Terpene synthase (TPS) plays important roles in the synthesis of terpenoids which are the main fragrances in Rhododendron flowers. To understand the function of TPS genes in terpenoid metabolism in relation to flower aroma formation, we identified all TPS gene family members in Rhododendron by analyzing its genome database. We then used a transcriptomic approach to analyze the differential gene expression patterns of TPS gene family members in the scented flower Rhododendron fortunei compared to the non-scented flower Rhododendron 'Nova Zembla'. The contents of terpenoid compounds in petals of the above two Rhododendron species at different developmental stages were also measured by using qRT-PCR and head space-solid phase micro-extraction combined with gas chromatography-mass spectrometry. Our results showed that a total of 47 RsTPS members, with individual lengths ranged from 591 to 2 634 bp, were identified in the Rhododendron genome. The number of exons in RsTPS gene ranged from 3 to 12, while the length of each protein encoded ranged from 196 to 877 amino acids. Members of the RsTPS family are mainly distributed in the chloroplast and cytoplasm. Phylogenetic analysis showed that RsTPS genes can be clustered into 5 subgroups. Seven gene family members can be functionally annotated as TPS gene family since they were temporally and spatially expressed as shown in the transcriptome data. Notably, TPS1, TPS10, TPS12 and TPS13 in Rhododendron fortunei were expressed highly in flower buds reached the peak in the full blossoming. Correlation analysis between gene expression levels and terpenoid content indicates that the expression levels of TPS1, TPS4, TPS9, TPS10, TPS12 and TPS13 were positively correlated with the content of terpenoids in the petals of R. fortunei at all flower developmental stages, suggesting that these six genes might be involved in the aroma formation in R. fortunei.
Rhododendron/metabolism* ; Phylogeny ; Terpenes/metabolism* ; Family ; Gene Expression Regulation, Plant

Thirteen compounds were isolated from the leaves of Rhododendron rubiginosum var. rubiginosum by various chromatographic techniques. On the basis of spectroscopic data, their structures were elucidated as 3,9-dihydroxy-megastigma-5-ene (1), 3 beta-hydroxy-5alpha ,6 alpha-epoxy-7-megastigmen-9-one (2), loliolide (3), ursolic acid(4), 2 alpha, 3 beta-dihydroxy-urs-12-en-28-oic acid (5), 2 alpha, 3 beta,23-trihydroxy-urs-12-en-28-oic acid (6), 7,9-dimethoxyrhododendrol (7), 7-methoxyrhododendrol (8), zingerone (9), isofraxidin (10), scopoletin (11), (+)-pinoresinol (12) and 3'-O-demethylepipinorisenol (13). All compounds were isolated from this plant for the first time, and compounds 1-3, 7-9, and 11-13 were isolated from the genus Rhododendron for the first time.
Organic Chemicals ; analysis ; chemistry ; Plant Leaves ; chemistry ; Rhododendron ; chemistry

Erysiphe azaleae, a powdery mildew fungus on Rhododendron spp., was originally described from North America, and has only recently been recorded in Germany, England, Switzerland and Poland. The present paper records plentiful collections of this species from Poland, and provides additional information of its anamorphic state for taxonomic purposes.
England ; Fungi ; Germany ; North America ; Poland* ; Rhododendron ; Switzerland

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.
Adult ; Atropine ; Bradycardia ; Drug Combinations ; Emergencies ; Flowers ; Humans ; Intention ; Piperonyl Butoxide ; Pyrethrins ; Rhododendron ; Thirst

Mad-honey poisoning results from the ingestion of grayanotoxin-contaminated honey, which is extracted by bees from the leaves and the flowers Rhododendron species. The grayanotoxins bind to sodium channels in cell membranes and prevent inactivation; thus, excitable cells are maintained in a state of depolarization. Cardiac disturbances are the main signs in this poisoning. Bradycardia, and arterial hypotension have the potential to cause death in untreated cases but no fatalities have been reported in the literature. Here, we report three cases of mad-honey poisoning. All of the patients showed bradycardia, hypotension, and syncope. The hypotension responded to the administration of fluids, and the bradycardia responded to atropine treatment. All three patients recovered fully within 24 hours. Mad-honey poisoning should be kept in mind for any patients admitted with unexplained hypotension, bradycardia, and other rhythm disturbances, and patients who have eaten honey must be examined carefully.
Atropine ; Bees ; Bradycardia ; Cell Membrane ; Eating ; Emergencies* ; Flowers ; Honey ; Humans ; Hypotension ; Poisoning* ; Rhododendron ; Sodium Channels ; Syncope

Rhododendron brachycarpum has been known as a panacea in Korean folk medicine, and is used to treat various diseases including hypertension. Excessive ingestion can cause intoxication by grayanotoxin. We experienced a 59 year-old man suffering of grayanotoxin intoxication following excessive ingestion of Rhododendron brachycarpum. The patient presented dizziness, weakness, and chest discomfort with cold sweats. Electrocardiography showed marked sinus bradycardia with atrio-ventricular dissociation. With intravenous saline and atropine, the patient recovered. This case calls attention to the potential cardiotoxicity of Korean folk medicine Rhododendron brachycarpum.
Atropine ; Bradycardia* ; Dizziness ; Eating* ; Electrocardiography ; Humans ; Hypertension ; Medicine, Traditional ; Middle Aged ; Rhododendron* ; Sweat ; Thorax

Intoxifications caused by toxic honey were occurred recently in Korea. Honey poisoning is known to be induced by grayanotoxins, that appear in flowers of different species of Rhododendron. These toxic compounds cause depolarization of membranes that contain fast Na channel by increasing in Na permeability. After ingestion of toxic honey patients may present with neurological, cardiovascular, gastrointestinal sign and symptoms. Two cases of honey poisoning are described here. Both patients experienced syncope and severe arterial hypotension after ingestion of honey which was brought from Nepal and Brazil. Conservative treatement was fully successful in both patients within 24 hours. We report the first case of honey poisoning in Korea.
Brazil ; Eating ; Flowers ; Honey* ; Humans ; Hypotension ; Korea ; Membranes ; Nepal ; Permeability ; Poisoning* ; Rhododendron ; Sick Sinus Syndrome ; Syncope*

An unusual natural product named 2,4,6-trihydroxacetophenone-3, 5-di-C-beta-D-glucoside (18) were isolated from aerial parts of Rhododendron lepidotum grows in Tibet, along with other 17 known compounds: hopenol-B (1), lupeol (2), ursolic acid (3), avicularin (4), quercetin (5), myricetin (6), hyperoside (7), myricetin-3'-O-beta-D-xyloside (8), (+)-taxifolin-3-O-alpha-L-arabinopyranoside (9), (+)-taxifolin-3-O-beta-D-glucopyranoside (10), lyoniside (11), confluentin (12), 2-(4-hydroxyphenyl)-ethyltriacontanoate (13), 2, 6-dimethoxy-4-hydroxyphenyl-1-O-beta-D-glucopyranoside (14), (-)-2-hydroxy-5-(2-hydroxyethyl) phenyl-O-beta-D-glucopyranoside (15), (-)-isola-riciresinol (16) and isofraxoside (17). All the compounds were firstly isolated from this plant as well as compounds 1, 13-18 were reported occurrence in R. spp. for the first time. The structures were identified based on analyses of spectroscopic data and physico-chemical evidences.
Chromatography, High Pressure Liquid ; Drugs, Chinese Herbal ; chemistry ; Organic Chemicals ; analysis ; isolation & purification ; Rhododendron ; chemistry

Eight phenolic compounds were isolated from Rhododendron phaeochrysum var. agglutinatum and their sructures were identified as phaeochrysin (1), (2R)-4-(3',4'-dihydroxyphenyl) -2-butanol (2), (-) -rhododendrol (3), rhododendrin (4), (+) -isolariciresinol (5), (-) -lyoniresinol (6), lyoniresinol-9'-O-β-D-xylopyranoside (7), and dihydrodehydrodiconiferyl-3a-O-α-L-rhamnopyranoside (8). Compound 1 is new, and compounds 2, 5-8 were isolated from this plant for the first time.
Drugs, Chinese Herbal ; chemistry ; Mass Spectrometry ; Molecular Structure ; Phenols ; chemistry ; Rhododendron ; chemistry

To elucidate the chemical material basis of Rhododendron nivale, this study comprehensively used various chromatographic techniques to isolate and obtain five new meroterpenoid enantiomers(1a/1b-5a/5b) from the ethyl acetate extract of R. nivale. A variety of spectral analytical methods, such as high-resolution mass spectrometry(HRMS), nuclear magnetic resonance spectroscopy(NMR), and infrared(IR) spectrum, were used to evaluate the structure, combined with the measurement and calculation of electronic circular dichroism(ECD). The new compounds 1a/1b-4a/4b were named as(±)-nivalones A-B(1a/1b-2a/2b) and(±)-nivalnoids C-D(3a/3b-4a/4b), along with one known enantiomer(±)-anthoponoid G(5a/5b). Human neuroblastoma cells(SH-SY5Y cells) induced by hydrogen peroxide(H_2O_2) were used as oxidative stress models to evaluate the protective activity of the isolated compounds against oxidative damage to nerve cells. It was found that compounds 2a and 3a had a certain protective effect on nerve cells against H_2O_2-induced oxidative damage at concentrations of 50 μmol·L~(-1), which increased the cell survival rate from 44.02%±2.30% to 67.82%±1.12% and 62.20%±1.87%, respectively. Other compounds did not show a significant ability to protect cells from oxidative damage. These findings enrich the chemical constituents of R. nivale and provide valuable information for identifying the structure of its meroterpenoids.
Humans ; Rhododendron/chemistry* ; Neuroblastoma ; Oxidative Stress ; Magnetic Resonance Spectroscopy ; Stereoisomerism ; Molecular Structure