• Journal of the Korean Chemical Society
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• v.56 no.6
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• pp.725-730
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• 2012

HEMA (2-hydroxyethyl methacrylate), EGDMA (ethylene glycol dimethacrylate; cross-linker), MMA (methyl methacrylate) and AA (acrylic acid) were copolymerized with ethyl gallate and propyl gallate as additives in the presence of AIBN (2,2'-azobisisobutyronitrile; initiator). The measurement of physical properties of the produced copolymers exhibited that refractive index, water content, visible transmittance, tensile strength, and contact angle were in the range of 1.433-1.435, 38.71-38.99%, 85.4-88.8%, 0.2468-0.2740 kgf and $49.77-36.29^{\circ}$, respectively. The transmittances of the copolymers were measured to be in the range of 49.0-7.4% and 71.0-43.4% for UV-B and UV-A, respectively, indicating that the copolymers have UV-blocking effect. The produced copolymers containing ethyl gallate and propyl gallate satisfied the basic physical properties required for the fabrication of hydrogel contact lenses. The copolymers showed an increase of wettability and UV-blocking effects while having no significant change in water content compared to the gallate-free copolymers.

• Journal of the Korean Wood Science and Technology
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• v.37 no.2
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• pp.164-170
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• 2009

The bark of Acer barbinerve was extracted with 70% aqueous acetone and the organic extracts were concentrated to small volume using rotary evaporator and then fractionated successively with n-hexane, dichloromethane, ethyl acetate and water. The chromatographic separation of ethyl acetate soluble fraction led to the isolation of five phenolic compounds. By means of spectroscopic method, the structures of these compounds were identified to methyl gallate (1), methyl gallate-4-O-${\beta}$-D-glucose (2), (+)-catechin (3), (-)-epicatechin (4) and (-)-epicatechin-3-O-gallate (5). These compounds (1-5) have not been reported in this plant yet.

• Journal of Applied Biological Chemistry
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• v.49 no.1
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• pp.24-27
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• 2006

Four ursane-type triterpenoids, 2${\alpha}$,3${\alpha}$,19${\alpha}$-trihydroxy-24-norurs-4(23),12-dien-28-oic acid (1), 4(R),23-epoxy-2${\alpha}$,3${\alpha}$,19${\alpha}$-trihydroxy-24-norurs-12-en-28-oic acid (2), myrianthic acid (3), and tormentic acid (4), and a phenolic compound, ethyl gallate (5), from an EtOAc-soluble extract of the stems of Rumex japonicus, were subjected to in vitro bioassays to evaluate advanced glycation end products (AGEs) and rat lens aldose reductase (RLAR) inhibitory activity. Compounds 1 and 5 exhibited a significant inhibitory activity on AGEs formation with $IC_{50}$ value of 87 ${\mu}M$ and on RLAR with $IC_{50}$ value of 14.3 ${\mu}M$, respectively. Ethyl gallate (5) was isolated for the first time from this plant.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.3
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• pp.188-192
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• 2008

Methyl gallate isolated from bark of the tree Rhus verniciflua Stokes has significant antimicrobial activity against the fish pathogenic bacteria Edwardsiella tarda and Vibrio anguillarum. To evaluate the antimicrobial activity of gallate derivatives, eight alkyl gallates were tested. Ethyl gallate and propyl gallate had the highest activities, with MICs of $15.6-31.3{\mu}g/mL$ against E. tarda. For V. anguillarum, propyl gallate and butyl gallate were highly effective, with MICs of $7.81-31.3{\mu}g/mL$. When used in combination with antibiotics, methyl gallate exhibited synergistic effects with oxytetracycline against E. tarda and with norfloxacin against V. anguillarum. These results suggest that short-chain alkyl gallates can be used as alternatives to antibiotics against the fish pathogenic bacteria.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.212.2-212.2
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• 2003

In the course of searching for BACE1 (${\beta}$-secretase) inhibitors from natural products, the ethyl acetate soluble fraction of green tea, which was suspected to be rich in catechin content, showed potent inhibitory activity. (-)-Epigallocatechin gallate, (-)-epicatechin gallate, and (-)-gallocatechin gallate ware isolated with IC$\_$50/ values of 1.6${\times}$10$\^$-6/ M, 4.5${\times}$10$\^$-6/ M, and 1.8${\times}$10$\^$-6/ M, respectively. Seven additional authentic catechins were tested for a fundamental structure-activity relationship. (-)-Catechin gallate, (-)-gallocatechin, and (-)-epigallocatechin significantly inhibited BACE1 activity with IC$\_$50/ values of 6.0${\times}$10$\^$-6/ M, 2.5${\times}$10$\^$-6/ M, and 2.4${\times}$10$\^$-6/ M, respectively. (omitted)

• Natural Product Sciences
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• v.14 no.3
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• pp.202-205
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• 2008

The antioxidant activity of Paeonia suffruticosa (Paeoniaceae) was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl). The methanolic extract of P. suffruticosa showed the strong antioxidant activity. The antioxidant activity of ethyl acetate soluble fraction was stronger than that of the others ($IC_{50}$, $1.2\;{\mu}g/mL$), and the fraction was subjected to purification by repeated silica gel and Sephadex LH-20 column chromatography. Suffruticosol A, suffruticosol B, methyl gallate, and gallic acid, were isolated from the ethyl acetate soluble fraction. Their structures were elucidated by physico-chemical and spectroscopic studies.

• ALGAE
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• v.32 no.4
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• pp.379-388
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• 2017

In the present study, we enhanced the phenolic content of 70% ethanol extracts of Spirogyra sp. (SPE, $260.47{\pm}5.21$ gallic acid equivalent $[GAE]mg\;g^{-1}$), 2.97 times to $774.24{\pm}2.61GAE\;mg\;g^{-1}$ in the ethyl acetate fraction of SPE (SPEE). SPEE was evaluated for its antiradical activity in online high-performance liquid chromatography-ABTS analysis, and the peaks with the highest antiradical activities were identified as gallic acid derivatives containing gallic acid, methyl gallate, and ethyl gallate. Isolation of ethyl gallate from Spirogyra sp. was performed for the first time in this study. In ultraviolet B (UVB)-irradiated keratinocytes (HaCaT cells), SPEE improved cell viability by 8.22%, and 23.33% and reduced accumulation of cells in the sub-$G_1$ phase by 20.53%, and 32.11% at the concentrations of 50 and $100{\mu}g\;mL^{-1}$, respectively. Furthermore, SPEE (50 and $100{\mu}g\;mL^{-1}$) reduced reactive oxygen species generation in UVB-irradiated zebrafish by 66.67% and 77.78%. This study suggests a protective activity of gallic acid and its derivatives from Spirogyra sp. against UVB-induced stress responses in both in vitro and in vivo models, suggesting a potential use of SPEE in photoprotection.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.2
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• pp.171-179
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• 2012

This study is focused on finding new natural materials that have antimicrobial activity. We found that 3 plants extracts, Magnolia sieboldii K. Koch (M. sieboldii K. Koch), Rhus chinensis (R. chinensis) and Metasequioa glyptostroboides (M. glyptostroboides), have antimicrobial activities by disk diffusion method. We determined the Minimum Inhibitory Concentation (MIC) of each and found that 0.3 ~ 0.35 % of M. glyptostroboides essential oil and 0.35 ~ 0.4 % of M. sieboldii K. Koch extracts inhibited fungal growth and 0.45 ~ 0.5 % of R. chinensis extracts inhibited bacterial growth. We isolated compounds from extracts and verified what have antimicrobial activity. As a result we found that caryophyllene oxide and caryophyllene isolated from M. glyptostroboides, costunolide and dehydrocostus lactone from M. sieboldii K. Koch and ethyl gallate, ethyl-3-gallate from R. chinensis have antimicrobial activities. In accordance with antimicrobial activity, O/W cosmetic emulsion containing mixture of 3 plants extracts showed preservative efficacy against both bacteria and fungi. Based on the above data we suggest that extracts from M. siebodii K. Koch, R. chinensis, and M. glyptostroboides, replace chemical synthetic preservatives and be applied as a natural preservative.

• KSBB Journal
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• v.14 no.5
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• pp.517-522
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• 1999

A green tea used in this experiment was cultivated at Bosung (Chonnam) and purchased from a domestic market. The extract at 5$0^{\circ}C$ water from the powder of green tea partitioned with chloroform and ethyl acetate. The resulting solution was further purified with a chromatographic column (4.6$\times$250 mm, 15${\mu}{\textrm}{m}$, Lichrospher 100RP-18). Finally separation was achieved on a $\mu$-Bondapak $C_18$(3.9$\times$300mm, 10${\mu}{\textrm}{m}$) column. The elution order of the catechin compounds contained in the green tea was EGC(Epigallocatechin, C(catechin), EC(Epicatechin), EGCG(Epigallocatechin Gallate) and ECG(Epicatechin Gallate). From the experimental results the mobile phase for isolating EGCG from the extract consisted of 0.1% acetic acid in water/acetonitrile, 87/13%(v/v). The flow rate of mobile phase was 1.0 $m\ell$/min, and UV wavelength was fixed at 280 nm. 121.3 mg of EGCG, higher than 98% of purity, was obtained from 5 g of dry green tea.

• YAKHAK HOEJI
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• v.37 no.5
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• pp.453-457
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• 1993

Platelet anti-aggregating activities were tested with analogs of protocatechuic acid and gallic acid. Six of them which showed comparable inhibitory effects with aspirin against collagen induced platelet aggregation were selected and their anti-thrombotic effects were evaluated in the mouse thrombosis model and compared with those of aspirin and paeonol. At the dose of 50 mg/kg, p.o., ethyl gailate(13) treated group showed higher % of recovery within 6 min of thrombotic challenge and lower mortality within 5 min than aspirin treated group.