• Food Science and Industry
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• v.51 no.2
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• pp.127-135
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• 2018

The action of antioxidants was different depending on the environments where antioxidants were located. Although basic mechanisms of lipid oxidation and antioxidants were related each other, their contribution on the degree of oxidation was different. In thisreview, terminology on antioxidant properties were defined such as antioxidant activity and antioxidant capacities. In addition, antioxidant mechanisms including primary and secondary antioxidants or hydrogen donating or electron transferring antioxidants were introduced. Also, the impact of physical points of view and antioxidant polar paradox were introduced. Depending on the types of food matrice including bulk oil, oil-in-water emulsion (O/W), or solid state, antioxidant actions showed different degree and this point was explained in detail.

• Food Science and Preservation
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• v.30 no.2
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• pp.235-246
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• 2023

Yellowball (Citrus hybrid cv. Yellowball ) is a new citrus hybrid between Haruka (C. tamurana × natsudaidai ) and Kiyomi (C. unshiu × sinensis) and is known to possess strong antioxidant activity. However, detailed information on the antioxidant components of its peel has not yet been reported. This study evaluated the antioxidant activity of the peel and identified the antioxidant components by fractionating a methanolic extract of Yellowball peels using liquid-liquid extraction with n-hexane, ethyl ether (ether), ethyl acetate (EA), butanol, and water. The phenolic contents and antioxidant activities of the n-hexane, ether, and EA fractions were higher than those of the other fractions, and these fractions were further separated by semi-preparative high-performance liquid chromatography (HPLC). Four antioxidant peaks, EA1, EA2, EA3, and He1, were isolated and analyzed using ultra-performance liquid chromatography-quadrupole-time- of-flight mass spectrometry (UPLC-Q-TOF MS). Sinapoyl glucoside and hesperidin were identified in EA2 and EA3, respectively, and a polymethoxylated flavone (PMF) complex (5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone, natsudaidain, tetrameth- oxyflavone, and tangeretin) was identified in He1. A compound in EA1 with m/z 223.0246 [M-H] could not be identified and was named unknown2. The antioxidant activity of unknown2 (IC₅₀=69.17 ㎍/mL) was similar to that of Trolox, which was noted as a major antioxidant in Yellowball peel. Further studies on the antioxidant capacity of Yellowball peel are required; however, these results provide a foundation for using Yellowball peel as an antioxidant.

• Korean Journal of Pharmacognosy
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• v.45 no.1
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• pp.35-40
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• 2014

In this study, in order to search for new functional materials from natural products, was carried out the study of antioxidant active ingredients in persimmon calyx(calyx of Diospyros kaki Thunberg). I have experimented with the effect of antioxidant activity of five different extract(MeOH, n-hexane, EtOAc, n-BuOH and $H_2O$ extract) obtained from persimmon calyx. As a result, the butanol extract, that is the main component fraction of antioxidant activity was found. Three compounds were isolated by silica gel column chromatography from the n-BuOH extract of persimmon calyx. Their structures of compound 1, 2 and 3 isolated from n-BuOH extract of persimmon calyx were identified as quercetin, (+)-catechin and gallic acid by using the TLC, $^1H$-NMR and $^{13}C$-NMR.

• The Korean Journal of Food And Nutrition
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• v.7 no.4
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• pp.332-337
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• 1994

The antioxidant activity of solvent extracts isolated from barley leaves was investigated by measuring peroxide value. The fractions of methanol extract obtained from preparative TLC was also studies, with UV-Visible spectrum, total phenol contents and hydrogen donating ability(HDA) The antioxidant activity of various solvent extracts was, in decreasing order, methanol> ethyl ether> methylene chloride $\geq$ ethyl acetate $\geq$acetone> hexane. The antioxidant activity of the fractions of methanol extract was, in decreasing order, fraction 2> fraction 3> fraction 1 and their activity was all superior to that of tocopherol at 500 ppm level. All fraction(1, 2 and 3) exhibited a strong UV absorption at 280 m which would be specifically produced by phenolic compound. UV absorption at 280 m of fraction 2 was greater than those of fraction 1 and 3. In the visible spectrum of these fractions, the maximum .absorption wavelengths of fraction 1, 2 and 3 were 660, 460 and 460 m, respectively. Antioxidant activity of barley leaves seemed to be due to the flavonoids containing phenolic group by UV spectrum and total phenol content.

• Biomedical Science Letters
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• v.28 no.4
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• pp.307-311
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• 2022

The extract of EA lacks studies showing its efficacy other than that it contains caffeic acid, an active compound that has antioxidant and neuroprotective effects on nerve cells. Therefore, in this study, we attempted to determine the effectiveness of EA extraction. In this study, we performed a DPPH assay to determine the antioxidant potential of EA. And then, the cytotoxic concentration of EA in HaCaT keratinocytes was determined, and the antioxidant effect was determined by measuring the malondialdehyde (MDA). The results of DPPH, a chemical antioxidant assay, clearly demonstrated the antioxidant capacity of EA extracted with distilled water. In addition, cell-based assays provide useful information on the protective effect of EA on oxidative stress-induced apoptosis.

• Journal of Photoscience
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• v.9 no.2
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• pp.138-141
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• 2002

A photo-labile compound which is bioinactive but, upon irradiation with light, yields bioactive species is called as "caged compound". Photolysis of caged compounds generating bioactive species, has become a general method to produce a desired amounts of bioactive species in the specific time interval at the desired place or area of the target biological systems. For this purpose, we designed and synthesized caged hydroxyl radical., "Photo-Fenton Reagent" NP-IIl. NP-IIl has a strong absorption maximum at 377 nm and yields hydroxyl radicals upon UV light irradiation. The antioxidant activity of the ${\alpha}$ -lipoic acid and other naturally occurring compounds has been examined by using NP-IIl as a molecular probe. For example, upon photoirradiation of NP-lII with BSA or apolipoprotein of human low density (LDL), the significant oxidative modifications were observed in both cases. The oxidation was completely suppressed in the presence of ${\alpha}$-lipoic acid, which clearly demonstrates the strong hydroxyl radical scavenging activity of ${\alpha}$-lipoic acid. Other applications of NP-lII will also be described

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.520-522
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• 2008

A new compound named soraphinol C (1) was isolated from myxobacteria Sorangium cellulosum KM1001 a soil isolate, together with a structurally related known compound, 4-hydroxysattabacin (2). These compounds were isolated by silica gel column chromatography and recycling preparative HPLC, consecutively. The structures of the compounds were determined on the basis of combined spectroscopic analyses. Compounds 1 and 2 exhibited antioxidant activity as a radical scavenger in the experiment using a hydrophilic free-radical initiator, 2,2'-azobis(2-amidinopropane)dihydrochloride with ORAC values of 0.956 and 0.617, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.138-142
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• 2001

Solid contents, free sugars, phenlic compounds and glycyrrhizin of extracts obtained from by-products of Glycyrrhizia uralensis by three different methods, i.e., shaking, heating, and static methods, were determined. Solid contents of extracts obtained by shaking, heating and static method were 15.6%, 15.0% and 5.3%, respectively. Phenolic compound contents of them were 11.33 mg/100 mL, 11.21 mg/100mL and 10.15 mg/100 mL. Main free sugars in the extracts from the by-products of G. uralensis were fructose, glucose, sucrose, and maltose. Glycyrrhizin content of the extracts from the by-products of G. uralensis were 2.79%, 3.54% and 0.63%, respectively. Extract obtained by the shaking methods had an ability of donating electron to DPPH. The relative antioxidant effects of th extract obtained from the shaking method showed 70% inhibitory effect of peroxidation on egg yolk lecithin.

• Archives of Pharmacal Research
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• v.28 no.9
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• pp.1023-1026
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• 2005

A new furofuran lignan (1) was isolated from the n-butanol fraction of the methanolic extract of the leaves of Petasites japonicus (Sieb. et Zucc.) Maxim. (Compositae). The structure of compound 1 was determined to be $2{\alpha}-(4'-hydroxy-3'-methoxyphenyl)-6{\alpha}-(4"-hydroxy-3"-methox­yphenyl)-8{\alpha}-hydroxy-3, 7-dioxabicyclo[3.3.0]octane\;4'-O-({\beta}-D-glucopyranoside)$ by spectroscopic methods including 2D-NMR. In further studies, it was found that the compound 1 expressed an antioxidant activity in DPPH radical scavenging assay, and moreover, ameliorated the seizure in kainic acid-treated mice.

• Fisheries and Aquatic Sciences
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• v.13 no.1
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• pp.12-17
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• 2010

This study was conducted to evaluate the potential of a microbial fermentation procedure to improve the functional qualities of seaweeds. Aspergillus oryzae, which has been used in traditional Korean fermented foods, was inoculated and cultivated in an aqueous extract of sea tangle (Laminaria japonica). Fermentation of the sea tangle extract by A. oryzae for 4 days resulted in a 3-fold increase in $\gamma$-aminobutyric acid (GABA) content. GABA is known to be a bioactive compound. Fungal fermentation of the extract also enhanced its antioxidant activity and increased its total content of phenolic compounds. It was assumed that these changes stemmed from the biodegradation of active compounds of the sea tangle packaged within its rigid structural matrix or occurred as result of fungal fermentation. These results suggested that the application of microbial fermentation to the processing of seaweeds will help in the development of processed foods to meet consumer demands.