Antioxidant activity of flavonoids

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ANTIOXIDANT ACTIVITY OF FLAVONOIDS ISOLATED FROM THE FRUITS OF XYLOPIA PARVIFLORA (A. RICH.) BENTH

ANTIOXIDANT ACTIVITY OF FLAVONOIDS ISOLATED FROM THE FRUITS OF XYLOPIA PARVIFLORA (A. RICH.) BENTH

The present study evaluates the antioxidant activity of the different flavonoids of the fruits of Xylopia parviflora used in Cameroon as spice in common traditional dishes. The fruits were successively extracted with hexane and methanol. The isolation of flavonoids was guided by the DPPH-TLC technique. The methanol crude extract and isolated compounds were screened for antioxidant and free radical scavenging activities using DPPH radical-scavenging, β-carotene/linoleic acid and ferric reducing antioxidant power (FRAP) assays. The total phenolic content of the methanol crude extract was determined by Folin–Ciocalteu method. The DPPH-TLC technique led to the isolation of (+)-catechin (1), kaempferol 3-O-arabinofuranoside (2) and quercetin 3-O- arabinofuranoside (3) identified by NMR and mass spectra analysis. In the colorimetric DPPH test, compound 1 had the same activity (EC 50 8.1µg/ml) as butylated hydroxytoluene (BHT) used as standard while compound 3
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Flavonoids of Miconia Alypifolia and Their Antioxidant Activity

Flavonoids of Miconia Alypifolia and Their Antioxidant Activity

No phytochemical or pharmacological studies are available in the literature on M. alypifolia. However, several species of the genus Miconia have been investigated. Triterpenes have been isolated from the wood of M. albicans Steud. (5), M. stenostachya DC. (6) and M. fallax DC. (7), some of which showing trypanocidal activity in vitro (7). The benzoquinone primin and its quinol miconidin isolated from some Miconia species, have been reported for their antibacterial, cytotoxic (8, 9) and antifeedant activities (10). Primin was also reported for its cytotoxicity in M109 and A2780 tumor cell lines (11) and showed antineoplastic activity in patients with basic cellular carcinoma (12). Fatty acid synthase inhibitors were isolated from M. pilgeriana Ule. (13). Flavonoids have been isolated from M. trailii Cogn. (14) and M. myriantha Benth., these latter inhibitors of Candida aspartic proteases (15). Moreover, extracts of some Miconia species have been reported for their analgesic effects (16, 17, 18). Moreover, in spite of Melastomataceae are among the most abundant and diversified groups of plant throughout the tropics, their intrafamily relationships and morphological evolution are poorly understood (19). In this paper we studied the flavonoid fraction of a methanol extract of leaves of M. alypifolia and we evaluated the antioxidant activity in vitro of isolated compounds.
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Estimation of Total Flavonoids and Antioxidant Activity of Spilanthes acmella Leaves 

Estimation of Total Flavonoids and Antioxidant Activity of Spilanthes acmella Leaves 

Preliminary phytochemical screening showed the presence of alkaloids, polyphenol, tannins, flavonoids and glycoside in ethanol extract of Spilanthes acmella leaves. It was supported by earlier reports for the presences of phenols and flavonoids in the Spilanthes acmella leaves. Flavonoids and phenols exhibit a wide range of biological activities, one of which is they have the properties of antioxidant activity. Being plant secondary metabolites, the phenolics or polyphenols are very important judging from the virtue of their antioxidant activities by chelating redox-active metal ions, inactivating lipid free radical chains, and avoiding the hydroperoxide conversions into reactive oxyradicals.
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Assessment of flavonoids contents and in vitro antioxidant activity of Launaea procumbens

Assessment of flavonoids contents and in vitro antioxidant activity of Launaea procumbens

cancer, tissue inflammatory and cardiovascular disease [19-22]. Also, the number of publications on the health benefits of polyphenol has been increased [23,24]. Various free radical scavenging methods used in this study are sim- ple and have provided reproducible results showing anti- oxidant properties of various fractions of LP. The antioxidant capacity of different fractions observed in this experiment could be, because of the presence of high phe- nolics compounds. LPME is more potent compared to other fractions and found in accordance with previous reports [25,26], which have shown that high total polyphe- nol content increases the antioxidant activity and proves a linear correlation between phenolics content and antioxi- dant activity. LPME exhibited a significant correlation as was reported by Bortolomeazzi et al. [27]. Phenolic com- pounds such as flavonoids, phenolics acid and tannins pos- sess diverse biological activities such as anti-inflammatory, anticarcinogenic and antiatherosclerotic. The presence of these bioactive compounds might contribute to diverse scavenging effects of LP [28]. Free radicals of 1, 1-diphenyl 1-2-picrylhydrazyl (DPPH) are widely used for screening of medicinal plants to investigate their antioxidant potential. In these procedure-free, DPPH radicals when dissolves in methanol, give violet color in methanol solution. The results existed clearly indicate that in screening of various fractions of LP, methanol fraction had marked scavenging affect with IC50 2.6 ± 0.004 at 50–250 μg/ml. Our results are supported by other investigation [29]. The potential of various fractions to scavenge free radical was also assessed by their ability to quench ABTS, and depicts that LPME possessed IC50 (66.1 ± 1.02 μg/ml) value, showing the strongest activity even more than reference compounds. According to Oszmianski et al. [30], the antioxidant activities against ABTS or DPPH were correlated to the concentration, chemical structures
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Total flavonoids, phenolics, tannins and antioxidant activity in seeds of lentil and grass pea

Total flavonoids, phenolics, tannins and antioxidant activity in seeds of lentil and grass pea

Natural phenolics exert their beneficial health effects mainly through their antioxidant activity. Typical phenolics that possess antioxidant activity are known to be mainly phenolic acid and flavonoids [13]. TPC contribute to the overall antioxidant activities of plant foods. Proanthocyanidins (condensed tannins) are a class of phenolic compounds widely distributed in the plant kingdom including legume seeds [18]. In the present study, genotypes differed significantly for TPC, TFC and CT contents in seeds of both pulse crops. Results in table 1 indicated that IPL 406 contained highest level of TPC, TFC and CT, followed by WBL 58 and B 256 in lentil. The results agreed well with the comparative analyses of phenolic composition, and antioxidant capacity of lentil varieties grown in the cool-temperate regions of USA where considerable genotypic differences were found in their individual phenolic compounds, as well as chemical and cellular antioxidant activities [1]. Moderate to high level of TPC and TFC was also found in methanolic extracts from leaves and pods of lentil grown in Pakistan [25]. Similar results were obtained in Iranian germplasm of lentil seeds in different solvent (hexane, methanol and acetone) extractions [26]. In the present study, ethanolic extract of seeds were used. The three lentil lines used here have been developed through inter-crossing and subsequent selection for high grain yield in India and released for cultivation in different parts of the country. Despite extensively used in daily meal, different cuisines and ethno-medicinal purposes, no reports are available regarding antioxidant composition of lentils grown in India. The present revelation, thus, assumes significance in this regard.
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Chemical profile, total phenols, total flavonoids and antioxidant activity of
five species of the Caatinga biome

Chemical profile, total phenols, total flavonoids and antioxidant activity of five species of the Caatinga biome

These findings emphasize the influence of popular knowledge about the choice of species for therapeutic treatments. However, the scientific information is essential for verification of their activities. In this study species were identified with significant antioxidant activity. This result is related to the presence of phytochemicals classes such as phenols and flavonoids that actively participate in biological actions. These were identified in all species. Considering the importance of this study can be said that the use of natural products derived from Caatinga species as antioxidants is genuine, thereby this work offers complementary scientific contribution of five species of the Caatinga biome.
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The antioxidant activity and hypolipidemic activity of the total flavonoids from the fruit of Rosa laevigata Michx

The antioxidant activity and hypolipidemic activity of the total flavonoids from the fruit of Rosa laevigata Michx

Hyperlipemia is the largest endocrine disease in the world, involving metabolic disorders of carbohydrate, fat and protein. Therefore, it is necessary to search for new drugs that can be used to amendment this metabolic dis- order without any side effect. Oxidative stress is cur- rently suggested as a mechanism underlying hyperli- pemia, which is one of the major risk factors for coro- nary artery diseases [21]. In our study, the TFs with high flavonoids showed a good antioxidant activity in vitro, which encouraged us to check the antioxidant activity in vivo in hyperlipemic mice.
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ANTIOXIDANT ACTIVITY OF ISOLATED FLAVONOIDS FROM THE LEAVES OF CORCHORUS AESTUANS LINN

ANTIOXIDANT ACTIVITY OF ISOLATED FLAVONOIDS FROM THE LEAVES OF CORCHORUS AESTUANS LINN

Preliminary phytochemical investigation of various extracts of leaves of Corchorus aestuans Linn showed the presence of flavonoids, carbohydrates, saponins, phytosterols, phenolic compounds, triterpenoids, cardiac glycosides and tannins. An attempt has been made to isolate flavonoids and perform antioxidant potential of the same. The antioxidant activity was performed by two in-vitro testing methods, such as scavenging activity on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals and hydroxyl radical scavenging activity by EDTA. The data obtained in these testing systems clearly established the antioxidant potency of Corchorus aestuans Linn.
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NOVEL PROPENYL FLAVONOIDS GLYCOSIDE AND ANTIOXIDANT ACTIVITY OF EGYPTIAN BAUHINIA RETUSA

NOVEL PROPENYL FLAVONOIDS GLYCOSIDE AND ANTIOXIDANT ACTIVITY OF EGYPTIAN BAUHINIA RETUSA

INTRODUCTION: The genus Bauhinia (Fabaceae, Leguminosae) consists of approximately 300 species, which are commonly known as ‘cow’s paw’ or ‘cow’s hoof’, because of the shape of their leaves. They are widely distributed in most tropical countries, including Africa, Asia and South America 1 . Many plants of the genus have been used frequently in folk medicine as a remedy for different kinds of pathologies, diabetes, pain, cytotoxic, asthma, diuretic, antimalarial as well as antioxidant, hepatoprotective and anti-inflammatory activities 2-
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Structure activity relationships regarding the antioxidant effects of the flavonoids on human erythrocytes

Structure activity relationships regarding the antioxidant effects of the flavonoids on human erythrocytes

ATPase inhibitory activities of the flavonoids [36,43]. The antioxidant activity of flavonoids could also be dependent on their partitioning abilities between the aqueous and lipophilic environments [44,45]. The pre- sent study does suggest that the anti-protein-degradation activity would require the flavonoid to have partitioning ability towards lipophilic environment, as the flavonoids which showed anti-protein-degradation activity ranged from a very lipophilic such as 3-hydroxy flavone (in- soluble in water) to quercetin which has an equal distri- bution between aqueous and lipophilic environments, whereas rutin which is more hydrophilic than quercetin (due to the presence of a disaccharide at C-3) did not prevent protein-degradation [33]. On the other hand, it seems unlikely for the anti-lipid-peroxidant activity to be dependent on the partitioning abilities of the flavonoids, as this activity was reported for various antioxidants ranging from a very water soluble compounds such as vitamin C to a very lipophilic compounds such as vita- min E [24,42].
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Antioxidant Activity of Methoxylated Flavonoids in Oils in Deep Frying Processes

Antioxidant Activity of Methoxylated Flavonoids in Oils in Deep Frying Processes

Methoxylated flavonoids isolated from cold acetone leaf wash of Polygonum senegalense ; 5-hydroxy-7-methoxyflavanone 1 and 5-hydroxy-6,7-dimethoxy- flavanone 3, were tested for their ability to enhance thermal stability of veg- etable oils. Determination of the peroxide value (P.V.) and the p -Anisidine value ( p -A.V.) was done according to the standard methods of analysis. The compounds were tested for in vitro cytotoxicity against a mammalian cell-line, Chinese Hamster Ovarian (CHO) using the 3-(4,5-dimethylthiazole- 2-yl)-2,5-diphenyltetrazoliumbromide (MTT)-assay. Studies on changes in peroxide and p -Anisidine values for the oils heated to temperatures between 180˚C and 200˚C recorded better stability enhancement at 100 ppm concen- tration with these flavonoids than the commercial antioxidant, butylated hy- droxytoluene (BHT). The plant-based flavonoids had no significant cytotoxic effect against the CHO cell-line and may serve as alternative antioxidants to synthetic ones which have previously raised great concern over the health of consumers.
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Target guided isolation, in vitro antidiabetic, antioxidant activity and molecular docking studies of some flavonoids from Albizzia Lebbeck Benth  bark

Target guided isolation, in vitro antidiabetic, antioxidant activity and molecular docking studies of some flavonoids from Albizzia Lebbeck Benth bark

The 3D coordinates of crystal structure of B. cereus oligo- 1,6—glucosidase (PDB ID: 1UOK) was downloaded from the RCSB protein data bank (http://www.rcsb.org/pdb) set up at Brookhaven National Laboratory in 1971. It is a worldwide repository of information about the 3D struc- tures of large biological molecules, including proteins and nucleic acids. Water molecules were removed from the protein 1UOK before the instigation of molecular docking. The protein structure was corrected by the utilization of alternate conformations and valence monitor options as some crystallographic disorders as well as some unfilled valance atoms were present in the protein file. The result- ant protein file was subjected to energy minimization by applying Chemistry at HARvard Macromolecular Me- chanics (CHARMm) force fields. CHARm is a program which provides a large suite of computational tools that Table 1 α - glucosidase and α -amylase inhibition activity of Compounds 1, 2 and 3
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Investigation of an Interaction of Flavonoids on the Antioxidant Activity of Alpha Tocopherol

Investigation of an Interaction of Flavonoids on the Antioxidant Activity of Alpha Tocopherol

Oxidative stress is clearly associated with a wide range of chronic and acute disease processes. From the standpoint of oxidative stress mechanisms, the hypotheses on etiology of heart disease, cancer, neuro-degenerative, and other diseases are certainly plausible. They are also “proven” to work theoretically in vitro. However, the real test of efficacy is in the living system. The epidemiological data generally indicate a benefit of consuming diets that are higher in the antioxidant nutrients. In some studies, it is not clear whether the benefit is derived from the specific nutrients under study, or another food component with health benefits yet to be discovered. Or, perhaps there is a particular combination of antioxidant nutrients that provide protection. It seems to be apparent that supplementation with natural vitamin E in 100-400 IU/day doses for more than two years is protective against heart disease. Some studies also show β-carotene, vitamin C and flavonoids to be protective. However, some of this enthusiasm must be diminished when reviewing the clinical trial data which give very mixed results ranging from 47% reduction MI with vitamin E supplementation to 28% increase in lung cancer with β- carotene supplementation.
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Some Natural Antioxidants Sources From Foods And Tree Barks

Some Natural Antioxidants Sources From Foods And Tree Barks

- Rubiaceae) Contents of total phenolics, flavonoids and tannins were found higher in bark than that of leaf and fruit parts of this plant Similar trend was also found in total antioxidant activity where maximum antioxidant potential is measured in case of bark is more potent than the leaf and fruit parts in respect of its phytochemical content and antioxidant activity. Bark is known to accumulate large amounts of polyphenolic compounds which exhibit a wide range of biological effects, including antioxidant, antibacterial and anti- inflammatory activity (Ferreira et al.( 2015);( Dedrie et al. 2015) Bark trees showed higher phenolic content and better scavenging activity. The ethanolic extracts from bark of young trees show good an-tioxidant activity (Rosales-Castro, 2015) phytochemical screening strongly suggested that there was a strong association between high free radical scavenging and amount of antioxidant compounds, particularly polyphenols in wood bark (Saefudin, , Basri, , & Sukito, 2018) a high concentration of total phenols was found in the Quercus sp. bark crude extracts, including different classes of phenolic compounds, like flavonoids, hydroxycinnamic acids, and proanthocyanidins, confirming that the Mexican species oak barks analyzed a good source of phenolic compounds
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ASSESMENT OF PHYTOCHEMICALS AND ANTIOXIDANT ACTIVITY OF MURRAYA KOENIGII LINN

ASSESMENT OF PHYTOCHEMICALS AND ANTIOXIDANT ACTIVITY OF MURRAYA KOENIGII LINN

ABSTRACT: Objective: To analyze phytochemicals both qualitatively and quantitatively and to estimate in vitro antioxidant activity, total phenolic content and concentration of flavonoids of methanolic extract of leaf, stem and fruit of an important medicinal plant Murraya koenigii Linn. Methods: Phytochemical screening of extracts was carried out. Aluminium chloride colorimetric method was used to estimate TFC (total flavonoid content) and TPC (total phenolic content) was measured by Folin-ciocalteu method. Two different assays- DPPH free radical scavenging and LPO were used for determination of antioxidant activity. Results: Quantitative estimation of primary metabolites showed maximum amount of sugar, starch in stem, while lipid and protein in leaf. The TPC were ranging between 18.4±0.21 to 25.2±0.16 mg GAE/gm DW while TFC were found maximum 13.53±0.16 mg QE/gm DW in leaves. The DPPH radical scavenging capacity was found maximum in leaves (IC50 49.86±1.16) and maximum activity in LPO assay was shown by leaf extract (23.715±1.68 μM MDAg-1DW). Conclusions: These results are suggestive of primary bioactive compounds of commercially importance and also Murraya koenigii Linn is effective against free radical mediated diseases .
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“Estimation of the Effect of Drying on the Chemical Composition and Antioxidant Activity of the Fruits of Momordica charantia (Karela)” by Sukriti Nehra, M. K. Deen, India.

“Estimation of the Effect of Drying on the Chemical Composition and Antioxidant Activity of the Fruits of Momordica charantia (Karela)” by Sukriti Nehra, M. K. Deen, India.

In the present investigation, fresh and dried fruits of Momordica charantia (Karela), extracted with acetone, ethanol and water were used to evaluate total phenolics, flavonoids and ascorbic acid content. Their antioxidant activities were determined by the 2, 2’- Diphenyl-1-picrylhydrazyl (DPPH • ) free radical scavenging method, β-carotene bleaching method (BCBT) and Ferric Thiocyanate (FTC) method. In fresh fruits total phenols (12.08 ± 0.23 mg GAE/g) and ascorbic acid (1.01 ± 0.02 mg/g) were high in acetone extract while flavonoid content (7.61 ± 0.21 mg CAE/g) was high in ethanol extract. While these components decreased in the acetone, ethanol and water extracts of the dried fruits. In dried fruits also total phenolics (6.83 ± 0.12 mg GAE/g), flavonoids (4.78 ± 0.14 mg CAE/g) and ascorbic acid (0.27 ± 0.01 mg/g) were high in acetone extract. In the case of fresh fruits, according to DPPH method, antioxidant activity of water extract was found to be maximum (91.21 ± 0.65%) while by FTC method and β-carotene bleaching method, antioxidant activity of acetone extract was found to be maximum (62.06 ± 0.81% and 67.16 ± 0.96% respectively). According to DPPH and FTC method, antioxidant activity of acetone extract was found to be maximum (86.41 ± 1.11% and 80.53 ± 1.25% respectively) and by β-carotene bleaching method, it was maximum for acetone extract (85.51 ± 0.96%). The acetone extracts in general showed maximum antioxidant activity and can be used as antioxidant in foods and medicines. The antioxidant activity of the acetone extract of the dried fruits of Karela increases in all the test methods hence dried fruit extracts can be used as rich source of antioxidants.
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HONEYDEW HONEY: CORRELATIONS BETWEEN CHEMICAL COMPOSITION, ANTIOXIDANT CAPACITY AND ANTIBACTERIAL EFFECT

HONEYDEW HONEY: CORRELATIONS BETWEEN CHEMICAL COMPOSITION, ANTIOXIDANT CAPACITY AND ANTIBACTERIAL EFFECT

Selected physico-chemical parameters, total polyphenols, flavonoids, antioxidant and antibacterial activity of honeydew honey samples from Romanian were determined. Regarding the chemical composition, analysed honey samples framed in this type of honey, phenolic content, determined as gallic acid equivalents, presented a mean value of 116.45mg GAE/100 g honey. Total flavonoid content expressed as quercetin equivalents, was 1.53 mg in honeydew honey. Antioxidant activity expressed as % inhibition of a solution of DPPH, ranged between 47.84 and 62.99%. The concentration of honey that inhibit with 50% the DPPH solution was established to be 16.16%. 10 strains of Staphylococcus aureus presented different inhibition percentages when were treatred with a solution of honey. In conclusion, Honeydew honey could be recommended to complement other polyphenol source in human diet and also used in medical treatment
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CHEMISTRY AND PATHOPHYSIOLOGY OF 2–PHENYL–4H–CHROMEN–4–ONE DERIVATIVES AS HOLISTIC FLORA IN THE FORM OF GLYCOSIDIC AGLYCONE

CHEMISTRY AND PATHOPHYSIOLOGY OF 2–PHENYL–4H–CHROMEN–4–ONE DERIVATIVES AS HOLISTIC FLORA IN THE FORM OF GLYCOSIDIC AGLYCONE

Health benefits to humans: Flavonoids are important antioxidants, and promote several health effects. Aside from antioxidant activity, these molecules provide the following beneficial effects: Anti–viral, Anti–cancer, Anti–inflammatory, Anti–allergic anti–inflammatory, anti–allergic, hepatoprotective, anti–thrombotic, anti– viral, and anti–carcinogenic activities etc. One flavonoid called quercetin can help to alleviate eczema, sinusitis, asthma, and hay fever. Some studies have shown that flavonoid intake is inversely related to heart disease, with these molecules inhibiting the oxidation of low–density lipoproteins (LDL) and therefore reducing the risk of atherosclerosis developing. Flavonoids are also abundant in red wine, which some have theorized is the reason why the incidence of heart disease may be lower among the French (who have a relatively high red wine intake) compared with other Europeans, despite a higher consumption of foods rich in cholesterol (French paradox). Many studies have also shown that one to two glasses of wine a day can help protect against heart disease.
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Antioxidant and antidiabetic activity of isolated flavonoids from Alangium salvifolium leaves extracts

Antioxidant and antidiabetic activity of isolated flavonoids from Alangium salvifolium leaves extracts

The reducing power of ascorbic acid was found to be higher than ethanol and aqueous extracts. It has been reported that the reducing power of substances is probably because of their hydrogen donating ability. The ethanol extract of A. salvifolium might, therefore, contain a high amount of reductions than aqueous extract. The result indicates that extract act as electron donors and could react with free radicals to convert them into more stable products and then terminate the free radical chain reactions. During the study, it was found that antioxidant activity was produced due to the presence of phenolic compounds. So here reducing power assay justify that ethanol extract of A. salvifolium contains the maximum amount of the total polyphenol and flavonol.
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Structure-activity relationship and MM2 energy minimized conformational analysis of quercetin and its derivatives in the DPPH• radical scavenging capacity

Structure-activity relationship and MM2 energy minimized conformational analysis of quercetin and its derivatives in the DPPH• radical scavenging capacity

21 Structural requirement in flavonoids for the hydrogen-donation by single-electron transfer includes ortho-dihydroxyl substituent in the B ring and C2-C3 double bond in conjugation with C-4 carbonyl group in the C ring, which expands electron delocalization for radical stabilization and determines the co-planarity of the hetero ring. Quercetin, a pentahydroxy flavone (1), seems to be a paradox which satisfies these structural variations and so efficiently captures free radicals thereby exhibiting high antioxidant activity. In case of absence of a catecholic structure in B ring, the antioxidant activity is compensated by 3- and/or 5- hydroxyl substituent(s). Blocking or removing the 3-OH group decreases antioxidant property. The dihedral angle of the B ring with respect to remaining structure in flavones is considered for strong influence on radical scavenging activity [18, 27]. However, the roles of chemical structure and underlying molecular phenomena have stayed elusive [23, 28].
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