• Korean Journal of Food Science and Technology
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• v.45 no.6
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• pp.667-674
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• 2013

This study was aimed to investigate the effect of microwave-assisted extraction on Schizandra fruit extract dried by two different treatments: freeze-drying and hot air-drying. Two extraction parameters were measured in particular: total polyphenol content and antioxidant activity. Both values were found to increase as the microwave power increased, for both drying processes. However, the extract from the freeze-dried sample exhibited higher antioxidant activity than that from the hot air-dried samples. Additionally, the total polyphenol content and antioxidant activity of the extract from the freeze-dried samples increased with the extraction time, whereas they decreased with the extraction time in the case of the hot air-dried sample. Solvent concentration was also found to have a significant effect on total polyphenol content and antioxidant activity; the highest values for both properties were achieved at 50 and 70% ethanol concentrations, respectively. In summary, a higher total polyphenol content and antioxidant activity were observed for Schizandra fruit extracted by freeze-drying than that by hot air-drying.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.3
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• pp.282-287
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• 2008

Gardeniae Fructus (GF) is a fruit of Gardenia jasminoides Ellis (Rubiaceae) which has been used in traditional medicine. It contains not only geniposide but also resveratrol, a kind of stilbene as a natural antioxidant. In this study, we investigated physiological activities of GF extracts by measuring electron donating ability (EDA), nitrite scavenging ability (NSA), super oxide dismutase (SOD)-like activity and inhibitory effect of tyrosinase activity (ITA). As a solvent, it was extracted with water, 50 and 100% ethanol using microwave. At the concentration of 6 mg/mL, EDA was the highest at 50% ethanol extract but the lowest at 100% ethanol extract, $96.43{\pm}0.25%\;and\;77.06{\pm}0.22%$ respectively. NSA showed the strongest activity at 50% ethanol extract like EDA (6 mg/mL: $75.26{\pm}0.28%$). ITAs were below 20% in all samples and their activities reduced according to increasing concentration. Likewise, SOD-like activities decreased with increasing concentration of extracts in all samples. In conclusion, GF extracts showed low SOD-like activities and ITAs but EDAs and NSAs were fairly high; especially EDA of 50% ethanol extract (6 mg/mL) was high as those of 0.1 and 1% L-ascorbic acid. Therefore the results suggest that GF extracts may be useful as potential sources of natural antioxidants.

• Journal of Ginseng Research
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• v.23 no.3 s.55
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• pp.164-171
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• 1999

Microwave-assisted extraction, which is known to rapidly extract target compounds from natural products, was monitored by response surface methodology (RSM) while extracting ginsenosides by using microwave extraction system (MES) equipped with closed vessels, and was confirmed on its extraction efficiency. On the whole, coefficients of determinations $(R^2)$ of the models on ginsenoside contents of extracts with various extraction conditions were above 0.83 (p<0.1). $Ginsenoside-Rb_2,\;-Rc,\;-Re\;and\;-Rg_1$ were maximized in $140^{\circ}C$ of extraction temperature and $50\~75\%$ range of ethanol concentration. Unknown compound peak on HPLC chromatogram observed at extraction temperature over $120^{\circ}C$, increased at the extraction temperature of $150^{\circ}C$. The extraction temperature of $ginsenoside-Rb_2$ and -Re increased from $129^{\circ}C\;to\;147^{\circ}C$ with including unknown compound, and $R^2$ of the models on ginsenoside contents of extracts increased with including unknown compound into ginsenoside $Rb_2$ and Re. Contents of unknown compound were minimized in $67.33\%$ of ethanol concentration, $99.34^{\circ}C$ of extraction temperature and 3.65 min of extraction time. Ginsenoside contents extracted by microwave system for 8 min showed a similar tendency to those of the current extraction method for 40 hrs.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.10
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• pp.1309-1314
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• 2006

This study analyzed the contents of vitamin C, polyphenol compounds, and evaluated the inhibitory activities against xanthine oxidase and tyrosinase of Lepista nuda extract prepared by the reflux and microwave-assisted methods. The vitamin C content of the fresh L. nude was $9.92{\pm}0.02$ mg/100 g. The content of phenolic compounds in the fresh L. nuda was $1.87{\pm}0.02\;mg/g$. The ethanol extracts prepared by reflux method and microwave-assisted method showed the highest phenol contents of $12.06{\pm}0.12\;mg/g\;and\;11.84{\pm}0.17\;mg/g$, respectively. The inhibitory rates on xanthine oxidase and tyrosinase of ethanol extracts prepared by the microwave assisted method showed the highest value of 99.78% and 30.30% at the concentration of $3,000{\mu}g/mL$. The inhibitory activities on xanthine oxidase and tyrosinase were increased depending on the extract concentration.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.192-198
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• 2023

In this study, the components of microwave-assisted extracts obtained from Thuja orientalis leaves were analyzed, and the cytotoxicity, antibacterial and antiviral activities were evaluated. The predominant components from microwave-assisted extraction were catechin, leucopelargonidin, arecatannin, quinolone, and kaempferol derivatives, which are classified in the flavonoid and tannin groups. We observed that the 0.11 mg/mL of extract concentration did not show cytotoxicity in HaCaT cells. The antibacterial activities were tested according to the guidelines of methods for determining the bactericidal activity of antimicrobial agents. The extracts showed 99.9% antibacterial efficiency against gram-positive S. aureus, while the antibacterial effect on gram-negative E. coli was insignificant. When the extract concentration and contact time with bacteria were increased, 99.9% antibacterial efficiency was observed for E. coli as well as S. aureus. Following the standard to assess the activity of microbicides against viruses in suspension (ASTM-E1052-20), the antiviral efficiency was more than 99.99% for influenza A (H1N1) and SARS-CoV-2. These results suggest its potential use in antiviral disinfectants, surface coatings, personal protective equipment, and textiles.

• Journal of Food Hygiene and Safety
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• v.33 no.3
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• pp.168-175
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• 2018

The use of microwave-assisted extraction and an acid-base clean-up process to determine the amount of methylmercury (MeHg) in marine products was suggested in order to improve the complicated sample preparation process. The optimal conditions for microwave-assisted extraction was developed by using a 10% NaCl solution as an extraction solution, setting the extraction temperature at $50^{\circ}C$, and holding for 15 minutes to extract the MeHg in marine products. A NaOH solution was selected as a clean-up substitute instead of L-cysteine solution. Overall, 670 samples of marine products were analyzed for total mercury (Hg). Detection levels were in the range of $0.0006{\sim}0.3801{\mu}g/kg$. MeHg was analyzed and compared using the current food code and the proposed method for 49 samples which contained above 0.1 mg/kg of Hg. Detection ranges of methylmercury followed by the Korea Food Code and the proposed method were $75.25(ND{\sim}516.93){\mu}g/kg$ and $142.07(100.14{\sim}244.55){\mu}g/kg$, respectively. The total analytical time of proposed method was reduced by more than 25% compared with the current food code method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.7
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• pp.942-947
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• 2005

This study was investigated to analyze the effect of extracts from the Lepista nuda, on the antioxidant activity to form a part of studies on the functional materials of L. nuda. Antioxidant activity of L. nuda extracts was evaluated by measuring the electron-donating ability (EDA), the superoxide dismutase (SOD)-like activity, and the nitrite-scavenging ability. The EDAs of water and ethanol extracts at the concentration of 1,000 ppm by the rotary heating method from L. nuda were $60.47\%$ and $60.13\%$, respectively and those of water and ethanol extracts by microwave-assisted method were $87.73\%$ and $84.84\%$, respectively. The measurements of SOD-like activity were in the range of $24.58\%\~42.03\%$ at 1,000 ppm. EDA and SOD were increased with the concentrations of extracts. The nitrite-scavenging ability at the concentration of 1,000 ppm was the highest and $29.77\%$ at pH 1.2, and was decreased with an increment of pH value. These results indicated that microwave­assisted water extract from L. nuda showed the highest activities on the EDA and nitrate-scavenging ability, while the rotary heating ethanol extract had the highest effect on the SOD-like activity.

• Food Science and Preservation
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• v.12 no.1
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• pp.62-67
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• 2005

Microwave-assisted extraction (50 W, 2,450 MHz, MAE) with properties of selective heating and subsequent extraction for certain phytochemicals from natural materials was applied to pre-establish the extraction conditions for total yield total phenolics, and electron donating ability (EDA) from Brossica oleacea. The experiments with $50\%$ EtOH solvent showed that 20 mesh in particle size of cabbage flake $(moisture\;4.5\%)$ and 1:10 (g/mL) in the sample to solvent ratio for both raw $(moisture\;90.2\%)$ and flake cabbages were optimal for MAE efficiency. Under these conditions, total yield increased with extraction tim, which was highest for raw cabbage extract in $50\%\;EtOH$ solvent followed by $100\%\;EtOH$ and water. While that of flake cabbage extracts was highest in $50\%\;EtOH$ followed by water and $100\%\;EtOH$. The contents of total phenolics and EDA in extracts gradually increased after 3 min of MAE, which were highest when using $100\%\;EtOH$ solvent followed by $50\%\;EtOH$ and water in raw cabbage and $50\%\;EtOH$ followed by water and $100\%\;EtOH$ in flake cabbage, respectively.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.374-379
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• 2016

When using an ionic liquid as co-solvent, the extraction efficiency of anticancer agent paclitaxel from biomass was dramatically improved. However, the residual ionic liquid had a significant negative effect on convenient and feasibility of following concentration and drying steps. In this study, a novel method was developed for the effective drying of the crude extract obtained from biomass extraction with ionic liquid. The residual ionic liquid was easily and conveniently removed by drying alone after pre-treatment and additional washing of a sample with water. The optimal crude extract/water ratio and mixing time for pre-treatment and crude extract/water ratio for additional washing were 1:70 (w/v), 4 min, and 1:100 (w/v), respectively. In the microwave-assisted drying process, the drying time was 9-fold shorter than in the vacuum oven drying process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.12
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• pp.1491-1496
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• 2007

As an oriental medicinal plant, wild grape (WG, Vitis coignetiae) has been known to contain abundant nutrients compared to grape (Vitis vinifera L.) and as a source of stilbenes, a kind of polyphenol. This study was performed to investigate the antioxidative activity of WG extracts by measuring electron donating ability (EDA), nitrite scavenging ability (NSA), super oxide dismutase (SOD)-like activity and total polyphenol content (TPC). The extracts were obtained using microwave-assisted extraction (microwave power: 90 W, extraction time: 5 min, extractant: water, 50 and 100% ethanol). EDAs, SOD-like activities and TPCs were the highest at 50% ethanol extracts while conversely lowest at 100% ethanol extracts. EDAs of 50% and 100% ethanol extracts at 1.6 g/dL concentration, $97.70{\pm}0.55\;and\;98.05{\pm}0.36%$, were higher than those of 0.1 and 1% L-ascorbic acids, $101.44{\pm}0.98%\;and\;99.43{\pm}0.78%$, respectively. At the concentration of 1.6 g/dL, 50% ethanol extract showed lower NSA (pH 1.2) than water extract unlike EDA, TPC and SOD-like activity. Regarding TPCs of WG extracts, the activities were the highest at 50% ethanol extracts (1.6 g/dL: $38.76{\pm}0.23$ mM gallic acid equiv.) followed by water and 100% ethanol extracts. The results suggest the usefulness of developing functional foods using antioxidative active compounds of WG with high polyphenol contents.