Rheum

IntroductionVarious species of the genus Rheum (Polygonaceae) are known for their high content of medicinally important hydroxyanthraquinones. However, little information is available concerning the polyphenolic composition of garden or dietary rhubarb Rheum rhaponticum L. (R. rhaponticum).Various species of the genus Rheum (Polygonaceae) are known for their high content of medicinally important hydroxyanthraquinones. However, little information is available concerning the polyphenolic composition of garden or dietary rhubarb Rheum rhaponticum L. (R. rhaponticum).ObjectiveDetermination of further polyphenols in the roots and petioles of R. rhaponticum.Determination of further polyphenols in the roots and petioles of R. rhaponticum.MethodologyThe dried plant material was extracted with 10-fold excess (v/w) of methanol and subsequently diluted five times with methanol–water (1:1) and analysed by reversed-phase liquid chromatography using tandem UV-photodiode array and mass selective detection (RP-HPLC-UV-ESI/MS2). Polyphenols were identified using either HPLC-ESI/MS2 data obtained for respective commercial standards or by comparison of a parent ion fragmentation picture with the respective MS2 spectrum from the literature.The dried plant material was extracted with 10-fold excess (v/w) of methanol and subsequently diluted five times with methanol–water (1:1) and analysed by reversed-phase liquid chromatography using tandem UV-photodiode array and mass selective detection (RP-HPLC-UV-ESI/MS2). Polyphenols were identified using either HPLC-ESI/MS2 data obtained for respective commercial standards or by comparison of a parent ion fragmentation picture with the respective MS2 spectrum from the literature.ResultsThe roots of R. rhaponticum were very rich in various hydroxystilbenes and contained four main substance groups –derivatives of trans-piceatannol, trans-resveratrol, trans-rhapontigenin and trans-deoxyrhapontigenin. Additionally, pterostilbene acetylglucosides and a number of hydroxyanthraquinones and their glycosides were identified in the root samples. The profile of polyphenols in the petioles of R. rhaponticum was similar to that of the roots but the content of individual substances was remarkably lower. The petioles of the R. rhaponticum additionally contained significant amounts of derivatives of flavonol quercetin, which is a good antioxidant.The roots of R. rhaponticum were very rich in various hydroxystilbenes and contained four main substance groups –derivatives of trans-piceatannol, trans-resveratrol, trans-rhapontigenin and trans-deoxyrhapontigenin. Additionally, pterostilbene acetylglucosides and a number of hydroxyanthraquinones and their glycosides were identified in the root samples. The profile of polyphenols in the petioles of R. rhaponticum was similar to that of the roots but the content of individual substances was remarkably lower. The petioles of the R. rhaponticum additionally contained significant amounts of derivatives of flavonol quercetin, which is a good antioxidant.ConclusionThe study has shown that roots of R. rhaponticum contain a wide variety of hydroxystilbenes and deserve further consideration as a source of medicinally interesting compounds. Copyright © 2008 John Wiley & Sons, Ltd.The study has shown that roots of R. rhaponticum contain a wide variety of hydroxystilbenes and deserve further consideration as a source of medicinally interesting compounds. Copyright © 2008 John Wiley & Sons, Ltd.

The methanolic extract of rhizome of Himalayan rhubarb Rheum emodi displayed mild yeast as well as mammalian intestinal alpha-glucosidase inhibitory activity. However, further fractionation of active extract led to the isolation of several potent molecules in excellent yields, displaying varying degrees of inhibition on two test models of alpha-glucosidase. Rhapontigenin, desoxyrhapontigenin, chrysophanol-8-O-beta-d-glucopyranoside, torachrysone-8-O-beta-d-glucopyranoside displayed potent yeast alpha-glucosidase inhibition. However chrysophanol-8-O-beta-d-glucopyranoside, desoxyrhaponticin and torachrysone-8-O-beta-d-glucopyranoside displayed potent to moderate mammalian alpha-glucosidase inhibitory activity. Other compounds displayed mild activity on both the tests. Except desoxyrhapontigenin and rhapontigenin that increased Vmax, other compounds including crude extract decreased the Vmax significantly (p<0.02) in yeast alpha-glucosidase test. Further kinetic analysis on mammalian alpha-glucosidase inhibition showed that chrysophanol-8-O-beta-d-glucopyranoside, desoxyrhaponticin and torachrysone-8-O-beta-d-glucopyranoside may be classified as mixed-noncompetitive inhibitors. However, desoxyrhapontigenin and rhapontigenin may be classified as modulators of enzyme activity. Presence and position of glycoside moiety in compounds appear important for better inhibition of mammalian alpha-glucosidase. This is the first report assigning particularly, mammalian intestinal alpha-glucosidase inhibitory activity to these compounds. Chrysophanol-8-O-beta-d-glucopyranoside, desoxyrhaponticin, desoxyrhapontigenin and rhapontigenin have been isolated in substantial yields from R. emodi for the first time. Therefore, these compounds may have value in the treatment and prevention of hyperglycemia associated diabetes mellitus.

Protein misfolding and aggregation are associated with more than twenty diseases, such as neurodegenerative diseases and metabolic diseases. The amyloid oligomers and fibrils may induce cell membrane disruption and lead to cell apoptosis. A great number of studies have focused on discovery of amyloid inhibitors which may prevent or treat amyloidosis diseases. Polyphenols have been extensively studied as a class of amyloid inhibitors, with several polyphenols under clinical trials as anti-neurodegenerative drugs. As oxidative intermediates of natural polyphenols, quinones widely exist in medicinal plants or food. In this study, we used insulin as an amyloid model to test the anti-amyloid effects of four simple quinones and four natural anthraquinone derivatives from rhubarb, a traditional herbal medicine used for treating Alzheimer's disease. Our results demonstrated that all eight quinones show inhibitory effects to different extent on insulin oligomerization, especially for 1,4...

Rheum australe D. Don (Polygonaceae) has been commonly used in traditional medicine for a wide range of ailments related to the circulatory, digestive, endocrine, respiratory and skeletal systems as well as to infectious diseases. To provide the up-to-date information that is available on the botany, traditional uses, phytochemistry, pharmacology and toxicology of Rheum australe. Additionally, to highlight the possible uses of this species to treat different diseases and to provide a basis for future research. The present review covers the literature available from 1980 to 2011. The information was collected from scientific journals, books, theses and reports via a library and electronic search (Google Scholar, Web of Science and ScienceDirect). Ethnomedical uses of Rheum australe have been recorded from China, India, Nepal and Pakistan for 57 different types of ailments. The phytochemical studies have shown the presence of many secondary metabolites belonging to anthraquinones, stilbenes, anthrones, oxantrone ethers and esters, chromones, flavonoids, carbohydrate, lignans, phenols and sterols. Crude extracts and isolated compounds from Rheum australe show a wide spectrum of pharmacological activities, such as antidiabetic, anti-inflammatory, antifungal, antimicrobial, antioxidant, anticancer, hepatoprotective and immune-enhancing activities, as well as a usefulness for improving renal function. Rheum australe has been widely used source of medicine for years without any adverse effects. Many studies have provided evidence for various traditional uses. However, there is a need for additional studies of the isolated compounds to validate the traditional uses in human models. The present review on the botany, traditional uses, phytochemistry and toxicity has provided preliminary information for further studies and commercial exploitations of the plant.

IntroductionVarious species of the genus Rheum (Polygonaceae) are known for their high content of medicinally important hydroxyanthraquinones. However, little information is available concerning the polyphenolic composition of garden or dietary rhubarb Rheum rhaponticum L. (R. rhaponticum).Various species of the genus Rheum (Polygonaceae) are known for their high content of medicinally important hydroxyanthraquinones. However, little information is available concerning the polyphenolic composition of garden or dietary rhubarb Rheum rhaponticum L. (R. rhaponticum).ObjectiveDetermination of further polyphenols in the roots and petioles of R. rhaponticum.Determination of further polyphenols in the roots and petioles of R. rhaponticum.MethodologyThe dried plant material was extracted with 10-fold excess (v/w) of methanol and subsequently diluted five times with methanol–water (1:1) and analysed by reversed-phase liquid chromatography using tandem UV-photodiode array and mass selective detection (RP-HPLC-UV-ESI/MS2). Polyphenols were identified using either HPLC-ESI/MS2 data obtained for respective commercial standards or by comparison of a parent ion fragmentation picture with the respective MS2 spectrum from the literature.The dried plant material was extracted with 10-fold excess (v/w) of methanol and subsequently diluted five times with methanol–water (1:1) and analysed by reversed-phase liquid chromatography using tandem UV-photodiode array and mass selective detection (RP-HPLC-UV-ESI/MS2). Polyphenols were identified using either HPLC-ESI/MS2 data obtained for respective commercial standards or by comparison of a parent ion fragmentation picture with the respective MS2 spectrum from the literature.ResultsThe roots of R. rhaponticum were very rich in various hydroxystilbenes and contained four main substance groups –derivatives of trans-piceatannol, trans-resveratrol, trans-rhapontigenin and trans-deoxyrhapontigenin. Additionally, pterostilbene acetylglucosides and a number of hydroxyanthraquinones and their glycosides were identified in the root samples. The profile of polyphenols in the petioles of R. rhaponticum was similar to that of the roots but the content of individual substances was remarkably lower. The petioles of the R. rhaponticum additionally contained significant amounts of derivatives of flavonol quercetin, which is a good antioxidant.The roots of R. rhaponticum were very rich in various hydroxystilbenes and contained four main substance groups –derivatives of trans-piceatannol, trans-resveratrol, trans-rhapontigenin and trans-deoxyrhapontigenin. Additionally, pterostilbene acetylglucosides and a number of hydroxyanthraquinones and their glycosides were identified in the root samples. The profile of polyphenols in the petioles of R. rhaponticum was similar to that of the roots but the content of individual substances was remarkably lower. The petioles of the R. rhaponticum additionally contained significant amounts of derivatives of flavonol quercetin, which is a good antioxidant.ConclusionThe study has shown that roots of R. rhaponticum contain a wide variety of hydroxystilbenes and deserve further consideration as a source of medicinally interesting compounds. Copyright © 2008 John Wiley & Sons, Ltd.The study has shown that roots of R. rhaponticum contain a wide variety of hydroxystilbenes and deserve further consideration as a source of medicinally interesting compounds. Copyright © 2008 John Wiley & Sons, Ltd.

The 1,8-dihydroxyanthraquinones from the culinary and medicinally important plant Rheum emodi exert anti-hyperglycemic potential but notably different α-glucosidase actions as established by in vitro, in vivo, kinetics and molecular docking studies.

Aloe-emodin (AE) is derived from Aloe vera and rhubarb (Rheum palmatum) and exhibits anticancer activities via multiple regulatory mechanisms in various cancers. AE can also enhance the anticancer efficacy of cisplatin, doxorubicin, docetaxel, and 5-fluorouracil; however, its effects remain poorly characterized. MCF-7, MDA-MB-231, MDA-MB-468, BT-474, and HCC-1954 breast cancer cell lines were treated with the indicated conditions of AE, and cell viability assays were performed. The expression levels of signaling proteins were determined by western blot analysis, intracellular reactive oxygen species (ROS), cell cycle distributions, and rates of apoptosis as estimated by flow cytometry. In comparison with other cells, MCF-7 cells were more sensitive to AE treatment; AE enhanced the cytotoxicity of 9[Formula: see text][Formula: see text]g/ml tamoxifen by reducing EGFR, ER[Formula: see text], Ras, ERK, c-Myc, and mTOR protein expression and blocking PI3K and mTOR activation. Finally, a...

to evaluate the antibacterial activity of Sapindus mukorossi (S. mukorossi) and Rheum emodi (R. emodi). Powders of S. mukorossi and R. emodi were extracted successively with petroleum ether, benzene, chloroform and ethanol and were concentrated in vacuum. The disk diffusion method was used for in vitro studies and in vivo studies were performed on male Wister rats. Thirty resistant clinical isolates of H pylori, as determined by their antibiotic sensitivity patterns by E-test, along with two Gram +ve (S. aureus, B. subtilis) and two Gram -ve (E. coli, P. vugaris) organisms were screened for their susceptibility patterns against these extracts. In our screening, all 30 resistant isolates and the other four organisms (two Gram +ve S. aureus, B. subtilis and two Gram -ve, E. coli, P. vugaris) were sensitive to the test compounds. It was found that ethanol and chloroform extracts of S. mukorossi and ethanol and benzene extracts of R. emodi inhibited H pylori at very low concentrations. ...

In previous studies, rhein, one of the major bioactive constituents in the rhizome of rhubarb, inhibited the proliferation of various human cancer cells. However, because of its water insolubility, the anti-tumor efficacy of rhein was limited in vivo. In this study, we observed the anti-tumor activity of rhein lysinate (the salt of rhein and lysine easily dissolves in water) in vivo and investigated its mechanism. Inhibition of ovarian cancer SKOV-3 cell proliferation was determined by MTT assay and the mechanism of action of rhein lysinate was investigated by Western blot analysis. The therapeutic efficacy of rhein lysinate was evaluated by intragastric and intraperitoneal administrations in H22 hepatocellular carcinoma mice. Rhein lysinate inhibited the proliferation of SKOV-3 cells and the IC50 value was 80 microM. Rhein lysinate inhibited the phosphorylation of MEK and ERK and increased the anti-tumor activity of Taxol in vitro. It inhibited tumor growth by both intragastric and intraperitoneal administrations and improved the therapeutic effect of Taxol in H22 hepatocellular carcinoma mice. In conclusion, rhein lysinate offers an anti-tumor activity in vivo and is hopeful to be a chemotherapeutic drug.

To evaluate the combination of rhubarb, astragalus, red sage, ginger, and turmeric (mixture referred to as "NT") together with gallic acid for evidence of reproductive toxicity in rats.