Meroterpenoids from Rhododendron nivale / 中国中药杂志

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

Mechanism of total flavonoids of Rhododendra simsii in alleviating ischemic brain injury / 中国中药杂志

This study explores the effect of total flavonoids of Rhododendra simsii(TFR) on middle cerebral artery occlusion(MCAO)-induced cerebral injury in rats and oxygen-glucose deprivation/reoxygenation(OGD/R) injury in PC12 cells and the underlying mechanism. The MCAO method was used to induce focal ischemic cerebral injury in rats. Male SD rats were randomized into sham group, model group, and TFR group. After MCAO, TFR(60 mg·kg~(-1)) was administered for 3 days. The content of tumor necrosis factor-α(TNF-α), interleukin-1(IL-1), and interleukin-6(IL-6) in serum was detected by enzyme-linked immunosorbent assay(ELISA). The pathological changes of brain tissue and cerebral infarction were observed based on hematoxylin and eosin(HE) staining and 2,3,5-triphenyltetrazolium chloride(TTC) staining. RT-qPCR and Western blot were used to detect the mRNA and protein levels of calcium release-activated calcium channel modulator 1(ORAI1), stromal interaction molecule 1(STIM1), stromal intera-ction molecule 2(STIM2), protein kinase B(PKB), and cysteinyl aspartate specific proteinase 3(caspase-3) in brain tissues. The OGD/R method was employed to induce injury in PC12 cells. Cells were randomized into the normal group, model group, gene silencing group, TFR(30 μg·mL~(-1)) group, and TFR(30 μg·mL~(-1))+gene overexpression plasmid group. Intracellular Ca~(2+) concentration and apoptosis rate of PC12 cells were measured by laser scanning confocal microscopy and flow cytometry. The effect of STIM-ORAI-regulated store-operated calcium entry(SOCE) pathway on TFR was explored based on gene silencing and gene overexpression techniques. The results showed that TFR significantly alleviated the histopathological damage of brains in MCAO rats after 3 days of admini-stration, reduced the contents of TNF-α, IL-1, and IL-6 in the serum, down-regulated the expression of ORAI1, STIM1, STIM2, and caspase-3 genes, and up-regulated the expression of PKB gene in brain tissues of MCAO rats. TFR significantly decreased OGD/R induced Ca~(2+) overload and apoptosis in PC12 cells. However, it induced TFR-like effect by ORAI1, STIM1 and STIM2 genes silencing. However, overexpression of these genes significantly blocked the effect of TFR in reducing Ca~(2+) overload and apoptosis in PC12 cells. In summary, in the early stage of focal cerebral ischemia-reperfusion injury and OGD/R-induced injury in PC12 cells TFR attenuates ischemic brain injury by inhibiting the STIM-ORAI-regulated SOCE pathway and reducing Ca~(2+) overload and inflammatory factor expression, and apoptosis.

The effect of rhododendron honey on mice liver tissue / Efecto de la miel de rododendro en el tejido hepático de ratón

Rhododendron honey, made by bees from rhododendron pollen, contains a toxic substance called grayanotoxin. Depending on the dose, the poisonous honey can result in serious effects such as cardiac arrhythmia, fibrillation, and myocardial infarction. The purpose of this study is to investigate the effects of the poisonous RH of the Black Sea Region on the liver. Male mice were divided into five groups of twelve mice each, two being the control groups (distilled water) and the others being the rhododendron honey (RH) groups (25, 50, and 75 mg/kg) and 0.01 mg/kg grayanotoxin (GTx) groups. Liver tissues were collected 24 and 48 h later. The sections were stained with hematoxylin, eosin and PAS, then the histopathological score was performed. Significant statistical differences were observed between the RH and control groups in terms of congestion, steatosis, sinusoid dilatation, and inflammation. The control group demonstrated a normal liver structure in the light microscopy, while the GTx-applied 24 h group exhibited expansions in the sinusoids and congestion. Higher levels of congestion, steatosis, and inflammatory cells were seen in the GTx-applied 48 h group. In the same group, giant cells consisting of many nuclei were observed in the sinusoids. The results of the 25 mg RH-applied groups were similar in 24 and 48 h, histopathological score levels were increased slightly, congestion and steatosis were prominent in the 48 h group. Dense steatosis was seen in the hepatocytes around the vena centralis in 50 mg/kg RH-applied 48 h group. Congestion, steatosis and an increase in inflammatory cells were observed in the hepatocytes in the 75 mg/kg RH-applied 24- and 48 h groups. PAS (+) stained hepatocytes were decreased in the RH- and GTx-applied groups. The toxic effects of the rhododendron honey were observed in the mice liver tissue with respect to dose and time.

La miel de rododendro, elaborada por las abejas a partir del polen de rododendro, contiene una sustancia tóxica llamada grayanotoxina. Dependiendo de la dosis, la miel venenosa puede resultar en efectos graves, tales como arritmia cardiaca, fibrilación e infarto de miocardio. El propósito de este estudio fue investigar los efectos en el hígado de la miel venenosa de rododendro de la región del Mar Negro. Se distribuyeron ratones machos en cinco grupos de doce ratones cada uno, dos grupos control (agua destilada) y los otros grupos se trataron con la miel de rododendro (MR) (25, 50 y 75 mg/kg) y con 0,01 mg/kg grayanotoxina (GTX). Los tejidos hepáticos se recogieron 24 y 48 h más tarde. Las secciones fueron teñidas con hematoxilina-eosina y PAS. A continuación, se realizó la puntuación histopatológica. No se observaron diferencias estadísticamente significativas entre MR y los grupos de control en términos de congestión, esteatosis, dilatación sinusoidal e inflamación. El grupo control demostró una estructura normal del hígado en el microscopio de luz, mientras que el grupo de las 24 horas de aplicación de GTX exhibió expansiones en los sinusoides y congestión. Mayores niveles de congestión, esteatosis y células inflamatorias se observaron en el grupo de 48-horas de aplicación de GTX. En el mismo grupo, se observaron células gigantes que consistían en la presencia de muchos núcleos en los sinusoides. Los resultados de los grupos con aplicación de 25 mg de RH fueron similares en los resultados de 24 y 48 h, los niveles de puntuación histopatológica aumentaron ligeramente, la congestión y la esteatosis fueron prominentes en el grupo de 48 h. Se observó esteatosis densa en los hepatocitos en toda la vena central en el grupo de aplicación de 50 mg/kg de RH, 48 h. La congestión, la esteatosis y un aumento en las células inflamatorias se observaron en los hepatocitos en el grupo de 75 mg/kg de MR de 24 h y los grupos de 48 h. Hepatocitos teñidos con PAS (+) disminuyeron en los grupos de GTX y MR. Se observaron los efectos tóxicos de la miel de rododendro en el tejido hepático de ratones con respecto a la dosis y el tiempo.

Estimation of antioxidant, antimicrobial activity and brine shrimp toxicity of plants collected from Oymyakon region of the Republic of Sakha (Yakutia), Russia

BACKGROUND: Several plants are reported to be produced various biological active compounds. Lichens from the extreme environments such as high altitude, high UV, drought and cold are believed to be synthesized unique types of secondary metabolites than the other one. Several human pathogenic bacteria and fungi have been muted into drug resistant strains. Various synthetic antioxidant compounds have posed carcinogenic effects. This phenomenon needs further research for new effective drugs of natural origin. This manuscript aimed to screen new source of biological active compounds from plants of subarctic origin. RESULTS: A total of 114 plant species, including 80 species of higher plants, 19 species of lichens and 15 species of mosses, were collected from Oymyakon region of the Republic of Sakha (Yakutia), Russia (63˚20′N, 141˚42′E - 63˚15′N, 142˚27′E). Antimicrobial, DPPH free radical scavenging and brine shrimp (Artemia salina) toxicity of all crude extract were evaluated. The obtained result was analyzed and compared with commercial standards. A total of 28 species of higher plants showed very strong antioxidant activity (DPPH IC50, 0.45-5.0 µg/mL), 13 species showed strong activity (DPPH IC50, 5-10 µg/mL), 22 species showed moderate antioxidant activity (DPPH IC50,10-20 µg/mL) and 17 species showed weak antioxidant activity (DPPH IC50 more than 20 µg/mL). Similarly, 3 species of lichen showed strong antioxidant activity, one species showed moderate and 15 species showed weak DPPH reducing activity. In addition, 4 species of mosses showed moderate antioxidant activity and 11 species showed weak antioxidant activity. Similarly, extracts of 51 species of higher plants showed antimicrobial (AM) activity against Staphylococcus aureus and 2 species showed AM activity against Candida albicans. Similarly, 11 species of lichen showed AM activity against S. aureus and 3 species showed AM activity against Escherichia coli. One species of moss showed AM activity against S. aureus. And finally, one species of higher plant Rheum compactum and one species of lichen Flavocetraria cucullata showed the toxicity against Brine shrimp larvae in 100 µg/mL of concentration. CONCLUSION: The experimental results showed that subarctic plant species could be potential sources of various biologically active natural compounds.

Studies on the chemical constituents of the roots of Rhododendron molle G. Don / 华中科技大学学报（医学）（英德文版）

The compounds from the root of Rhododendron molle G. Don were isolated, purified by various chromatographic techniques, and their structures were identified according to the physical and chemical features and spectral data. Three compounds were separated from the root of Rhododendron molle G. Don and identified as Rhodojaponin-III, taraxerol, beta-sitosterol for the first time.