• Applied Biological Chemistry
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• v.48 no.3
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• pp.280-284
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• 2005

Several biological activities of Rhododendron mucronulatum were investigated. The electron donating abilities of ethanol extracts of Rhododendron mucronulatum were more than 90% at 100 ppm, 500 ppm and 1,000 ppm. Xanthine oxidase was inhibition about 46% by the ethanol extracts of R. mucronulatum at 500 ppm 48% of tyrosinase activity relating to skin-whitening was shown at 1,000 ppm. Uniquely, the anti-microbial effects of water extract and ethanol extract were shown only on Staphylococcus aureus. The water extract 1 mg/disc showed the higher activity than ethanol extract. The growth inhibition effect of each sample on lung cancer (A549) and melanoma (B16F10) cell lines were over 70% at 1,000 ppm, while the effects on the melanoma (G361) and liver cancer (HepG2) were about 50% at the same concentration.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.3
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• pp.55-66
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• 2012

This study was carried out to investigate vegetation of Rhododendron mucronulatum habitat in Mt. Biseul to recommend basic information for synecological characteristics and management methods. The survey was carried out from May to July, 2011 and totally 46 vegetation data including 42 families 93 genera 108 species 16 varieties and 5 forma were collected and analyzed. Among the investigated 129 taxa, the numbers of rare plant resources were summarized as 19 taxa; The rare plants designated by Korea Forest Service, the specific plants by floristic region and the endemic plants were listed as 3 taxa, 15 taxa and 4 taxa, respectively. Rhododendron mucronulatum habitat of Mt. Biseul was classified into 3 plant communities (Carex lanceolata-Rhododendron mucronulatum community, Potentilla dickinsii-Selaginella rossii community, Carex lanceolata-Quercus mongolica community). Carex lanceolata-Rhododendron mucronulatum community was subdivided into Tripterygium regelii subunit and Miscanthus sinensis for. purpurascens subunit by human interference degree. And synecology, syndynamics, synchorology of these plant communities were identified, and Site-species ordination analysis by Principal Coordinate Analysis (PCoA) reflected that human impact, soil moisture condition were main ecological factors determining the distribution pattern of classified plant communities. Therefore these plant communities correspond to quite distinctive 4 habitat types : unstable-dry type=Miscanthus sinensis for. purpurascens subunit, unstable-moderate type=Tripterygium regelii subunit, stable-dry type=Potentilla dickinsii-Selaginella rossii community, stable-moderate type=Carex lanceolata-Quercus mongolica community. Finally, through the vegetational diagnosis, proper management methods such as a limit on the access of visitors, planting of native woody plants after removing unwanted vines or grass were suggested.

• Journal of Forest and Environmental Science
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• v.38 no.3
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• pp.159-173
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• 2022

Genus of Rhododendron has been used in traditional medicine since ancient times and is known to be effective in immune function, inflammation, and cold symptoms. And the reason for this activity is the flavanonol type among flavonoids in the genus of Rhododendron. Among the flavanonol types, Taxifolin-3-O-arabinopyranoside was isolated from the root of native R. mucronulatum in Korea, and the structure was finally identified through HPLC, LC-MS/MS, ¹H-NMR, and ¹³C-NMR. Taxifolin-3-O-arabinopyranoside is a compound mainly found in R. mucronulatum, a representative species of the genus of Rhododendron, and exhibits antioxidant, anti-inflammatory, and anti-atopic activities. In this study, Taxifolin-3-O-arabinopyranoside was chemotaxonomic significant in 5 species of the genus Rhododendron native to Korea (R. mucronulatum, R. mucronulatum var. ciliatum, R. schlippenbachii, R. yedoense var. Poukhanense, R. japonicum for. Flavum). Compared with the existing literature, Taxifolin-3-O-arabinopyranoside was identified for the first time in 4 species of Rhododendron except for the R. mucronulatum.

• Journal of Environmental Science International
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• v.20 no.4
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• pp.527-540
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• 2011

The investigation was made about distribution and ecological characteristics of Rhododendron mucronulatum var. mucronulatum, R. dauricum and R. schlippenbachii on Mt. Changbai in China. The Ericaceae plants are known to be highly ornamental and easy to cultivate. The results of investigations are like followings. The plant species diversity was the highest in habitats of R. mucronulatum var. mucronulatum, followed by those of R. schlippenbachii and R. dauricum. R. mucronulatum var. mucronulatum community was found in the northwest exposure areas of 300m in altitude. Corylus heterophylla, Carex humilis var. nana, Atractylodes japonica species also grew in the R. mucronulatum var. mucronulatum community. R. dauricum communities were widely distributed in the west exposure areas of 1226-1860m above sea level. R. schlippenbachii populations were found in areas of under 300m above sea level, which has dry soil. But humidity of air was relatively high in the place. Artemisia japonica, Lespedeza bicolor and Dactylis glomerata were found around the habitats of R. schlippenbachii. Phalanx type of plants were dominant near the habitats of Ericaceae plants as 61%. Further, there appeared higher plant life totalling to 72 taxa comprising 54 species, 16 varieties and 2 forma with 31 families and 59 genuses at the whole survey area. Among these, Compositae plants excellent in resistance to environment was surveyed the most, accounting for 30.0%.

• Korean Journal of Agricultural Science
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• v.12 no.1
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• pp.31-36
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• 1985

Peroxidase banding patterns were obtained by disc electrophoresis of leaf extractions from flowering plants, R. mucronulatum, R. yedoense var. poukhanese, and R. schlippenbachii. A total of 21 peroxidase isoenzymes were resolved from these species, R. mucronulatum, P. yedoense var. poukhanese, and R. schlippenbachii. Five identical peroxidase isoenzymes were resolved in R. yedoense var. poukhanese and R. schlippenbachii. It means that there is a close relationships between two species. The peroxidase banding patterns of all three Rhododendron species were not correlated with each other on percentage total density of each band. The correlation coefficients for peroxidase band densities compared with leaf areas and leaf width/length ratios of Rhododendron plants were not significant at the 5% level. Wide variation was observed in R. yedoense var. poukhanese and R. schlippenbachii compared with R. mucronulatum.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.273-279
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• 2005

To develop cosmetics using Jindalae flowers (Rhododendron mucronulatum), the surface tensions of extracts were measured and the properties and stability of cream with extracts were investigated. The surface tension of 0.1% ethanol extract was 30.42 mN/m and that of distilled water was 72.2 mN/m. The surface tension of cream with 0.1% ethanol extract was similar to that of sample cream and the measured pH were weakly alkalic. The surface tension of 1% ethanol extract was the lowest value of 24.98 mN/m, the measured pH of cream with 1% ethanol extract was weakly acidic and the particle size of cream was stable. According to an oscillatory test, linear viscoelastic region was extended by adding of 1% water extract and 1% ethanol extract to cream, indicating that the cream had greater enhanced resistance for preserving inner structure as compared to outside stress.　Besides, as a result of the diminished loss angle of ethanol extract cream, the elasticity of cream was increased more than that of sample cream and cream with 0.1% ethanol extract. In contrast, in the case of the increased loss angle of water extract cream, the viscosity of cream was increased. In conclusion, Rhododendron mucronulatum can be deliberated as a cosmetic material because 0.1% water and ethanol extracts showed efficacious physiological activities and cream with 1% extracts could extend linear viscoelastic region.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.2
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• pp.105-114
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• 2013

This study was carried out to find growth increasing methods of Rhododendron mucronulatum in Mt. Biseul. 4 treatments(heavy pruning, light pruning, non-pruning+fertilization, non-pruning(control)) were used in the study area with different pruning methods. Growth characteristics of new shoot, number of creation of flower buds and leaf buds in new shoot were analysed. Significant differences were observed among the treatments and stem diameter degree. Diameter, length of new shoots and the number of flower buds, leaf buds per new shoots increased in the pruning treatments. But heavy pruning showed more effective growth increasing way than light pruning. Non-pruning and fertilization treatments were not effective to increase growth of Rhododendron mucronulatum. And pruning at the end of May was the most effective way for growth of new shoot.

• Korean Journal of Pharmacognosy
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• v.38 no.3 s.150
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• pp.227-233
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• 2007

Seven compounds were isolated from the n-BuOH soluble fraction of stem of Rhododendron mucronulatum as cytotoxic principles against brine shrimp lethality test. On the basis of spectral data, seven compounds were identified as (-)-catechin (1), (+)-epicatechin (2), taxifolin (3), scopoletin (4), quercetin (5), $taxifolin-3-O-{\alpha}-L- arabinopyranoside$ (6), and astragalin (7). Among tested compounds, $taxifolin-3-O-{\alpha}-L-arabinopyranoside$ (6) exhibited potent activity with $LC_{50}$ value at 4.6 ${\mu}g/ml$.

• Journal of Applied Biological Chemistry
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• v.60 no.1
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• pp.29-33
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• 2017

The methanol extract of Rhododendron mucronulatum for. albiflorum (RMFA) stems inhibited aldose reductase (AR) activity. The RMFA fractions obtained by stepwise extraction with solvents of different polarity were tested for AR inhibition in vitro using the lens of a rat. Among them, the ethyl acetate (EtOAc) fraction inhibited AR more than the other fractions. Quercetin (1) from the EtOAc fraction showed a high AR inhibition with $IC_{50}$ of $2.11{\mu}M$. The stems of RMFA contained the highest amount (5.12 mg/g extract) of quercetin. Our results suggest that RMFA, which contained quercetin, could be a useful material for the development of supplementary functional foods.

• Natural Product Sciences
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• v.11 no.2
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• pp.97-102
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• 2005

From the n-BuOH soluble traction of the 70% aqueous acetone extract of Rhododendron mucronulatum stem, twelve compounds were isolated. On the basis of spectral data, they were identified as scopoletin (1), (+)-taxifolin (2), quercetin (3), (-)-catechin (4), (+)-epicatechin (5), scopolin (6), lyoniside (7), ssioriside (8), fraxin (9), $(+)-lyoniresinol-3{\alpha}-O-{\beta}-D-glucopyranoside$ (10), $(+)-taxifolin-3-O-{\alpha}-L-arabinopyranoside$ (11), and astragalin (12), respectively. All isolated compounds were tested antioxidant activity against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical. Compounds 2 and 3 showed the potent antioxidant activity, and compounds 5, 8, and 11 showed moderate activity.