• Journal of the Korean Chemical Society
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• v.55 no.1
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• pp.136-140
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• 2011

• Journal of Applied Biological Chemistry
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• v.57 no.4
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• pp.353-358
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• 2014

Antioxidant activities of ethanol and water extracts of flesh, leaves, and peels of green and purple Kohlrabi were measured by rancimat method, total phenolic compound (TPC), DPPH radical scavenging effect, chelating effect, and reducing power analysis. The highest TPC was observed in ethanol extract from green peel and water extract from purple leaf with 12.00 and 11.70 mg/g of dry sample, respectively. The ethanol extracts from purple Kohlrabi leaf and peel exhibited strong DPPH radical scavenging effects with reducing power while water extracts from purple Kohlrabi leaf and peel also showed strong DPPH radical scavenging with chelating effects. Antioxidant index of ethanol and water extracts from green and purple Kohlrabi measured by rancimat was lower than butylated hydroxytoluene. These results suggest that extracts from purple Kohlrabi leaf and peel exhibited higher antioxidant activities than those of green Kohlrabi, and can be potentially used as proper natural antioxidants.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.11
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• pp.1776-1782
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• 2013

Rhus verniciflua was extracted at different temperatures and times, and the extracts were evaluated for contents of total phenolics and flavonoids, and antioxidant activities using DPPH and ABTS radical scavenging activities. Extraction temperatures and times were 80, 100, 120, 140 and $160^{\circ}C$, and 1, 3 and 5 hr. The total phenolic and flavonoid contents as well as antioxidant activities by DPPH and ABTS increased as the extraction temperature increased. The total phenolic contents did not significantly increase at less than $100^{\circ}C$ with different extraction times. However, they were increased at 3 hr and decreased at more than $120^{\circ}C$. The total flavonoid contents reached a high value of 8.04 mg CE/g at $140^{\circ}C$. The antioxidant activity by DPPH increased as the extraction temperature increased and reached high values of 34.28 mg TE/g at $140^{\circ}C$. The total antioxidant activity by ABTS was similar to DPPH. These results presumed that the optimum extraction temperature and time in the process of Rhus verniciflua extraction are $140^{\circ}C$ for 3 hr.

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.11-20
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• 2012

Methanol extracts of aquatic plants were analyzed for allelopathic activities against Escherichia coli JM109 and $Microcystis$ $aeruginosa$ UTEX2385 which were compared to its 2,2-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities. The radical scavenging activities were detected from the extracts of $Persicaria$ $thunbergii$, $Persicaria$ $amphibia$, $Trapa$ $japonica$, $Myriophyllum$ $spicatum$, and $Brasenia$ $schreberi$. Also, the inhibitory activities against cyanobacteria were analyzed according to the order of $B.$ $schreberi$, $T.$ $japonica$, $P.$ $amphibia$, and $M.$ $spicatum$. Most of the extracts from aquatic plants did not show any inhibition against $E.$ $coli$ except $B.$ $schreberi$. We found a positive correlation between the antioxidental activities of methanol extract of aquatic plants and the growth inhibitory activities for cyanobacteria in terms of the DPPH radical scavenging activities ($R^2$=0.381, $P$ <0.0001). The inhibitory activities of methanol extract against $E.$ $coli$ growth was not correlated with the other activities of aquatic plants ($P$ >0.04). We suggest from this study that the allelopathic effects of aquatic plants against cyanobacteria could be screened by using the bioassay based on DPPH.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.8
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• pp.1151-1156
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• 2005

The comparison on antioxidative activity of 13 kinds of vegetables that showed efficient oxygen radical absorbance capacity was carried out under in uitro and cellular model using LLC-$ PK_{1}$ renal epithelial cell, and also the total Phenol contents were analyzed. Beets, eggplant, and kale exerted the strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect and also these vegetables showed high contents of total phenol, indicating the positive relationship between DPPH radical scavenging effect and total phenol content. In addition, the treatment of 1 mM 2,2'-azobis (2-amidinopropane) dihydrochloride for 24 hrs to LLC-$PK_{1}$ cell susceptible to oxidative stress led to the decline of cell viability to 68.1$\%$, whereas the cellular oxidative damage was ameliorated by vegetables, especially eggplant and cauliflower, resulting in the elevation of cell viability to higher than 90$\%$ at the concentration of 5 $\mu$g/mL. This study suggests that 13 kinds of vegetables exert antioxidative activity under in uitro and cellular oxidative damage model, in particular among them eggplant showed the most effective antioxidative activity with higher total phenol content.

• Food Science and Preservation
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• v.22 no.1
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• pp.129-133
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• 2015

The antioxidant potentials of ten kinds of medicinal plants used as natural dyeing agents were tested. Among the plant extracts and floral waters that were examined in this study, the antioxidant activities of the DPPH and ABTS radical scavengers increased with increasing amounts of the extracts. The hot-water extracts from Aphis chinensis, Caesalpinia sappan L., Rumex crispus L., and Areca catechu effectively inhibited the DPPH and ABTS radicals at concentration below 0.1 mg/mL. The floral water obtained through steam distillation from Areca catechu, Rubia akane Nakai, Coptis chinensis, and Phellodendron amurense showed relatively valid antioxidant activities. In particular, the natural colorants extracted from Rumex crispus L., Areca catechu, and Aphis chinensis effectively suppressed the photogenerated singlet oxygen induced by a photosensitizer in in-vitro assay systems. The concentrations ($IC_{50}$) of the hot-water Aphis chinensis extract required to exert a 50% reduction effect on DPPH, ABTS, and singlet oxygen were found to be 8.5, 8.0, and $210{\mu}g/mL$, respectively. The study results suggest that extracts derived from naturally occurring colorants as well as floral waters could be used as natural antioxidants in the food and health-care industries.

• Journal of Life Science
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• v.27 no.1
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• pp.44-49
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• 2017

Natural anti-oxidative compounds have important disease prevention and food preservation properties, in addition to anti-bacterial, anti-inflammation, anti-cancer, and skin whitening effects. High-performance liquid chromatography (HPLC), with an ultra vilolet (UV) detector coupled to a reverse phase C18 column and an online measurement system for 1, 1-diphenyl-2-picryl hydrazyl (DPPH) radicals, was used to search for potent antioxidative compounds in crude extracts. The online HPLC-DPPH assay was then applied to confirm antioxidative compounds in water extracts from Radix of Pueraria lobata, Rhizoma of Zingiber officinale, Fructus of Chaenomeles sinensis, Cortex of Ulmus pumila, and Radix of Astragalus membranaceus. To determine the yields of the extracts, the Brix% of each extract solution was measured using a refractometer. When the relative DPPH radical scavenging ability values of the water extracts were compared with those of a positive control (ascorbic acid), the water extracts of P. lobata, C. sinensis, and U. pumila were 7.77%, 4.71%, and 4.19%, respectively. The results suggest that this method provides a useful assay for rapid measurement of DPPH radical scavenging abilities and conformation of antioxidative compounds in natural products. Moreover, it can reduce the time spent on the separation of active compounds from natural materials, such as medicinal plants, in addition to the use of reagents for separation.

• Korean Journal of Medicinal Crop Science
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• v.6 no.3
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• pp.181-187
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• 1998

This study was carried out to investigate the antioxidative activities of medicinal plants. Through the examination of methanol extracts from 30 species for radical scavenging effects using DPPH method, the extracts from Rhus javanica Linne, Smilax china Linne and Polygonum cuspidatum Siebold et Zucarinii showed strong antioxidative activity. Because of its highest antioxidative activity among 30 medicinal plants, radical scavenging effects of 4 different extract compartments (n- Hexane, EtOAc, BuOH and $H_2O$ extracts) from Galla Rhois MeOH extract of Rhus javanica Linne were examined by DPPH method and antioxidant effects on the 4 different extract compartments were tested by Ferric-Thiocyanate method. Antioxidative activities of n- Hexane, EtOAc and BuOH extracts were similar or even higher than that of natural (tocopherol) or synthetic antioxidants (BHA), suggesting that major fractions for the antioxidative activity of Rhus javanica Linne were the n- Hexane, EtOAc and BuOH extract compartments.

• Korean Journal of Pharmacognosy
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• v.39 no.2
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• pp.146-149
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• 2008

From the leaves of Angelica keiskei (Umbelliferae), luteolin, protocatechuic acid, guaijaverin, hyperoside and cynaroside were isolated and characterized by spectral data. Luteolin and protocatechuic acid showed potent DPPH radical scavenging activity.

• Food Science and Preservation
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• v.18 no.2
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• pp.250-255
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• 2011

As part of our continuing search for novel bioactive natural products, antioxidant and pancreatic lipase inhibitory activities of the aqueous ethanolic extract of Polygonum aviculare were investigated. In addition, the total phenolic content was quantified by a spectrophotometric method. The antioxidant properties of the extract were evaluated by radical scavenging assays such as DPPH and $ABTS^+$ radicals. The anti-obesity efficacy of P. aviculare extract was tested by porcine pancreatic lipase assay. All tested samples showed a dose-dependent pancreatic lipase inhibitory and radical scavenging activities. In terms of the $IC_{50}$ value, the ethyl acetate (EtOAc) soluble portion was most potent than other solvent soluble portions. The results suggested that P. aviculare could be considered as a new potential source of natural antioxidant and anti-obesity agent for food, nutraceutical, cosmetics industries.