Search Results (5)

The composition of low-polarity extracts obtained by sequential extraction of the aerial parts of Rhododendron adamsii Rehd. with hexane and methyl tert-butyl ether (MTBE) was investigated using GC-MS. The hexane extract was dominated by non-polar components: squalene, n-alkanes (nonacosane, hentriacontane), sesquiterpenes (trans-nerolidol, spathulenol, β-farnesene), and β-sitosterol. The subsequent MTBE extract was enriched in more polar lipids, primarily free triterpenic acids (ursolic and oleanolic acids). A critical finding was the complete absence of diterpene grayanotoxins in all tested extracts, confirming the safety of the non-polar extraction approach. In bioactivity assays, the total hexane extract demonstrated potent inhibitory activity against the SARS-CoV-2 main protease (3CLpro) with IC₅₀ values of 0.0125–0.025 mg/mL, only one order of magnitude higher than the reference inhibitor disulfiram. Fractionation revealed that the activity was distributed among free acids, bound acids, and the unsaponifiable residue, indicating a multicomponent mechanism. Importantly, none of the samples inhibited HIV-1 protease (IC₅₀ > 0.1 mg/mL), demonstrating selectivity for the cysteine protease 3CLpro over the aspartyl protease of HIV-1. These results highlight that sequential non-polar extraction of R. adamsii provides a grayanotoxin-free lipophilic complex with selective anti-SARS-CoV-2 protease activity, paving the way for bioactivity-guided identification of individual inhibitors. Full article

Rhododendron adamsii Rehder, also known as sagan dali, is one of the most valued northern rhododendron species of Siberia and Mongolia as both a medicinal and food plant. Its flowers are traditionally used by indigenous communities in daily life to prepare teas that are attributed with medicinal properties in local traditional medicine. However, the lack of reliable data on the chemical composition and bioactivity of R. adamsii flowers has limited their broader application and underscores the need for comprehensive studies to verify their beneficial properties. The application of liquid chromatography–mass spectrometry enabled the identification of fifty-four compounds in sixteen samples of different origins, with flavonoids representing the dominant group and belonging to various aglycone types. Among the identified metabolites were dihydroflavonols of the taxifolin series; flavonols of the myricetin, quercetin, and kaempferol series; as well as several minor flavonoid and non-flavonoid compounds. Thirty-seven of these compounds are reported for the first time in this species. The total phenolic content in R. adamsii flowers can reach 155.82 mg/g, of which up to 147.54 mg/g are flavonoids. The analysis revealed variation in both the qualitative profile and quantitative levels of individual compounds among different populations, suggesting the presence of distinct R. adamsii chemotypes. The preparation of flower tea was associated with high rates of flavonoid transfer into the decoction, particularly when pulverized raw material was used compared with unground or hand-ground samples. This was reflected in the enhanced antioxidant activity of the decoctions, which was maximal for pulverized flowers in in vitro assays against artificial and natural free radicals, as well as in nitric oxide scavenging and Fe²⁺-chelating tests. These results suggest that R. adamsii flowers and their tea represent a new possible source of flavonoids and after additional clinical evidence may serve as valuable antioxidant ingredients for the development of functional foods. Full article

Background: In Siberian folk medicine, Sagan-Dalya (Rhododendron adamsii Rehder) of the Ericaceae family is used as a tonic and restorative in the form of infusions and decoctions. Pharmacological studies have shown that alcoholic extracts of this plant enhance performance and have anti-inflammatory and immunomodulatory effects. Rhododendron adamsii shoots accumulate essential oil (up to 1.6%), flavonoids (1.8–3.0%), tannins (up to 6.9%), phenolic carbolic acids, β-sitosterin, oleanolic and ursolic acids, simple phenolic compounds, and coumarins. Methods: Supercritical carbon dioxide extraction (SC-CO₂) is the most preferred environmentally friendly and selective method for extracting these natural compounds from the plant matrix of Rh. adamsii due to their high thermolability. Tandem mass spectrometry was applied to detect chemical compounds. Mass-spectrometry (MS) analysis was performed on an ion trap equipped with an ESI source in negative and positive ion modes. The capture rate was one spectrum/s for MS and two spectrum/s for MS/MS. All experiments were repeated three times. A four-stage ion separation mode (MS/MS mode) was implemented. Results: The operative parameters and working conditions have been optimized by different pressure (100–400 bars) and temperature (31–70 °C) regimes, and CO₂ flow rate (10–25 mL/min) with 1 C₂H₅OH as a co-solvent. The extraction time varied from 60 to 90 min. The maximum global yield of biologically active substances (BAS) from R. adamsii leaves and stems was observed under the following extraction conditions: Pressure: 350 bar, extraction temperature: 65 °C, extraction time: 1 h; the global yield of BAS was 8.5 mg/g of plant sample; the share of the co-solvent (C₂H₅OH) was 2%. In total, forty-nine different BAS were identified in the Rh. adamsii SC-CO₂ extracts. Conclusions: The obtained results may shed new light on the scientific basis for the traditional medicinal use of Rh. adamsii leaf and stem extracts. The pharmacological contribution of the identified phytocannabinoids requires further detailed study. It is hypothesized that the excellent transdermal permeability of supercritical extracts may open new therapeutic approaches using transdermal formulations based on SC-CO₂ extracts of Rh. adamsii. Full article

Adams’ rhododendron (Rhododendron adamsii Rehder) or Sagan Dalya tea is a famous Siberian evergreen medical plant of the Ericaceae family used in traditional medicines of Buryats, Yakuts, and Mongols as a tonic, stimulant, and adaptogenic drug. The high popularity of R. adamsii coupled with poor scientific knowledge prompted the addressing of gaps related to metabolic and biomedical data of Sagan Dalya tea. The application of solid-phase extraction and liquid chromatography-mass spectrometric techniques for the metabolomic study of R. adamsii leaf extracts resulted in the identification of more than 170 compounds, including carbohydrates, organic acids, simple phenol glycosides, triterpene glycosides, flavonoids, prenylated phenols, benzoic acid derivatives, hydroxycinnamates, dihydrochalcones, catechins, and procyanidins, most of which were identified for the first time in the plant. Extended surveys of the seasonal content of all detected compounds prove that specific metabolite variations reflect the bioactivity of R. adamsii extracts. Regarding in vitro methods, the expressed antioxidant potential of R. adamsii extracts was investigated via radical-scavenging, nitric oxide scavenging, and ferrous (II) ion chelating assays. The animal-based swimming to exhaustion test demonstrates the stimulating influence of R. adamsii extract on physical performance and endurance, concluding that the drug could act as an adaptogen. Thus, Sagan Dalya tea (R. adamsii) has confirmed its “old” application as a tonic remedy and requires further precise study as a novel adaptogenic plant. Full article

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. Full article