Antioxidant Activity in Rheum emodi Wall (Himalayan Rhubarb).

Using natural products as antioxidant agents has been beneficial to replace synthetic products. Efforts have been made to profile the antioxidant capacities of natural resources, such as medicinal plants. The polyphenol content of Himalayan rhubarb, Rheum emodi wall, was measured and the antioxidant activity was determined using DPPH and ABTS+ assay, and the oxidative stress was assessed using SOD enzymatic assay. Five different solvent fractions, n-hexane, n-butanol, ethyl acetate, dichloromethane, and water, were used for screening the antioxidant capacity in effort to determine the optimum extraction solvent. The total phenolic contents for R. emodi fractions ranged from 27.76 to 209.21 mg of gallic acid equivalents (GAE)/g of dry weight. DPPH and ABTS+ assay results are presented into IC50 values, ranged from 21.52 to 2448.79 µg/mL and 90.25 to 1718.05 µg/mL, respectively. The ethyl acetate fraction had the highest antioxidant activity among other fractions. Also, n-butanol and water fractions showed significantly lower IC50 values than the positive control in DPPH radical scavenging activity. The IC50 values of SOD assay of fractions ranged from 2.31 to 64.78 µg/mL. A similar result was observed with ethyl acetate fraction showing the highest SOD radical scavenging activity. The study suggests that the ethyl acetate fraction of R. emodi possess the strongest antioxidant activity, thus the most efficient in extracting antioxidant contents. Moreover, a highly significant correlation was shown between total polyphenol content and antioxidant activity screening assays. The compounds related to the antioxidant activity of R. emodi were identified to myricitrin, myricetin 3-galloyl rhamnoside, and myricetin, which have not been reported in studies about R. emodi before.

Assessment of conventional and novel extraction techniques on extraction efficiency of five anthraquinones from Rheum emodi.

Rheum emodi is principally known to consist 1,8-dihydroxyanthraquinones (DHAQs) that find immense use in the chemical, pharmaceutical, cosmetic industries and in herbal medication and food sector. The aim of this study was to compare non-conventional and classical methods for extraction of anthraquinones from R. emodi. Optimisation of the extraction parameters for various methods was done and their extraction efficiency was evaluated. In preliminary screening experiments, choice of solvent and solid : solvent ratio was optimised. Comparison of extraction efficiency for classical methods like maceration, heat-reflux, soxhletion and non-conventional methods like ultra-sonication and sublimation was done for five DHAQs - aloe emodin, rhein, emodin, chrysophanol and physcion using HPLC-UV and fluorescence detection in native and acid hydrolysed samples. It was observed that ethanol was the best solvent for extraction of anthraquinones with a solid : solvent ratio of 1:20. A prior acid hydrolysis led to significant increase in anthraquinone extraction. Among the extraction methods heat reflux for 45 min was the most prominent extraction method with highest recovery of the DHAQs. In ultrasonic assisted extraction, an increase in the anthraquinone extraction was seen till 45 min after which the concentration declined. A novel, solvent-free, green and selective method of extraction by sublimation was found to be effective for extraction of anthraquinones.

Design, synthesis, cytotoxic, and anti-inflammatory activities of some novel analogues of aloe-emodin isolated from the rhizomes of Rheum emodi.

In connection with our continuous efforts in the synthesis of derivatives from major compounds isolated from traditional medicinal plants, in the present study we have attempted to synthesize the furan-conjugated aloe-emodin derivatives (5a-j) using a three-component reaction. The synthesized derivatives were assessed for anticancer activity against five different cancer cell lines using the in vitro MTT assay and the results showed that most of the derivatives are potent against cancer cells comparing with the control. Compounds 5a and 5e showed excellent activity against all the cancer cells with less than 12.5 µM and arrested the cell cycle at the G0/G1 phase in both CAL27 and SCC9 cells. Compound 5e induces the early apoptosis in CAL27 cells and compounds 5a and 5e induce early and late apoptosis, respectively, in SCC9 cells. Moreover, compounds 5b, 5c, 5i, and 5j showed excellent anti-inflammatory activity in LPS-stimulated RAW 264.7 cells by inhibiting IL-6 production. The molecular docking studies revealed that compound 5e has strong interaction with the CLK kinase and protein kinase II through hydrogen binding Asp325 and Lys290.

Molecular docking studies of phytocompounds of Rheum emodi Wall with proteins responsible for antibiotic resistance in bacterial and fungal pathogens: in silico approach to enhance the bio-availability of antibiotics.

Rheum emodi Wall. (Himalayan rhubarb) has many pharmacological activities such as antioxidant, antimicrobial, antiviral, anticancer and wound healing. The present study was aimed to understand if major phytocompounds of Rheum emodi could bind proteins responsible for antibiotic resistance in bacterial and fungal pathogens and enhance the potency of antibiotics. The major phytocompounds of R. emodi (emodin, rhein-13c6 and chrysophenol dimethy ether) were retrieved from the Pubchem and target proteins were retrieved from RCSB protein data bank. The docking study was performed by using AutoDock vina software and Molinspiration, swiss ADME servers were used for the determination of Lipinski rule of 5, drug-likeness prediction respectively, whereas, admetSAR and Protox-II tools were used for toxicity prediction. To study the docking accuracy of protein-ligand complexes, MD simulation for 100 ns was done by using Desmond program version 2.0 (Academic version). Among all the selected phytocompounds, emodin showed the best binding affinity against bacterial (Penicillin binding protein 3, 3VSL and fungal target (cytochrome P450 14 alpha-sterol demethylase 1EA1) with binding energy -8.2 and -8.0 Kcal mol-1 respectively. Similarly, rhein-13C6 showed the best binding affinity against fungal target (n-myristoyl transferase 1IYL) with binding energy -8.0 Kcal mol-1 which is higher than antibacterial and antifungal antibiotics. All the selected phytocompounds also fulfill Lipinski rule, non-carcinogenic and non-cytotoxic in nature. These compounds also showed high LD50 value showing non-toxicity of these phytocompounds. MD simulation studies of phytocompounds (emodin and rhein-13C6) define the stability of protein-ligand complexes with in 100 ns time scale.Communicated by Freddie R. Salsbury.

Effect of stress tolerance endophytic bacteria on the growth of Rheum emodi under abiotic stress.

RESEARCH CONDUCTED: Rheum emodi is a perennial herb that grows at high altitudes (1800-4400m) and possesses many medicinal properties. Due to over-exploitation, the plant has become endangered in its natural habitat. The present research focuses on the effect of stress tolerance endophytic bacteria on the growth of Rheum emodi grown at lower altitudes (748ft) under salt and heavy metal stress. METHODS: Endophytic bacteria Pelomonas Aquatica AIS1S and Solibacillus silvestris DL3R2 were isolated from Abutilon indicum and Hermocallis fulva and were identified by 16s rRNA sequence. The seeds were inoculated with the bacteria and sown in sterile soil with low carbon, potassium, and phosphorous content. The growth of the plants was regularly monitored for three months. The phytochemicals of the experimental plant were compared with the in-situ plants taken as control. RESULTS: The results have shown that seeds inoculated with Pelomonas Aquatica AIS1S and Solibacillus silvestris DL3R2 have higher germination than control. The maximum number of seeds germinated is 2.33±0.47 at 2% salt concentration on inoculation with Pelomonas Aquatica AIS1S. The least number of seeds germinated is 0.33±0.47 at 6% cadmium concentration on inoculation with Pelomonas Aquatica A1S1S. HPLC analysis has shown that the 0.41%and 0.16% of quercetin and gallic were produced at higher altitudes which is less than a plant grown at a lower altitude, i.e., 0.47% 0.18%, respectively. Emodin, physcoin, and rhein are the other compounds found at 254nm. CONCLUSION: This study provides a basis that plants can be grown under stress conditions with the help of stress-tolerant endophytic bacteria, thus providing a new strategy for the conservation of plants.

Antioxidant Activities of Bioactive Compounds Isolated from Rheum emodi Wall (Himalayan Rhubarb) Based on LC-DAD-ESI/MS and Preparative LC/MS System.

Natural compounds are a good substitute for synthetic antioxidants. Attempts have been made to characterize the antioxidant capacity of natural resources (e.g., medicinal plants). Thus, the Rheum emodi Wall was evaluated using liquid chromatography with diode array detection and electrospray ionization-mass spectrometry. Three antioxidant compounds (i.e., myricitrin, myricetin-3-galloyl rhamnoside, and myricetin) were isolated, identified, and used to screen the antioxidant capacity of the new compounds. 2,2-Diphenyl-1-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and superoxide dismutase assay results are presented in the half-maximal inhibitory concentration values ranging 1.50∼28.46, 102.01∼137.55, and 4.06∼15.74 µg/mL, respectively. Myricetin had the highest antioxidant activity among the other compounds. A significantly positive correlation was noted between the ethyl acetate fraction and the antioxidant compound. In a partial least squares-discriminant analysis model, identified antioxidant compounds were shown to play a role in the structure of the compound and its contents based on the antioxidant activity. The study suggests that myricetin from R. emodi possesses the most potent antioxidant activity, and thus is the most efficient in extracting antioxidant contents.

Emodin - A natural anthraquinone derivative with diverse pharmacological activities.

Emodin (1,3,8-trihydroxy-6-methyl-anthraquinone) is a natural anthraquinone derivative that is present in numerous globally renowned herbal medicines. It is recognised as a protein tyrosine kinase inhibitor and as an anticancer drug, active against various tumour cells, including lung, breast, liver, and ovarian cancer cells. Recently, its role in combination chemotherapy with various allopathic medicines, to minimize their toxicity and to enhance their efficacy, has been studied. The use of emodin in these therapies is gaining popularity, due to fewer associated side effects compared with standard anticancer drugs. Emodin has a broad therapeutic window, and in addition to its antineoplastic activity, it displays anti-ulcer, anti-inflammatory, hepatoprotective, neuroprotective, antimicrobial, muscle relaxant, immunosuppressive and antifibrotic activities, in both in vitro and in vivo models. Although reviews on the anticancer activity of emodin have been published, none coherently unite all the pharmacological properties of emodin, particularly the anti-oxidant, antimicrobial, antidiabetic, immunosuppressive and hepatoprotective activities of the compound. Hence, in this review, all of the available data regarding the pharmacological properties of emodin are explored, with particular emphasis on the modes of action of the molecule. In addition, the manuscript details the occurrence, biosynthesis and chemical synthesis of the compound, as well as its toxic effects on biotic systems.

Bioassay guided fractionation of rhizome extract of Rheum emodi wall as bio-availability enhancer of antibiotics against bacterial and fungal pathogens.

ETHNOPHARMACOLOGICAL RELEVANCE: Rheum emodi Wall., is an important medicinal plant extensively used in Ayurvedic and Unani systems of traditional medicine. It is known to possess antioxidant, antibacterial, antifungal, anticancer, wound healing and immune enhancing activities. AIM OF THE STUDY: The aim of the current study was to investigate the antimicrobial activity and synergistic potential of different solvent fractions and phytocompounds of Rheum emodi rhizome against bacterial and fungal pathogens. MATERIAL AND METHODS: The antimicrobial and synergistic potential of the crude methanolic extract, different solvent fractions (n-hexane, chloroform, ethyl acetate, and residual aqueous) and isolated phytocompounds of the rhizome of Rheum emodi were assayed by broth microdilution method. The bioactive phytocompounds were isolated through silica TLC and quantified using HPTLC and HPLC. The bioactive phytocompounds were identified by LC-MS analysis. RESULTS: Phytochemical analysis of the sub-fractions showed that the TPC (417.94 ± 1.2 mg g-1 GAE) and TFC (187.40 ± 0.5 mg g-1 RE) were highest in residual aqueous extracts. The chloroform sub-fraction possessed the highest antimicrobial activity against bacterial (Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae) and fungal strains (Candida albicans MTCC 277 and ATCC 90028). The MIC of chloroform sub-fraction against S. aureus, K. pneumoniae, E. coli, C. albicans was 1.95, 3.91, 15.62 and 62.5 µg ml-1, respectively. TLC and LC-MS analysis of chloroform sub-fraction identified phytocompounds namely emodin D4 (m/z 274.262), rhein13c6 (m/z 290.176), chrysophanol dimethyl ether (m/z 282.291), and resveratrol (m/z 340.456). Quantification of emodin content showed that the chloroform sub-fraction (101.4543 µg mg-1, 194.8037 µg mg-1 measured through HPTLC and HPLC, respectively), and its TLC fraction (II) (75.18 µg mg-1, 232.384 µg mg-1 measured through HPTLC and HPLC, respectively) are rich in emodin. Furthermore, chloroform sub-fraction, its TLC fractions and emodin showed profound synergistic activity in combination with antibacterial and antifungal antibiotics and lowered the dosage of antibiotics by 4-257 folds. CONCLUSIONS: The bioassay guided fractionation of R. emodi rhizome methanolic extract identified phytocompounds (emodin, rhein13c6, chrysophanol dimethyl ether and resveratrol) that act as bioavailability enhancers of antibacterial and antifungal antibiotics, hence revealing their potential in treating multidrug resistance.

Biosynthesis of hematite nanoparticles using Rheum emodi and their antimicrobial and anticancerous effects in vitro.

The synthesis of magnetic Hematite nanoparticles (α-Fe2O3) via green route has been a long lasting challenge for the scientific and technological fascination of many researchers. In the present investigation, iron oxide nanoparticles (α-Fe2O3) were synthesized using Rheum emodi roots in a cost effective and ecofriendly method. Their physicochemical property orchestration involved techniques such as UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray (EDX), X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), Vibrating sample magnetometer (VSM), and Atomic force microscopy (AFM). Through TEM, FESEM and AFM analysis, α-Fe2O3NPs were confirmed spherical in shape and the average diameter of particle is ~12 nm as depicted through TEM image. Thermal property was investigated by TGA. Magnetic behavior was observed in R. emodi mediated α-Fe2O3NPs by magnetic hysteresis measurements. FTIR analysis revealed the presence of anthraquinones in R. emodi roots extract which play the central role in stabilization of the α-Fe2O3NPs. Further, the crystalline nature of the nanoparticle sample was determined with XRD experiment and SAED fringes calculation. The crystal was also confirmed with Rietveld refinement of XRD profile fitted with R-3c model Additionally, magnetic interaction with bacterial cell wall showed antimicrobial property against Escherichia coli, Gram-negative and Staphylococcus aureus, Gram-positive species. The approach transcribed in this paper reveals a novel methodology that utilizes α-Fe2O3 NPs to initiate apoptosis and inhibition of cervical cancer cells.

Scientific evaluation of the acute toxicity and 13-week subchronic toxicity of Rheum emodi rhizome extracts in Sprague Dawley rats.

Rheum emodi has been used as an edible and medicinal plant in Tibet and Kashmir for a long period of time, while safety evaluation of this plant has not yet been investigated. In this study, acute and subchronic oral toxicity studies of aqueous extract of R. emodi (AERE) rhizome were conducted in SD rats. Animals were treated with a single dose of 1000, 2000, 4000 or 10,000 mg/kg of AERE in the acute toxicity. In subchronic oral toxicity, animals were randomly divided into four groups (10 rats/sex/group) and received doses of 0, 1000, 2000, and 4000 mg/kg/d of AERE for 90 days. Daily clinical observations, weekly measurement of body weight and food consumption were conducted. Blood and urine were collected on days 91 to measure changes. At necropsy, selected organs were weighed and recorded, and histological examination was performed. During the subchronic oral toxicity study, no mortality, obvious treatment-related clinical signs and urinalysis parameters were observed. Differences in weight gain, food consumption, hematology, biochemistry, relative organ weight and histopathology examinations between the treated group and the control group were not considered treatment-related. Our results indicated that the no-observed-adverse-effect level (NOAEL) for AERE was 4000 mg/kg/d in both genders.

Preparation of novel antiproliferative emodin derivatives and studies on their cell cycle arrest, caspase dependent apoptosis and DNA binding interaction.

Emodin (1) is the major bioactive compound of several herb species, which belongs to anthraquinone class of compound. As a part of our drug discovery program, large quantities of emodin (1) was isolated from the roots of Rheum emodi and a library of novel emodin derivatives 2-15 were prepared to evaluate their antiproliferative activities against HepG2, MDA-MB-231 and NIH/3T3 cells lines. The derivatives 3 and 12 strongly inhibited the proliferation of HepG2 and MDA-MB-231 cancer cell line with an IC50 of 5.6, 13.03 and 10.44, 5.027, respectively, which is comparable to marketed drug epirubicin (III). The compounds 3 and 12 were also capable of inducing cell cycle arrest and caspase dependent apoptosis in HepG2 cell lines and exhibit DNA intercalating activity. These emodin derivatives hold promise for developing safer alternatives to the marketed epirubicin.

Study of Optimum Process of Microwave Technique to Extract Free Anthraquinones in Rhubarb / 中国中医药信息杂志

Objective To optimize the extraction process of free anthraquinones from Rheum Emodi Wall. with microwave technique. Methods Single factor and orthogonal test design were used to investigante the effects of the four main factors including microwave power, alcohol concentration, extraction time and the ratio of materials and solution on the extraction efficiency of free anthraquinones. Results Using 70% ethanol solution in high-fire and the ratio of materials and solution of 1∶8 for 5 min to extract two times, the extraction rate of Rhubarb anthraquinones was 1.31% and the relative rate was 88.52%. Conclusion Microwave extraction method is high efficient, easy and timesaving for extracting anthraquinones in Rheum Emodi Wall..

Chemical constituents of Rheum emodi / 中草药

Objective To isolate and determine the structures of chemical constituents from the roots and rootstalks of Rheum emodi.Methods The chemical constituents were isolated and purified by silica gel and polyamide column chromatography.Chemical methods and spectroscopic methods,such as 1H-NMR,13C-NMR,and MS spectra were used for the structure identification.Results Eighteen compounds were obtained.Sixteen of them were identified as:chrysophanol(1),physcion(2),?-sitosterol(3),emodin(4),aloe-emodin(5),rheumin(6),daucosterol(7),d-catechin(8),piceatannol(9),piceatannol-4'-O-?-D-glucopyranoside(10),piceatannol-4'-O-?-D-(6″-O-p-coumaroyl)-glucopyranoside(11),chrysophanol-8-O-?-D-glucopyranoside(12),physcion-1 and 8-O-?-D-glucopyranoside(13a and 13b),emodin-8-O-?-D-glucopyranoside(14),and sucrose(15).Meanwhile,one compound structure simi-lar to rhein was detected.Conclusion Compound 11 is a new compound named rheoside,compounds 13a and 13b are obtained from R.emodi for the first time.

Application of microwave technique to extraction of free anthraquinones in Rheum emodi / 中草药

Object To apply microwave technique to the extraction of free anthraquinones from Rheum emodi Wall. and the methods of microwave extraction and traditional extraction were comparied. Methods The orthogonal test design was used to arrange sequent experiments to test the effect of the three main factors including microwave power, particle size of herb and extraction time on the extraction efficiency of free anthraquinones and to establish optimal extraction process. A parallel test was carried out using the three different methods including the optimal extraction process, the traditional decocting method and the alcohol refluxing method. Results Particle size of herb and microwave power are the significant factors with P

Effect of Rheum emodi Wall on express level of TNF-?、IL-1? and IL-6 on acute ischemic stroke at high altitude / 中成药

AIM:To observe the effect of Rheum emodi Wall on expess level of TNF-?、IL-1? and IL-6 on acute ischemic stroke(ACI)at high altitude. METHODS: 65 patients aith ACI at high altitude(2 260 m)were randomly divided into treatment group(34) and control groups(31).both groups received danshen-safflower injection.Meanwhile treatment group took Rheum emodi decoction orally for 4 weeks,while control group doesn't.Serum levels of TNF-?、IL-1? and IL-6 were measured by radioimmumoassay. RESULTS: The treatment group showed much higher rates of improvement than control group(88.24%;70.97%)after weeks.Serum levels of TNF-?、IL-1? and IL-6 decreased significantly in patients with ACI at treatment group as compared with those of control group. CONCLUSION: Rheum emodi Wall can improve the nervous function of ACI by reducing TNF-?、IL-1? and IL-6 content in serun.