• 분석과학
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• 제37권2호
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• pp.87-97
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• 2024

The appropriate intake of fluoride (F^-) is beneficial to human health; however, the over-consumption can result in various potentially harmful effects. This study compared different colorimetric reagents, i.e., aluminium-xylenol orange (Al-XO), zirconium-xylenol orange (Zr-XO), and zirconium-alizarin red S (Zr-ARS), for fluoride measurements by the UV-Vis, in terms of reaction mechanisms, method sensitivity, and interferences from aluminium and ferric ions. The colorimetric procedures were optimized, and the analytical methods were evaluated. The goodness of linearity (R² > 0.998) was obtained for all three assays within the concentration range of 1.0-20.0 mg/L fluoride in deionized water, in which the method sensitivity followed the descending order of Zr-XO > Al-XO > Zr-ARS. The Zr-XO was applied for determining the fluoride in different tea extracts in water (90 ℃ and 60-minute-brewing) and black tea demonstrated the highest fluoride content (3.0-3.6 mg/L). The effects of brewing time and temperature on the release of fluoride in the tea extracts were also investigated, indicating these are critical factors for the fluoride extraction. This study highlighted the application potentials of the UV-Vis measurement as a simple, convenient, and cheap analytical approach and discussed different colorimetric reagents used for fluoride determination in tea extracts in the context that the UV-Vis spectrophotometers are commonly equipped in most laboratories.

• Journal of Nutrition and Health
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• 제28권1호
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• pp.15-22
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• 1995

The antioxidant effects of aqueous green tea extracts with $\alpha$-tocopherol and lecithin dissolved in lard were investigated on the lipid metabolism in serum and liver of Sprague-Dawley male rats. Elderly male rats were fed for 8 weeks by different experimental diets containing 10% lard(w/w), 0.5% aqueous green tea extracts, 0.05% $\alpha$-tocopherol and 1.0% lecithin. By the addition of the mixture of the antioxidants, the level of total cholesterol. HDL-cholesterol and triglyceride in serum and liver were not changed. The activities of glutathione peroxidase were significantly increased in the case of addition of the antioxdant mixtures but the activities of superoxide dismutase and glutathione S-transferase were not affected.

• Toxicological Research
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• 제28권2호
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• pp.113-116
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• 2012

Various kinds of positive effects of green tea extracts had been studied for long time which included anti-inflammation, anti-aging, and cardiometabolic effects. Although topical steroid and non-steroidal calcineurin inhibitors may control clinical symptoms of allergic contact dermatitis, some of patients also present allergic reaction to these topical agents. Therefore, we have tried green tea extracts for managing this skin disorder with expectation of anti-inflammatory effect without potential side effects including skin irritation and toxic responses. The toxicity test of green tea extract also did not show any sign of irritation in the skin throughout the test period. Moderate severity of allergic contact dermatitis presented satisfactory clinical outcome at second week follow-up which was final visit of outpatient. This result mean that green tea extract has a positive effect for managing allergic contact dermatitis but its potency and efficacy seem to be so not strong enough to control moderate severity allergy skin lesion. In this pilot study, we were able to conclude that green tea cell extracts might be applied for potential anti-inflammatory soaking without skin toxicity.

• 한국염색가공학회지
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• 제18권1호
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• pp.10-19
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• 2006

Despite several recent attempts to measure the concentration of individual catechins by HPLC, it has not been so easy to separate catechins accurately. The aim of the present work is to provide a proper condition for separating each component of catechins by HPLC analysis, and also to evaluate the experimental variables including color differences, and metal ion contents after dyeing and mordanting. Four kinds of Catechins, (-)-epicatechin(EC), (-)-epicatechin gallate(ECG), (-)-epigallocatechin(EgC), (-)-epigallocatechin gllate(EgCG) were isolated from the residues after dyeing. Catechins in Korean green tea leaves are richer when e tea leaves are younger. Higher concentration of catechins owes it to e way it is processed. The contents of catechins adsorbed in silk fabrics after dyeing were in order of EGCG>ECG>EGC>EC. We have found $68\%$ uptake of EGCG, and 116.8mg of EGCG in the silk fabrics after it was dyed with $1\%$ Korean green tea extracts. The absorbance intensity and K/S values of dyed silk fabrics were increased with dyeing temperature and time. Only the surface color of the silk fabric dyed with green tea extracts was yellowish red, but it changed from yellowish red to red with an increase in the mordant concentration. Post-mordanted silk fabrics with ferrous sulfate changed from yellowish red to red and purple color shade. In a practical evaluation, there is no significant change in color after twenty times of the continuous dry cleaning process. However, post-mordanted fabrics with ferrous sulfate faded the brightness of color after dry cleaning. Dyeing silk fabrics with a Korean tea extract reduced the metal ion contents in the silk fabrics when compared to the untreated silk fabrics. Metal contents in silk fabrics dyed and post-mordanted with $1\%$ each metal solution were 0.194 ppm for Aluminum, 1.601ppm for Copper, and 0.334 ppm for Iron. After the post-mordanting process, the heavy metal ion absorption increased, which was mainly attributed to the catechins and polyphenols in dyed silk fabrics.

• 한국식품조리과학회:학술대회논문집
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• 한국식품조리과학회 2004년도 학술대회
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• pp.85-85
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• 2004

• 한국식품저장유통학회지
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• 제11권4호
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• pp.544-549
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• 2004

자연 유래의 미생물 효소를 이용하여 제조되는 후발효차의 주요성분과 항산화능을 조사하였다. 후발효차의 총 플라보노이드와 총 페놀 함량에서 각각 ethanol 추출물($481.4\;{\mu}g/g$, 33.5 g/100g)이 가장 높았으나, 1년 저장한 시료에서는 ethyl acetate 추출물($495.2\;{\mu}g/g$, 39.5 g/100g)이 다른 모든 추출물보다 가장 높았다. 후발효차의 catechin류는 EGC, GC, catechin, catechol 및 EGCG가 검출되었으며, 열수 추출물에서는 EGCG가 검출되지 않았다. DPPH free radical 소거능은 모든 추출물에서 그 농도가 증가할수록 활성이 증가하였는데, 저장하지 않은 후발효차와 1년간 저장한 것의 ethanol 추출물에서는 각각 $72.4\%$ 및 $80.9\%$였다. 금속 화합물 형성에 대한 환원력의 효과는 에탄올 추출물 $500\;{\mu}g/mL$에서 0.78과 0.88(1년 저장)의 환원력을 나타났고, ${\beta}$-carotene-linoleate system에서 ethyl acetate 추출물 $3000\;{\mu}g/mL$의 항산화능은 $86.6\%$와 $73.7\%$(1년 저장)를 나타내었다.

• 한국자원식물학회지
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• 제24권2호
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• pp.236-242
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• 2011

제주산 녹차 및 발효 정도를 20%, 50%, 80%로 달리한 3종류의 발효차를 $90^{\circ}C$ 열수에 추출하여 추출물의 항산화능, 지질과산화 억제능 그리고 혈관내피세포(CPAE)를 이용하여 산화스트레스에 대한 세포 보호효과를 조사하였다. 녹차나 다른 발효차에 비해 20% 발효차에서 항산화능을 평가하는 DPPH 소거능이 가장 우수한 것으로 나타났다. 20% 발효차의 80 ${\mu}g/mL$ 처리 시 50 ${\mu}M$ 농도의 EGCG 처리와 거의 유사한 free radical 소거율을 보였다. 녹차와 3종류의 발효차 모두 LDL 산화를 억제하여 우수한 지질과 산화 억제능을 보였으나 특히 저농도인 40 ${\mu}g/mL$ 처리 시에 녹차와 20% 발효차의 경우 다른 발효차에 비해 25~30% 정도 더 LDL의 산화가 억제 되어 50 ${\mu}M$/mL EGCG 처리 시와 거의 동일한 수준의 지질과산화 억제 효과를 보였다. CPAE 세포에 녹차 및 3종류의 발효차 추출물을 처리한 실험에서 전혀 추출물을 처리하지 않은 세포에 비해 세포활성이 40~60% 증가하였다. 특히 세포에 1 mM 과산화수소를 처리하여 산화스트레스를 유발한 실험에서 녹차 및 발효차 추출물의 처리가 세포의 산화스트레스에 대한 보호효과를 나타내는 것을 알 수 있었다. 이상의 결과들은 녹차 및 발효차 추출물이 세포 내 free radical을 제거함으로써 산화스트레스에 대한 세포 보호효과에 중요한 기능 중의 하나로 작용한 것과 20% 발효차가 다른 발효차에 비해 우수한 항산화기능을 나타낸다는 것을 보여주었다.

• 한국식품영양과학회지
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• 제37권11호
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• pp.1382-1388
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• 2008

9월에 수확하여 엽차용 녹차로 시판되는 보성산 녹차를 온수, $80^{\circ}C$ 열수, 70% ethanol 용액으로 추출하고, 70% ethanol 추출물을 다시 hexane, chloroform, ethyl acetate, butanol로 분획한 다음 녹차 추출물과 분획물의 그램 양성균과 그램 음성균 8종에 대한 항균활성에 대하여 조사를 하였다. 녹차의 추출 수율은 70% ethanol 추출물은 33.0%, ethyl acetate 분획물은 11.2%를 보였다. 8종의 세균에 대한 녹차 추출물 간의 항균활성은 70% 에탄올 추출물의 경우 수 추출물에 비하여 Vibrio parahaemolyticus(V. parahaemolyticu) 및 Staphylococcus aureus(S. aureus)에 대하여 가장 높았다. 70% 에탄올 추출물로부터 여러 가지 용매를 달리하여 분획한 분획물 간의 항균활성은 70% ethanol 추출물에 비하여 ethyl acetate 분획물의 경우 Klebsiella pneumoniae, V. parahaemolyticus, S. aureus, Bacillus subtilis(B. subtilis) 및 Streptococcus mutans(S. mutans)와 같은 5종의 세균에 대하여 높았다. 70% ethanol 추출물 유래 ethyl acetate 분획물의 MIC는 B. subtilis의 경우 $5\;{\mu}L$/disc이었고, S. aureus 와 S. mutans의 경우 $3\;{\mu}L$/disc이었으며, V. parahaemolyticus의 경우 $3\;{\mu}L$/disc 이하로 아주 낮았다. Ethyl acetate 분획물의 첨가 농도에 따른 항균효과는 B. subtilis와 S. mutans 두 균종에서 확연히 나타났고 B. subtilis는 0.05% 이상의 첨가로 24시간 증식시켰을 때 control에 비하여 균증식이 90% 이상 억제됨을 보였으며, S. mutans는 동일한 균증식 억제 효과를 얻기 위하여 0.1% 이상의 ethyl acetate 분획물 농도가 요구되었다. Ethyl acetate 분획물의 열처리($121^{\circ}C$, 20분)는 균종에 따라 10%정도의 항균활성을 감소시켰다. 이와 같은 결과를 종합할 때 9월에 채엽된 저렴한 녹차로 천연 항균제 혹은 식품보존료의 개발은 충분한 잠재력이 있는 것으로 판단되었다.

• Archives of Pharmacal Research
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• 제21권3호
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• pp.348-352
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• 1998

Different bacteria wwere seperated from saliva and teeth of cariogenic patients and identified by a variety of morphological and biochemical tests. Extracts of green tea strongly inhibited Escherichia coli, Streptococcus salivarius and Streptococcus mutans. The antibacterial effect of green and black tea extracts were compared with those of amoxicillin, cephradine and eugenol.

• Food Science and Biotechnology
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• 제18권5호
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• pp.1212-1217
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• 2009

This study examined the influence of manufacturing processes and extraction conditions on the chemical compositions of green tea. Green tea samples grown in various areas (Korea, China, and Japan) and processed by 4 different methods (steaming, pan-firing, steaming and pan-firing, and heavy roasting after steaming and pan-firing) were collected for study. The chemical compositions of the green tea extracts and infusions were different according to their processing methods and extraction conditions, including catechins, caffeine, and free amino acids contents. In all samples analyzed, (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), and theanine were determined as the major catechins and free amino acid, respectively. Studies of samples grown in the same area (Jeju; Korea) showed that there were significant differences in the concentrations of catechins and caffeine in extract and infusion according to the processing methods. These results indicate that processing methods influenced the chemical compositions of the green tea extracts and infusions.