Rhododendron tomentosum (Ledum palustre). A review of traditional use based on current research

Anti-insect Activity of Benzylacetone and Its Structural Analogs Against Tribolium castaneum (Coleoptera: Tenebrionidae)

Several studies have confirmed that the volatile oil of Rhododendron anthopogonoides Maxim has good anti-insect activity and is expected to become an environmentally friendly botanical insecticide, with benzylacetone as its main active component. Benzylacetone has a simple chemical structure, containing only three elements of carbon, hydrogen and oxygen, low toxicity, and easy degradation. Therefore, in this study, benzylacetone and its seven structural analogues were selected for testing their anti-insect activity to Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), in order to explore the key structural sites where benzylacetone plays a role in combating T. castaneum. Benzylacetone demonstrated better repellent activity compared to the positive control pyrethroid, and when the single bonds at positions 3 and 4 were transformed into double bonds, the percent repellency increased. Additionally, the fumigation activity of benzylacetone exhibited a concentration-dependent trend and was significantly higher than that of the positive control pyrethroid. After losing two methylene groups at positions 3 and 4, the LC50 decreased to 13.10 mg/L air, which was approximately 9.4 times lower than that of benzylacetone. In terms of contact activity against T. castaneum, benzylacetone was about 2 times more effective than pyrethroids. Moreover, when the single bond at positions 3 and 4 became a double bond, the contact mortality was 2.5 times higher than that of benzylacetone, and the LD50 reached 10.47 μg/adult. Based on the results of repellent, fumigation, and contact toxicity experiments, it was found that the side chains of benzylacetone, carbonyl groups on the side chains, and benzene ring unsubstituted were the key structures for its prevention and control against T. castaneum. This study is an exploration of the structure-activity relationship of benzylacetone in the anti-insect of T. castaneum, providing ideas for its structural modification.

Bioactive Lignan Glycosides in Stems of Marsh Rosemary (Rhododendron tomentosum): Non-Targeted Screening and Identification Using Two-Stage Analytical Strategy

Rhododendron tomentosum is a widespread evergreen shrub used in folk medicine due to the high biological activity of its secondary metabolites, including lignans, that has not been sufficiently studied, and overcoming this problem requires advanced analytical techniques. This study proposes a two-stage analytical strategy for non-targeted screening and identification of lignans in plant extracts that involves the detection of specific lignan-related structures by 2D NMR and the establishment of corresponding fragment ions for further mass spectrometry analysis (HPLC-ESI-MS/MS). The polyphenolic fraction of R. tomentosum stem extract was the object of the study. Eight secoisolariciresinol-type lignans (xylosides, glucosides, and rhamnoside), including one previously unknown compound (5-methoxysecoisolariciresinol 9-xyloside), were identified for the first time. The structures of the five compounds were additionally confirmed by preparative HPLC isolation and NMR studies. All of the obtained compounds had antioxidant activity (FRAP and DPPH) similar to that of ascorbic acid. The proposed analytical strategy can be considered an efficient tool for rapid and reliable group screening and identification of lignan derivatives in plant extracts. Its application in the study of R. tomentosum extracts has revealed a number of lignan glycosides that may contribute to the medicinal properties of the plant.

Biological Properties and Phytochemicals of Multipurpose Tree Plant Hagenia abyssinica

Hagenia abyssinica (HA) is a monotypic tree species used as traditional medicine against various diseases and conditions in African countries. HA is also a multipurpose plant used for furniture, fuel wood, soil fertility management, and rainwater conservation, along with medicinal usage. In different in vitro, in vivo, ex vivo, and human studies, the potential of HA for different pharmacological properties, including anti-parasite, antibacterial, antifungal, antispasmodic, anticancer, anti-diabetes, antidiarrheal, wound healing, antioxidant, and anti-inflammatory activities were observed. Antioxidant and anti-inflammation properties of HA may be the primary reason for the multi-pharmacological activities of HA. Initial toxicity studies and the presence of various phytochemicals, especially flavonoids, also support the therapeutic potential of HA. The diverse medicinal properties of the plant have different challenges to overcome for its development. Limited studies to decipher the molecular mechanism behind the pharmacological activity restrict the utilization of the complete potential of HA as therapeutics. Still, the compilation of phytochemical, pharmacological activities, and target pathways of HA is missing in the literature. The current review not only compiles the pharmacological activities and phytochemicals but also highlights the gaps and proposes the future direction to develop HA as a candidate against important diseases.

The Paradigm Shift of Using Natural Molecules Extracted from Northern Canada to Combat Malaria

Parasitic diseases, such as malaria, are an immense burden to many low- and middle-income countries. In 2022, 249 million cases and 608,000 deaths were reported by the World Health Organization for malaria alone. Climate change, conflict, humanitarian crises, resource constraints and diverse biological challenges threaten progress in the elimination of malaria. Undeniably, the lack of a commercialized vaccine and the spread of drug-resistant parasites beg the need for novel approaches to treat this infectious disease. Most approaches for the development of antimalarials to date take inspiration from tropical or sub-tropical environments; however, it is necessary to expand our search. In this review, we highlight the origin of antimalarial treatments and propose new insights in the search for developing novel antiparasitic treatments. Plants and microorganisms living in harsh and cold environments, such as those found in the largely unexploited Northern Canadian boreal forest, often demonstrate interesting properties that are not found in other environments. Most prominently, the essential oil of Rhododendron tomentosum spp. Subarcticum from Nunavik and mortiamides isolated from Mortierella species found in Nunavut have shown promising activity against Plasmodium falciparum.

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.

Spectrophotometric and Chromatographic Assessment of Total Polyphenol and Flavonoid Content in Rhododendron tomentosum Extracts and Their Antioxidant and Antimicrobial Activity

In the literature, the chemical composition of Rhododendron tomentosum is mainly represented by the study of isoprenoid compounds of essential oil. In contrast, the study of the content of flavonoids will contribute to the expansion of pharmacological action and the use of the medicinal plant for medical purposes. The paper deals with the technology of extracts from Rh. tomentosum shoots using ethanol of various concentrations and purified water as an extractant. Extracts from Rh. tomentosum were obtained by a modified method that combined the effects of ultrasound and temperature to maximize the extraction of biologically active substances from the raw material. Using the method of high-performance thin-layer chromatography in a system with solvents ethyl acetate/formic acid/water (15:1:1), the following substances have been separated and identified in all the extracts obtained: rutin, hyperoside, quercetin, and chlorogenic acid. The total polyphenol content (TPC) and total flavonoid content (TFC) were estimated using spectrophotometric methods involving the Folin-Ciocalteu (F-C) reagent and the complexation reaction with aluminum chloride, respectively. A correlation analysis was conducted between antioxidant activity and the polyphenolic substance content. Following the DPPH assay, regression analysis shows that phenolic compounds contribute to about 80% (r2 = 0.8028, p < 0.05) of radical scavenging properties in the extract of Rh. tomentosum. The extract of Rh. tomentosum obtained by ethanol 30% inhibits the growth of test cultures of microorganisms in 1:1 and 1:2 dilutions of the clinical strains #211 Staphylococcus aureus and #222 Enterococcus spp. and the reference strain Pseudomonas aeruginosa ATCC 10145.

Vaccinium uliginosum L. (bog bilberry) and the search for its alleged toxicity: a review

Bog bilberry (Vaccinium uliginosum L.) is a wild-growing berry native to all circumboreal regions. There is however a significant discrepancy in the uses of bog bilberry fruits around the world. There exists a strong prejudice against the use of these berries in many European countries as well as a few incidences of poisoning reported between 1906 and 1944. In Asia and North America, this fear is completely absent from the local knowledge and the bog bilberry is valued as an excellent food and medicinal plant. There has been a lack of research on the topic in the last 50 years and thus the presumed toxicity remains unproven. This review aims to gather the conflicting information from all regions where bog bilberry grows and present them in a critical way to elucidate the possible explanations for the discrepancies. There are several possible explanations for the alleged toxicity of the bog bilberry, including a fungal infection of the fruits, individual intolerance or accidental poisoning by a different plant species; the local names meaning "drunk, inebriating, vomit-inducing berry" may be related to the alcoholic drinks made from them. This review highlights the gap in knowledge and serves as a theoretical framework for future research.

A Review of the Ethnobotanical Use, Chemistry and Pharmacological Activities of Constituents Derived from the Plant Genus Geijera (Rutaceae)

Geijera Schott is a plant genus of the Rutaceae Juss. (rue and citrus) family, comprising six species which are all native to Oceania. Of the plants belonging to this genus, the most significant species that has a customary use is Geijera parviflora, which was used by Indigenous Australians, primarily as a pain reliever. Herein, a comprehensive review of the literature published on the genus Geijera from 1930 to 2023 was conducted. This is the first review for this plant genus, and it highlights the chemical constituents reported to date, together with the range of pharmacological properties described from the various species and different parts of the plant. These properties include anti-inflammatory, anti-microbial, anti-parasitic, insect repellent, analgesic, neuroactive, and anti-cancer activities. Finally, a reflection on some of the important areas for future focused studies of this plant genus is provided.

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.

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.

Oral nicotine pouches with an aftertaste? Part 1: screening and initial toxicological assessment of flavorings and other ingredients

Nicotine pouches are oral products that deliver nicotine without containing tobacco. Previous studies mainly focused on the determination of known tobacco toxicants, while yet no untargeted analysis has been published on unknown constituents, possibly contributing to toxicity. Furthermore, additives might enhance product attractiveness. We therefore performed an aroma screening with 48 different nicotine-containing and two nicotine-free pouches using gas chromatography coupled to mass spectrometry, following acidic and basic liquid-liquid extraction. For toxicological assessment of identified substances, European and international classifications for chemical and food safety were consulted. Further, ingredients listed on product packages were counted and grouped by function. Most abundant ingredients comprised sweeteners, aroma substances, humectants, fillers, and acidity regulators. 186 substances were identified. For some substances, acceptable daily intake limits set by European Food Safety Agency (EFSA) and Joint FAO/WHO Expert Committee on Food Additives are likely exceeded by moderate pouch consumption. Eight hazardous substances are classified according to the European CLP regulation. Thirteen substances were not authorized as food flavorings by EFSA, among them impurities such as myosmine and ledol. Three substances were classified by International Agency for Research on Cancer as possibly carcinogenic to humans. The two nicotine-free pouches contain pharmacologically active ingredients such as ashwagandha extract and caffeine. The presence of potentially harmful substances may point to the need for regulation of additives in nicotine-containing and nicotine-free pouches that could be based on provisions for food additives. For sure, additives may not pretend positive health effects in case the product is used.

Essential Oils and Supercritical CO2 Extracts of Arctic Angelica (Angelica archangelica L.), Marsh Labrador Tea (Rhododendron tomentosum) and Common Tansy (Tanacetum vulgare)-Chemical Compositions and Antimicrobial Activities

Traditionally, arctic Finnish Angelica (Angelica archangelica L.), marsh Labrador tea (Rhododendron tomentosum, syn. Ledum palustre) and common tansy (Tanacetum vulgare) have been used as medicinal herbs in folklore medicine. However, these underutilised plants are a source of, e.g., oil-based compounds, which could benefit many modern applications implemented by the green chemistry extraction methods, as well. We extracted Angelica, marsh Labrador tea and common tansy by non-toxic and recyclable extraction methods, i.e., hydrodistillation and supercritical carbon dioxide (scCO₂) extraction; characterised the essential oils (EOs) and scCO₂ extracts by combination of gas chromatography and mass spectrometry (GC-MS), and in addition, analysed the antimicrobial properties. As expected for Angelica root and common tansy inflorescence, the scCO₂ extraction method produced less amount of volatile compounds compared to hydrodistillation. On the other hand, more coumarins, alkanes, fatty alcohols and fatty acids were obtained. Additionally, sesquiterpenoids palustrol and ledol were predominant compounds in both marsh Labrador tea EO and scCO₂ extract. According to our results, however, all the EOs and scCO₂ extracts showed broad spectrum of antimicrobial activities against the selected microbes, but the effects were extract-specific. The strongest and broadest antimicrobial activities were performed by marsh Labrador tea scCO₂ extract, which showed extremely strong effect on Staphylococcusaureus subsp. aureus and strong effect on Candida albicans.

Essential Oils and Bioactive Components against Arthritis: A Novel Perspective on Their Therapeutic Potential

Essential oils (EOs) are known to possess a number of beneficial properties. Their antimicrobial, anti-inflammatory, antioxidant, antidiabetic, and cancer-preventing activities have been extensively reported. Due to their wide use as food preservers and additives, as well as their use in agriculture, perfumes, and make-up products, these complex mixtures of volatile compounds have gained importance from a commercial point of view, not only in the pharmaceutical industry, but also in agronomic, food, cosmetic, and perfume industries. An analysis of the recent scientific literature allowed us to highlight the presence of an increasing number of studies on the potential antiarthritic properties of EOs and their main constituents, which seems to suggest a new interesting potential therapeutic application. The aim of this review is to examine the current knowledge on the beneficial effects of essential oils in the treatment of arthritic diseases, providing an overview of the reports on the in vivo and in vitro effects of EOs. Furthermore, this review critically examines the recent findings on the potential roles of the main components of EOs in the exerted beneficial effects. Obtained negative results are also reported.

Comparative Analysis of Far East Sikhotinsky Rhododendron (Rh. sichotense) and East Siberian Rhododendron (Rh. adamsii) Using Supercritical CO2-Extraction and HPLC-ESI-MS/MS Spectrometry

Rhododendron sichotense Pojark. and Rhododendron adamsii Rheder have been actively used in ethnomedicine in Mongolia, China and Buryatia (Russia) for centuries, as an antioxidant, immunomodulating, anti-inflammatory, vitality-restoring agent. These plants contain various phenolic compounds and fatty acids with valuable biological activity. Among green and selective extraction methods, supercritical carbon dioxide (SC-CO₂) extraction has been shown to be the method of choice for the recovery of these naturally occurring compounds. Operative parameters and working conditions have been optimized by experimenting with different pressures (300–400 bar), temperatures (50–60 °C) and CO₂ flow rates (50 mL/min) with 1% ethanol as co-solvent. The extraction time varied from 60 to 70 min. A HPLC-UV-VIS-ESI-MS/MS technique was applied to detect target analytes. A total of 48 different biologically active components have been identified in the Rh. adamsii SC-CO₂ extracts. A total of 31 different biologically active components have been identified in the Rh. sichotense SC-CO₂ extracts.

Hydrophilic Interaction Chromatography Analysis of Esculin in Ointments with UV Detection

Background:

Esculin (ESCN) is used in the pharmaceutical industry with intravenous effect, stimulant and anti-inflammatory capillaries, like vitamin P. It is a significant component of many anti-inflammatory remedies such as esqusan, esflazid and anavenol [14]. It is also found in numerous other remedies available in the market such as proctosone, anustat, and ariproct.

Objective:

To determine experimental conditions, to elucidate retention behavior of esculin in HILIC mode. Moreover, to suggest new ways to separate and determinate esculin in ointments.

Methods:

Two hydrophilic columns were obtained by attaching molecules of sulfobetaine to polystyrene- divinylbenzene particles were studied for chromatographic separation of esculin. The various lengths of the chain are used as an investigative instrument for esculin retention conduct. The change of ACN percentage, buffer concentrations and pH of mobile phase in order to study the retention conduct of esculin.

Results:

A mixed mode hydrophilic interaction and ion exchange is the separation mechanism of esculin. A calibration graph was created for two columns. The concentration range was 8-1200 ng.ml-1, LOD 2.33 and 1.40, RSD% 0.31-1.02, , LOQ 7.07 and 4.25 ng.ml-1, Erel% 0.83 ± 0.68 and 0.545 ± 0.45, Recovery% 100.86 ± 0.68 and 1054 ± 0.45.

Conclusion:

The findings of the current study introduced new ZIC-HILIC methods for the separation and quantitation of esculin.

The essential oil of Lactuca longidentata Moris and its antioxidant and antimicrobial activities

Lactuca longidentata Moris (Asteraceae) is an endemic species growing only on Mesozoic limestone of central Sardinia. In the present study, the essential oil of the epigeal part of the plant was analyzed by gas chromatography-mass spectrometry (GC/MS). The main volatile components were α-terpineol (27.64%) and limonene (25.8%). The essential oils showed a noteworthy ability of scavenging free radical species (1,1-diphenyl-2-picrylhydrazyl (DPPH) test systems) with a mean half maximal inhibitory concentration IC₅₀ of 32.24 μg/mL. More significant was the inhibition of lipid oxidation that corresponded to an activity 1.5 times lower than that of 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT). The essential oil was also assayed on Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, and Candida albicans by the microdilution broth method and was particularly active against B. subtilis, with a minimal inhibitory concentration (MIC) value of 100 μg/mL.

Toxic, Radical Scavenging, and Antifungal Activity of Rhododendron tomentosum H. Essential Oils

The chemical composition of eight (seven shoot and one inflorescence) essential oils (EOs) of Rh. tomentosum H. plants growing in Eastern Lithuania is reported. The plant material was collected during different phases of vegetation (from April to October). The oils were obtained by hydrodistillation from air-dried aerial parts (leaves and inflorescences). In total, up to 70 compounds were identified by GC−MS and GC (flame-ionization detector, FID); they comprised 91.0 ± 4.7%–96.2 ± 3.1% of the oil content. Sesquiterpene hydrocarbons (54.1 ± 1.5%–76.1 ± 4.5%) were found to be the main fraction. The major compounds were palustrol (24.6 ± 2.6%–33.5 ± 4.4%) and ledol (18.0 ± 2.9%–29.0 ± 5.0%). Ascaridol isomers (7.0 ± 2.4%–14.0 ± 2.4% in three oils), myrcene (7.2 ± 0.3% and 10.1 ± 1.3%), lepalol (3.3 ± 0.3% and 7.9 ± 3.0%), and cyclocolorenone isomers (4.1 ± 2.5%) were determined as the third main constituents. The toxic activity of marsh rosemary inflorescence and shoot oils samples was evaluated using a brine shrimp (Artemia sp.) bioassay. LC₅₀ average values (11.23–20.50 µg/mL) obtained after 24 h of exposure revealed that the oils were notably toxic. The oil obtained from shoots gathered in September during the seed-ripening stage and containing appreciable amounts of palustrol (26.0 ± 2.5%), ledol (21.5 ± 4.0%), and ascaridol (7.0 ± 2.4%) showed the highest toxic activity. Radical scavenging activity of Rh. tomentosum EOs depended on the plant vegetation stage. The highest activities were obtained for EOs isolated from young shoots collected in June (48.19 ± 0.1 and 19.89 ± 0.3 mmol/L TROLOX (6-hydroxy-2,5,7,8-tetra-methylchromane-2-carboxylic acid) equivalent obtained by, respectively, ABTS^•+ (2,2′-amino-bis(ethylbenzothiazoline-6-sulfonic acid) diammonium salt) and DPPH^•(2,2-diphenyl-1-picrylhydrazyl) assays). Agar disc diffusion assay against pathogenic yeast Candida parapsilosis revealed the potential antifungal activity of EOs. An alternative investigation of antifungal activity employed mediated amperometry at yeast Saccharomyces cerevisiae-modified electrodes. The subjection of yeast cells to vapors of EO resulted in a three to four-fold increase of electrode responses due to the disruption of yeast cell membranes.

Trace elements in Labrador Tea (Rhododendron groenlandicum): How predominant sources to the plants impact the chemical composition of hot water extracts

Labrador Tea (Rhododendron groenlandicum) has been an important food and medicinal plant to First Nations communities in North America for millenia, but little is known of its geochemical properties. Using plants from 10 sites in 4 provinces, including pristine and industrial regions, and employing the metal-free, ultraclean SWAMP laboratory facilities and procedures, we provide an estimate of the natural abundance of trace elements in the leaves, and the extent of their release during hot water extraction. Elements decrease in abundance in the order Mn > Al > Fe > Zn > Cu > Ni > V > Pb > La > Mo > Y > La > Tl > Cd > Th > Ag. The greatest concentrations of conservative, lithophile elements such as Al, La, Th and Y, are found in samples collected on lands reclaimed from open pit bitumen mines in northern Alberta, reflecting elevated inputs of atmospheric dusts. In contrast, micronutrients such as Cu and Zn are remarkably uniform which suggests that these are supplied almost exclusively by plant uptake via roots. Deionized, reverse osmosis water is more effective in removing some elements (e.g. Al, La, Y, Fe, Zn, Cd) whereas others are more readily extracted using groundwater (e.g. Cu, Ni, Pb); V behaves independently of water composition. In both types of water, the elements most readily extracted are plant micronutrients (Mn, Ni, Cu, and Zn) whereas those supplied primarily by dust exhibit much lower yields; Al shows behaviour intermediate between these two extremes. While element concentrations in the infusions increase with increasing concentrations in the leaves, the abundance of potentially toxic chalcophile elements such as Cd, Pb, Sb and Tl in the infusions are extremely low (ng/l). Plants from British Columbia, Ontario and Quebec provide evidence of atmospheric Pb contamination, yielding greater ratios of Pb/La compared to the samples from Alberta where crustal values are found. Given that this plant is common and found across the northern half of the continent, it shows great promise as a tool for biomonitoring of air quality. For consumers, Labrador Tea may represent an important dietary source of Mn.

Medicinal plants and their uses recorded in the Archives of Latvian Folklore from the 19th century

ETHNOPHARMACOLOGICAL RELEVANCE

The records of folk medicine present historical evidence of medicinal plant usage in the territory of Latvia and describe native and imported plants and plant products that were used as medicine.

AIM OF THE STUDY

To collect and analyse the ethnobotanical knowledge found in records of Latvian folk medicine available in the Archives of Latvian Folklore.

MATERIALS AND METHODS

Following the International Classification of Primary Care, plant uses were grouped into one of the 17 categories based on the body systems and psychological and social problems. Each plant was identified by its scientific name according to The Plant List website. Additionally, the plant parts used, dosage forms of herbal medicines and routes of administration were analysed.

RESULTS

In total, 211 genera belonging to 71 families were mentioned in the analysed materials. The most common health conditions were digestive system disorders, respiratory system disorders and skin disorders. The plant families with the largest number of taxa were Asteraceae, Rosaceae, Lamiaceae, and Apiaceae. The most frequently mentioned native plant taxa were Achillea millefolium L., Matricaria chamomilla L., Allium cepa L., Artemisia absinthium L., and Plantago sp. L. Leaves and flowers were the most commonly used parts, and herbal tea was the most common dosage form. Only 59 out of 211 taxa mentioned in this study are included in the official herbal monographs of the European Medicines Agency.

CONCLUSIONS

One hundred and fifty-two plant taxa mentioned in the records of Latvian folk medicine are not included in the European Union herbal monographs providing scientific information on the safety and efficacy and deserve further exploration as traditional herbal medicines.

Ascaridole-rich essential oil from marsh rosemary (Ledum palustre) growing in Poland exerts insecticidal activity on mosquitoes, moths and flies without serious effects on non-target organisms and human cells

Marsh rosemary (Ledum palustre, Ericaceae) has been widely used in the traditional medicine of various regions worldwide, and as insect repellent. Little is known on its essential oil insecticidal potential. This study explored the insecticidal effects of the essential oil obtained from L. palustre growing in Poland on selected insect pests and vectors. GC-MS analysis evidenced an uncommon chemotype characterized by ascaridole (35.3% as sum of cis-ascaridole and isoascaridole) and p-cymene (25.5%). The essential oil was effective against Culex quinquefasciatus, Spodoptera littoralis and Musca domestica, showing LC₅₀/LD₅₀ of 66.6 mg L^-1, 117.2 μg larva^-1 and 61.4 μg adult^-1, respectively. It was not toxic to non-target Eisenia fetida earthworms and moderately toxic to Daphnia magna microcrustaceans, over the positive control α-cypermethrin. The essential oil cytotoxicity on human keratinocytes and fibroblasts showed high IC₅₀ values (71.3 and 84.4 μg mL^-1, respectively). Comet assay data highlighted no DNA damages. Based on our findings, this essential oil, characterized by the ascaridole/p-cymene chemotype, could be a candidate for the formulation of botanical insecticides; large-scale production of green insecticides by this rare species may be assured by ex situ cultivation and biotechnological techniques.

Chemical variability of Rhododendron tomentosum (Ledum palustre) essential oils and their pro-apoptotic effect on lymphocytes and rheumatoid arthritis synoviocytes

Rhododendron tomentosum (Ledum palustre) is an aromatic plant traditionally used for alleviating rheumatic complaints which makes it a potential candidate for a natural drug in rheumatoid arthritis (RA) treatment. However, the effects of plants' volatiles on apoptosis of synovial fibroblasts and infiltrating leucocytes of RA synovia, have not been reported. Volatile fraction of R. tomentosum is chemically variable and chemotypes of the plants need to be defined if the oil is to be used for therapeutic purposes. In the presented work, cluster analysis of literature data enabled to define 10 chemotypes of the plant. The volatile fractions of known composition were then tested for bioactivity using a RA-specific in vitro models. Essential oils of two wild types (γ-terpineol and palustrol/ledol type) and one in vitro chemotype (ledene oxide type) were obtained by hydrodistillation and their bioactivity was tested in two in vitro models: I - peripheral blood lymphocytes of healthy volunteers and II - synoviocytes and immune cells isolated from synovia of RA patients. The influence of oils on blood lymphocytes' proliferation and apoptosis rates of synovia-derived cells was determined by flow cytometry. Dose-dependent inhibitory effect of the serial dilutions of R. tomentosum oils on proliferation rates of blood lymphocytes was found. At 1:400 dilutions, all the tested oils increased the number of necrotic cells in synovial fibroblasts from RA synovia. Additionally, increased proportions of late apoptotic cells were observed in leucocyte populations subjected to oils at 1:400 dilution.

Two new taraxerane-type triterpenes from Ledum palustre L

Two new compounds, namely 6α-hydroxy-14-taraxerene-3,16,21-trione and 6α,26-dihydroxy-14-taraxerene-3,16,21-trione were isolated from the Ledum palustre L. Their chemical structures were confirmed after a combined analysis of IR, HR-ESI-TOFMS, 1D-NMR, and 2D-NMR. The compounds were evaluated for cell growth inhibitory activity against two cancer cell lines.

Exploring the Insecticidal Potential of Boldo (Peumus boldus) Essential Oil: Toxicity to Pests and Vectors and Non-target Impact on the Microcrustacean Daphnia magna

Every year Chile exports about 2000 tons of boldo folium (Peumus boldus), which is used around the world as a traditional herbal medicinal product (THMP), mostly to relieve gastrointestinal disorders. This biomass may be a resource for the agrochemical industry to manufacture botanical insecticides. In this regard, the insecticidal potential of boldo has been poorly investigated. In the present work, hydrodistillation of a commercial boldo folium gave 1.5% (w/w) of a yellowish essential oil (boldo essential oil, BEO) containing 1,8-cineole (20.7%), p-cymene (18.5%), limonene (9.1%), ascaridole (9.1%) and β-phellandrene (6.4%) as the main constituents, as determined by gas chromatography-mass spectrometry (GC-MS). NMR analysis allowed us to determine that ascaridole was mainly represented by the cis-isomer. BEO was toxic to larvae of the filariasis vector Culex quinquefasciatus and adults of the housefly Musca domestica, showing LC50/LD50 values of 67.9 mg·L-1 and 98.5 µg·adult-1, respectively. On the other hand, lower insecticidal activity was observed against larvae of the moth pest Spodoptera littoralis (LD50 of 268.9 µg·larva-1). It is worth noting that, when tested at LC90 concentration, BEO was significantly less toxic to aquatic microcrustacean Daphnia magna than the conventional insecticide α-cypermethrin. Finally, in the attempt to explore the BEO mode of action, we tested it for acetylcholinesterase (AChE) inhibitory properties using the Ellman method, obtaining negligible effects (IC50 = 0.45 mg·mL-1). Taken together, these results gave new insights into the potential of BEO as a future ingredient of botanical insecticides.

Simultaneous Determination of Aesculin, Aesculetin, Fraxetin, Fraxin and Polydatin in Beagle Dog Plasma by UPLC-ESI-MS/MS and Its Application in a Pharmacokinetic Study after Oral Administration Extracts of Ledum palustre L

A rapid, simple and sensitive ultra-performance liquid chromatography-electrospray-ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) method was developed and validated for the simultaneous determination of aesculin, aesculetin, fraxetin, fraxin and polydatin in beagle dog plasma for the first time. Plasma samples were pretreated by protein precipitation with methanol. Chromatographic separation was performed on an Acquity UPLC HSS T3 C18 column (2.1 mm × 100 mm, 1.8 μm) with gradient elution at a flow rate of 0.4 mL/min, using a mobile phase consisting of 0.1% formic acid (A) and acetonitrile (B). The analytes and IS were detected by multiple reaction monitoring (MRM) via negative ion mode with ion transitions of m/z 339.1–m/z 176.8 for aesculin, m/z 176.8–m/z 88.9 for aesculetin, m/z 206.8–m/z 192.1 for fraxetin, m/z 369.1–m/z 206.9 for fraxin, m/z 389.1–m/z 227.0 for polydatin and m/z 415.2–m/z 295.1 for puerarin. This method was validated according to the FDA guidelines and the results met the requirements of analysis. The calibration curves of analytes were linear with correlation coefficients more than 0.9980. The intra- and inter-day precisions were less than 15% and the accuracy was within ±15%. The maximum plasma concentration (Cmax) of aesculin, aesculetin, fraxetin, fraxin and polydatin was 46.75 ± 7.46, 209.9 ± 57.65, 369.7 ± 48.87, 67.04 ± 12.09 and 47.14 ± 12.04 ng/mL, respectively. The time to reach the maximum plasma concentration (Tmax) was 1.32 ± 0.38 h for aesculin, 1.03 ± 0.27 h for aesculetin, 0.94 ± 0.23 h for fraxetin, 0.83 ± 0.18 h for fraxin and 1.15 ± 0.15 h for polydatin. The results indicated that the absorption of aesculin might be slow in beagle dog plasma. This method was successfully applied for pharmacokinetics in beagle dog plasma after oral administration of the extracts of Ledum palustre L. at a dosage of 0.27 g/kg.

Understorey Rhododendron tomentosum and Leaf Trichome Density Affect Mountain Birch VOC Emissions in the Subarctic

Subarctic vegetation is composed of mountain birch [Betula pubescens ssp. czerepanovii (MB)] forests with shrubs and other species growing in the understorey. The effects of the presence and density of one understorey shrub, Rhododendron tomentosum (RT), on the volatile emissions of MB, were investigated in a Finnish subarctic forest site in early and late growing season. Only MB trees with an RT-understorey emitted the RT-specific sesquiterpenoids, palustrol, ledol and aromadendrene. Myrcene, which is the most abundant RT-monoterpene was also emitted in higher quantities by MB trees with an RT-understorey. The effect of RT understorey density on the recovery of RT compounds from MB branches was evident only during the late season when sampling temperature, as well as RT emissions, were higher. MB sesquiterpene and total emission rates decreased from early season to late season, while monoterpene emission rate increased. Both RT and MB terpenoid emission rates were linked to density of foliar glandular trichomes, which deteriorated over the season on MB leaves and emerged with new leaves in the late season in RT. We show that sesquiterpene and monoterpene compounds emitted by understorey vegetation are adsorbed and re-released by MB, strongly affecting the MB volatile emission profile.

Ozone disrupts adsorption of Rhododendron tomentosum volatiles to neighbouring plant surfaces, but does not disturb herbivore repellency

The perennial evergreen woody shrub, Rhododendron tomentosum, confers associational resistance against herbivory and oviposition on neighbouring plants through passive adsorption of some of its constitutively emitted volatile organic compounds (VOCs). The adsorption process is dependent on transport of VOCs in the air. In polluted atmospheres, the VOCs may be degraded and adsorption impeded. We studied the effect of elevated ozone regimes on the adsorption of R. tomentosum volatiles to white cabbage, Brassica oleracea, and the oviposition of the specialist herbivore Plutella xylostella on the exposed plants. We found evidence for adsorption and re-emission of R. tomentosum volatiles by B. oleracea plants. Ozone changed the blend of R. tomentosum volatiles and reduced the amount of R. tomentosum volatiles recovered from B. oleracea plants. However, plants exposed to R. tomentosum volatiles received fewer P. xylostella eggs than control plants exposed to filtered air irrespective of whether R. tomentosum volatiles mixed with ozone. Ozone disrupts a volatile mediated passive plant-to-plant interaction by degrading some compounds and reducing the quantity available for adsorption by neighbouring plants. The change, however, did not affect the deterrence of oviposition by P. xylostella, suggesting that aromatic companion plants of Brassica crops may confer pest-deterring properties even in ozone-polluted environments.

Therapeutic effect of Northern Labrador tea extracts for acute myeloid leukemia

Acute myeloid leukemia (AML) is an aggressive hematological malignancy that is one of the more common pediatric malignancies in addition to occurring with high incidence in the aging population. Unfortunately, these patient groups are quite sensitive to toxicity from chemotherapy. Northern Labrador tea, or Rhododendron tomentosum Harmaja (a.k.a. Ledum palustre subsp. decumbens) or "tundra tea," is a noteworthy medicinal plant used by indigenous peoples in Alaska, Canada, and Greenland to treat a diversity of ailments. However, laboratory investigations of Northern Labrador tea, and other Labrador tea family members, as botanical sources for anticancer compounds have been limited. Utilizing an AML cell line in both in vitro and in vivo studies, as well as in vitro studies using primary human AML patient samples, this study demonstrated for the first time that Northern Labrador tea extracts can exert anti-AML activity and that this may be attributed to ursolic acid as a constituent component. Therefore, this medicinal herb holds the potential to serve as a source for further drug discovery efforts to isolate novel anti-AML compounds.

Passive Adsorption of Volatile Monoterpene in Pest Control: Aided by Proximity and Disrupted by Ozone

Plant volatiles mediate a range of interactions across and within trophic levels, including plant-plant interactions. Volatiles emitted by a plant may trigger physiological responses in neighboring plants or adhere to their surfaces, which, in turn, may affect the responses of the neighboring plant to herbivory. These volatiles are subject to chemical reactions during transport in air currents, especially in a polluted atmosphere. We conducted a field experiment to test for the adsorption of dispenser-released myrcene on the surfaces of cabbage plants and the effects of distance from the dispenser and elevated ozone levels (1.4× ambient) on the process. We also tested the effects of the same treatments on oviposition on cabbage plants by naturally occurring Plutella xylostella. Under low ambient ozone conditions of central Finland, there was evidence for the adsorption and re-release of myrcene by cabbage plants growing at a distance of 50 cm from myrcene dispensers. This effect was absent at elevated ozone levels. The number of eggs deposited by P. xylostella was generally lower in plots under elevated ozone compared to ambient control plots. Our results indicate that passive adsorption and re-release of a volatile monoterpene can occur in nature; however, this process is dependent upon the distance between emitter source and receiver plants as well as the concentration of atmospheric pollutants in the air. We conclude that, in the development of field-scale use of plant volatiles in modern pest control, the effects of distances and air pollution should be considered.

In Vitro Propagation of Rhododendron tomentosum – an Endangered Essential Oil Bearing Plant from Peatland

Rhododendron tomentosum Harmaja (formerly Ledum palustre L.) is a medicinal peat bog plant native to northern Europe, Asia and North America. This plant has a distinctive aroma thanks to the presence of essential oil, to which it also owes its anti-inflammatory, analgesic, antimicrobial and insecticidal properties. However, in Europe R. tomentosum is classified as an endangered species, mainly due to degradation of peatlands. In the present work, the micropropagation protocol for R. tomentosum was established for the first time, providing both an ex situ conservation tool and a means of continuous production of in vivo and in vitro plant material for further studies. R. tomentosum microshoots were initiated from leaf explants and further multiplied using Schenk-Hildebrandt (SH) medium supplemented with 9.84 μM 2iP and 1.00 μM TDZ. The shoots were elongated on the SH medium supplemented with 24.6 μM 2iP and subsequently rooted using the perlite substrate saturated with half-strength Woody Plant medium supplemented with 1.0% sucrose and 4.92 μM IBA. The regenerated plants were hardened on the phytohormone-free SH medium and acclimatized using 3:1:1 deacidified peat:perlite:gravel substrate. The identity of the mother plant was confirmed at morphological and molecular levels and Random Amplified Polymorphic DNA (RAPD) method was implemented to assess the genetic fidelity of the regenerants. The essential oil content of the maternal plant, in vitro shoots and the regenerants was determined by steam-distillation, and the obtained volatile fractions were analyzed by GC/MS.

Interspecific differences in foliar 1 PAHs load between Scots pine, birch, and wild rosemary from three polish peat bogs

Pine needles are one of the most commonly used bioindicators of polycyclic aromatic hydrocarbons (PAHs) in the environment. Therefore, the main objective of the current research was the assessment of PAHs accumulation potential of Scots pine (Pinus sylvestris L.) needles in comparison to wild rosemary (Rhododendron tomentosum Harmaja) and birch (Betula spp.) leaves. Our study was carried out on three peat bogs subjected to different degree of anthropopression, which gave us also the opportunity to identify local emission sources. Pine needles had the lowest accumulation potential from all the studied species. The highest accumulation potential, and hence carcinogenic potential, was observed for wild rosemary leaves. As far as emission sources are concerned, the most pronounced influence on atmospheric PAHs loads had traditional charcoal production, resulting in great influx of heavy PAHs. Observed seasonal changes in PAHs concentrations followed the pattern of winter increase, caused mainly by heating season, and summer decrease, caused mainly by volatilization of light PAHs.

Labrador tea--the aromatic beverage and spice: a review of origin, processing and safety

Labrador tea is a name for the dried leaves of Rhododendron groenlandicum, R. tomentosum or R. neoglandulosum (family Ericaceae, previously genus Ledum) as well as for the beverage native to North America, which is made from them. The above species are rich in the essential oil, which gives a conifer aroma to the tisane. Labrador tea is a valuable source of ascorbic acid, with tonic, improving digestion and relaxing activity. However, this beverage should not be drunk more than once daily because of the ledol and grayanotoxin toxicity. The common recipe for making Labrador tea is to add one teaspoonful of dried leaves to one cup of boiling water and to brew for 5 min. It is often sweetened or enriched with other flavors. Additionally, Labrador tea dried leaves are used to spice meat, soups, sauces, salads, beer, cakes and other dishes. In agriculture, its insecticidal properties can be useful for controlling pests.

Phylogenetic spectrum and analysis of antibacterial activities of leaf extracts from plants of the genus Rhododendron

BACKGROUND

Plants are traditionally used for medicinal treatment of numerous human disorders including infectious diseases caused by microorganisms. Due to the increasing resistance of many pathogens to commonly used antimicrobial agents, there is an urgent need for novel antimicrobial compounds. Plants of the genus Rhododendron belong to the woody representatives of the family Ericaceae, which are typically used in a range of ethno-medical applications. There are more than one thousand Rhododendron species worldwide. The Rhododendron-Park Bremen grows plants representing approximately 600 of the known Rhododendron species, and thus enables research involving almost two thirds of all known Rhododendron species.

METHODS

Twenty-six bacterial species representing different taxonomic clades have been used to study the antimicrobial potential of Rhododendron leaf extracts. Agar diffusion assay were conducted using 80% methanol crude extracts derived from 120 Rhododendron species. Data were analyzed using principal component analysis and the plant-borne antibacterial activities grouped according the first and second principal components.

RESULTS

The leaf extracts of 17 Rhododendron species exhibited significant growth-inhibiting activities against Gram-positive bacteria. In contrast, only very few of the leaf extracts affected the growth of Gram-negative bacteria. All leaf extracts with antimicrobial bioactivity were extracted from representatives of the subgenus Rhododendron, with 15 from the sub-section Rhododendron and two belonging to the section Pogonanthum. The use of bacterial multidrug efflux pump mutants revealed remarkable differences in the susceptibility towards Rhododendron leaf extract treatment.

CONCLUSIONS

For the first time, our comprehensive study demonstrated that compounds with antimicrobial activities accumulate in the leaves of certain Rhododendron species, which mainly belong to a particular subgenus. The results suggested that common genetic traits are responsible for the production of bioactive secondary metabolite(s) which act primarily on Gram-positive organisms, and which may affect Gram-negative bacteria in dependence of the activity of multidrug efflux pumps in their cell envelope.

Medicinal plants of the Russian Pharmacopoeia; their history and applications

ETHNOPHARMACOLOGICAL RELEVANCE

Due to the location of Russia between West and East, Russian phytotherapy has accumulated and adopted approaches that originated in European and Asian traditional medicine. Phytotherapy is an official and separate branch of medicine in Russia; thus, herbal medicinal preparations are considered official medicaments. The aim of the present review is to summarize and critically appraise data concerning plants used in Russian medicine. This review describes the history of herbal medicine in Russia, the current situation and the pharmacological effects of specific plants in the Russian Pharmacopoeia that are not included in the European Pharmacopoeia.

MATERIALS AND METHODS

Based on the State Pharmacopoeia of the USSR (11(th) edition), we selected plant species that have not yet been adopted in Western and Central Europe (e.g., selected for inclusion in the European Pharmacopoeia) and systematically searched the scientific literature for data using library catalogs, the online service E-library.ru, and databases such as Medline/Pubmed, Scopus, and the Web of Science regarding species, effectiveness, pharmacological effects, and safety.

RESULTS

The Russian Federation follows the State Pharmacopoeia of the USSR (11(th) edition), which contains 83 individual plant monographs. Fifty-one of these plants are also found in the European Pharmacopoeia and have been well studied, but 32 plants are found only in the Pharmacopoeia of the USSR. Many articles about these medicinal plants were never translated in English, and much of the information collected by Russian scientists has never been made available to the international community. Such knowledge can be applied in future studies aimed at a safe, evidence-based use of traditional Russian medicinal plants in European and global phytopharmacotherapy as well as for the discovery of novel leads for drug development.

CONCLUSION

The review highlights the therapeutic potential of these Russian phytopharmaceuticals but also highlights cases where concern has been raised about product safety and tolerability, which would aid in supporting their safe use.

Composition of the essential oil of the Rhododendron tomentosum Harmaja from Estonia

Wild Rhododendron tomentosum Harmaja shoots were collected from four localities of Estonia. Essential oils, isolated from dried samples by simultaneous distillation and extraction, were analysed using GC-FID and Gas chromatography-mass spectrometry methods. The yields of oils were in the range 0.14-0.87%. A total of 72 constituents, accounting for over 95% of the total oil yield, were identified. The major components in the all four oils studied were palustrol (15.9-53.5%), ledol (11.8-18.3%), γ-terpineol (0-31.2%), p-cymene (0.1-13.9%), lepalone (0.7-6.5%), lepalol (1.0-6.5%) and cyclocolorenone (1.0-6.4%). Two different chemotypes of R. tomentosum were found in Estonia and one of them was rich in palustrol (41.0-53.5%) and ledol (14.6-18.3%). The second chemotype, for the first time, was rich in γ-terpineol (24.7-31.2%) and contained less of palustrol (15.9-16.7%) and ledol (11.8-12.8%), but more p-cymene (12.5-13.9%). Also, γ-terpineol was identified for the first time in the oils of R. tomentosum.