• Preventive Nutrition and Food Science
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• v.22 no.2
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• pp.131-137
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• 2017

Maximum production of isoquercetin and quercetin simultaneously from rutin by subcritical water hydrolysis (SWH) was optimized using the response surface methodology. Hydrolysis parameters such as temperature, time, and $CO_2$ pressure were selected as independent variables, and isoquercetin and quercetin yields were selected as dependent variables. The regression models of the yield of isoquercetin and quercetin were valid due to the high F-value and low P-value. Furthermore, the high regression coefficient indicated that the polynomial model equation provides a good approximation of experimental results. In maximum production of isoquercetin from rutin, the hydrolysis temperature was the major factor, and the temperature or time can be lower if the $CO_2$ pressure was increased high enough, thereby preventing the degradation of isoquercetin into quercetin. The yield of quercetin was considerably influenced by temperature instead of time and $CO_2$ pressure. The optimal condition for maximum production of isoquercetin and quercetin simultaneously was temperature of $171.4^{\circ}C$, time of 10.0 min, and $CO_2$ pressure of 11.0 MPa, where the predicted maximum yields of isoquercetin and quercetin were 13.7% and 53.3%, respectively. Hydrolysis temperature, time, and $CO_2$ pressure for maximum production of isoquercetin were lower than those of quercetin. Thermal degradation products such as protocatechuic acid and 2,5-dihydroxyacetophenone were observed due to pyrolysis at high temperature. It was concluded that rutin can be easily converted into isoquercetin and quercetin by SWH under $CO_2$ pressure, and this result can be applied for SWH of rutin-rich foodstuffs.

• Journal of Food Hygiene and Safety
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• v.31 no.5
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• pp.356-364
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• 2016

In vivo genotoxic potential of isoquercetin, a plant common flavonoid, in comparison with quercetin was investigated for the DNA breakage and the clastogenicity endpoints. Male ICR mice were administered by oral gavage for 3 days with $3{\times}0.5%$ carboxymethyl cellulose (CMC), 3 ${\times}$ isoquercetin (250, 500 mg/kg/day), 3 ${\times}$ quercetin (250, 500 mg/kg/day) and 2 ${\times}$ ethyl methanesulfonate (EMS, 200 mg/kg/day). Tissues were collected 48 hours after the first treatment and within 3 hours after the last treatment. The DNA damages were evaluated using Comet assay in liver and stomach, while the clastogenicities were determined using micronucleus test in bone marrow of same animals. The treatment of isoquercetin as well as quercetin did not cause the DNA damages in liver and stomach, and not induce the frequencies of micronucleus polychromatic erythrocytes in bone marrow. In conclusion, isoquercetin as well as quercetin did not cause the DNA breakages and the chromosomal damages in vivo system in these study conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.12
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• pp.1858-1864
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• 2014

In the present investigation, the anti-diabetic potential of 80% ethanol extract of Eleutherococcus senticosus leaves (EEES) was examined based on ${\alpha}$-glucosidase inhibitory activities. EEES was sequentially fractionated with n-hexane, chloroform, ethyl acetate (EtAOc), n-butanol, and $H_2O$. Of the various fractions, EtAOc fraction effectively inhibited ${\alpha}$-glucosidase activity by 68.05%. Therefore, EtAOc fraction was selected for further isolation and identification studies. EtAOc fraction was separated by medium pressure liquid chromatography with silica and ODS gel to yield eight fractions (EAA~EAH). Based on the results of ${\alpha}$-glucosidase inhibitory activity, EAH fraction was re-chromatographed to yielded four more fractions (EAHA~EAHD). Of these, EAHC fraction showed higher ${\alpha}$-glucosidase inhibitory activity of 93.60%. EAHC fraction was re-chromatographed and yielded EAHCA and EAHCB fractions. Further, identification and chemical structures of these two fractions were analyzed using $^1H$-NMR, $^{13}C$-NMR, and mass spectra data. Based on the results of the spectral data, the isolated compounds were identified as hyperoside and isoquercetin. Results of the present study indicate that the isolated compounds, hyperoside, and isoquercetin from leaves of E. senticosus could be used for the development of new anti-diabetic drugs.

• Journal of Applied Biological Chemistry
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• v.62 no.4
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• pp.367-374
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• 2019

Euphorbia humifusa Willd (EuH), called Ttang-Bin-Dae in Korea, is a traditional medicinal plant widely used for its anti-inflammatory and antiviral activity. Ethyl acetate (EA) extracts of EuH (EA/EuH) inhibit invasion and metastasis by inhibiting tumor necrosis factor TNFá-induced matrix metalloproteinases (MMP)-9 expression in human breast cancer cells. However, the bioactive components of EA/EuH mediating the inhibition of MMP-9 expression have not been identified. In the present study, three bioactive constituents of EA/EuH were isolated using high-performance liquid chromatography. Nuclear magnetic resonance spectroscopy revealed isoquercetin, avicularin, and astragalin as the bioactive compounds responsible for preventing TNFα-induced MMP-9 mRNA expression in breast cancer cells. These findings suggest that isoquercetin, avicularin, and astragalin could be used as valuable anti-metastatic agents against metastatic cancers.

• Journal of Applied Biological Chemistry
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• v.58 no.1
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• pp.51-54
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• 2015

Flavonoids from Morus alba fruits were evaluated for recovery effect on the damage of alloxan-induced pancreatic islet in zebrafish. Alloxan treatment on the zebrafish embryo surely decreased the pancreatic islet size (p <0.001). Rutin, isoquercetin, and quercetin very significantly recovered the size (p <0.001) and the fluorescence intensity of pancreatic islet.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.3
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• pp.54-63
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• 2018

Nymphaea tetragona, also known as waterlilies, is aquatic plant in the family of Nymphaeceae. Three flavonoids(3, 4, and 5) and one mixed flavonoids were separated from this plant. The mixed flavonoid consisted of two flavonoids; a well-known quercetin(1) and a new natural flavonoid(2). The latter also has two chiral centers and their configurations were established by ROESY experiment. Two glycoflavonoids were determined as isoquercetin and quercetin-3-O-${\beta}$-xyropyranosyl-($1{\rightarrow}2$)-${\beta}$-galactopyroside. The $^1H$ NMR spectra for 4 and 5 dissoloved in $DMSO-d_6$ solvent showed resonance proximity and and severely overlap in the glycoside region, hindering the determination of the configurations of the stereogenic centers of the sugar moieties. This problem was solved through the spin simulation. Here, the exact NMR parameters for the sugar moieties of 4 and 5 were listed.

• International Journal of Industrial Entomology and Biomaterials
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• v.35 no.2
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• pp.89-96
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• 2017

Various health promoting effects of steamed and freeze-dried mature silkworm powder (SMSP) have been reported. However, it is not still clear which substances in SMSP are responsible for those health promoting effects yet. In this study, we examined and compared the quantities of phytochemicals in SMSP and freeze-dried mulberry leave powder (FMLP). To investigate the optimal solvent for extracting phytochemicals from SMSP and FMLP, we used four different solvents. Among them, 80% ethanol extracts from SMSP and FMLP contained the highest amount of five flavonoids examined. In addition, FMLP had high contents of flavonoids compared with those of SMSP. The amounts of rutin, isoquercetin, astragalin, quercetin, and kaempferol in FMLP were $5.078{\pm}0.187mg/g$, $5.162{\pm}0.083mg/g$, $2.989{\pm}0.061mg/g$, $3.317{\pm}0.236mg/g$, and $2.243{\pm}0.237mg/g$, respectively, while the amounts of rutin, isoquercetin, astragalin, quercetin, and kaempferol in SMSP were $0.171{\pm}0.024mg/g$, $0.252{\pm}0.032mg/g$, $0.374{\pm}0.031mg/g$, $0.645{\pm}0.063mg/g$, and $0.0512{\pm}0.047mg/g$, respectively. Taken together, SMSP could be a source for providing various and readily absorbable flavonoids.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.266-271
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• 2023

The antioxidant capacity of the Psidium guajava leaf extracted with EtOH and their MeOH fractions using column chromatography were evaluated by 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging assays, total phenolic and flavonoid content, and Superoxide dismutase (SOD) assay. To determine its utility as a functional material, the crude extract was fractionated by flash column chromatography on ODS using a stepwise elution with combinations of MeOH/H₂O and then all the fractions were also investigated. In the results of antioxidant activities, the 40% and 60% MeOH fractions show the meaningful values, and then the two fractions were selected to examine the isolation and identification of the major constituents via HPLC and nuclear magnetic resonance. Further purification led to isolation of two quercetin derivatives; quercitrin (1) and isoquercetin (2). Through SOD assay, some methanol fractions via column chromatography and isolated compounds showed improved antioxidant activities compared to the extract.

• Microbiology and Biotechnology Letters
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• v.51 no.1
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• pp.83-92
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• 2023

In this study, bioconversion of rutin to quercetin was confirmed by the fermentation of Korean indigenous probiotics and tartary buckwheat. Based on whole genome sequencing of 17 probiotics species, α-rhamnosidase, related to bioconversion of isoquercetin (quercetin 3-β-D glucoside) from rutin, is identified in the genome of CBT BG7, LC5, LR5, LP3, LA1, and LGA1. β-Glucosidase, related to bioconversion of isoquercetin to quercetin, is identified in the genome of all 17 species. Among the 17 probiotics species, 6 probiotics including CBT BG7, LR5, LP3, LA1, LGA1 and ST3 performed the bioconversion of rutin to quercetin up to 21.5 ± 0.3% at 7 days after fermentation. The fermentation of each probiotics together with enzyme complex Cellulase KN^® was conducted to reduce the time of bioconversion. As a result, CBT LA1 which showed the highest yield of bioconversion of 21.5 ± 0.3% when the enzyme complex was not added showed high bioconversion yield of 84.6 ± 0.5% with adding the enzyme complex at 1 day after fermentation. In particular, CBT ST3 (96.2 ± 0.4%), SL6 (90.1 ± 1.4%) and LP3 (90.0 ± 0.4%) showed high yield of bioconversion more than 90%. In addition, such probiotics including high levels in quercetin indicated the inhibitory effects of NO production in LPS-induced RAW264.7 cells. In this study, we confirmed that the fermentation of Korean indigenous probiotics and enzyme complex together with roasted tartary buckwheat increased the content of quercetin and reduced the time of bioconversion of rutin to quercetin which is a bioactive compound related to anti-inflammatory, antioxidants, anti-obesity, and anti-diabetes.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.4
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• pp.341-351
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• 2019

In this study, we investigated anti-oxidative and anti-bacterial constituents from Rhododendron weyrichii leaves. DPPH and ABTS⁺ radical scavenging activities were screened for the ethanol extract and solvent fractions. Potent scavenging activities were appeared from the extract, ethyl acetate (EtOAc) and n-butanol (BuOH) fractions. Upon the anti-bacterial tests using Staphylococcus epidermidis and Propionibacterium acnes, extract, n-hexane (Hex) and EtOAc fractions showed strong activities. To isolate the active constituents, the EtOAc fraction was further purified to afford five phytochemicals; ursolic acid (1), corosolic acid (2), asiatic acid (3), astragalin (4) and isoquercetin (5). All of the compounds 1-5 were isolated for the first time from this plant. Among the isolates, the compound 4 and 5 showed strong DPPH and ABTS⁺ radical scavenging activities. Also, compound 3 exhibited the most potent anti-bacterial activity. In addition, the content of astragalin isolated from this plant was determined by UPLC and the quantity was about 8.1 mg/g for the 70% ethanol extract and 34.8 mg/g for the EtOAc fraction. Based on these results, it is concluded that R. weyrichii extract could be potentially applicable as anti-oxidative and anti-bacterial ingredients in cosmetic formulations.