The complete chloroplast genome of rhododendron williamsianum (ericaceae).

Rhododendron williamsianum Rehder & E. H. Wilson 1913, is a plant with important horticultural value. Here we report its chloroplast genome. The total length of the chloroplast genome was 205,424 bp, with a GC content of 35.8%. It consisted of a 107,968 bp large single copy, a 2606 bp small single copy, and a pair of 47,425 bp inverted repeats separating them. Within the chloroplast genome, there were a total of 110 unique genes, which included 76 protein-coding genes, 4 rRNA genes, and 30 tRNA genes. Our phylogenetic analyses indicated that R. williamsianum was closely genetically related to R. sutchuenense and R. jingangshanicum. The findings from this study not only contribute to the genetic database of Rhododendron plants but also have implications for evolutionary research within the family Ericaceae.

Pollinator shifts despite hybridisation in the Cape's hyperdiverse heathers (Erica, Ericaceae).

Interrogating the ecological and geographic factors that influence population divergence dynamics can reveal why some groups of organisms diversify more prolifically than others. One such group is the heathers (Erica, Ericaceae), the largest plant genus in the Cape Floristic Region. We study Erica abietina, a highly variable species complex with four subspecies differing in geographic range, habitat and pollination syndrome. We test for population differentiation, hybridisation, introgression and pollinator-driven divergence using genotyping-by-sequencing on samples across the entire distribution. We find five variably distinct genetic groups, with one subspecies comprising two independent lineages that are geographically isolated and occur on different soil types. Phylogenetic analysis suggests two independent shifts between bird and insect pollination, with accompanying genetic divergence. However, for one pair of populations with different pollinators, we uncover several individuals of hybrid origin at a site of sympatry. These results suggest that floral differentiation driven by divergent selection acts in concert with geographic isolation to maintain reproductive isolation and promote speciation. Our investigations reveal a highly dynamic system whose diversity has been shaped by a variety of interacting forces. We suggest that such a system could be a model for much of the diversification of the Cape flora.

Phytocannabinoid-like meroterpenoids from twigs and leaves of Rhododendron spinuliferum.

Six pairs of previously undescribed enantiomeric phytocannabinoid-like meroterpenoids, (±)-spinulinoids A‒F, and two naturally occurring compounds, (+)-rhododaurichromanic acid A and (E)-4-((3,7-dimethylocta-2,6-dien-1-yl)oxy)benzoic acid, together with one known congener, (-)-rhododaurichromanic acid A, were obtained from the twigs and leaves of Rhododendron spinuliferum. Their structures were established by their extensive spectral data (NMR and HRESIMS), ECD calculations, and single-crystal X-ray diffraction data. Spinulinoids A and B are unprecedented phytocannabinoid-like meroterpenoids constructed by the resorcinol moiety and a ß-bisabolene unit, whereas spinulinoid C represents a rare adduct of quinone and ß-bisabolene with a tricyclic 6/6/6 ring system.

A new isocoumarin derivative from endophytic fungus Pezicula neosporulosa VDB39 from Vaccinium dunalianum.

Four isocoumarin derivatives (1-4) and five phenols (5-9) were obtained from the endophytic fungus Pezicula neosporulosa VDB39, which was isolated from the branches of Vaccinium dunalianum Wight (Ericaceae). Compound 1 is a new derivative of isocoumarin. The structures were elucidated by spectroscopic methods. Single X-ray crystallography confirmed the absolute configuration of compound 1. Additionally, the antiphytopathogenic fungi activity of isocoumarin derivatives (1-4) was evaluated.

Three new antinociceptive diterpenoids from the fruits of Rhododendron molle.

Investigation of the fruits of Rhododendron molle G. Don led to the isolation of three new grayanane-type diterpenoids, rhodomolleins LIV-LVI (1-3). The structures and absolute configurations of new compounds were fully elucidated by spectroscopic analysis and single-crystal X-ray diffraction, including HRESIMS, 1 D and 2 D NMR data. Compounds 1-3 were evaluated for analgesic activities utilizing an acetic acid-induced writhing test in mice. Compound 1 showed a significant antinociceptive effect with writhe inhibition rates of 72.9% and 100% at doses of 6 mg/kg and 20 mg/kg in mice, respectively. The binding mode of 1 to N-ethylmaleimide-sensitive factor (NSF, PDB: 6IP2) was explored by molecular docking, indicating the presence of hydrogen bond interactions which account for its analgesic activity.

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, ß-unsaturated ketone carbonyl and Δ12(13) double bond functionalities exhibited enhanced anti-inflammatory properties.

Genus Erica: An identification aid version 4.00.

Species identification is fundamental to all aspects of biology and conservation. The process can be challenging, particularly in groups including many closely related or similar species. The problem is confounded by the absence of an up-to-date taxonomic revision, but even with such a resource all but professional botanists may struggle to recognise key species, presenting a substantial barrier to vital work such as surveys, threat assessments, and seed collection for ex situ conservation. Genus Erica: An Identification Aid is a tool to help both amateurs and professionals identify (using a limited number of accessible characteristics) and find information about the 851 species and many subspecific taxa of the genus Erica. We present an updated version 4.00, with new features including integrating distribution data from GBIF and iNaturalist, links to taxonomic resources through World Flora Online, and a probability function for identifications, that is freely available for PCs. It remains a work in progress: We discuss routes forward for collaboratively improving this resource.

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.

Discovery, biosynthesis, organic synthesis, and bioactivities of meroterpenoids from Rhododendron species.

Meroterpenoids discovered in Rhododendrons species possess unique chemical structures and biological activities and are expected to become new drug targets for Alzheimer's disease, metabolic disorders, and chronic kidney disease, and these compounds have attracted increasing attention in recent years. In this study, Rhododendron meroterpenoids and their structures, classifications, racemate distribution, biosynthetic pathways, chemical synthesis, and bioactivities are reviewed prior to 2023.

Phytochemical Profiling and Biological Activities of Rhododendron Subsect. Ledum: Discovering the Medicinal Potential of Labrador Tea Species in the Northern Hemisphere.

Rhododendron subsect. Ledum is a distinct taxonomic subdivision within the genus Rhododendron, comprising a group of evergreen shrubs and small trees. This review will comprehensively analyse the phytochemical profiles and biological properties of the Rhododendron subsect. Ledum species subsect. Ledum consists of eight plant species indigenous to temperate and subarctic regions of the Northern Hemisphere, collectively known as Labrador tea. Recent investigations have concentrated on the phytochemical constituents of these plants due to limited data, emphasizing their evergreen nature and potential industrial significance. This review summarizes their major phytochemical constituents, including flavonoids, phenolic acids, and terpenoids, and discusses their potential biological activities, such as antioxidant, anti-inflammatory, antimicrobial, antitumor, hypoglycemic, hepatoprotective, neuroprotective, and cardioprotective effects. Traditional uses of these plant species align with scientific findings, emphasizing the significance of these plants in traditional medicine. However, despite promising results, gaps exist in our understanding of specific compounds' therapeutic effects, necessitating further research for comprehensive validation. This review serves as a valuable resource for researchers, identifying current knowledge, uncertainties, and emerging trends in the study of the Rhododendron subsect. Ledum species.

Recent Advances in Grayanane Diterpenes: Isolation, Structural Diversity, and Bioactivities from Ericaceae Family (2018-2024).

Diterpenes represent one of the most diverse and structurally complex families of natural products. Among the myriad of diterpenoids, grayanane diterpenes are particularly notable. These terpenes are characterized by their unique 5/7/6/5 tetracyclic system and are exclusive to the Ericaceae family of plants. Renowned for their complex structures and broad spectrum of bioactivities, grayanane diterpenes have become a primary focus in extensive phytochemical and pharmacological research. Recent studies, spanning from 2018 to January 2024, have reported a series of new grayanane diterpenes with unprecedented carbon skeletons. These compounds exhibit various biological properties, including analgesic, antifeedant, anti-inflammatory, and inhibition of protein tyrosine phosphatase 1B (PTP1B). This paper delves into the discovery of 193 newly identified grayanoids, representing 15 distinct carbon skeletons within the Ericaceae family. The study of grayanane diterpenes is not only a deep dive into the complexities of natural product chemistry but also an investigation into potential therapeutic applications. Their unique structures and diverse biological actions make them promising candidates for drug discovery and medicinal applications. The review encompasses their occurrence, distribution, structural features, and biological activities, providing invaluable insights for future pharmacological explorations and research.

Mycorrhizas in South American Ericaceae.

Mycorrhizal symbioses (mycorrhizas) of Ericaceae, including ericoid mycorrhiza (ErM), have been mainly studied in the Northern Hemisphere, although the highest diversity of ericaceous plants is located in the Southern Hemisphere, where several regions remain largely unexplored. One of them is South America, which harbors a remarkably high diversity of Ericaceae (691 species and 33 genera) in a wide range of environmental conditions, and a specific mycorrhizal type called cavendishioid. In this review, we compile all available information on mycorrhizas of Ericaceae in South America. We report data on the mycorrhizal type and fungal diversity in 17 and 11 ericaceous genera, respectively. We show that South American Ericaceae exhibit a high diversity of habitats and life forms and that some species from typical ErM subfamilies may also host arbuscular mycorrhiza. Also, a possible geographical pattern in South American ErM fungal communities is suggested, with Sebacinales being the dominant mycorrhizal partners of the Andean clade species from tropical mountains, while archetypal ErM fungi are common partners in southern South America species. The gathered information challenges some common assumptions about ErM and suggests that focusing on understudied regions would improve our understanding of the evolution of mycorrhizal associations in this intriguing family.

Bioactive neolignan, iridoid and flavonoid glycosides from the leaves of Vaccinium bracteatum.

Two neolignan glycosides including a new one (1), along with seven iridoid glycosides (3 - 9) and nine flavonoid glycosides (10 - 18), were isolated from the leaves of Vaccinium bracteatum. Their structures were established mainly on the basis of 1D/2D NMR and ESIMS analyses, as well as comparison to known compounds in the literature. The structure of 1 with absolute stereochemistry was also confirmed by chemical degradation and ECD calculation. Selective compounds showed antiradical activity against ABTS and/or DPPH. Moreover, several isolates also suppressed the production of ROS in RAW264.7 cells and exerted neuroprotective effect toward PC12 cells.

Antioxidative and anti-inflammatory activities of Erica spiculifolia extracts and fractions.

There is little data on the phytochemical/pharmacological properties of Erica spiculifolia Salisb. (syn. Bruckentalia spiculifolia (Salisb.) Rchb.). This study examines the antioxidative and anti-inflammatory activities of different extracts and fractions of E. spiculifolia in vitro on isolated rat peritoneal macrophages, in the carrageenan-induced rat paw oedema test, BSA test, and two complementary antioxidant assays. Ethanolic extracts of leaves, flowers, and aboveground parts, and petroleum ether, ether, ethyl acetate, and water fractionations of the ethanol extract of E. spiculifolia applied at doses of 50-200 mg/kg p.o. exhibited dose-dependent anti-inflammatory activity comparable with indomethacin. All tested samples, except for the petroleum ether fraction, exerted excellent in vitro antioxidant activity, and all of them exhibited significant and similar inhibition of BSA denaturation comparable with diclofenac. Ethanolic extract of the aboveground parts obtained by percolation, ethyl acetate and water fractions had the highest efficiency, attenuating inflammation by more than 50% in the lowest applied concentration alongside exceptional radical scavenging activity.

The complete chloroplast genome sequence of Rhododendron farrerae Tate ex Sweet (Ericaceae).

Rhododendron farrerae Tate ex Sweet 1831 is a species of ornamental plant found in southern China. In the present study, the complete chloroplast genome of R. farrerae was sequenced. The genome was 149,453 bp in length and lacked the typical quadripartite structure. The plastid genome contained 112 genes, including 74 protein-coding genes, 34 tRNA genes, and 4 rRNA genes. The overall GC content of the genome was 35.65%. Phylogenetic analysis of 25 chloroplast genomes revealed that R. farrerae was closely related to Rhododendron huadingense. This study could provide fundamental information for the distribution, utilization, and phylogenomics of Rhododendron.

Structurally diverse analgesic diterpenoids from the flowers of Rhododendron molle.

Thirteen diterpenoids (1-13), classified into four structurally diverse carbon skeletons, including 1,5-seco-kalmane (1 and 6), grayanane (2-11), kalmane (12), and rhodomollane (13), were isolated from the flowers extract of Rhododendron molle. Among them, rhodomollinols A - E (1-5) were five new diterpenoids and their structures were elucidated by extensive spectroscopic methods including HRESIMS, UV, IR, 1D and 2D NMR, as well as quantum ECD calculations. Rhodomollinol A (1) is the first representative of a 6-deoxy-1,5-seco-kalmane diterpenoid. The abnormal NMR phenomenon of the presence of only 9 carbon resonances instead of 20 carbons in the 13C NMR spectrum of 1 was observed and elucidated by the quantum NMR calculations. All diterpenoids 1-13 showed significant analgesic activities in an acetic acid-induced writhing model. It's the first time to report the analgesic activity of a rhodomollane-type diterpenoid. At a dose of 1.0 mg/kg, diterpenoids 1-3, 6, 8, 9, and 12 reduced the writhe numbers with inhibition rates over 50%, and 9 exhibited stronger analgesic activity with a writhe inhibition rate of 89.7% than that of the positive control morphine. Importantly, even at the lowest dose of 0.04 mg/kg, rhodomollinols A (1) and B (2), rhodomollein X (7), and 2-O-methylrhodojaponin VI (9) still showed more potent analgesic effects than morphine with the writhe inhibition rates of 51.8%, 48.0%, 61.7%, and 60.0%, respectively. A preliminary structure-activity relationship might provide some clues to design potential analgesics on the basis of structurally diverse Ericaceae diterpenoids.

An updated review of the genus Rhododendron since 2010: Traditional uses, phytochemistry, and pharmacology.

Rhododendron, the largest genus of Ericaceae, consists of approximately 1000 species that are widely distributed in Europe, Asia, and North America but mainly exist in Asia. Rhododendron plants have not only good ornamental and economic value but also significant medicinal potential. In China, many Rhododendron plants are used as traditional Chinese medicine or ethnic medicine for the treatment of respiratory diseases, pain, bleeding and inflammation. Rhododendron is known for its abundant metabolites, especially diterpenoids. In the past 13 years, a total of 610 chemical constituents were reported from Rhododendron plants, including 222 diterpenoids, 122 triterpenoids, 103 meroterpenoids, 71 flavonoids and 92 other constituents (lignans, phenylpropanoids, phenolic acids, monoterpenoids, sesquiterpenoids, coumarins, steroids, fatty acids). Moreover, the bioactivities of various extracts and isolates, both in vitro and in vivo, were also investigated. Our review summarized the research progress of Rhododendron regarding traditional uses, phytochemistry and pharmacology in the past 13 years (2010 to December 2022), which will provide new insight for prompting further research on Rhododendron application and drug development.

Discovery of highly functionalized grayanane diterpenoids from the flowers of Rhododendron molle as potent analgesics.

A systematical investigation on the chemical constituents of the flowers of Rhododendron molle (Ericaceae) led to the isolation and characterization of thirty-eight highly functionalized grayanane diterpenoids (1-38), including twelve novel analogues molleblossomins A-L (1-12). Their structures were elucidated by comprehensive methods, including 1D and 2D NMR analysis, calculated ECD, 13C NMR calculations with DP4+ probability analysis, and single crystal X-ray diffraction. Molleblossomins A (1), B (2), and E (5) are the first representatives of 2ß,3ß:9ß,10ß-diepoxygrayanane, 2,3-epoxygrayan-9(11)-ene, and 5,9-epoxygrayan-1(10),2(3)-diene diterpenoids, respectively. Molleblossomins G (7) and H (8) represent the first examples of 1,3-dioxolane-grayanane conjugates furnished with the acetaldehyde and 4-hydroxylbenzylidene acetal moieties, respectively. All grayanane diterpenoids 1-38 were screened for their analgesic activities in the acetic acid-induced writhing model, and all of them exhibited significant analgesic activities. Diterpenoids 6, 13, 14, 17, 20, and 25 showed more potent analgesic effects than morphine at a lower dose of 0.2 mg/kg, with the inhibition rates of 51.4%, 68.2%, 94.1%, 66.9%, 97.7%, and 60.0%, respectively. More importantly, even at the lowest dose of 0.04 mg/kg, rhodomollein X (14), rhodojaponin VI (20), and rhodojaponin VII (22) still significantly reduced the number of writhes in the acetic acid-induced pain model with the percentages of 61.7%, 85.8%, and 64.6%, respectively. The structure-activity relationship was summarized and might provide some hints to design novel analgesics based on the functionalized grayanane diterpenoids.

A cryptic root isolate belonging to Geoglossales from potted Rhododendron: its molecular phylogeny and ability to colonize an ericoid mycorrhizal host in vitro.

Although the lifestyle of Geoglossales remains largely unknown, recent advancements have established a hypothesis regarding the ericoid mycorrhizal lifestyle of geoglossoid fungi. In this study, we focused on one isolate of Geoglossales sp. obtained from surface-sterilized roots of potted Rhododendron transiens. We aimed to reveal the phylogenetic position and in vitro colonizing ability of this species in the hair roots of ericoid mycorrhizal plants. Based on our multigene phylogenetic tree, this species is a sister of the genus Sarcoleotia which has not been reported from either other studies or field environment. Its ascocarps could not be obtained, and conspecific sequences were not found in the databases and repositories examined. The Geoglossales sp. colonized the vital rhizodermal cells of blueberries in vitro with hyphal coils. There were relatively large morphological variations of coils consistent with extraradical hyphae; however, overall, the colonization morphologically resembled those by Sarcoleotia globosa and representative ericoid mycorrhizal fungi. The taxonomy and ecological significance of the species remain to be resolved; nevertheless, our results suggest that the ericoid mycorrhizal lifestyle may be widespread within Geoglossales.

Phylogenetic relationship and characterization of the complete chloroplast genome of Rhododendron przewalskii subsp. przewalskii Maximowicz 1877, an ornamental and medicinal plant in China.

As one of the top 10 famous flowers in Chinese tradition, Rhododendron przewalskii subsp. przewalskii known as 'beauty in flowers,' which has high ornamental and medicinal value. The complete chloroplast (cp) genome of R. przewalskii subsp. przewalskii was determined in this study. The complete chloroplast genome of R. przewalskii subsp. przewalskii was 201,233 bp in length and contained a large single-copy region (LSC, 108,077 bp), and a small single-copy region (SSC, 2624 bp) and a pair of inverted repeat regions (IRa and IRb, 45,266 bp). A total of 142 functional genes were observed in this cp genome, including 91 protein-coding genes (PCGs), 43 transfer RNA genes (tRNAs), and eight ribosomal RNA genes (rRNAs). The R. przewalskii subsp. przewalskii cp genome has an A + T content of 64.06% and presents a positive AT-skew (0.53%) and a negative GC-skew (-1.56%). The maximum likelihood phylogenetic analysis based on the concatenated nucleotide sequences of 13 PCGs strongly supported the monophyletic relationship of R. przewalskii subsp. przewalskii the clade of R. henanense subsp. lingbaoense. This study provides genomic evidence for the vegetation classification of Rhododendron.