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Dictamnine alleviates oxidative stress in rheumatoid arthritis via modulation of the NR1D1-Keap1/Nrf2/ARE axis.

Rheumatoid arthritis (RA) is a persistent systemic disorder of autoimmune origin, with its core pathological manifestation being inflammation of the synovial tissue. The excessive growth of fibroblast-like synoviocytes (FLS) represents a critical pathological mechanism in RA, actively driving the advancement of the condition. Dictamnus dasycarpus Turcz. (D. dasycarpus) exhibits prominent anti-inflammatory effects and shows favorable therapeutic efficacy against RA. Dictamnine (Dic) is a major active component of D. dasycarpus, however, its therapeutic effectiveness and underlying mechanisms in RA have yet to be fully elucidated. This study investigated the effect of Dic on synovial hyperplasia in RA and elucidated the underlying mechanisms. Using a TNF-α-induced human fibroblast-like synoviocyte (HFLS-RA) model and a collagen-induced arthritis (CIA) mouse model, Dic was found to effectively inhibit synovial cell proliferation and pathological hyperplasia. Proteomics analysis was employed to clarify its potential mechanism in ameliorating the disease, and the findings were further validated through hematoxylin and eosin (H&E) staining, immunofluorescence (IF), ROS detection, JC-1 staining, cellular thermal shift assay (CETSA), drug affinity responsive target stability (DARTS) analysis, quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting (WB). The results suggested that the anti-RA activity of Dic is associated with its interaction with the nuclear receptor NR1D1. Moreover, the NR1D1 antagonist SR8278 reversed Dic's effects on Nrf2 and cytoprotection, confirming that Dic functions through NR1D1. This activation consequently influences the Keap1/Nrf2/ARE cascade, leading to decreased intracellular reactive oxygen species (ROS) accumulation and an improvement in compromised mitochondrial membrane potential. siRNA knockdown experiments further confirmed that NR1D1 is a target of Dic and regulates the downstream Keap1/Nrf2/HO-1 signaling pathway, through which Dic ameliorates RA both in vitro and in vivo by upregulating NR1D1 expression to activate the Keap1/Nrf2/ARE antioxidant pathway, thereby mitigating oxidative stress, inhibiting synovial cell proliferation, and ultimately alleviating pathological synovial hyperplasia.

Arthritis, Rheumatoid↗

Analytical procedure for the in-vial derivatization--extraction of phenolic acids and flavonoids in methanolic and aqueous plant extracts followed by gas chromatography with mass-selective detection.

An in-vial simple method for the combined derivatization and extraction of phenolic acids and flavonoids from plant extracts and their direct determination with GC-MS, is described. The method is taking advantage of the beneficial potentials of phase transfer catalysis (PTC). Catalysts in soluble and polymer-bound form were tested with the latter being the format of choice due to its high reaction yield and facile separation from the rest of the reaction system. Optimization of experimental conditions was established. Chromatographic separation of eight phenolic acids and four flavonoids methylated via the PTC derivatization step was achieved in 45 min. The detection limits for the described GC-MS(SIM) method of analysis ranged between 2 and 40 ng/ml whereas limits of quantitation fall in the range 5-118 ng/ml, with flavonoids accounting for the lowest sensitivity due to their multiple reaction behavior. Four methanolic extracts from Tilia europea, Urtica dioica, Mentha spicata and Hypericum perforatum grown wild in north-western Greece and four aquatic infusions from commercially available Mentha spicata, Origanum dictamnus, Rosemarinus officinalis and Sideritis cretica were analyzed. Good trueness of the method was demonstrated as no matrix effects were found for the analytes concerned.

Flavonoids↗

Starter substrate specificities of wild-type and mutant polyketide synthases from Rutaceae.

Chalcone synthases (CHSs) and acridone synthases (ACSs) belong to the superfamily of type III polyketide synthases (PKSs) and condense the starter substrate 4-coumaroyl-CoA or N-methylanthraniloyl-CoA with three malonyl-CoAs to produce flavonoids and acridone alkaloids, respectively. ACSs which have been cloned exclusively from Ruta graveolens share about 75-85% polypeptide sequence homology with CHSs from other plant families, while 90% similarity was observed with CHSs from Rutaceae, i.e., R. graveolens, Citrus sinensis and Dictamnus albus. CHSs cloned from many plants do not accept N-methylanthraniloyl-CoA as a starter substrate, whereas ACSs were shown to possess some side activity with 4-coumaroyl-CoA. The transformation of an ACS to a functional CHS with 10% residual ACS activity was accomplished previously by substitution of three amino acids through the corresponding residues from Ruta-CHS1 (Ser132Thr, Ala133Ser and Val265Phe). Therefore, the reverse triple mutation of Ruta-CHS1 (mutant R2) was generated, which affected only insignificantly the CHS activity and did not confer ACS activity. However, competitive inhibition of CHS activity by N-methylanthraniloyl-CoA was observed for the mutant in contrast to wild-type CHSs. Homology modeling of ACS2 with docking of 1,3-dihydroxy-N-methylacridone suggested that the starter substrates for CHS or ACS reaction are placed in different topographies in the active site pocket. Additional site specific substitutions (Asp205Pro/Thr206Asp/His207Ala or Arg60Thr and Val100Ala/Gly218Ala, respectively) diminished the CHS activity to 75-50% of the wild-type CHS1 without promoting ACS activity. The results suggest that conformational changes in the periphery beyond the active site cavity volumes determine the product formation by ACSs vs. CHSs in R. graveolens. It is likely that ACS has evolved from CHS, but the sole enlargement of the active site pocket as in CHS1 mutant R2 is insufficient to explain this process.

Acyltransferases↗

Sulphorhodamine B assay for measuring proliferation of a pigmented melanocyte cell line and its application to the evaluation of crude drugs used in the treatment of vitiligo.

A rapid 96-well plate assay using sulphorhodamine B (SRB) protein stain for cell number has been adopted to screen herbs used in traditional treatments of vitiligo for substances capable of stimulating melanocyte proliferation. Its applicability to melan-a cells, a mouse pigmented cell line, has been validated. SRB assay produced good linearity up to 11 x 10(4) cells/well and interference by melanin present in the cells accounted for less than 10% of the total optical density readings. The intra-assay variation was small but interassay variation was marked. For better assay precision, it is recommended that the results to be compared should be performed on the same day and controls should be plated in the same experiment, ideally in the same plate. Optimum conditions for exponential melan-a cell growth were established: viz. initial plating density (3-8 x 10(3) cells/well), incubation period (4 days) and foetal bovine serum concentration (5%). Under these conditions cells were responsive to the mitogen tetradecanoyl phorbol acetate (TPA). Out of 28 herbal extracts screened in this assay, significant stimulation (P < 0.05) of melanocyte proliferation was observed, in the absence of TPA, using aqueous extracts of Astragalus membranaceous root, Citrus reticulata peel, Dictamnus dasycarpus root bark. Ophiopogon japonicus root, Poria cocos sclerotium and Tribulus terrestris fruit.

Animals↗

Essential oils of Satureja, Origanum, and Thymus species: chemical composition and antibacterial activities against foodborne pathogens.

The chemical composition of the essential oils obtained from the species restricted to Greece and the eastern Mediterranean region, Satureja spinosa L. and Thymus longicaulis L.; species endemic to central and south Greece, Satureja parnassica ssp. parnassica Heldr. and Sart ex Boiss.; species endemic to the island of Crete, Origanum dictamnus L.; and species widely distributed in the Mediterranean region, Satureja thymbra L. and Origanum vulgare L. subsp. hirtum, were determined by gas chromatography (GC) and GC/mass spectrometry (MS) analysis. The in vitro antibacterial activities of the essential oils were evaluated against a panel of five foodborne bacteria (Escherichia coli 0157:H7 NCTC 12900, Salmonella enteritidis PT4, Staphylococcus aureus ATCC 6538, Listeria monocytogenes ScottA, and Bacillus cereus FSS 134). The analytical data indicated that various monoterpene hydrocarbons and phenolic monoterpenes constitute the major components of the oils, but their concentrations varied greatly among the oils examined. The antibacterial assay results showed that 5 muL doses of the essential oils extracted from the endemic Satureja species in Greece possess remarkable bactericidal properties, which are clearly superior as compared to those of Origanum and Thymus species essential oils. Therefore, they represent an inexpensive source of natural mixtures of antibacterial compounds that exhibit potentials for use in food systems to prevent the growth of foodborne bacteria and extend the shelf life of the processed food.

Anti-Bacterial Agents↗

Hepatitis associated with Chinese herbs.

Traditional Chinese herbal medicines are widely available in Western society and are popular as a form of 'natural' alternative medicine. Their use is increasing, as they are perceived to be free of side effects, but they remain largely unregulated. We describe two patients who suffered severe hepatitis, one of whom died, after taking Chinese herbal remedies for minor complaints. We also review the English-language literature on hepatitis associated with Chinese herbs. Two products appear to be implicated frequently: Jin bu huan was taken by 11 patients, and Dictamnus dasycarpus was taken by six patients, including both fatal cases. It is difficult to provide conclusive evidence of what caused hepatitis, as these products are mixtures that may contain adulterants. These cases highlight not only the potential dangers of these products to consumers but also the need for greater control of their manufacture and use.

Adult↗

Phytophotodermatitis: an experimental study using the chamber method.

Experimental phytophotodermatitis was produced using crushed leaves from the gas plant, Dictamnus albus. The tests were made using the chamber method and irradiated with ordinary black light tubes. An occlusion time of not less than 30 min was needed to give a phototoxic reaction in all test subjects. An occlusion time 30-120 min gave the optimal results, but contact for 24 h produced only weak and inconsistent reactions. The phototoxic substance was readily absorbed into the skin within 10-15 min. The phototoxic tendency already began to disappear within 30 min after the tests were removed. UVA energy of 0.3 J/cm2 was enough to evoke a phytophotoreaction in all of the test subjects when other conditions were optimal. The reactions were enhanced by adding water to the test sites. Deep-freezing of the plant material did not destroy the phototoxicity within a 4-month period.

Humans↗

Alternations of Clonorchis sinensis EPG by administration of herbs in rabbits.

In order to investigate clonorchicidal activity in vivo, boiled water extracts of 32 species of clonorchicidal raw drugs in vitro were orally administered into rabbits infected with Clonorchis sinensis. The results of the observation of EPG variation were as follows: Suppression effects of egg-laying capacity from the rabbits administered Prunus mume and Inula helenium were greatest. Those from Dictamnus dasycarpus and Saussurea lappa were somewhat effective. Machilus thunbergii and Cassia obutusifolia, however, were less effective.

Animals↗

Structural investigation on the effects of the herbs on Clonorchis sinensis in rabbits.

The effects of boiled water extracts of clonorchicidal raw drugs screened by the EPG counts in vivo on the structure of Clonorchis sinensis were investigated. The extracts of Cassia obutusifolia and Dictamnus dasycarpus did not seem to induce the morphological changes of the worms, and in those of Machilus thunbergii and Prunús mume, widening of bladder to lower level of seminal receptacle was visible without any other changes. Those of Inula helenium and Saussurea lappa, however, disclosed regressive and progressive changes as degeneration, atrophy, necrosis, dilatation, etc. of viscera of the worms. The recover rates of the worms from experimentally infected rabbits administered with the extracts of I. helenium and S. lappa for 30 days, beginning at the 3rd day of inoculation, were as low as 2% and 2.8%, respectively.

Animals↗

Nutrient antioxidants in oregano.

Oregano and its various extracts have been studied as inhibitors of autoxidation but so far the research work has focused mainly on the polar non nutrient compounds. Very little is known about the non polar fraction extracted by hexane which is also antioxidant and has been reported to suppress the mutagenicity of Trp-P-2, a dietary carcinogen. In this work four different species of oregano, Origanum vulgare subsp. hirtum, Satureja thymbra, Origanum dictamnus and Origanum onites, were extracted with hexane. The extracts were saponified and in the unsaponifiable fraction thin layer chromatography and high performance liquid chromatography were applied for the isolation, detection and determination of tocopherols. The four known homologues of tocopherol, alpha-, beta-, gamma- and delta-, were found to be present in all the samples but the concentration of the gamma-homologue was significantly higher. Total tocopherol content ranged from 288 ppm to 672 ppm.

Antioxidants↗

Pressurized liquid extraction followed by high-performance liquid chromatography for determination of seven active compounds in Cortex Dictamni.

A new method based on pressurized liquid extraction (PLE) followed by a sensitive and specific HPLC-DAD analysis is developed for determination of seven compounds in Cortex Dictamni. The operational parameters of PLE, such as extraction solvent, extraction temperature, extraction pressure, static extraction time, flush volume and extraction cycles were optimized, using the extraction efficiencies of dictamnine, obacunone and fraxinellone as targets. The optimized procedure employed MeOH as extraction solvent, 150 degrees C of extraction temperature, 1,500 psi extraction pressure, 5 min of static extraction time, 60% flush volume and the extraction recoveries of the three compounds were nearly to 100% for only one cycle. The following HPLC analysis was performed on a reversed-phase C(18) column with methanol-water as mobile phase in gradient manner, detected at 236 and 218 nm. The limits of detection (LOD) and limits of quantification (LOQ) of the seven compounds were in the range of 0.4-15.6 ng and 1.2-38.8 ng. This assay can be readily utilized as a quality control method for Cortex Dictamni and other related medicinal plants.

Chromatography, High Pressure Liquid↗

Microbial transformation of fraxinellone by Aspergillus niger.

Microbial transformation of fraxinellone (1) by Aspergillus niger (AS 3.421) has been carried out. Two converted products, dasycarpol (2) and a new compound fraxinigerllone (3) were obtained. Their structures have been identified on the basis of spectroscopic methods. Dasycarpol shows moderate inhibitory activity on lung cancer cell line A549.

Antineoplastic Agents, Phytogenic↗