Quality assessment of Rheum species cultivated in Japan by focusing on M2 polarization of microglia

In traditional Japanese medicine, Rhei Rhizoma is used as a purgative, blood stasis-resolving and antipsychotic drug. The latter two properties are possibly related to anti-inflammatory effects. Microglia regulate inflammation in the central nervous system. M1 microglia induce inflammation, while M2 microglia inhibit inflammation and show neurotrophic effects. This study investigated the effects from water extracts of roots of cultivated Rheum species in Nagano Prefecture, Japan (strain C, a related strain to a Japanese cultivar, 'Shinshu-Daio'; and strain 29, a Chinese strain) and 3 kinds of Rhei Rhizoma available in the Japanese market, and also examined their constituents on the polarization of cultured microglia. All extracts significantly decreased M1 microglia, and strains C and 29 significantly increased M2 microglia. Furthermore, the extracts of both strains significantly increased the M2/M1 ratio. Among the constituents of Rhei Rhizoma, ( +)-catechin (2), resveratrol 4'-O-β-D-(6″-O-galloyl) glucopyranoside (5), isolindleyin (8), and physcion (15) significantly increased the M2/M1 ratio. The contents of the constituents in water extract of each strain were quantified using HPLC. The extracts of strains C and 29 contained relatively large amounts of 2 and 5; and 2, 8, and 15, respectively. This study showed the water extracts of roots of cultivated Rheum strains in Japan had the effects of M2 polarization of microglia, suggesting that these strains become the candidate to develop anti-inflammatory Rhei Rhizoma. Moreover, the suitable chemical composition to possess anti-inflammatory activity in the brain was clarified for the future development of new type of Rhei Rhizoma.

Global warming pushes the distribution range of the two alpine 'glasshouse' Rheum species north- and upwards in the Eastern Himalayas and the Hengduan Mountains

Alpine plants' distribution is being pushed higher towards mountaintops due to global warming, finally diminishing their range and thereby increasing the risk of extinction. Plants with specialized 'glasshouse' structures have adapted well to harsh alpine environments, notably to the extremely low temperatures, which makes them vulnerable to global warming. However, their response to global warming is quite unexplored. Therefore, by compiling occurrences and several environmental strata, we utilized multiple ensemble species distribution modeling (eSDM) to estimate the historical, present-day, and future distribution of two alpine 'glasshouse' species Rheum nobile Hook. f. & Thomson and R. alexandrae Batalin. Rheum nobile was predicted to extend its distribution from the Eastern Himalaya (EH) to the Hengduan Mountains (HM), whereas R. alexandrae was restricted exclusively in the HM. Both species witnessed a northward expansion of suitable habitats followed by a southerly retreat in the HM region. Our findings reveal that both species have a considerable range shift under different climate change scenarios, mainly triggered by precipitation rather than temperature. The model predicted northward and upward migration for both species since the last glacial period which is mainly due to expected future climate change scenarios. Further, the observed niche overlap between the two species presented that they are more divergent depending on their habitat, except for certain regions in the HM. However, relocating appropriate habitats to the north and high elevation may not ensure the species' survival, as it needs to adapt to the extreme climatic circumstances in alpine habitats. Therefore, we advocate for more conservation efforts in these biodiversity hotspots.

Phytoremediation potential evaluation of three rhubarb species and comparative analysis of their rhizosphere characteristics in a Cd- and Pb-contaminated soil

Screening or breeding exceptional plant species for heavy metal phytoremediation is as important as adopting feasible measures to enhance phytoremediation efficiency, which are largely based on clarifying the mechanisms of heavy metal tolerance and accumulation by plants. In this study, cadmium (Cd) and lead (Pb) tolerance and accumulation characteristics of Rheum officinale, R. palmatum, and R. tanguticum were analysed to assess their phytoremediation potential. The seed germination test indicated that these three rhubarb species could tolerate 10 mg L^-1 Cd and 100 mg L^-1 Pb. However, when sown in Cd- and Pb-contaminated soil, all three rhubarb species exhibited a relatively high Cd accumulation capacity but a considerably low Pb accumulation capacity according to the bioconcentration factors of Cd (0.42-0.47 in shoots and 0.11-0.15 in roots) and Pb (0.004-0.008 in shoots and 0.007-0.013 in roots). The high Cd translocation factors (3.04-4.24) indicated that these three rhubarb species were suitable for Cd phytoextraction. The changes in rhizospheric physicochemical indices were generally similar among the three rhubarb plants in comparison with those of the unplanted soil. However, differential indicator rhizobacteria were identified for the three rhubarb plants, which may be primarily attributed to their different root system characteristics. These enriched rhizobacteria included many plant growth-promoting bacteria, and several of them were also involved in regulating heavy metal uptake by plants, indicating that three rhubarb species likely recruit differentially beneficial rhizobacteria to maintain plant growth and vitality and to regulate heavy metal uptake in the Cd- and Pb-polluted soil. This study identifies new candidate plant resources for the phytoremediation of Cd-polluted soils and provides novel insights into understanding the interactions among heavy metals, rhizobacteria, and plants.

In Vitro Propagation Method for Production of Phenolic-Rich Planting Material of Culinary Rhubarb 'Malinowy'

Culinary rhubarb is a popular vegetable crop, valued for its long, thickened stalks, very rich in different natural bioactive ingredients. Tissue cultures are a useful tool for vegetative propagation of virus-free rhubarb plants and rapid multiplication of valuable selected genotypes. The aim of this study was to develop an effective method for in vitro propagation of selected genotypes of Polish rhubarb ‘Malinowy’ characterized by high yield and straight, thick and intensive red stalks. Identification and quantification of anthocyanins and soluble sugars by the HPLC method in shoot cultures and ex vitro established plantlets were also performed. Shoot cultures were established from axillary buds isolated from dormant, eight-year-old rhizomes. Effective shoot multiplication of rhubarb ‘Malinowy’ was obtained in the presence of 6.6 µM benzylaminopurine or 12.4 µM meta-topolin. Both cytokinins stimulated shoot formation in a manner that depended on sucrose concentration. Increasing the sucrose concentration from 59 to 175 mM decreased the production of shoots and outgrowth of leaves by 3-fold but enhanced shoot length, single shoot mass and callus formation at the base of shoots. This coincided with increased accumulation of soluble sugars (fructose, glucose) and anthocyanins-cyanidin-3-O-rutinoside (max. 208.2 mg·100 g⁻¹ DM) and cyanidin-3-O-glucoside (max. 47.7 mg·100 g⁻¹ DM). The highest rooting frequency (94.9%) and further successful ex vitro establishment (100%) were observed for shoots that were earlier rooted in vitro in the presence of 4.9 µM indole-3-butyric acid. Our results indicated that anthocyanin contents in leaf petioles were influenced by developmental stage. Under in vitro conditions, it is possible to elicit those pigments by sucrose at high concentration and meta-topolin.

Ethnobotanical Uses, Phytochemistry and Pharmacology of Different Rheum Species (Polygonaceae): A Review

Today, there is an increased tendency to use herbal remedies. Rhubarb refers to several species of the genus Rheum L. in the Polygonaceae family. This species-rich genus is mainly distributed in Asian countries. Several medicinal effects have been attributed to the Rheum spp. in the traditional and modern medicine such as healing lungs, liver, kidney, womb and bladder diseases, cancer, diabetes, insect bites, relapsing fevers, diarrhea and constipation. Various in vitro, in vivo and clinical studies have investigated the therapeutic effect of extracts, fractions and pure compounds isolated from different species of this genus. Considering the positive findings, several pharmaceutical formulations containing rhubarb extract like capsules, drops, mouthwashes and different topical formulations are now present in the market. However, there are other traditional therapeutic effects of rhubarb that have not been studied yet and it is of great importance to perform confirmatory experiments or clinical investigations. The current review summarizes general information regarding botany, phytochemistry, ethnobotany and pharmacological aspects of Rheum spp. It is hoped that the present review could motivate subsequent research on the other medicinal properties of these plants that have been neglected until today.

Complete chloroplast genome sequence determination of Rheum species and comparative chloroplast genomics for the members of Rumiceae

Complete plastomes of Rheum species facilitated to clarify the phylogeny of Polygonaceae, and comparative chloroplast genomics contributed to develop genetic markers for the authentication of Rheum species. Rheum (Polygonaceae) is widely distributed throughout the temperate and subtropical areas of Asian interior. Rheum species are usually perennial herbs, and half of them are endemic to China with important medicinal properties. On account of similar morphological characteristics, species delimitation of Rheum still remains unclear. Chloroplast genomes of eight Rheum species, Rumex crispus and Oxyria digyna were characterized. Based on the comparison of genome structure of these species and the two published Rheum species, it is shown that plastome sequences of these species are relatively conserved with the same gene order, and three Sect. Palmata species remarkably showed high sequence similarities. Some hotspots could be used to discriminate the Rheum species, and 17 plastid genes were subject to positive selection. The phylogenetic analyses indicated that all the Polygonaceae species were clustered in the same group and showed that Rheum species, except for Rheum wittrockii, formed a monophyletic group with high maximum parsimony/maximum likelihood bootstrap support values and Bayesian posterior probabilities. The molecular dating based on plastomes indicated that the divergences within Polygonaceae species were dated to the Upper Cretaceous period [73.86-77.99 million years ago (Ma)]. The divergence of Sect. Palmata species was estimated to have occurred around 1.60 Ma, indicating that its diversification was affected by the repeated climatic fluctuation in the Quaternary.

In vitro study of the nephrotoxicity of total Dahuang (Radix Et Rhizoma Rhei Palmati) anthraquinones and emodin in monolayer human proximal tubular epithelial cells cultured in a transwell chamber

OBJECTIVE

To examine changes in the morphology and physiological functions of human proximal tubular epithelial cells (HK-2 cells) caused by total Dahuang (Radix Et Rhizoma Rhei Palmati) anthraquinones (TDA) and emodin.

METHODS

HK-2 cells were cultured on polycarbonate (PCF) membranes to form a complete monolayer of cells. A fluorescein isothiocyanate-dextran (FITC) permeability assay was conducted and secretion of γ-glutamyltranspeptidase (GGT), lactate dehydrogenase (LDH), N-acetyl-β-D-glucosaminidase (NAG) and kidney injury molecule 1 (KIM-1) was examined. The reabsorption of glucose and the excretion of para-aminohippuric acid (PAH) by HK-2 cells were also examined. The morphology of HK-2 cells was observed using optical microscopy and scanning electron microscopy. The cytoskeleton of HK-2 cells was observed under a fluorescence microscope.

RESULTS

Compared with the results for the dimethyl sulfoxide group, treatment of cells with TDA and emodin showed statistically significant differences in the FITC leakage rate, the apical / basolateral ratio of LDH and GGT, and the secretion of GGT, LDH, NAG and KIM-1. At 64 μg/mL, TDA markedly inhibited blood glucose reabsorption and remarkably suppressed PAH excretion by HK-2 cells. Both TDA and emodin caused various degrees of damage to the morphology and cytoskeleton of HK-2 cells with the degree of damage correlating positively with the dosage of the tested substances.

CONCLUSION

Both TDA and emodin caused damage to human renal proximal tubular epithelial cells at certain dosages. At the same dosage, TDA caused more severe damage than emodin to the HK-2 cells.

Genetic polymorphism of Japanese cultivated Rheum species in the internal transcribed spacer region of nuclear ribosomal DNA

In order to develop new domestic production of Rhei Rhizoma (RR) from Rheum specimens cultivated in the Sugadaira Medicinal Plant Cultivation Test Field (SMPCF), the ITS sequences of 12 SMPCF specimens and Chinese Rheum specimens of four species, as well as RR samples produced in North Korea, China and Japan, were determined by subcloning and their sequences were compared. As the ITS sequences of 10 SMPCF specimens showed significant intra-individual polymorphism, identification of pseudogenes was conducted by detecting the three motifs of the 5.8S sequence and the stability of the 5.8S secondary structure. Approximately 46% of sequences obtained from the SMPCF specimens were putative pseudogenes. The maximum likelihood tree based on ITS sequences showed three main groups-the outer group and inner clusters I and II; clones from 10 SMPCF specimens including putative pseudogenes belonged to the outer group. Cluster I was composed of two clades, one including clones from R. officinale specimens and R. palmatum-derived samples with matK genotype Rp9, and another including clones from R. coreanum-derived samples. Cluster II consisted of three clades, one including clones from R. palmatum specimens with genotype Rp5, another including clones mainly from R. tanguticum specimens with genotype Rt4, and the third including clones from R. palmatum or R. tanguticum specimens with various matK genotypes. Clones from SMPCF specimen RC5 showed a close relationship with those from R. tanguticum specimens with matK genotype Rt4, whereas those from specimen RC9 related to R. coreanum-derived samples. As a result, specimens RC5 and RC9 were considered as candidates for the development of domestic RR.

Antibacterial and antioxidative properties of different parts of garden rhubarb, blackcurrant, chokeberry and blue honeysuckle

BACKGROUND

It is important to find plant materials that can inhibit the growth of Listeria monocytogenes and other food-spoiling bacteria both in vitro and in situ. The aim of the study was to compare antibacterial and antioxidative activity of selected plant-ethanol infusions: leaves and berries of blackcurrant (Ribes nigrum L.), berries of chokeberry (Aronia melanocarpa (Michx.) Elliott) and blue honeysuckle (Lonicera caerulea L. var. edulis); petioles and dark and light roots of garden rhubarb (Rheum rhaponticum L.) for potential use in food matrices as antibacterial and antioxidative additives.

RESULTS

The strongest bacterial growth inhibition was observed in 96% ethanol infusions of the dark roots of rhubarbs. In 96% ethanol, nine out of ten studied plant infusions had antibacterial effect against L. monocytogenes, but in 20% ethanol only the infusions of dark rhubarb roots had a similar effect. Chokeberry and other berries had the highest antioxidative activity, both in 20% and 96% ethanol infusions.

CONCLUSION

The combination of dark rhubarb roots or petioles and berries of black chokeberry, blackcurrant or some other anthocyanin-rich berries would have potential as both antibacterial and antioxidative additives in food. © 2018 Society of Chemical Industry.

Comparative Chloroplast Genome Analysis of Rhubarb Botanical Origins and the Development of Specific Identification Markers

Rhubarb is an important ingredient in traditional Chinese medicine known as Rhei radix et rhizome. However, this common name refers to three different botanical species with different pharmacological effects. To facilitate the genetic identification of these three species for their more precise application in Chinese medicine we here want to provide chloroplast sequences with specific identification sites that are easy to amplify. We therefore sequenced the complete chloroplast genomes of all three species and then screened those for suitable sequences describing the three species. The length of the three chloroplast genomes ranged from 161,053 bp to 161,541 bp, with a total of 131 encoded genes including 31 tRNA, eight rRNA and 92 protein-coding sequences. The simple repeat sequence analysis indicated the differences existed in these species, phylogenetic analyses showed the chloroplast genome can be used as an ultra-barcode to distinguish the three botanical species of rhubarb, the variation of the non-coding regions is higher than that of the protein coding regions, and the variations in single-copy region are higher than that in inverted repeat. Twenty-one specific primer pairs were designed and eight specific identification sites were experimentally confirmed that can be used as special DNA barcodes for the identification of the three species based on the highly variable regions. This study provides a molecular basis for precise medicinal plant selection, and supplies the groundwork for the next investigation of the closely related Rheum species comparing and correctly identification on these important medicinal species.

Rhubarb-based Chinese herbal formulae for hepatic encephalopathy: a systematic review and Meta-analysis

OBJECTIVE

To evaluate the effectiveness and safety of rhubarb-based Chinese herbal formulae (RCHF), which are widely used to treat hepatic encephalopathy (HE) in China.

METHODS

Nine online databases were searched from inception to November 22, 2016. Eligible studies were randomized controlled trials of Traditional Chinese Medicine (TCM) treatment for adult patients (≥ 18 years old) with HE. Outcomes such as mortality rate, clinical response rate, blood ammonia level, and alanine aminotransferase were evaluated between TCM group and control group.

RESULTS

Thirty studies involving 2661 HE patients were analyzed. Most studies used RCHF treatment. Compared with conventional treatment as usual, lactulose, and vinegar, RCHF were associated with significant improvement in clinical response rate [risk ratio (RR) = 1.33, 95% confidence interval (CI) = 1.25, 1.43, I 2 = 0%; RR = 1.26, 95% CI = 1.14, 1.38, I 2 = 22%; and RR = 1.19, 95% CI = 1.06, 1.33, I 2 = 0%, respectively] and significant reductions in levels of blood ammonia and alanine aminotransferase. Only minor RCHF-associated adverse events, such as abdominal pain (0.3%), anal tenesmus (0.3%), and diarrhea (2.3%), were reported, and there were no significant differences in these events between the treatment group and the three types of control group.

CONCLUSION

The findings suggest that RCHF may be an alternative treatment option for HE patients. More rigorous multicenter studies with larger samples and longer observational periods are needed to confirm these findings.

Randomized clinical trial of the effectiveness of complementary therapies for recurrent aphthous stomatitis

BACKGROUND AND OBJECTIVE

Despite the high prevalence of recurrent aphthous stomatitis (RAS), its etiology is not yet completely clear and there is no completely remedial treatment available at present. The objective of this study was to evaluate the clinical efficacy and safety of 4 treatments (silver nitrate, propolis, rhubarb and walnut) for RAS.

PATIENTS AND METHOD

A randomized clinical trial was conducted with 125 patients with minor aphthae, including 25 patients per group: cauterization with silver nitrate, propolis, rhubarb extract, walnut extract and placebo.

RESULTS AND CONCLUSIONS

No patient reported adverse effects related to the treatment received. There were significant (P<.001) differences in the time elapsed until symptom resolution. The fastest treatment was silver nitrate (1.16 days), followed by the 3 alternative treatments (1.60 days with propolis, 1.84 with rhubarb and 2.00 with walnut; with no differences between them), and finally the placebo (4.64 days). The mean healing time of the lesions was statistically higher (8.96 days) for the placebo than for the 4 treatments: silver nitrate (7.32 days), propolis (6.80), rhubarb (7.72) and walnut (8.00).

Host specificity of two pollinating seed-consuming fly species is not related to soil moisture of host plant in the high Himalayas

Studying the drivers of host specificity can contribute to our understanding of the origin and evolution of obligate pollination mutualisms. The preference–performance hypothesis predicts that host plant choice of female insects is related mainly to the performance of their offspring. Soil moisture is thought to be particularly important for the survival of larvae and pupae that inhabit soil. In the high Himalayas, Rheum nobile and R. alexandrae differ in their distribution in terms of soil moisture; that is, R. nobile typically occurs in scree with well‐drained soils, R. alexandrae in wetlands. The two plant species are pollinated by their respective mutualistic seed‐consuming flies, Bradysia sp1. and Bradysia sp2. We investigated whether soil moisture is important for regulating host specificity by comparing pupation and adult emergence of the two fly species using field and laboratory experiments. Laboratory experiments revealed soil moisture did have significant effects on larval and pupal performances in both fly species, but the two fly species had similar optimal soil moisture requirements for pupation and adult emergence. Moreover, a field reciprocal transfer experiment showed that there was no significant difference in adult emergence for both fly species between their native and non‐native habitats. Nevertheless, Bradysia sp1., associated with R. nobile, was more tolerant to drought stress, while Bradysia sp2., associated with R. alexandrae, was more tolerant to flooding stress. These results indicate that soil moisture is unlikely to play a determining role in regulating host specificity of the two fly species. However, their pupation and adult emergence in response to extremely wet or dry soils are habitat‐specific.

Rhubarb extract partially improves mucosal integrity in chemotherapy-induced intestinal mucositis

AIM

To investigate the effects of orally gavaged aqueous rhubarb extract (RE) on 5-fluorouracil (5-FU)-induced intestinal mucositis in rats.

METHODS

Female Dark Agouti rats (n = 8/group) were gavaged daily (1 mL) with water, high-dose RE (HDR; 200 mg/kg) or low-dose RE (LDR; 20mg/kg) for eight days. Intestinal mucositis was induced (day 5) with 5-FU (150 mg/kg) via intraperitoneal injection. Intestinal tissue samples were collected for myeloperoxidase (MPO) activity and histological examination. Xenopus oocytes expressing aquaporin 4 water channels were prepared to examine the effect of aqueous RE on cell volume, indicating a potential mechanism responsible for modulating net fluid absorption and secretion in the gastrointestinal tract. Statistical significance was assumed at P < 0.05 by one-way ANOVA.

RESULTS

Bodyweight was significantly reduced in rats administered 5-FU compared to healthy controls (P < 0.01). Rats administered 5-FU significantly increased intestinal MPO levels (≥ 307%; P < 0.001), compared to healthy controls. However, LDR attenuated this effect in 5-FU treated rats, significantly decreasing ileal MPO activity (by 45%; P < 0.05), as compared to 5-FU controls. 5-FU significantly reduced intestinal mucosal thickness (by ≥ 29% P < 0.001) as compared to healthy controls. LDR significantly increased ileal mucosal thickness in 5-FU treated rats (19%; P < 0.05) relative to 5-FU controls. In xenopus oocytes expressing AQP4 water channels, RE selectively blocked water influx into the cell, induced by a decrease in external osmotic pressure. As water efflux was unaltered by the presence of extracellular RE, the directional flow of water across the epithelial barrier, in the presence of extracellular RE, indicated that RE may alleviate water loss across the epithelial barrier and promote intestinal health in chemotherapy-induced intestinal mucositis.

CONCLUSION

In summary, low dose RE improves selected parameters of mucosal integrity and reduces ileal inflammation, manifesting from 5-FU-induced intestinal mucositis.

Molecular ion index assisted comprehensive profiling of B-type oligomeric proanthocyanidins in rhubarb by high performance liquid chromatography-tandem mass spectrometry

Proanthocyanidins (PAs) are major anti-diarrhea constituents in rhubarb, one of the frequently used traditional medicines. However, the phytochemical investigation of PAs in rhubarb was hampered by their strenuous purification and identification. In the present study, aiming to clarify the distribution of PAs in different rhubarb species, a molecular ion index was priorly established according to the structural features of B-type PAs, which led to a series of targeted discovery of oligomeric PAs in rhubarb by the HPLC-ESI-MS/MS method. Totally, 66 oligomeric PAs including 27 dimers, 29 trimers, and 10 tetramers were tentatively identified on the basis of their MS/MS spectra from 28 rhubarb samples derived from 5 Rheum species as R. palmatum, R. tanguticum, R. officinale, R. coreanum, and R. laciniatum. It is noteworthy that 6 propelargonidins, 14 prodelphinidins, and 10 procyanidin-tetramers were identified from rhubarb for the first time. The profiling comparison of these oligomeric PAs in different rhubarb samples was achieved by visualizing their abundance in a heat map, which indicated the dominant PAs in rhubarb were procyanidin-dimer and its galloylated derivatives.

The Effect of Chinese rhubarb, Rheum officinale, with and without benazepril on the progression of naturally occurring chronic kidney disease in cats

Background

Renal fibrosis is common in progressive kidney disease. Transforming growth factors β (TGF‐β) are important mediators of all types of fibrosis, including renal fibrosis. Chinese rhubarb has been shown to have antifibrotic properties in part because of inhibition of TGF‐β and has slowed the progression of kidney disease in rodent models.

Hypothesis

That administration of a Chinese rhubarb supplement will slow the progression of chronic kidney disease (CKD) in cats and the concurrent administration of Chinese rhubarb and benazepril will be more effective than either alone.

Animals

Twenty‐nine client‐owned cats with naturally occurring IRIS Stage 2 or early Stage 3 CKD and without comorbidity such as cancer, urinary tract obstruction, urinary tract infection, poorly controlled hyperthyroidism, or systemic hypertension were enrolled in the study.

Methods

A randomized, positive‐controlled, prospective study was performed. Cats received Chinese rhubarb, benazepril, or both in addition to standard treatment for CKD. Repeated measures ANOVA was used to assess changes in serum creatinine concentration, body weight, hematocrit, urine protein: urine creatinine ratio (UPC), and systemic arterial blood pressure over time between and within treatment groups over an average of 22 months.

Results

No significant differences were detected in serum creatinine concentration, body weight, hematocrit, UPC, and systemic arterial pressure over time between or within treatment groups.

Conclusions and Clinical Importance

This study failed to detect a significant difference in the progression of CKD in cats treated with Chinese rhubarb, benazepril, or both. Further study in specific subsets of cats with CKD is warranted.