical scavenging activities.

Statistical Analysis of the Relationship Between Antioxidant Activity and the Structure of Flavonoid Compounds

Using different methods of statistics, this paper aims to highlight the potential link between the antioxidant activity of flavonoids and the corresponding molecular descriptors. By calculating the descriptors (van der Waals surface (A), molar volume (V), partition coefficient (LogP), refractivity (R), polarizability (a), forming heat (Hformation), hydration energy (Ehidr), the dipole moment (mt)), together with antioxidant activities (RSA) calculated or taken from the literature, number of phenolic -OH groups and the presence (2) or absence (1) of C2=C3 double bond) for 29 flavonoid compounds and by intercorrelation between the studied parameters, the link between the number of phenolic groups grafted to the basic structure of flavonoids and their antioxidant activity was confirmed. Simultaneously, by using the chi-squared test and the intercorrelations matrix, a satisfactorily correlation coefficient (r2=0.5678; r=0.7536) between the structure of the flavonoids and their activity was obtained, fact that confirms the correlation of the antioxidant activity with the number of -OH phenolic groups.

Recognition of antioxidants and photosensitizers in Dyssodia pinnata by EPR spectroscopy.

Previous studies report the isolation mainly of terthiophene derivatives and flavonoids from Dyssodia species. Terthiophenes are known as photosensitizers by their capacity to generate singlet oxygen (1 O2 ), and flavonoid antioxidant activity is recognized. These opposite properties could represent interesting options in photodynamic therapy. To determine the antioxidant and photosensitizer activities of extracts and isolates of Dyssodia pinnata by electron paramagnetic resonance (EPR). Extracts and isolates were evaluated as antioxidants by the interactions with copper ion (Cu2+ ) observed in EPR, and by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and the thiobarbituric reactive substances (TBARS) methods. Their abilities as 1 O2 producers were also estimated by EPR. Terthiophenes were obtained from hexane (DPH) and acetone (DPA) extracts, and flavonoids from DPA and methanol (DPM) extracts. The interaction with Cu2+ of extracts and isolated compounds of Dyssodia pinnata showed two effects in EPR: reduction and chelation; flavonoids exhibited both effects, while terthiophenes showed only reduction. DPA, DPM, and flavonoids were active in DPPH and TBARS assays. Quercetagetin-7-O-β-glucoside showed the highest antioxidant and chelating activities, 3-glycosidated flavonoids were less active. Upon irradiation extracts and terthiophenes induced 1 O2 formation. Flavonoid reducing activity on Cu2+ and free radical scavenging capacity were related to the number of hydroxy groups and to the conjugation between the B and C rings. All tested flavonols showed a major complex with Cu2+ , with the most probable site of chelation between the 5-hydroxy and 4-oxo groups. Extracts and terthiophene derivatives showed photosensitizer activity. Thus, EPR is useful to evaluate free radical scavenging and pro-oxidant properties.

Extraction, purification by macrospores resin and in vitro antioxidant activity of flavonoids from Moringa oliefera leaves

To promote extraction of flavonoids compounds from Moringa oliefera leaves (MOL) by ultrasound-assisted extraction, Box behken desing as a kind of response surface methodology was utilized. Moreover, five macrospores resins were used to investigate the kinetics of purification of flavonoids from the MOL extract. As results, the optimal conditions for maximizing flavonoids extraction were determined as follows: ratio of aqueous ethanol solution to material 52 mL/g, extraction time 43 min and extraction temperature 76 °C. Nevertheless, AB-8 resin was the suitable resin for purification of flavonoids with the following conditions: initial flavonoids concentration 20 mg/mL, eluting solvent 70% aqueous ethanol solution and 1.5 mL/min eluting flow rate. Moreover, five flavonoids (rutin, kaempferol acetyl glycoside, quercetin-3-glucoside, quercetin-3-acetyl-glucoside and kaempferol 3-glucoside) were identified by HPLC-ESI-MS. Regarding to antioxidant activity purified flavonoids, the results showed that the scavenging activity against 2,2-diphenyl-1-picrylhydrazyl free radicals was 85.99% at a concentration of 100 μg/mL, while the scavenging activity against 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) radicals was 84.72% at 50 μg/mL. The results suggest that the flavonoids from MOL can be used in the development of functional foods.

Optimal extraction and antioxidant activities of flavonoids from Penthorum chinense Pursh

Based on the results of single factor experiments, response surface methodology was used to optimize the extraction conditions of flavonoids from Penthorum chinense Pursh (PCF). The optimal extraction conditions were the ratio of liquid to material 22 mL/g, ethanol concentration 68%, extraction temperature 82 °C, and extraction time 2.2 h, respectively. Under these optimized conditions, the PCF yield was 10.72%, which closely agreed with the predicted value (10.75%). In addition, PCF significantly scavenged DPPH radical, hydroxyl radical and superoxide radical in vitro. In the in vivo assays, PCF enhanced the resistance of Caenorhabditis elegans against heat stress, which might be attributed to PCF increased the activities of catalase (CAT) and superoxide dismutase (SOD), and decreased the level of malondialdehyde (MDA). In summary, these results suggested that the optimized extraction was a very effective method to extract PCF and the PCF could be explored as a potential antioxidant for medicine and function food.

Extraction of Flavonoids from the Saccharification of Rice Straw Is an Integrated Process for Straw Utilization.

To date, bioethanol is not economically competitive. One strategy to overcome this limitation is co-producing ethanol and high value-added products as an integrated process. The results of this study demonstrated that flavonoids could be extracted from rice straw, and the flavonoids apigenin and kaempferol were detected by HPLC. Compared with untreated straw, ball-milling slightly increased the total amount of flavonoids and antioxidant activity measured by ABTS, DPPH, and FRAP assays. The saccharification step in the bioconversion of straw strongly affected the extraction of flavonoids from straw. The residue obtained after saccharification of ball-milled straw for glucose production was more suitable for flavonoid extraction than untreated and ball-milled straw. The yield of flavonoids from the residue was 1.51-fold higher than that from untreated straw. The antioxidant activity of flavonoids derived from the residue was similar to that of flavonoid-rich biomasses such as rice bran and wheat bran. More importantly, saccharification may significantly affect the conditions of flavonoid extraction. In this respect, treatment with cellulase may reduce the extraction time from 2.0 to 0.5h and the extraction temperature from 80 to 30°C. Therefore, saccharification in the bioconversion of straw may be considered as an enzyme pretreatment step for the efficient extraction of flavonoids from straw, serving as a sustainable process for straw utilization.