• Korean Journal of Medicinal Crop Science
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• v.19 no.4
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• pp.251-256
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• 2011

The leaves of Hippophae rhamnoides were extracted with methanol and then further fractioned with hexane, ethyl acetate, butanol and water in order to investigate biological activity. Two flavonol glycosides were isolated and identified from ethyl acetate soluble fraction, which showed the strongest antioxidant activity ($RC_{50}$ = 4.33 ${\mu}g/ml$). Isolated two compounds have shown strong free radical scavenging activity. Especially, quercetin 3-O-glucoside ($RC_{50}$ = 2.60 ${\mu}g/ml$) was more active than ${\alpha}$-tocopherol ($RC_{50}$ = 4.67 ${\mu}g/ml$). Total phenol and flavonoid contents were the highest to 4.17 and 1.14 mg/ml in the ethyl acetate soluble fraction. In addition, ethyl acetate soluble fraction was shown to the strongest ${\alpha}$-glucosidase inhibitory activity ($IC_{50}$ = 137.88 ${\mu}g/ml$) among the fractions. The results suggest that leaves of H. rhamnoides could be a potential source of natural antioxidant.

• Natural Product Sciences
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• v.16 no.1
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• pp.1-5
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• 2010

$\beta$-Glucuronidases (E.C. 3.2.1.31) from Escherichia coli, Helix pomatia, and bovine liver activity have been investigated on 7-O-glucuronides (baicalin, wogonoside, and luteolin-7-O-glucuronide) and 3-O-glucuronides (quercetin-3-O-glucuronide and kaempferol-3-O-glucuronide). Bovine liver enzyme was not active on any of these substrates. E. coli and H. pomatia enzymes were active on 7-O-glucuronides, however, 3-O-glucuronides were resistant to $\beta$-glucuronidase hydrolysis. These results suggest that glucuronic acid at 7-position is more susceptible to E. coli and H. pomatia $\beta$-glucuronidases than that at 3-position. In addition, the subtle difference of aglycone structure on 7-O-glucuronides affected the preference of enzyme. E. coli enzyme was favorable for the hydrolysis of baicalin, however, H. pomatia enzyme was found to be efficient for the hydrolysis of wogonoside. Both enzymes showed the similar hydrolytic activity towards luteolin-7-O-glucuronide. When the Scutellaria baicalensis crude extract was subjected to enzymatic hydrolysis, baicalin and wogonoside were successfully converted to their aglycone counterparts with H. pomatia at 50 mM sodium bicarbonate buffer pH 4.0. Accordingly, the enzymatic transformation of glycosides may be quite useful in preparing aglycones under mild conditions.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.176-184
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• 2018

In the present study, we investigated the antioxidative properties, cellular protective effects and component analyses of 50% ethanol extract, ethyl acetate fraction and aglycone fraction obtained from Lysimachia christinae Hance (L. christinae Hance). In the evaluation of antioxidative properties, the free radical scavenging activities ($FSC_{50}$) of 50% ethanol extract, ethyl acetate fraction and aglycone fraction were 146.8, 22.2 and $27.2{\mu}g/mL$, respectively and total antioxidant capacities ($OSC_{50}$) were 29.3, 2.9 and $4.5{\mu}g/mL$, respectively. The ethyl acetate fraction showed the highest free radical scavenging activity and total antioxidant capacity. Also, the cellular protective effects (${\tau}_{50}$) of 50% ethanol extract, ethyl acetate fraction and aglycone fraction on $^1O_2$ induced photohemolysis of human erythrocytes were 26.9, 57.5 and 103.9 min at $5{\mu}g/mL$, respectively. In particular, ${\tau}_{50}$ of the aglycone fraction exhibited a higher cellular protective effect than that of (+)-${\alpha}$-tocopherol (37.7 min). The cell viability of the ethyl acetate fraction on the UVB-induced cell damage increased up to 90.1%. In addition, the ethyl acetate fraction ($5-25{\mu}g/mL$) showed cellular protective effects on the $H_2O_2-induced$ cell damages in a dose-dependent manner. TLC, HPLC, UV-vis spectroscopy and LC-MS were used to analyse components of the ethyl acetate fraction and the main components were quercetin, kaempferol and their glycosides. In conclusion, L. christinae Hance extract/fraction can function as antioxidants to protect the skin exposed to UV radiation and may also be used as a novel functional cosmetic material, for example, an antioxidant against skin photoaging.