• The Korean Journal of Ecology
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• v.21 no.5_2
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• pp.519-529
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• 1998

The vegetation of alpine and subalpine zone from timber line, 2,000m altitude, to the upper area of Mt. Packtu were investigated by phytosociological method. The plant distribution along to the different altitudes shown as follows: Betula ermani community with Rhododendron redowskianum occupied dominantly at 2,000m area as patch forms, Rhododendron redowskianum community with Vaccinium uliginosum, at 2,180-2,200m area, both Vaccinium uliginosum and Rhododendron redowskianum community were compatible with each other at 2,243m area. Rhododendron redowskianum community at 2,250, Salix rotundifolia community, Erigeron thunbergii var. glabrata community, Dryas octopetala var. asiatica community and Carex atrata community were occurred frequently at 2,263m around Chonji Lake. Rhododendron aureum, Thunbergii coccinea and V accinium uliginosum showed higher cover degree than other species at 2,370m area, Phyllodoce coerulea-Rhododendron aureum community at 2,400m, Rhododendron redowskianum community at 2,470m, Rhododendron aureum community at 2,490m, Salix rotundifolia at 2,520m, Rhododendron redowskianum community at 2,580m, Dryas octopetala var. asiatica community, Salix rotundifolia, and bistorta achotensis etc. at 2,650 altitude area were settled as sparse, creeping shape on the surface soil and dwarf plants of about 15cm heights.

• Journal of Forest and Environmental Science
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• v.40 no.2
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• pp.123-140
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• 2024

More than half of the global distribution of the Rhododendron genus is found in China, with over 74% being endemic species. However, there is still insufficient data to chemically classify the Rhododendron genus native to China. Therefore, in this study, a chemotaxonomic study was conducted to determine the presence of taxifolin-3-O-arabinopyranoside, a flavonoid compound, in the Rhododendron genus native to China. Forty-three species of Rhododendron native to China-20 from across China, 8 from Beijing, 6 from Yanbian, and 9 from Yunnan-were utilized in the experiment. Through HPLC analysis, the retention time was compared with that of taxifolin-3-O-arabinopyranoside, a standard compound, and quantitative analysis was conducted. As a result, taxifolin-3-O-arabinopyranoside was detected in 22 out of 43 the Chinese Rhododendron species. Afterwards, LC-MS/MS analysis was performed on the 22 species in which taxifolin-3-O-arabinopyranoside was detected to determine whether the molecular weight was consistent with the standard compound. Under negative conditions, it was confirmed that all samples exhibited the same molecular weight as taxifolin-3-O-arabinopyranoside, 435-436 m/z. The same compound was detected in more than half of the Rhododendron species used in the experiment, and taxifolin-3-O-arabinopyranoside was determined to be an indicator compound for Rhododendron species native to China. In addition, the possibility of using the above results as basic data for chemical classification of Chinese Rhododendron genus was confirmed.

• Journal of Environmental Science International
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• v.20 no.10
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• pp.1319-1328
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• 2011

Rhododendron brachycarpum is a evergreen broad-leaved shrub and belongs to the Ericaceae family and the Rhododendron genus. It is well known for its beautiful leaves and flowers. There are 11 species of the Rhododendron genus in Korea. It includes 3 species - Rhododendron brachycarpum, Rhododendron aureum Georgi and Rhododendron brachycarpum var. roseum Koidz. They grow naturally over 1,000 meters above sea level of the Baekdu Mountain Range in Korea. These habitats, according to investigations of 9 Rhododendron brachycarpum natural habitats, are mostly located on the slope of mountains facing north at an altitude of 1,200 m to 1,526 m above sea level with angle of inclination from 30 degrees to 45 degrees. Based on the result of vegetation analysis of dominance species in the quadrates, there are Quercus aliena, Quercus mongolica Fisch. ex Ledeb, Abies holophylla in species of upper trees, and so on. Dominant species of woody plants in tree layer are Quercus aliena, Quercus mongolica Fisch. ex Ledeb, Abies holophylla, Betula platyphylla and Veeatrum patulum Loes. fil, Erythronium japonicum, Dryopteris crassirhizoma, Paeonia japonica var. glabra Makino are founded in herbaceous plants. And we can see another result of the investigation that the flowering rates of the plants with the buds are highly ranked mountains such as Mt. Hambaek 68%, Mt. Gyebang 40%, Mt. Yagksu 9%, Mt. Gaein 7% and Mt. Seolag 0%. The results show that there are 24 over 15-year-old Rhododendron brachycarpums in Mt. Odae and are 56 under 15-year-old trees in Mt. Hambaek and are no trees in Mt. Gyebang and are 9 over 30-year-dead trees only in Mt. Taebaeg. Out of found trees, the highest tree is 7 m in height and 0.6 m in diameter. Also this result shows what are the vulnerability factors of the natural habitats. They are as follows: indiscriminate trails in mountains, damages by mountain climbers, uncareful plant collecting, the fierce competitions with other plants such as Acer pseudosieboldianum var. ishidoyanum Uyeki, Quercus aliena, Celastrus orbiculatus and damages by disease and insect, unusual temperature in natural habitats, etc. Rhododendron brachycarpums have high ornamental value and excellent pharmaceutical effect. But the areas of its habitats decrease dramatically. So we need measures to protect and their natural habitats. It is necessary that we conductfurther investigations to designate conservation area for Rhododendron brachycarpums.

• Journal of Veterinary Clinics
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• v.26 no.4
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• pp.344-347
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• 2009

Four sheep and five Korean native goats became intoxicated after eating Rhododendron schlippenbachii clippings that a ranchman threw into the animal barn. The clinical signs included loss of appetite, lethargy, nausea, salivation, vomiting, dyspnea, staggering gait, and bradycardia. The animals were treated with atropine and carbo-pulbit. One goat died 8 hours later, and a field postmortem revealed a considerable quantity of rhododendron leaves in the rumen. The other sheep and goats recovered within 3 days after treatment.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.4
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• pp.47-53
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• 1999

In order to elucidate physiological factors involved in causing the winter injuries of evergreen Japanese rhododendron (Rhododendron obtusum cv. Hinodegiri) and semi-evergreen rhododendron (Rhododendron yedoense var. poukhanense), these studies were conducted from late winter to early spring. The results were summarized as follows; The water potential, water content in stem, water potential and content have continuously increased in both species between February and May. In R. yedoense, shading treatment had 0.3MPa upper water potential and 3% upper water content than the control. Rhododendron obtusum, the treatments with shading had 0.9MPa upper water potential and 11% upper water content that the control. The difference of water balance by treatments could be found in vitality of stem measured by TTC test. Especially R. obtusum in the treatments with shading in has higher vitality than the control. we find that winter damage of evergreen R. obtusum was determined by whether water balance could be recovered from water deficient state during the dehardening period, or not. In order to recover of the water balance, decreasing water loss more important than increasing water supply, and that was effectively acrueved by the treatment with shading.

• Korean Journal of Plant Taxonomy
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• v.52 no.2
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• pp.102-107
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• 2022

Rhododendron keiskei var. hypoglaucum (Ericaceae) was recently reported in Korea, with a disjunct distribution on the southern islands of the Korean Peninsula. Although chromosome numbers and ploidy variations are important traits in angiosperms, gaining a clear understanding the cytological features of Rhododendron has been hampered by the small size of its chromosomes. We herein report the chromosome number, karyotype structure, and genome size of R. keiskei var. hypoglaucum for the first time. The chromosome number of the investigated plants was 2n = 26 with x = 13 as the base chromosome number, which is the one of the frequently encountered base chromosome numbers in Rhododendron. The karyotype of R. keiskei var. hypoglaucum is composed of metacentric and submetacentric chromosomes similar in length, which ranged from 1.39 to 2.40 ㎛. The DNA 1C-value in all examined accessions was small, ranging from 0.63 to 0.65 pg, further supporting the stable genome size in Rhododendron. These comprehensive cytological results provide a framework for detailed molecular, cytogenetic, and phylogenomic analyses that can be used to interpret the slow species diversification rate in Rhododendron.

• 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.

• 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.

• Archives of Pharmacal Research
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• v.9 no.4
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• pp.233-236
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• 1986

The flavonoids isolated form the leaves of rhododendron brachycarpum were identified as quercetin, avicularin, quercitrin and hyperin.

• Korean Journal of Pharmacognosy
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• v.22 no.1
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• pp.18-21
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• 1991

Campanulin, ${\alpha}-amyrin$, ${\beta}-amyrin$, uvaol, simiarenol, ursolic acid and oleanolic acid were isolated from the ethyl acetate fraction of the leaves of Rhododendron brachycarpum and their structures were identified by spectroscopic and chemical methods.