• Korean Journal of Food Science and Technology
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• v.47 no.3
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• pp.299-305
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• 2015

The Folin-Denis assay using the Folin-Ciocalteu (F-C) reagent has been commonly used for analyzing the total phenolic compound content in various food products. In the present study, the effects of proteins on the reactivity of the F-C reagent with different phenolic compounds were investigated. Bovine serum albumin (BSA) or skim milk proteins showed a concentration-dependent increase in color response in the Folin-Denis assay; these proteins decreased the color response of most phenolic compounds tested. The reactivity of phenolic compounds was significantly less pronounced in the presence of BSA and this interference was greater at higher concentrations of phenolic compounds. The reactivity of phenolic compounds with the F-C reagent was reduced significantly by their oxidation; the reaction of the oxidized products with the F-C reagent was more severely affected by BSA. The interfering effects in the Folin-Denis assay might be attributable to binding interactions of phenolic compounds with proteins.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.2
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• pp.205-213
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• 2011

The Folin-Ciocalteu (F-C) reagent has been extensively used for quantifying total phenolic contents in many different types of food materials. Since several different procedures of the assay methods using the F-C reagent have been applied, we investigated changes in reactivity of various phenolic compounds with the F-C reagent under three different assay conditions and factors affecting reactivity. Among 10 standard compounds tested, compounds with high hydroxyl density (number of -OH/molecular weight) showed a largely different response according to addition sequence of the F-C reagent or $Na_2CO_3$. Preincubation in $Na_2CO_3$ significantly reduced the reactivity of the phenolic compounds bearing galloyl moiety (e.g. gallic acid, tannic acid, and epigallocatechin-3-gallate) with the F-C reagent, while monophenol compounds including ferulic acid and sinapinic acid were more stable as compared to diphenols. There was little change in response to the F-C reagent of all phenolic compounds incubated in acidic pH; their reactivity except ferulic acid was reduced significantly when incubated in neutral or alkaline pH. Changes in reactivity of gallic acid incubated in $Na_2CO_3$ or neutral/alkaline pH conditions were the most prominent. $H_2O_2$ generated from phenolic compounds did not affect the reaction with the F-C reagents. The present results suggest that reactivity of different phenolic compounds with F-C reagent was affected considerably by different procedures of the assay, and the total phenolic contents could be fluctuated according to standard compounds and assay scheme.

• Journal of Pharmaceutical Investigation
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• v.31 no.3
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• pp.197-200
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• 2001

Lectin-conjugated ellagitannin (LET), a newly introduced melanoma-specific antitumor agent which has been synthesized by conjugation of wheat germ agglutinin as a lectin with praecoxin A as an ellagitannin, was encapsulated into sterically stabilized liposomes (SSL). Modified Folin phenol method was established for the quantitation of LET contents in liposomal formulations protein employing the standard calibration curve with bovine serum albumin. After removal of phospholipid by organic solvent extraction, which interferes the specific selectivity of the Folin-Ciocalteu reagent with the protein, recovery of LET was $94.5{\pm}2.3%$ and the encapsulation efficiency was revealed as $37.8{\pm}5.9%$ for 2.5 mg/ml LET solution.

• Natural Product Sciences
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• v.29 no.1
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• pp.24-30
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• 2023

Adenanthera pavonina L. is an important medicinal plant for Indonesian traditional medicine ("Jamu"). The present study is to determine the phenolic content and evaluate the antioxidant activity of ethyl acetate and ethanolic extracts of leaves and bark of A. pavonina. The total phenolic content was determined using the Folin-Ciocalteu reagent methods, and the antioxidant activity was performed by phosphomolybdate assay, through EC₅₀ values. The highest phenolic content (81.379 mg GAE/g) was found in the hydro-ethanolic extract of the leaves and (80.630 mg GAE/g) in the bark. The antioxidant activity of the two samples was 42.270 ㎍/mL (leaves) and 45.261 ㎍/mL (bark). Plants have the potential as drugs with good antioxidant potential and phenolic compound content. Further scientific studies of this plant are supported to evaluate the antioxidant activity using other methods to validate these preliminary experiments properly.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.6
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• pp.471-475
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• 2004

The Oligomeric proanthocyanidin (OPC) in green and black tea, grape seeds, grapes and wine has raised much attention but that OPC in wild grape seed remains to be intensively investigated. This study investigated the total OPC contents and total antioxidant activity of wild grape seeds and developed an efficient extraction process with various temperatures, solvent compositions and times. Also, a chromatography column packed with the Dia-ion HP-20 resin was used for further purification of the ope. The total OPC contents were determined with the Folin-Ciocalteu reagent, and the antioxidant activity using total antioxidant potential (TAP) and 1,1-dipheny|-2picrylhydrazy| (DPPH). The yield of final purified OPC was 1.78 (+)-catechin equivalent (CE) g/100 g, with $IC_{50}$ activities of TAP and DPPH of 31.60 and $15.70\;{\mu}\;g/mL$. These activi­ties of the final purified OPC were about two times higher than that of the BHA used as a refer­ence sample.

• Food Science and Biotechnology
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• v.17 no.1
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• pp.151-155
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• 2008

Oxidation of low density lipoprotein (LDL) is regarded to play an important role in the development of atherosclerosis. In the present study, salad vegetables with a remarkable DPPH radical-scavenging activity were extracted with methanol, and the methanol extracts were evaluated for the inhibition of $Cu^{2+}$-induced oxidation of human LDL. Separately, the amount of total phenolics was determined colorimetrically using Folin-Ciocalteu reagent. The vegetable extracts, expressing a strong inhibition of LDL oxidation ($IC_{50}$ values, <$100\;{\mu}g/mL$), were from angelica, dandelion, mustard leaf, and water spinach, which contained relatively high level of polyphenol content. Noteworthy, a highly positive correlation was observed between inhibition of LDL oxidation and amount of total polyphenol (p<0.01). Based on these results, it is suggested that salad vegetables, especially angelica, dandelion, and mustard leaf, may be used as easily accessible sources of natural antioxidants, especially in anti-atherosclerosis.

• Advances in Traditional Medicine
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• v.8 no.3
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• pp.260-265
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• 2008

Annona reticulata belonging to the family Annonaceae is traditionally used as anthelmintic and it is reported to have anticancer activity. Free radicals are known to be involved in various types of diseases like cancer, diabetes, neurological disorders etc. The present study was aimed to evaluate free radical scavenging property of methanol extract of the leaves of Annona reticulata in some in vitro models e.g. DPPH, nitric oxide, superoxide and lipid peroxide radical model. The extract showed good dose-dependent free radical scavenging property in all the models. $IC_{50}$ values were found to be 3.22, 170.01, 25.12 and $140.12\;{\mu}g/ml$ respectively in DPPH, nitric oxide, superoxide and lipid peroxidation inhibition assays. Reductive ability of the extract was also tested based on potassium ferricyanide reduction where dose dependant reducing capability was observed. Measurement of total phenolic compounds by Folin-Ciocalteu's phenol reagent indicated that 1mg of the extract contained $146.20\;{\mu}g$ equivalent of pyrocatechol. The findings ascertain promising free radical scavenging property of the extract and the antioxidant property of the extract may be due to the high content of phenolic compounds.

• CELLMED
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• v.5 no.2
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• pp.14.1-14.6
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• 2015

Antioxidative and free radical scavenging properties of different stem extracts of Euphorbia trigona were evaluated and correlated with its total phenolic content. Aqueous, acetone and methanolic extracts of shade dried stem were obtained and were concentrated in vacuo. The antioxidant and free radical scavenging activities of stem extracts was determined by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging assay, reducing power assay, deoxyribose degradation assay and $Fe^{2+}$ chelating assay. Total phenolic contents (TPC) were evaluated using Folin-Ciocalteu reagent. The results confirmed that the plant is a rich source of polyphenolic compounds which are invariably higher compared to other herbs. All extracts showed TPC in the range of 146.6 - 168.6 mg/g gallic acid equivalents at $300{\mu}g/ml$ of extract. Among the three extracts ME showed highest scavenging activity as evidenced by maximum scavenging of DPPH (83.2%), $OH{\bullet}$ radicals (94.81%), $Fe^{2+}$ chelating activity (88.59%) and a high reducing power 0.623 at $300{\mu}g/ml$. Our results demonstrate that Euphorbia trigona, an unexplored xerophytic plant could be potential source of natural antioxidants and phytotherapeutic agents. The plant possess invariably high amount of polyphenolic compounds with a broad spectrum of antioxidant properties and could be further used for food, feed and pharmaceutical applications.

• KSBB Journal
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• v.30 no.4
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• pp.191-196
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• 2015

Blueberry juice possesses rich-procyanidins and - anthocyanidin, comprised a group of with numerous health benefits such as protection against coronary heart disease, detoxification, and obesity. Blueberry (Vaccinium virgatum) juice extracts were analyzed and separated by an HPLC method for the purpose of the separation and quantification in polyphenolic groups. In specific HPLC conditions, a binary mobile phase consisting of formic acid: water (10:90, v/v, solvent A) and formic acid: water: acetonitrile (10:60:30, v/v/v, solvent B) was utilized and it is detected at 546 nm wavelength. The phenolic contents of the extracts are determined using Folin-Ciocalteu phenol reagent. In order to test anti-inflammation activity assay, after producing nitric oxide (NO) in lipopolysaccharide activated RAW 264.7 cells, at concentration of $20-500{\mu}g/mL$ it reduced to NO production at a dose-dependent manner. Importantly, cytotoxicity assay with up to $500{\mu}g/mL$ of the extract from blueberry juice showed ~100% cell viability for RAW264.7 cell line. Therefore, Korean blueberry juice might have potential as anti-oxidant and antiinflammation agents.

• Preventive Nutrition and Food Science
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• v.9 no.4
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• pp.289-294
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• 2004

The antioxidant activity of forty two kinds of salad vegetables grown in Korea was evaluated. Methanol extract of freeze-dried vegetable was assayed by radical scavenging activity using 1,2-diphenyl-2-picrylhydrazyl (DPPH) and Fe^{2+}$-catalyzed lipid peroxidation inhibition by TBA method. Total phenolics were determined colorimetrically using Folin-Ciocalteu reagent. The highest radical scavenging activity was expressed by perilla leaf, followed by dandelion leaf, red and green leafy lettuce, of which $IC_{50}$ was less than 0.10 mg/mL. Angelica leaf showed the highest inhibitory action for lipid peroxidation with $95\%$, and then dandelion leaf, water spinach, and perilla leaf inhibited over $80\%$. However, lettuce (Iceberg) and young Chinese cabbage exhibited the lowest antioxidant activity based on both assay methods. Highly positive correlations between antioxidative activities and total phenolics were observed (p < 0.001). The results suggested that salad vegetables, especially perilla leaf, leafy lettuce, dandelion or angelica, could be used for easily accessible sources of natural antioxidants.