Rheum Species Research Articles

대황 추출물의 항위염 작용과 유효성분에 관한 연구

현재 대황은 지표성분의 규격이 한국, 일본과 중국이 다르고, 유통시장에서 대황과 종대황이 혼재되어 있으며 다양한 기원식물이 혼재되어 수입되고 있다. 따라서 대황의 효능을 현대 약리학적으로 해석하는 과정을 통해 약재의 표준화, 과학화 및 위염에 대한 지표성분 검색에 기여할 수 있을 것으로 사료되어 Rheum tanguticum(당고특대황)과 그 비교생약으로 Rumex cripus(양제근), Rheum officinale(약용대황), Rheum palmatum(장엽대황) 및 Rheum undulatum(종대황)의 물 및 70% 에탄올 추출물을 비교하였다. 그 결과, 흰 쥐를 이용한 위염 모델에서 양제근 70% 에탄올 추출물(73.2%)와 종대황 물 추출물(71%)이 각각 70% 이상으로 우수한 위손상 억제활성을 보여주었지만, 당고특대황의 70% 에탄올 추출물 투여시 91.8%로 실험군 중 가장 우수한 위염 억제 효과를 확인할 수 있었다. 공격인자로써의 산을 중화시킬 수 있는 능력을 알아보기 위한 제산력 시험법으로는 당고특대황 물 추출물과 70% 에탄올 추출물이 각각 약 14.2%, 약 15.8%로 억제함을 알 수 있었다. 이 결과로 보아 양성대조군으로 사용한 hydrotalcite(49.9%)보다는 제산작용이 약하였지만 과량 혹은 장기간 복용하면 효과가 있을 것으로 생각된다. 소화성궤양, 위암 및 변연부 B세포 림프종 발생에 있어 중요한 원인 인자로 밝혀졌고, 기능성 소화불량증, 위의 과형성 용종, 철결핍성 빈혈 등 기타 질환과의 연관성들이 제시되고 있는 H. pylori에 대한 colonization 억제 활성을 확인한 결과 당고특대황의 70% 에탄올 추출물 <TEX>$100{\mu}g/mL$</TEX>에서 H. pylori에 대한 항균작용(+)을 확인할 수 있었다. DPPH 용액을 이용하여 free radical의 소거능을 <TEX>$IC_{50}$</TEX>으로 나타낸 결과, 당고특대황은 물 및 70% 에탄올 추출물에서 <TEX>$IC_{50}$</TEX>이 <TEX>$25.9{\mu}g/mL$</TEX>, <TEX>$5.8{\mu}g/mL$</TEX>로 양성대조군으로 사용한 L-ascorbic acid (<TEX>$IC_{50}=6.5{\mu}g/mL$</TEX>)와 유사한 free radical 소거능을 나타내었다. 이 결과로 당고특대황의 70% 에탄올 추출물이 휜 쥐 위염모델의 위손상을 가장 우수하게 억제하였으며 항산화 활성 또한 가장 우수한 것으로 확인되었다. 당고특대황의 성분인 chysophanol, chrysophanol-8-O-glc, desoxyrhaponticin desoxyrhapontigenin, emodin, isorhaponticin, 2-methoxy-4-hydroxyanthraquinone-5-O-glc, physcion, piracetannol-3'-O-glc, resveratrol, rhaponticin 및 rhapontigenin을 이용하여 실험한 결과로는 효성분들 중 physcion <TEX>$100{\mu}M$</TEX>과 rhaponticin <TEX>$50{\mu}M$</TEX> 및 <TEX>$100{\mu}M$</TEX>에서는 실험에 사용한 성분 들 중 비교적 우수한 colonization 억제작용(+)을 나타내었고, DPPH radical 소거 활성은 isorhaponticin, piracetannol-3'-O-glc, resveratrol 및 rhaponticin에서 <TEX>$IC_{50}$</TEX>이 각각 <TEX>$129.5{\mu}M$</TEX>, <TEX>$94.1{\mu}M$</TEX> <TEX>$80.1{\mu}M$</TEX> 및 <TEX>$104.6{\mu}M$</TEX>로 확인되었다. 실험결과를 토대로 항위염 효과가 있는 우수한 약용식물로써 천연물 의약품개발 가능성을 확인하였고 나아가 한약재의 효능을 과학적으로 검증하고 한약재 표준화에 기여할 수 있을 것으로 기대된다. Rheum tanguticum has long been used in oriental medicine as antipyretics, analgesics, anti-inflammation, aperient, hypertension medicine and medicine for skin disease. This study has investigated the effectiveness of defense for gastritis making use of Rheum tanguticum and its similar plants, Rumex cripus, Rheum officinale, Rhem palmatum and Rheum undulatum. Chysophanol, chrysophanol-8-O-glc, Desoxyrhaponticin desoxyrhaponti-genin, emodin, isorhaponticin, 2-methoxy-4-hydroxyanthraquinone-5-O-glc, physcion, pirace-tannol-3'-O-glc, resveratrol, rhaponticin and rhapontigenin are used as the components of Rheum tanguticum. In HCl ethanol-induced gastritis in rat, the most effective extract was 70 percent ethanol which is of Rheum tanguticum, showing the inhibition of 91.8 percent to the gastric lesions. 70% ethanol extract of Rhem palmatum and Rumex cripus shown inhibition of 75.6 percent and 73.2 percent, respectively. This effectiveness is considered as acid-neutralizing capacity, anti-H.pylori and anti-oxidant activity. 70% ethanol extract of Rheum tanguticum and its component, piracetannol-3'-O-glc exhibited higher free radical scavenging activity than others. These results suggest that Rheum species extracts and their active components could be utilized for the treatment of gastritis. Furthermore, these results are expected to contribute the standardization with objectivity and reliability for Rheum species, medicinal herbs. In addition, it can contribute to the prevention of indiscriminate distribution of imitation, and the rising rate of dependence on imports of medicinal herbs, and mixing prevention of low-quality goods.

Spectrum-effect relationship between anti-HIV 1 activities and ultra- performance liquid chromatography fingerprints of Rheum species

To study the relationship between ultra-performance liquid chromatography (UPLC) fingerprints of Rheum species and their anti-HIV 1 activities. Twenty two samples of 16 species belonging to genus Rheum from various sources were collected and analyzed in this study. Firstly they were assayed for the HIV-1 reverse transcriptase (RT) associated ribonuclease H (RNase H) activity. Secondly the fingerprints were established by an optimized UPLC method. Sample was analyzed by UPLC-TOF-MS/MS to identify major peaks. The possible relationship between UPLC fingerprints and anti-HIV 1 activities of Rheum species were deduced by mathematical statistics method. Samples of R. austral, R. austral, R. hotaoense exhibited good anti-HIV 1 activities with IC50 < or = 0.2 mg x L(-1). The correlation of anti-HIV 1 activities and fingerprints showed that three compounds were the main bioactive components, and their retention times were 4.74, 7.99, 21.18 min, respectively. Compounds in Rheum species with possible anti-HIV 1 activities were deduced by spectrum-effect relationship study. This study supported for study of medicinal plants in Rheum.

Rapid method for rhaponticin and deoxyrhaponticin separation and determination by TLC inRheum rhaponticumL. andRheum undulatumL.

Summary The study describes the solvent extraction procedure and improved version of TLC method for the determination of rhaponticin and deoxyrhaponticin in rhizomes and petioles of two species of Rheum L. genus. Extracts from underground parts and petioles of plant were separated on thin layers of silica using a mixture of dichloromethane-95% ethanol-methanol (8:1:1). The bands of rhaponticin and deoxyrhaponticin were satisfactorily separated from the remaining extract components permitting their densitometric quantitative and qualitative determination. The concentration of these compounds in Rheum undulatum was higher than in Rheum rhaponticum. The amount of rhaponticin and deoxyrhaponticin ranged between 0.3 and 31.5 mg/g.

Rutin- potent natural thrombolytic agent

Thrombosis, the formation of blood clots, is a cause not only of heart attacks and strokes, but of deep venous thrombosis (DVT) and pulmonary embolism as well. The number one killer of Americans is a blood clot that blocks blood flow to the heart or to the brain and approximately half of all morbidity and mortality in the United States can be attributed to heart attack or stroke. All the blood clot related conditions are life-threatening, and so there is a need for safe, effective and preventive treatment. A natural substance rutin, also called rutoside, is a citrus flavonoid glycoside found in Fagopyrum esculentum (buckwheat), the leaves and petioles of Rheum species, and Asparagus. This flavonoid compound has shown effective thrombolytic activity (prevents the formation of blood clots) by blocking the enzyme protein disulfide isomerase (PDI) found in all cells involved in blood clotting. Food and Drug Administration (FDA) has established that rutin is safe and, thus provides a safe and inexpensive drug that could reduce recurrent clots and help save thousands of lives.DOI: http://dx.doi.org/10.3329/icpj.v1i12.12454 International Current Pharmaceutical Journal 2012, 1(12): 431-435

Evidence-based quality criteria in research, development and application of Chinese medicines

TCM mainly consists of crude drugs, slices for decoction, extracts and Chinese patent medicine preparations. Crude drugs are the raw and starting materials of preparation of slices, extracted intermediates and the finished products. The crude drugs being collected or cultivated from nature has many factors affecting its quality. Different species/varieties,different produce areas, different harvest times , different processing methods and different storage conditions can all cause an enormous diversity on the quality. It has been evidenced that the multi-originated herbs showed diverse in chemical profiles and consequently un-equivalent in pharmacological potency. This situation may be well recognized by pharmacogosists, however are often neglect or ignored by pharmacologists and TCM doctors in the biological activity screening, in non-clinical investigation research, and in clinical trials, which undoubtedly led to unrepeatability of the results and even wrong conclusive direction. As examples, four species of Rheum are recorded for Rhubarb in Chinese Pharmacopoeia but only one or two species possess diarrhea effects. As for Curcumae Radix, only the root of Curcuma longa L showed potent choleretic activity among the fure species of Curcuma recorded in Chinese Pharmacopoeia. In view of this consideration, the importance of a pre-experiment assessment of the starting material and the standardized and advanced methodologies for the authentication and quality evaluation of TCM herbs/products will be addressed in this presentation.

Rapid radiation of Rheum (Polygonaceae) and parallel evolution of morphological traits

In this study, we examined diversification history of Rheum and tested the hypothesis that morphological traits related to plant ‘body-plans’ evolved in parallel in this genus. We sequenced eight chloroplast DNA fragments (representing more than 8000bps of the sequence for each species) of 34 species from the genus and 13 species from closely related genera. Phylogenetic analyses indicate that all species of Rheum form a monophyletic lineage sister to the two-species genus Oxyria, indicating that radiative diversifications have occurred in its evolutionary history. Our dating analyses further suggest that these radiations largely coincided with the extensive uplifts of the Qinghai–Tibetan Plateau (QTP). Ancestral state reconstruction and likelihood sensitivity tests strongly indicate that both decumbent and ‘glasshouse-like’ body-plan traits evolved in parallel in different clades. Our findings highlight the importance of the uplift of the QTP in promoting species diversification and the parallel evolution of morphological traits that are putatively adaptive during such an evolutionary history.

Gene duplication and adaptive evolution of the CHS-like genes within the genus Rheum (Polygonaceae)

Abstract It is suggested that gene duplication plays an important role in adaptation and evolution of plants. In this study, we examined whether the genus Rheum, with extensive diversification in the Qinghai-Tibeten Plateau (QTP) and adjacent regions, possessed the duplication of the chalcone synthase ( CHS ) genes and whether it underwent positive evolution. Here we cloned CHS -like genes from 16 Rheum species. Phylogenetic analyses suggested that CHS -like genes from Rheum comprised two monophyletic lineages (subfamilies), both of which were sisters to another related genus. The results showed that a genus-specific duplication occurred after this genus originated. The comparison of non-synonymous/synonymous substitution ratios between the two lineages in Rheum further indicated that a few sites along the duplicate branch underwent positive selection. The findings indicate that the duplication of Rheum species could contribute to their adaptive ability to rapidly changing environments which was resulted from the large-scale uplifts stages of QTP.

Quantitative Determination of Anthraquinones from Various Species of Cassia, Rumex, Rhamnus, Rheum, Aloe and Polygonum using UPLC-UV/MS

Anthraquinones are used as natural laxatives, and widely distributed in different species of Cassia, Rumex, Rhamnus, Rheum, Aloe and Polygonum. Usually anthraquinones are found in the form of aglycone or anthraquinone glycosides in plants. Various case reports of toxicity of natural laxatives are available. Anthraquinone purgatives in excess have caused degeneration of neurons. Toxicity studies separating toxic components of senna's anthraquinone derivatives have been performed [1]. For the purpose of quantitative determination of anthraquinones and chemical fingerprint analysis of plants containing anthraquinones, an ultra-performance liquid chromatography coupled with a PDA detector and a mass spectrometry (UPLC-UV/MS) method has been developed to characterize sennoside B (1), sennoside A (2), aloin B (3), aloin A (4), aloe emodin (5), rhein (6), danthron (7), emodin (8), chrysophanol (9) and physcion (10). The separation was achieved using C-18 column material. Mobile phase is composed of water and acetonitrile, both containing formic acid. The column temperature was maintained at 40°C. The method was validated for linearity, repeatability, limits of detection (LOD) and limits of quantification (LOQ). The developed method is useful for chemical fingerprint analysis of various species of Cassia, Rumex, Rhamnus, Rheum, Aloe and Polygonum, and also successfully applied for the analysis of herbal dietary supplements containing species of Cassia and Rhamnus.

Polyphenolic composition of roots and petioles of Rheum rhaponticum L.

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). Determination of further polyphenols in the roots and petioles of R. rhaponticum. 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/MS(2)). Polyphenols were identified using either HPLC-ESI/MS(2) data obtained for respective commercial standards or by comparison of a parent ion fragmentation picture with the respective MS(2 )spectrum from the literature. 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. 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.

Genetic Diversity of Rhubarb Cultivars

The genus Rheum L., commonly known as rhubarb, is composed of ≈60 species, primarily distributed throughout northern and central Asia. Rhubarb species have been used for medicinal purposes for thousands of years; however, it was not until the 18th century that the culinary use of petioles was first reported. Although the origin(s) of culinary rhubarb is not clear, it is thought that they originated from hybridization of rhubarb species originally brought to Europe for medicinal purposes. Most rhubarb cultivars lack pedigree information, and the genetic relationship among cultivars is largely unknown. Amplified fragment length polymorphism (AFLP) markers were generated for fingerprint analysis of 37 cultivars and four putative Rheum species accessions. Ten EcoRI and MseI primer combinations were analyzed for a total of 1400 scored polymorphisms, with an average of 140 polymorphisms per primer combination. Results show at least two clusters of related cultivars, as well as distantly related accessions. This study provides an estimate of rhubarb cultivar genetic diversity using AFLP analysis.

Comparison of Phenolic Compounds of Rhubarbs in the SectionDeserticolawithRheum palmatumby HPLC-DAD-ESI-MSn

A sophisticated LC-ESI-MS (n) method was utilized for the analysis of the phenolic compounds in five unofficial RHEUM species for the first time. These species belong to the section deserticola Maxim. of the Polygonaceae family, including Rheum racemiferum Maxim., R. nanum Siev. ex Pall., R. delavayi Franch., R. sublanceolatum C. Y. Cheng et T. C. Kao and R. pumilum Maxim. A total of 101 phenolic compounds, including sennosides, anthraquinones, stilbenes, glucose gallates, naphthalenes, procyanidins and chromones were identified or tentatively characterized based on their UV and mass spectral data from the methanol extracts. These chemical constituents were compared with those of an official species ( R. palmatum l.). The results showed that most sennosides and procyanidin derivatives were only present in R. palmatum rather than in the unofficial species; stilbenes and chromones were only found in the sect. deserticola species; while anthraquinones, glucose gallates and naphthalenes could be detected in all studied species. For anthraquinone glycosides, only emodin O-glucosides were detected in the sect. deserticola species. Moreover, remarkable difference was observed among unofficial species. These results may be useful for the quality control of rhubarb in order to guarantee its clinical effects, and may also be helpful for the further clarification of the taxonomic relationship of the plants in the sect. deserticola.

Analysis of Phenolic Compounds in Rhubarbs Using Liquid Chromatography Coupled with Electrospray Ionization Mass Spectrometry

Rhubarb is an important herbal medicine for the treatment of constipation, inflammation, and cancer. In this study, a facile method based on liquid chromatography coupled with electrospray ionization tandem mass spectrometry has been established for the analysis of bioactive phenolic compounds in rhubarbs. From six rhubarb species, official (Rheum officinale, R. palmatum, and R. tanguticum) and unofficial (R. franzenbachii, R. hotaoense, and R. emodi), a total of 107 phenolic compounds were identified or tentatively characterized based on their mass spectra. These compounds include sennosides, anthraquinones, stilbenes, glucose gallates, naphthalenes, and catechins. Ion chromatograms for the identified compounds of different rhubarbs were then compared. Consistent with previous reports, sennosides and rhein were only detected in official rhubarbs. Unexpectedly, we found that R. officinale contained very different phenolic compounds from the other two official species. Sennoside A, which has been considered as the major purgative component of rhubarb, was only detected in R. officinale, while its close isomers were observed in R. palmatum and R. tanguticum. In addition, the predominant anthraquinone glycosides in R. officinale were found to be rhein 8-O-glucoside and emodin 1-O-glucoside, whereas those in R. palmatum and R. tanguticum were rhein 1-O-glucoside and emodin 8-O-glucoside. Stilbenes, which are the major constituents of unofficial rhubarbs, were also different among the species. Our results clarify the chemical composition of rhubarbs comprehensively for the first time. Due to the significant differences in chemical components of rhubarbs, we suggest that different Rheum species be used separately in clinical practice.

Determination of five anthraquinones in medicinal plants by capillary zone electrophoresis with β-cyclodextrin addition

A simple and rapid method for the simultaneous determination of five anthraquinone derivatives including aloe-emodin, emodin, chrysophanol, physcoin and rhein in Rheum species and Polygonum cuspidatum was established by capillary zone electrophoresis (CZE) using β-cyclodextrin (CD) as modifier and urea to enhance its solubility. The apparent binding constants of these derivatives with β-CD were evaluated. After an optimization study, the best conditions were selected using 35 mM phosphate buffer (pH 11.0) containing 20 mM β-CD and 2 M urea, applied voltage 20 kV and detection at 254 nm. Under such conditions, all of the five anthraquinones were baseline-separated within a short analysis time of 12 min with symmetrical peaks and high theoretical plate numbers (189 000–314 000). The RSD values of the migration times and peak areas were 0.6–1.1, 1.3–1.9% (intra-day) and 0.6–1.5, 1.3–2.8% (inter-day, for a 5-day period), respectively. The limits of detection for the analytes (S/N = 3) were 0.33–0.62 μg/ml. The recoveries were ranged from 93.37 to 107.69%. The proposed method was successfully applied to the determination of anthraquinones in ethanol extracts of two kinds of Rheum plants ( R. palmatum and R. hotaoense) and P. cuspidatum.

Molecular phylogeny, recent radiation and evolution of gross morphology of the rhubarb genus Rheum (Polygonaceae) inferred from chloroplast DNA trnL-F sequences.

Rheum, a highly diversified genus with about 60 species, is mainly confined to the mountainous and desert regions of the Qinghai-Tibetan plateau and adjacent areas. This genus represents a good example of the extensive diversification of the temperate genera in the Qinghai-Tibetan plateau, in which the forces to drive diversification remain unknown. To date, the infrageneric classification of Rheum has been mainly based on morphological characters. However, it may have been subject to convergent evolution under habitat pressure, and the systematic position of some sections are unclear, especially Sect. Globulosa, which has globular inflorescences, and Sect. Nobilia, which has semi-translucent bracts. Recent palynological research has found substantial contradictions between exine patterns and the current classification of Rheum. Two specific objectives of this research were (1) to evaluate possible relationships of some ambiguous sections with a unique morphology, and (2) to examine possible occurrence of the radiative speciation with low genetic divergence across the total genus and the correlation between the extensive diversification time of Rheum and past geographical events, especially the recent large-scale uplifts of the Qinghai-Tibetan Plateau. The chloroplast DNA trnL-F region of 29 individuals representing 26 species of Rheum, belonging to seven out of eight sections, was sequenced and compared. The phylogenetic relationships were further constructed based on the sequences obtained. Despite the highly diversified morphology, the genetic variation in this DNA fragment is relatively low. The molecular phylogeny is highly inconsistent with gross morphology, pollen exine patterns and traditional classifications, except for identifying all samples of Sect. Palmata, three species of Sect. Spiciformia and a few species of Sect. Rheum as corresponding monophyletic groups. The monotypic Sect. Globulosa showed a tentative position within the clade comprising five species of Sect. Rheum. All of the analyses revealed the paraphyly of R. nobile and R. alexandrae, the only two species of Sect. Nobilia circumscribed by the possession of large bracts. The crude calibration of lineages based on trnL-F sequence differentiation implied an extensive diversification of Rheum within approx. 7 million years. Based on these results, it is suggested that the rich geological and ecological diversity caused by the recent large-scale uplifts of the Qinghai-Tibetan Plateau since the late Tertiary, coupled with the oscillating climate of the Quaternary stage, might have promoted rapid speciation in small and isolated populations, as well as allowing the fixation of unique or rare morphological characters in Rheum. Such a rapid radiation, combined with introgressive hybridization and reticulate evolution, may have caused the transfer of cpDNA haplotypes between morphologically dissimilar species, and might account for the inconsistency between morphological classification and molecular phylogeny reported here.

A molecular marker that is specific to medicinal rhubarb based on chloroplast trnL/trnF sequences.

"Da-Huang" (Radix et Rhizoma Rhei, medicinal rhubarb), a famous and important Traditional Chinese Medicine, has often been confused with the adulterant species in the same genus, Rheum. Through sequencing the trnL (UAA)/trnF (GAA) regions of chloroplast DNA of thirteen species of Rheum (three medicinal rhubarb species and ten adulterant ones), a molecular marker of the medicinal species was found. A pair of PCR primers based on the sequences, was thus designed, which amplified a highly specific DNA fragment in medicinal rhubarb exclusively, and absent in the adulterants at all under an optimized PCR condition.

Pollen morphology and its systematic and ecological significance in Rheum (Polygonaceae) from China

Pollen morphology of 40 species of Rheum, belonging to eight sections, was investigated under LM and SEM. Four new exine patterns were found in the species: a) microechinate‐foveolate, b) rugulate, c) verrucate‐perforate, and d) verrucate‐rugulate ornamentation. In addition, two patterns, the Rheum‐type pollens with microechinate‐perforate and fine‐reticulate, as previously described, were also confirmed in the present study. Based on above study the evolution trends of pollen morphology in the taxa involved were discussed phylogenetically as below. As microechinate‐perforate exine pattern existed commonly, the pattern is, therefore, regarded as the most primitive among all the six types. The fine‐reticulate type was thought as a derivative type, deriving from the basic microechinate‐foveolate‐perforate pattern, and followed by the rugulate and verrucate‐perforate ornamentation. The verrucate‐rugulate ornamentation should be the most advanced. More than one pollen type often exist in most of the sections in Rheum. The pollen morphology of Rheum was strongly correlated with its geographical and ecological distribution. Three medicinally important species R. officinale, R. palmatum and R. tanguticum can be palynologically distinguished by their ornamentations.

Phytoestrogens from the roots of Polygonum cuspidatum (polygonaceae): structure-Requirement of hydroxyanthraquinones for estrogenic activity

The methanolic extract from the roots of Polygonum (P.) cuspidatum was found to enhance cell proliferation at 30 or 100μg/mL in MCF-7, an estrogen-sensitive cell line. By bioassay-guided separation from P. cuspidatum with the most potent activity, emodin and emodin 8-O-β-d-glucopyranoside were isolated as active principles. The methanolic extracts from Polygonum, Cassia, Aloe, and Rheum species, which were known to contain anthraquinones, also showed the MCF-7 proliferation. As a result of the evaluation of various anthraquinones from plant sources and synthetic anthraquinones, aloe-emodin, chrysophanol, chrysophanol 8-O-β-d-glucopyranoside, and 1,8-dihydroxyanthraquinone showed weak activity. On the other hand, alizalin and 2,6-dihydroxyanthraquinone as well as emodin having the 2- and/or 6-hydoxyl groups showed potent activity. These results show that the unchelated hydroxyl group is essential for strong activity. Emodin and 2,6-dihydroxyanthraquinone also inhibited 17β-estradiol binding to human estrogen receptors (ERs) with Ki values of 0.77 and 0.31μM for ERα and 1.5 and 0.69μM for ERβ. These findings indicate that hydroxyanthraquinones such as emodin are phytoestrogens with an affinity to human estrogen receptors.

Anthranoid contents of rhubarb ( Rheum undulatum L.) and other Rheum species and their toxicological relevance

Extracts of different parts of rhubarb (Rheum undulatum L.) were investigated for their total content of anthranoids. After oxidation and hydrolyzation the anthranoid derivatives emodin, chrysophanol and physcion were detected in rhubarb leaves. The highest amount of anthranoids occurred in the lamina (0.06% of dry weight) of plants harvested in April. The lowest amounts were present in the part of the petiole proximal to the roots (0.001%), whereas the upper parts of the petioles contained up to 0.004% of hydroxyanthracene derivatives. With respect to the season, the highest anthranoid contents were always observed in leaves cut in the springtime (April) followed by a continuous decrease during the summer. The lowest anthranoid amounts were evident in the plants harvested in the late summer (September). Ethanolic extracts of different Rheum species were also compared with respect to their mutagenicity in the Salmonella/microsome assay. Positive effects were observed for the laminal parts of the leaves of Rh. undulatum in S. typhimurium strain TA 1537, whereas no evidence of mutagenicity could be detected in the edible parts of rhubarb (i.e. the petioles). The root extracts of Rh. officinale and Rh. rhaponticum, which are used for medicinal purposes, were clearly mutagenic in this assay. From these data it can be concluded that in contrast to Rheum species used in medicine, no risk is associated with the use of rhubarb as a food.

Cytogenetic studies of some members of Polygonaceae of Kashmir. III Rheum L.

Meiotic details of two species of Rheum have been studied. R. emodi, a dip-ploid species with 2n=22 chromosomes, an accessory chromosome was observed in most of the pollen mother cells studied. In 27% pollen mother cells this B chro-mosome was observed attached to one of the bivalents by a faintly staining connection. It is the first report of the presence of an accessory chromosome in this genus.Meiosis in both R. webbianum, a tetraploid species with 2n=44, and diploid R. emodi was mostly normal. The frequency of mutivalents in R. webbianum was very low, which may probably be due to its amphidiploid nature.

Hydroxylated glutamic acids in Phlox, lepidium and Rheum species

The two diastereoisomers, (2 S,4 R)-4-hydroxyglutamic acid and (2 S,4 S)-4-hydroxyglutamic acid, occur in characteristic concentration ratios in Phlox species. The second of these compounds is the principal free amino acid in the green parts of the plants. The presence of (2 S,4 R)-4-hydroxyglutamic acid in plants is reported for the first tiine. No other 4-substituted acidic amino acids were detected in the Phlox species analysed, although special attention was paid to the possible presence of 4-hydroxy-4-methylglutamic acids which have previously been reported in plants. It was found, however, that both diastereoisomers of (2 S)-4-hydroxy-4-methylglutamic acid co-exist in Ledenbergia roseoaenea and also in Pandanus veitchii. Although the presence of 3,4-dihydroxyglutamic acids in green parts of Lepidium sativum and Rheum rhaponticum has been previously reported, we were not able to detect or isolate any of the possible diastereoisomers from the green parts or seeds of these plants. We did isolate glutathione which was found to have some properties in common with those reported for the dihydroxy compounds.