Rhododendron Dauricum Research Articles

Chromene meroterpenoids from Rhododendron dauricum L. and their anti-inflammatory effects

Rhododendron dauricum L. is a perennial herb belonging to the genus Rhododendron, commonly utilized in formulations for treating coughs and bronchitis, as well as in herbal teas for enhancing immunity and preventing tracheitis. In this study, fifteen previously undescribed chromene meroterpenoids (1a/1b-4a/4b, 5–8, 9b, 10a, 11b), along with twenty-one known compounds were isolated from the dried twigs and leaves of Rhododendron dauricum L. Of these, (−)-rhodonoid E (9b), (+)-confluentin (10a), and (−)-rubiginosin D (11b) were separated for the first time by chiral HPLC separation. The elucidation of their structures, including absolute configurations, was achieved through a combination of techniques such as NMR, HRESIMS, modified Mosher's method and quantum-chemical calculation of electronic circular dichroism (ECD) spectra. Seven pairs of enantiomers, compounds 1a/1b-4a/4b and 9a/9b-11a/11b, were initially obtained in a racemic manner and were further separated by chiral HPLC preparation. The biological assessment of these compounds against NO production was conducted in the LPS-induced RAW264.7 macrophage cells model. Compounds 9a, 9b, and 11a displayed inhibitory rates exceeding 80%, with IC50 values ranging from 8.69 ± 0.94 to 13.01 ± 1.11 μM. A preliminary examination of the structure-activity relationship (SAR) for these isolates indicated that chromene meroterpenoids with α, β-unsaturated ketone carbonyl and Δ12(13) double bond functionalities exhibited enhanced anti-inflammatory properties.

Dauresorcinols A and B, two pairs of merosesquiterpenoid enantiomers with new carbon skeletons from Rhododendron dauricum

Five pairs of new merosesquiterpenoid enantiomers, named dauresorcinols A−E (1−5), were isolated from the leaves of Rhododendron dauricum. Their structures were elucidated by comprehensive spectroscopic data analysis, quantum chemical calculations, Rh2(OCOCF3)4-induced ECD, and single-crystal X-ray diffraction analysis. Dauresorcinols A (1) and B (2) possess two new merosesquiterpene skeletons bearing an unprecedented 2,6,7,10,14-pentamethyl-11-oxatetracyclo[8.8.0.02,7.012,17]octadecane and a caged 15-isohexyl-1,5,15-trimethyl-2,10-dioxatetracyclo[7.4.1.111,14.03,8]pentadecane motif, respectively. Plausible biosynthetic pathways of 1−5 are proposed involving key oxa-electrocyclization and Wagner−Meerwein rearrangement reactions. (+)/(−)-1 and 3−5 showed potent α-glucosidase inhibitory activity, 3 to 22 times stronger than acarbose, an antidiabetic drug targeting α-glucosidase. Docking results provide a basis to design and develop merosesquiterpenoids as potent α-glycosidase inhibitors.

Two new terpenoids from the branches and leaves of Rhododendron dauricum L. with neuroprotective activity

Two new terpenoids were isolated from the branches and leaves of Rhododendron dauricum L., named as rhodayritions A (1) and B (2), together with five known compounds which were identified litseachromolaevane A (3), 11-αH-dihydrodehydrocostus lactone (4), (+)-9β-hydroxyeudesma-4,11(13)-dien-12-al (5), macrostachyoside B (6) and aglaiabbreviatin E (7), respectively. The structures of isolated compounds were determined by UV, HR-ESI-MS, NMR analysis and X-Ray. Their neuroprotective activity was studied on serum deprivation-induced PC12 cells by the MTT method, compounds 1, 6, and 7 exhibited significant neuroprotective activity at 20 μΜ.

The Diverse Mycorrizal Morphology of Rhododendron dauricum, the Fungal Communities Structure and Dynamics from the Mycorrhizosphere.

It is generally believed that mycorrhiza is a microecosystem composed of mycorrhizal fungi, host plants and other microscopic organisms. The mycorrhiza of Rhododendron dauricum is more complex and the diverse morphology of our investigated results displays both typical ericoid mycorrhizal characteristics and ectomycorrhizal traits. The characteristics of ectendoomycorrhiza, where mycelial invade from the outside into the root cells, have also been observed. In order to further clarify the mycorrhizal fungi members and other fungal communities of R. dauricum mycorrhiza, and explore the effects of vegetation and soil biological factors on their community structure, we selected two woodlands in the northeast of China as samples-one is a mixed forest of R. dauricum and Quercus mongolica, and the other a mixed forest of R. dauricum, Q. mongolica, and Pinus densiflor. The sampling time was during the local growing season, from June to September. High-throughput sequencing yielded a total of 3020 fungal amplicon sequence variants (ASVs), which were based on sequencing of the internal transcribed spacer ribosomal RNA (ITS rRNA) via the Illumina NovaSeq platform. In the different habitats of R. dauricum, there are differences in the diversity of fungi obtained from mycorrhizal niches, and specifically the mycorrhizal fungal community structure in the complex vegetation of mixed forests, where R. dauricum is found, exhibits greater stability, with relatively minor changes over time. Soil fungi are identified as the primary source of fungi within the mycorrhizal niche, and the abundance of mycorrhizal fungi from mycorrhizal niches in R. dauricum is significantly influenced by soil pH, organic matter, and available nitrogen. The relationship between soil fungi and mycorrhizal fungi from mycorrhizal niches is simultaneously found to be intricate, while the genus Hydnellum emerges as a central genus among mycorrhizal fungi from mycorrhizal niches. However, there is currently a substantial gap in the foundational research of this genus, including the fact that mycorrhizal fungi from mycorrhizal niches have, compared to fungi present in the soil, proven to be more sensitive to changes in soil moisture.

Anthocyanin Metabolite and Transcriptome Sequencing Analysis Reveals White Flowers in Rhododendron dauricum var. albiflorum

Rhododendron dauricum is a cold-hardy shrub integrating ornamental, medicinal, and aromatic functions. Flower color is an important feature related to ornamental value for breeders and consumers. Nevertheless, the coloration mechanism of flower color in R. dauricum is still unclear. R. dauricum var. albiflorum is a white flower variety of R. dauricum. In this study, an integrative analysis of the metabolome and transcriptome was conducted between R. dauricum var. albiflorum and R. dauricum. A total of nine anthocyanins and two proanthocyanidins were differentially accumulated between R. dauricum var. albiflorum and R. dauricum. A decrease in malvidin-, delphinidin-, cyanidin-, peonidin-, and petunidin-based anthocyanins and an increase in procyanidin A2 and procyanidin B2 were responsible for the white flowers of R. dauricum var. albiflorum. Furthermore, a total of 4376 differentially expressed genes (DEGs) were identified using transcriptome sequencing. Integrated analysis of the metabolome and transcriptome showed that 21 DEGs encoding 9 enzymes (PAL, C4H, CHS, CHI, F3H, F3′5′H, DFR, ANR, and UFGT) were identified as structural genes involved in anthocyanin and proanthocyanidin biosynthesis, and 15 MYBs and 10 bHLHs were the transcriptional regulators of the anthocyanin biosynthesis pathways in R. dauricum var. albiflorum. Our results deepen the understanding of variations in azalea flower color, which is helpful for identifying important genes in the genetic engineering of azalea shrubs.

Research on the influencing factors and prevention measures of long-term forest fire risk in Northeast China

Forest fires damage ecological environment and increase carbon emissions. To reduce the adverse effects of fire on forests, the long-term (2002–2022) fires data were analyzed in the Great Xing'an Mountains region of Northeast China. The important influencing factors of forest fires were revealed by analyzing different combustibles, meteorological, climatic factors, and the spatial and temporal distribution characteristics of forest fires. The results showed that Ledum palustre, Pinus silvestris L., and Rhododendron dauricum L. were the main tree species with high probability of forest fires according to the flammability difference of combustibles. The young and middle-aged forests accounted for more than 60% of the total forests, which were high flammability. Based on the regression analysis of meteorological data, temperature and precipitation had significant effects on forest fires. Affected by the lightning strikes, the total number of fires in 2017–2022 was high, and the high frequency of fires was in June and August. Because the fires were influenced by factors such as surface vegetation combustibles, precipitation, temperature, and ground slope, the north and southwest slopes had the highest fire incidence rates. In addition to the resource utilization of dead branches and leaves, planting tree species with high fire resistance is an important measure. Artificial precipitations are taken in an extremely dry environment. The management of old trees are strengthened in the western region of Great Xing'an Mountains. The types of fires that cause negative impacts on forests are the focus of monitoring and prevention. This study is of great significance in reducing forest fire risk, improving forest carbon sequestration function, increasing wood resources, and improving the public climate environment.

Study on the Limit of Moisture Content of the Sub-Surface Fires Converted to the Surface Fires in the Boreal Forests of China

A sub-surface forest fire is a type of smoldering combustion with a slower spread rate, longer combustion time, and lower combustion temperature compared with flame combustion. Sub-surface fires are usually accompanied by surface fires, and the surface fires’ conversion from sub-surface fires has great uncertainty. Therefore, there are considerable difficulties in monitoring and fighting sub-surface fires. However, there are few studies on the conversion from sub-surface fires to surface fires, and the mechanism and influencing factors of the conversion remain unclear. This study focuses on Larix gmelinii forests, which are representative of the boreal forest of China and hot spots of sub-surface fires, studies the moisture content limit of sub-surface fires’ conversion to surface fires by simulating a smoldering experiment, and establishes a monitoring model of sub-surface fires and an occurrence probability prediction model of sub-surface fires’ conversion to surface fires. The results showed that the moisture content limit of the conversion was 25% in the grass–Larix gmelinii forest and Ledum palustre–Larix gmelinii forest and 20% in Rhododendron dauricum–Larix gmelinii forest. There was a significant positive correlation between the time and temperature caused by the smoldering. The monitoring model of the sub-surface fires based on the surface temperature and moisture content had a good fitting effect (p < 0.01). The occurrence probability prediction model of the sub-surface fires’ conversion to surface fires, based on a logistic regression model, had high prediction accuracy (AUC = 0.987). The lower the moisture content of the humus, the closer the smoldering came to the surface and the higher the probability of conversion. This research could contribute to the study of the mechanism of sub-surface fires’ conversion into surface fires.

Seasonal Variation of Emission Fluxes of CO2, CH4, and N2O from Different Larch Forests in the Daxing’An Mountains of China

Using a static chamber-gas chromatography method, we investigate the characteristics of soil CO2, CH4, and N2O fluxes and their relationships with environmental factors during the growing season in four typical Larix gmelinii forests (moss–Larix gmelinii forest, Ledum palustre–Larix gmelinii forest, herbage–Larix gmelinii forest, and Rhododendron dauricum–Larix gmelinii forest) in the Greater Khingan Mountains. Our results show that all four forest types are sources of CO2 emissions, with similar average emission fluxes (146.71 mg·m−2 h−1–211.81 mg·m−2 h−1) and no significant differences. The soil in the moss–Larix gmelinii forest emitted CH4 (43.78 μg·m−2 h−1), while all other forest types acted as CH4 sinks (−56.02 μg·m−2 h−1–−28.07 μg·m−2 h−1). Although all forest types showed N2O uptake at the beginning of the growing season, the N2O fluxes (4.03 μg·m−2 h−1–5.74 μg·m−2 h−1) did not differ significantly among the four forest types for the entire growing season, and all acted as sources of N2O emissions. The fluxes of CO2, CH4, and N2O were significantly correlated with soil temperature and soil pH for all four forest types. Multiple regression analysis shows that considering the interactive effects of soil temperature and moisture could better explain the changes in greenhouse gas emissions among different forest types. The average Q10 value (8.81) of the moss–Larix gmelinii forest is significantly higher than that of the other three forest types (3.16–3.54) (p < 0.05), indicating that the soil respiration in this forest type is more sensitive to temperature changes.

Highly oxygenated grayanane diterpenoids with structural diversity from the flowers of Rhododendron dauricum and their analgesic activities

Twenty-eight grayanane diterpenoids (1–28) including 13 new ones, named daublossomins A–M (1–13), and two new natural products, 3-O-acetylgrayanotoxin II (14) and 10-epi-grayanotoxin III (15), were isolated from the flowers of Rhododendron dauricum L. (Ericaceae). Their structures were elucidated by means of comprehensive spectroscopic methods and quantum chemical calculations (13C NMR-DP4+ analysis and calculated ECD), and the absolute configurations of ten grayanane diterpenoids 1, 4, 5, 7, 8, 22, 23, 25, 27, and 28 were determined by X-ray crystallographic analysis. Daublossomin A (1) represents the first example of an 11,16-epoxygrayan-6-one diterpenoid. Daublossomins B (2) and C (3) are the first examples of 9β,10β-epoxygrayanane diterpenoids, and daublossomin I (9) is the second conjugated grayan-1(5),6(7),9(10)-triene diterpenoid. Compounds 1–11 and 13–27 were evaluated for their analgesic activities in the HOAc-induced writhing test in mice, and 1–8, 10, 11, 13, 15, 17, 18, 22–24, and 26 exhibited significant analgesic effects at a dose of 5.0 mg/kg (inhibition rates > 50%). Among them, daublossomins A (1) and F (6) still showed potent analgesic activity even at a lower dose of 0.2 mg/kg with the inhibition rates of 54.4% and 55.2%, respectively. Grayanotoxin III (20) showed more potent analgesic activities than the positive control, morphine, at a dose of 0.04 mg/kg. A preliminary structure–activity relationship for the analgesic grayanane diterpenoids was discussed, providing some useful clues to design and develop structurally novel potent analgesics.

Post-fire restoration of pine forests in the Badary area, Tunkinskiy National Park, Russia

A morphological variety of pyrogenic transformations characterises burnt areas of the Badary area of the Tunkinskiy National Park (Russia), from heavily damaged areas with a partially remained forest stand to bare spaces of tens of square metres. This enabled us to study the dynamics of the post-fire reproduction of Pinus sylvestris (hereinafter – pine) forests in areas with various environmental conditions. The main goal of our study was to determine the nature of the pyrogenic transformation of ecosystems and to evaluate the success of the forest reproduction. The studies were based on the geobotanical monitoring in two burnt-out areas, differing in the degree and area of wildfire damage due to a creeping fire in 2010. Between 2014 and 2020, we considered the multi-temporal specificity of the species composition of the forest stand, shrub layer, and plant communities. The emergence of the first shoots of undergrowth and new growth has been recorded. The projective cover and the dynamics of the species abundance in all forest layers were fixed. The analysis of the natural reforestation dynamics revealed a similarity of the main geobotanical indicators. Pine seedlings dominated in the undergrowth of the study sites, with a small proportion of Betula pendula. The shrub layer consisted of Rosa acicularis. Rhododendron dauricum has been found there only at the late stage of the study. In the herbaceous layer, the largest proportion was represented by meadow species, with a small participation of forest plants. Differences were revealed during the emergence of first seedlings of undergrowth and new growth, as well as in the size of projective cover of species in all forest layers. The first pine seedlings on a heavily burnt-out study plot were recorded a year earlier than on a less transformed plot. Nevertheless, the height increment and the projective cover of the undergrowth were significantly higher on the burnt-out area of a medium damage degree. On the heavily fire-damaged area, we observed pine seedlings planted by the staff of the Tunkinskiy National Park. A satisfactory rate of seedling survival at the initial stage and further deceleration of growth parameters have been noted. The obtained results indicate the reforestation success and, therefore, a favourable forecast of post-fire recovery of light-coniferous forests in the Badary area of the Tunkinskiy National Park.

TDZ-induced two-step regeneration and histological analysis of morphogenesis from pedicel tissue of Rhododendron dauricum L., a semi-evergreen species

TDZ-induced two-step regeneration and histological analysis of morphogenesis from pedicel tissue of Rhododendron dauricum L., a semi-evergreen species

Anti-infammatory scalemic chromanoids and chromenoids from Rhododendron dauricum

Four pairs of undescribed chromane and chromene meroterpenoid scalemic mixtures (1a/1b-4a/4b), together with three pairs of known chromane meroterpenoid ones (5a/5b-7a/7b) were isolated from the twigs and leaves of Rhododendron dauricum L. Among them, 1a/1b-3a/3b and 5a/5b-7a/7b were the chromane ones derived from an intramolecular [2 + 2] cyclic addition of their respective chromene precursors, forming a 6/6/6/4 and 6/6/5/4 ring fused scaffold. The absolute configurations of the chiral center at C-15 of 2a/2b were determined by Snatzke's method, and comparing the experimental and calculated electronic circular dichroism (ECD) data. The inhibitory effects of the isolated compounds were tested against lipopolysaccharide (LPS)-induced nitric oxide production in RAW264.7 macrophage cells to evaluate their anti-inflammatory activity. Compounds 4a, 4b and 6a displayed inhibitory effects on nitric oxide (NO) production, and compound 4b exhibited the obvious anti-inflammatory activity, with an IC50 value of 6.91 ± 0.97 μM, by downregulating nuclear factor kappa B (NF-κB) and reducing the expression of inducible nitric oxide synthase (iNOS) in LPS-induced RAW264.7 cells. These results intimated that 4b could be used as a leading compound to develop anti-inflammatory drugs and is worthy of further investigated.

Rhodauricanol A, an analgesic diterpenoid with an unprecedented 5/6/5/7 tetracyclic system featuring a unique 16-oxa-tetracyclo[11.2.1.01,5.07,13]hexadecane core from Rhododendron dauricum

A novel diterpenoid with an unprecedented 5/6/5/7 tetracyclic system, rhodauricanol A (1), five new grayanane-derived diterpenoids, dauricanols A−E (2−6), and five known ones (7−11) were isolated from the flowers of Rhododendron dauricum. Rhodauricanol A (1) possesses a unique 5/6/5/7 tetracyclic ring system featuring a 16-oxa-tetracyclo[11.2.1.01,5.07,13]hexadecane core. Dauricanols A−C (2−4) are the first 1,3-dioxolane conjugates of grayanane diterpenoids and 5-hydroxymethylfurfural and vanillin, respectively, and dauricanols D (5) and E (6) represent the first examples of 6-deoxy-1,5-seco-grayanane diterpenoids. Their structures were determined by spectroscopic methods, quantum chemical calculation including 13C NMR-DP4+ analysis and ECD calculation, and single-crystal X-ray diffraction analysis. Plausible biosynthetic pathways for 1−4 were proposed. All the isolates showed significant analgesic activities, and dauricanols B (3) and C (4) showed more potent analgesic activities than the positive control, morphine.

Acetylation Modification, Characterization, and Anticomplementary Activity of Polysaccharides from Rhododendron dauricum Leaves.

This study focuses on the acetylation modification of polysaccharides from Rhododendron dauricum leaves (RDPs) with a high degree of substitution (DS) and then discusses their characterization and biological activity. The optimum acetylation conditions of RDPs were optimized by response surface methodology, which were reaction time 3 h, reaction temperature 50 °C, and the liquid-solid ratio 16 mL/g. Under the optima schemes, two eco-friendly acetylated polysaccharides from R. dauricum leaves (AcRDP-1 with DS of 0.439 ± 0.025 and AcRDP-2 with DS of 0.445 ± 0.022) were prepared. The results of structural characterization showed that the AcRDP-1 (9.3525 × 103 kDa) and AcRDP-2 (4.7016 × 103 kDa) were composed of mannose, glucose, galactose, and arabinose with molar ratios of 1.00:5.01:1.17:0.15 and 1.00:4.47:2.39:0.88, respectively. Compared with unmodified polysaccharides, the arabinose content and molecular weight of the two acetylated polysaccharides decreased, and their triple helix conformation disappeared, and further improved their anticomplementary activity. The two acetylated polysaccharides showed stronger a complement inhibition effect than the positive drug by blocking C2, C3, C4, C5, C9, and factor B targets in the classical and alternative pathways. This research indicated that acetylation modification could effectively enhance the anticomplementary activity of RDPs, which is beneficial for the development and utilization of R. dauricum leaves.

Static decolorization of polysaccharides from the leaves of Rhododendron dauricum: Process optimization, characterization and antioxidant activities

In this study, polysaccharides from the leaves of Rhododendron dauricum L. (RDPs) were decolorized using the static macroporous resin adsorption method. The RDPs were characterized and their antioxidant activities were investigated. An analytical hierarchy process (AHP) and a response surface method (RSM) were used to determine the optimum decolorization conditions as: a polysaccharide concentration of 8 mg/mL, decolorization time of 70 min, liquid–solid ratio of 6 mL/g, and decolorization temperature of 52 °C, with D101 as the best resin. Furthermore, two novel polysaccharides (RDP-1 and RDP-2) were isolated from R. dauricum leaves and characterized, which demonstrated that RDP-1 and RDP-2 were both composed of mannose, glucose, galactose, and arabinose in different molar ratios. These RDPs also exhibited a triple helix conformation, and primarily contained →6)-Glcp-(1→, →5)-Araf-(1→, →2,4)-Manp-(1→, →6)-Galp-(1→ and Glcp-(1→ residues with different connection sequences. Biological activity tests showed that the two polysaccharides possessed scavenging capacity against 1,1-Diphenyl-2-picrylhydrazyl (DPPH), hydroxyl, and 2,2-Azino-bis-(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radicals. The results indicated that the antioxidant activities of the RDPs obtained by the static decolorization method improved, which lays a theoretical foundation for developing techniques for utilising R. dauricum.

Fungal-Bacterial Networks in the Habitat of SongRong (Tricholoma matsutake) and Driving Factors of Their Distribution Rules.

Soil origin, mycorrhizal plant partners and environmental factors affect the growth and development of SongRong (Tricholoma matsutake). In order to clarify the relationships of fungi–bacteria networks and various influence factors in the habitat of SongRong, we chose three collection sites with a Quercus mongolica pure forest (plot A without SongRong was used as the control sample site), Q. mongolica mixed Rhododendron dauricum (plot B) and Q. mongolica mixed with R. dauricum and Pinus densiflora (plot C). By using high-throughput sequencing, we obtained a total of 4930 fungal and 55501 bacterial amplicon sequence variants (ASVs) based on internally transcribed spacer ribosomal RNA (ITS rRNA) and 16S ribosomal RNA (16S rRNA) sequencing via the Illumina NovaSeq platform. In the habitat soil of SongRong (plot B and plot C), alpha or beta diversity and species compositions of fungi and bacteria were different from plot A. The fungal–bacterial networks follow the selection rule that few dominant genera account for the greater relative abundance. Forest types, but not the host itself, drove the fungal–bacterial networks of the forest soil, and soil physicochemical characteristics and texture affected their abundance. The abundance of Tricholoma was affected by the fungal and bacterial abundance in the habitat.

Cover Picture

The cover picture shows eight analgesic kalmane diterpenoids with a 5/8/5/5 tetracyclic carbon skeleton, isolated from the flowers of Rhododendron dauricum at Xiaoxing'anling, China. Rhodokalmanol A represents the first 5,8‐epoxykalmane diterpenoid and also the first kalm‐15(16)‐ene diterpenoid. Rhodokalmanols B—D are the first examples of kalm‐7(8)‐ene, kalm‐16(17)‐ene, and 8α‐methoxykalmane diterpenoids, respectively. All the isolated kalmane diterpenoids exhibited significant analgesic effects in the acetic acid−induced writhing test in mice. Among them, rhodokalmanol C and kalmanol expressed more potent analgesic activity than morphine at doses of 0.2 and 0.04 mg/kg. More details are discussed in the article by Yao et al. on page 1019—1027.image

Study on phytochemical and pharmacological activities of four Rhododendron plants endemic to Northeast China

Rhododendron micranthum Turcz., Rhododendron capitatum Maxim., Rhododendron dauricum L. and Rhododendron schlippenbachii Maxim. are four species of Rhododendron with the same geographical distribution, mainly distributed in the northeast of China and abundant in sources. This paper is the first comprehensive review on the chemical composition and pharmacological activities of these four species. The review, showed 323 compounds including terpenoids, flavonoids, coumarins, lignans, and volatile components were found in the four plants, and these four plants of Rhododendron not only had many chemical constituents of novel structures but also possessed extensive pharmacological effects, such as insecticide, analgesic, antibacterial, antitumor and so on. These research papers and literatures about the four plants were carried out using resources including classic books about Chinese herbal medicine, Flora Reipublicae Popularis Sinicae, and scientific databases including Web of Science, Sci-Finder, CNKI, Pubmed, etc. In recent years, our research group has engaged in the study of chemical composition and pharmacological activities of Rhododendron plants. The terpenes and volatile components isolated from Rhododendron plants contributed greatly to insecticidal activity. Therefore, it is of great significance to review researches of the four endemic resource-rich Rhododendron plants to help make full use of them especially on plant-derived insecticide. This comprehensive review will be significant for the discovery of new bioactive compounds from the above four endemic plants and will be informative for researchers seeking for new pharmacological activity of the four species. • Four species of Rhododendrons from northeast China. • Main chemical components, pharmacological activities of these four Rhododendrons. • Volatile components (Essential oils) and some special compounds contributed to insecticidal activity. • Terpenes and some monomeric compounds with special chemical groups contributed greatly to the insecticidal. • Insecticidal mechanism, some special proteins especially odor-binding proteins (OBPs) of insect was briefly discussed.

Discovery of Kalmane Diterpenoids as Potent Analgesics from the Flowers of Rhododendron dauricum

Comprehensive SummaryKalmane diterpenoids, featuring a 5/8/5/5 tetracyclic carbon skeleton, are very rare in nature. The flowers of Rhododendron dauricum L. (Ericaceae) were phytochemically investigated for the first time, leading to the isolation of eight kalmane diterpenoids (1—8) including four new ones, named rhodokalmanols A—D (1—4). The structures of 1—8 were elucidated by comprehensive spectroscopic methods and 13C NMR‐DP4+ analysis, and the absolute configurations of 1, 2, 4, and 5 were defined by single‐crystal X‐ray diffraction analysis with Cu Kα radiation. Rhodokalmanol A (1) represents the first 5,8‐epoxykalmane diterpenoid and also the first kalm‐15(16)‐ene diterpenoid. Rhodokalmanols B—D (2—4) are the first examples of kalm‐7(8)‐ene, kalm‐16(17)‐ene, and 8α‐methoxykalmane diterpenoids, respectively. All the isolated kalmane diterpenoids 1—8 exhibited significant analgesic effects, and rhodokalmanol C (3) and kalmanol (8) expressed more potent analgesic activity than morphine at doses of 0.2 and 0.04 mg/kg. The preliminary structure‐activity relationships of kalmane diterpenoids as potent analgesics are discussed.

基于生命表的大兴安岭兴安杜鹃(Rhododendron dauricum)种群数量特征及动态分析

PDF HTML阅读 XML下载 导出引用 引用提醒 基于生命表的大兴安岭兴安杜鹃(Rhododendron dauricum)种群数量特征及动态分析 DOI: 10.5846/stxb202105101218 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划(2016YFC0500306);江西省科学院科技专项(2020YYB05) Demography analysis of Rhododendron dauricum (Ericaceae) population in the Great Khingan Mountains based on life table Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:兴安杜鹃(Rhododendron dauricum)是大兴安岭森林群落灌木层的优势种,其种群统计研究尚属空白。以大兴安岭呼中区不同海拔和林型的兴安杜鹃种群为对象,编制了静态生命表,计算生存分析函数,采用时间序列分析种群数量动态。结果表明,低海拔梯度(600m)的落叶松林中,兴安杜鹃幼龄级(Ⅰ-Ⅱ)个体较多,占67.31%,且幼龄级死亡率和消失率较低,存活率较高,存活曲线为Deevey Ⅰ型曲线,为增长型种群。种群的衰退期转折点在Ⅱ-Ⅲ龄级,未来种群数量呈增长趋势。中低海拔梯度(600-900m)的白桦林中,中龄级(Ⅱ-Ⅲ)个体数量较多,占45%以上,中龄级死亡率和消失率较低,存活率较高,存活曲线为Deevey Ⅰ型曲线,为稳定型种群。种群的衰退期转折点在Ⅲ-Ⅴ龄级之间,由于种群密度制约,未来种群数量逐渐趋于衰退。高海拔梯度(1200m)的落叶松林中,种群个体总数最少。其中,Ⅰ龄级个体数量最多,占33.52%,但死亡率和消失率较高,存活率较低,Ⅱ-Ⅴ龄级死亡率和消失率较低,存活率较高,存活曲线为Deevey Ⅲ型曲线,为增长型种群,但增长趋势较弱。种群的衰退期转折点在Ⅴ龄级,未来种群数量呈增长趋势,但由于环境限制,种群数量更趋于稳定。可以认为,大兴安岭兴安杜鹃种群数量整体稳定。海拔和林型是影响兴安杜鹃种群数量的重要因素,海拔为600-900m,郁闭度为45%-50%的白桦林为兴安杜鹃的适宜生境,成为灌木层中的主要优势种。 Abstract:Rhododendron dauricum is one of the main dominant species in the shrub layer of the Great Khingan Mountains. However, the demography analysis of the population is still in the blank. In this study, the population of wild R. dauricum with different elevations and forest types in Huzhong District of the Great Khingan Mountains was taken as the object. A static life table was compiled, the survival analysis functions were calculated, and population dynamics were analyzed by time series. The results showed that in the Larix gmelinii forest with low elevation gradient (600 m), there are more juvenile individuals (age class Ⅰ-Ⅱ) of R. dauricum, accounting for 67.31%. Their mortality and disappearance rate are low, and the survival rate is high. The survival curve is Deevey Ⅰ. Therefore, it is a growth population. The turning point of the population decline period is in the age class Ⅱ-Ⅲ, and the population number will increase in the future. In the Betula platyphylla forest with low and middle elevation gradient (600-900 m), there are more middle-aged individuals (age class Ⅱ-Ⅲ) of R. dauricum, accounting for more than 45%. Their mortality and disappearance rate are low, and the survival rate is high. The survival curve is Deevey Ⅰ. Therefore, it is a stable population. The turning point of the population decline period is between the age classes of Ⅲ-Ⅳ or Ⅳ-Ⅴ. Due to the restriction of population density, the population number will gradually decline in the future. In L. gmelinii forests with high elevation gradient (1200 m), the total number of individuals of R. dauricum is the smallest. The number of individuals at the age class Ⅰ is the largest, accounting for 33.52%, but their mortality and disappearance rate is higher, and the survival rate is lower. Moreover, the death and disappearance rate of individuals at the age class Ⅱ-Ⅴ is lower, and the survival rate is higher. The survival curve is Deevey Ⅲ. Therefore, it is a growth population, but the growth trend is weak. The turning point of the population decline period is at age class V, and the population number will increase in the future, but due to environmental constraints, the population number tends to be more stable. In conclusion, the population size of R. dauricum in the Great Khingan Mountains is stable overall. Elevation and forest type are important factors affecting the population number of R. dauricum. The B. platyphylla forest with an elevation of 600-900 m and canopy density of 45%-50% is the suitable habitat for R. dauricum, and R. dauricum is the main dominant species in shrub layer. 参考文献 相似文献 引证文献