• Food Science and Biotechnology
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• v.18 no.3
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• pp.818-821
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• 2009

Total phenol, total flavonoid, reducing powder, electron donating activity, ascorbic acid equivalent antioxidant capacity, antimicrobial and antiproliferative activities of olive leaf extracts were investigated. The contents of total phenol and flavonoid were 257.48 and 92.33 mg in 100 g of olive leaf extract, respectively. The reducing power of the olive leaf extract increased with concentration increasing. Electron donating activity was high in 100 ${\mu}g/mL$ treated olive leaf extract as 95.20%. The ascorbic acid equivalent antioxidant capacity of the olive leaf extract was 68.93 mg/g olive leaf extract. The olive leaf extracts showed relatively high antimicrobial activity against Escherichia coli, Salmonella typhimurium, Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, and Pseudomonas aeruginosa. All of the cancer cell lines including MKN45, HCT116, NCI-H460, and MCF7 have 70-81% as effective growth inhibition.

• Korean journal of food and cookery science
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• v.20 no.2
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• pp.204-210
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• 2004

This study was performed to provide basic physiological activities data to predict the usefulness of olive leaves as a food material. Total flavonoid and total phenol contents of 80% ethanol extract of olive leaf were 5.81% and 14.8%, respectively. Total flavonoid and total phenol contents were markedly higher in butanol and ethyl acetate fractions than in hexane, chloroform, and water fractions (p＜0.05). Oleuropein in olive leaf was the major phenolic compound. The oleuropein contents of 80% ethanol extract, butanol and ethyl acetate fractions of olive leaf were 102.11${\pm}$0.02, 173.35${\pm}$0.03 and 152.71${\pm}$0.03 mg/100g, respectively. The 80% ethanol extract, butanol and ethyl acetate fractions of olive leaf showed a growth inhibitory effect to Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Salmonella enteritidis, whereas antimicrobial activities of hexane and chloroform fractions were not observed. The inhibitory activity to ACE was determined to be very weekly positive in 80% ethanol extract and all fractions of olive leaf. The nitrite-scavenging ability of 80% ethanol extract, butanol and ethyl acetate fractions of olive leaf were 72.8%, 76.0% and 75.4%, respectively. Significant evidence was detected that the butanol and ethyl acetate fractions showed higher activity than that of hexane, chloroform, and water fractions (p＜0.05).

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.178-182
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• 2005

Basic optimal extraction condition and stability data were determined for prediction of usefulness of olive leaf as functional food material. Solid contents of olive leaf extracts increased with increasing extraction temperature and ethanol content, and was the highest (38%) under $85^{\circ}C$, 80% ethanol, and 5 hr treatment conditions, Total phenol contents and electron-donating abilities of olive leaf extracts also increased with Increasing ethanol content, and were the highest under $25^{\circ}C$, 80% ethanol, and 1 hr treatment conditions, then slightly decreased during storage at $25,\;55,\;and\;85^{\circ}C$. Olive leaf extract showed high stability under acidic storage condition, while low under alkalic condition.

• Carbon letters
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• v.24
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• pp.47-54
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• 2017

Different phytochemicals obtained from various natural plant sources are used as reduction agents for preparing gold, copper, silver and platinum nanoparticles. In this work a green method of reducing graphene oxide (rGO) by an inexpensive, effective and scalable method using olive leaf aqueous extract as the reducing agent, was used to produce rGO. Both GO and rGO were prepared and investigated by ultraviolet and visible spectroscopy, Fourier-transform infrared, scanning electron microscopy, atomic force microscopy, thermogravimetric analysis, cyclic voltammetry, X-ray photoelectron spectra, electrochemical impedance spectroscopy and powder X-ray diffraction.

• Food Science and Biotechnology
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• v.18 no.4
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• pp.965-970
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• 2009

Oleuropein content of olive leaf extracts (OLE; ethanol extract) was evaluated by high performance liquid chromatography analysis. Oleuropein contents were $4.21{\pm}0.57$, $3.92{\pm}0.43$, $0.32{\pm}0.03$, $5.76{\pm}0.32$, and $32.47{\pm}0.25$ mg/100 g for ethanol extract, and hexane, chloroform, ethyl acetate, and butanol fraction, respectively. The removal of DPPH free radical increased in OLE and all 5 fractions of OLE in a concentration dependent manner. In order to investigate the antioxidant effect of OLE in vitro, 80%(v/v) ethanol OLE, $H_2O_2$, or combined treatment of 80%(v/v) ethanol OLE and $H_2O_2$ were applied on mouse embryonic fibroblast (MEF) cells. Cells were damaged by oxidative stress decreased their viability followed by increasing concentration of $H_2O_2$, but co-treatment of OLE and $H_2O_2$ showed an increase in cell growth about 20% compare to the cells treated with $H_2O_2$. OLE suppresses cytotoxicity induced by $H_2O_2$ in dose dependent manner. OLE treatment on MEF cells was also examined by analyzing cell cycle and apoptotic rate using flow cytometry. Apoptotic and necrotic cell accumulation was decreased in addition of OLE to $H_2O_2$ compare to the oxidative damaged cells. Taken together, these results demonstrated that OLE suppresses cytotoxicity induced by $H_2O_2$ and protect cells against oxidative stress on MEF cells.

• Korean Journal of Food Science and Technology
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• v.40 no.3
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• pp.257-264
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• 2008

In this study, the antioxidant activities and nitrite scavenging abilities of olive leaf fractions acquired from plants cultivated in Australia (Olea europaea L. var. Picual) and Spain (Olea europaea L. var. Hojiblanca) were evaluated. Oleuropein was found to be the major phenolic compound in the leaves, with the butanol fractions presenting the highest contents. Antioxidant activity was evaluated in terms of superoxide dismutase (SOD)-like activity, 1,1-diphenyl-2-picryl hydroxyl (DPPH) radical scavenging activity, and the inhibitory effect on the auto-oxidation rate of linoleic acid. The SOD-like activities of the olive leaf extracts ranged from 0 to 36.8%. DPPH radical scavenging activity was highest in the ethanol extract of the Australian cultivated olive leaves. Finally, the chloroform fractions of the extracts showed inhibitory effects on the auto-oxidation rate of linoleic acid as well as nitrite scavenging ability.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1193-1198
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• 2009

Ethylacetate and butanol fractions of leaf extracts (OLE) showed the higher contents of total phenolic compounds than hexane and water fractions. Oleuropein contents were $4.21{\pm}0.57,\;3.92{\pm}0.43,\;0.32{\pm}0.03,\;5.76{\pm}0.32$, and $32.47{\pm}0.25mg$/100g for ethanol extract, and hexane, chloroform, ethyl acetate, and butanol fraction, respectively. Treatment of ultraviolet-B (UVB) irradiated cells with 3 OLEs prepared by using ethylacetate and butanol at concentrations 0.001, 0.005, and 0.01% respectively showed significant recovery of cell viabilities. Treatment of dexametason 1 mM reduced tumor necrotic factor (TNF)-${\alpha}$ secretion by about 40%. UVB irradiated immortalized human keratinocytes (HaCaT) cells were treated with 3 different OLEs at the same concentrations. Ethylacetate fraction showed the strongest inhibition activity with respect of reduction of the elevated (TNF)-${\alpha}$. Cytotoxicity of OLEs on the B16-F1 cells was evaluated through thiazolyl blue tetrazolium bromide (MTT) assay. Ethylacetate fraction has no cytotoxicity in the range of 0.005-0.01%. A slight cytotoxicity was observed at the concentration of 0.1% butanol fraction of OLE that caused 10% decrease in cell viability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3317-3326
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• 2011

Physicochemical properties of Achyranthes japonica and Smilax china extracts were investigated for the purpose of functionality research on the natural bio-resources. Extraction contents were order of distilled water>methanol>ethanol solvent, the highest free aminoacids were proline from Achyranthes japonica, phosphoserine and glutamic acid from Smilax china, respectively. BI and TAC by spectrophotometric absorbance were order of methanol>ethanol>water in Smilax china leaf extract, but water>methaol>ethanol in Achyranthes japonica leaf extract. EDA was high in ethanol extract from Smilax china leaf and in methanol extract from Smilax china root, and in water extract from Achyranthes japonica. TBA value of Achyranthes japonica leaf and Smilax china leaf-ethanol extracts on olive oil was 82.1% and 84.0%, respectively, for that of an artificial antioxidant BHT. Antimicrobial effect was observed in Achyranthes japonica stem-methanol extract on Bacillus subtillis, in Smilax china leaf-ethanol extract on Bacillus subtillis, Vibrio vulnificus and Salmonella enterica, respectively. And the adsorption of Pb(II) on Achyranthes japonica was higher than that of Cd(II) on Smilax china under the same metal ion concentration.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.4
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• pp.314-324
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• 2016

To improve the color stability of chlorophyll in young barley leaf used as functional green biomaterial, the absorption spectrum, color values, and antioxidative activities of young barley leaf (YBL) treated with zinc ion solutions were investigated. The small pieces of fresh YBL in aqueous solution mixtures were autoclaved twice at $110^{\circ}C$ for 30 min (pH 5). Distilled water (BLA), 0.01% zinc chloride (BLAZ), 0.01% zinc citrate (BLAC), and 0.01% zinc lactate (BLAL) solutions were used. Treated YBL powders were extracted with 80% EtOH for 4 h. Chlorophyll a and b contents differed with different treatments. BLA decreased chlorophyll a and b contents, whereas others were maintained. Absorbance spectrums of chlorophyll at 400~700 nm showed different maximum peak wavelengths. After heating in acidic and neutral solutions (pH 3, 5, and 7), the colors of YBL and BLA changed from green to olive green, whereas BLAZ, BLAC, and BLAL remained green color. The antioxidative activities showed higher values in YBL extract than in treated extracts. From the above results, autoclaved YBL in zinc solution would increase the color stability and maintain green color regardless of acid and heat treatments.

• Journal of Applied Biological Chemistry
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• v.64 no.2
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• pp.113-119
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• 2021

Olive (Olea europaea L.) leaves, a raw material for health functional foods and cosmetics have abundant polyphenols including oleuropein (major bioactive compound) with various biological activities: antioxidant, antibacterial, antiviral, anticancer activity, and inhibit platelet activation. Oleuropein has been reported as skin protectant, antioxidant, anti-ageing, anti-cancer, anti-inflammation, anti-atherogenic, anti-viral, and anti-microbial activity. Despite oleuropein is the important compound in olive leaves, there is still no quantitative approach to reveal oleuropein content in commercial products. Therefore, a validated method of analysis has to develop for oleuropein. In this study, the components and oleuropein content in 10 types of products were analyzed using a developed method with ultra-performance liquid chromatography to quadrupole time-of-flight mass spectrometry, charge of aerosol detector, and photodiode array. The total of 18 compounds including iridoids (1, 3, 4, 14, and 16-18), coumarin (2), phenylethanoids (5, 9, and 11), flavonoids (6-8, 10, 12, and 13), lignan (15), were tentatively identified in the leaves extract based high resolution mass spectrometry data, and the content of oleuropein in each product was almost identical between two detection methods. The oleuropein in three commercial product (A, G, H) was contained more over the suggested content, and it of five products (B, E, H, I, J) were analyzed within 5-10% error range. However, the two products (C, D) were found far lower than suggested contents. This study provides that analytical results of oleuropein could be a potential information for the quality control of leaf extract for a manufactured functional food.