• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.11 no.2
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• pp.223-225
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• 2008

Rhododendron species is one of the largest and most diverse genera in the plant kingdom, comprising over 800 species and existing all over the globe. Grayanotoxin intoxication is caused by ingestion of honey and flowers. Grayanotoxin exists in honey, flowers, pollen, and nectar of the Rhododendron species. Grayanotoxin-intoxicated patients may present with nausea, vomiting, dizziness, weakness, hypotension, bradycardia, and syncope for several hours. We report a case of grayanotoxin intoxication associated with mental changes. A 9-year-old male presented with impaired consciousness and delirium 26 hours after eating about 10 rhododendron sclippenbachii flowers. A brain MRI and EEG were normal. Parenteral fluids were administered and these symptoms resolved completely in 17 hours.

• 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 Clinical Toxicology
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• v.7 no.2
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• pp.180-182
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• 2009

It is well known that Rhododendron sclippenbashii contains the toxic material grayanotoxin. So, Koreans do not eat it, but they do eat azalea although it contains grayanotoxin. That is why there have been no reports about Rhododendron sclippenbashii intoxication after ingesting it intentionally, not accidentally. In this case, the patient was admitted to the emergency room with several toxic symptoms after intentionally consuming 50 blossoms of Rhododendron sclippenbashii to get rid of thirst. Treatment with saline infusion and atropine was successful and the outcome was favorable enough in this case to produce a complete cure without any sequelae at discharge. But toxic symptoms were seen for 24 hours, although the symptoms usually fade in 9 hours. Therefore, we should carefully treat and observe, for over 24 hours, the patient who intentionally ingests about 50 blossoms of Rhododendron sclippenbashii.

• 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.

• Korean Journal of Environment and Ecology
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• v.11 no.4
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• pp.397-406
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• 1998

To investigate the structure and the conservation strategy of natural forest at Taech'ongbong-Hangyeryong Area in Soraksan. 45 plots(20m*20m) set up with random sampling method were surveted. Four groups - Quercus mongolica - Acer pseudosieboldianum community, Avies nephrolepis - Tilia amurensis - Quercus mongolica community, Abies nephrolepis - Taxus cuspidata community, Abies nephrolepis - Qurecusmongolica community - were classified by cluster analysis. High positive correlations were proved between Abies nephrolepis and Betula ermanii; Abies nephrolepis and Pinus pumila; Aies nephrolepis and Rhododendron mucronulatum var. ciliatum; Betula ermanii and Pinus pumila; Betula ermanii and Rhododendron mucronulatum var. ciliatum; Pinus pumila and Rhododendron mucronulatm var. ciliatum; Quercus mongolica and Rhododendron schlippenbachii; Quercus mongolica and Qeigela subsessilis; Euonymus macroptera and Syringa reticulata; Euonymus macroptera and Viburnum wrightii; Acer ukurunduense and Euonymus oxyphyllus, and high nagative correlations were proved between Betula ermanii and Acer pseudosieboldianum; Quercus mongolica and Tripterygium regelii; Rhododendron schlippenbachii and Tripterygium regelii; Carpinus cordata and Acer pseudosieboldianum. Species diversity(H') of investigated area was calculated 2.1352~2.8016.

• 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.

• YAKHAK HOEJI
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• v.49 no.3
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• pp.244-248
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• 2005

From the methanol extract of Rhododendron brachycarpum four triterpenes, three phenylpropanes and a diterpene alkaloid were isolated. Their structures were identified as glutinol (1), 3$\beta$-hydroxyurs-12-ene (2), $\beta$-sitosterol (3), (E)-P-hydrox-ycinnamic acid hexadecylester (4), (-)-rhododendrol (5), (+)-rhododendrol (6), 3$\beta$-hydroxyurs-12-en-28-oic acid (7) and gray-anotoxin I (8) by spectroscopic methods. Compound 8 showed moderate cytotoxicity against five cultured human tumor cell lines with $ED_{50}$ values of $3.21\~4.05 {\mu}g/ml$. The other compounds were of marginal activity against the tested cell lines.