Rheum emodi (Gol chotial): Introduction, Scientific Classification, Origin, Discovery, Description, Phytochemistry and Uses
Rheum emodi (Rhubarb) is a perineal stout herb belonging to the family polygonaceae and has been cultivated for over 5000 years for its medicinal properties. It is distributed in the temperate and subtropical regions of the world, especially in Asia and can be cultivated at an altitude above 1800m. The herb is reported to possess antioxidant, antimicrobial, antifungal, anticancer, wound healing and immune enhancing activity and is commonly used worldwide herb and often known as “the wondrous drug” because of its extensive medicinal uses. Rhubarb contains a variety of compounds like flavonoids, anthraquinone glycosides, tannins, volatile oils and saponins and has long been used as an ingredient of purgative, laxative and stomachic. Paradoxically, although larger doses were used as a laxative, small doses were used to treat dysentery and diarrhoea. Rhubarb has also been used in jams, jelly and sauces of its tart flavour. There are three main types of rhubarbs, viz. the Chinese Rhubarb, the Indian Rhubarb, and the Rhapontic Rhubarb. Chinese Rhubarb comprises of dried rhizomes of Rheum palmatum L., and Rheum officinaleBaill. Rheum emodi, commonly known as Indian or Himalayan Rhubarb, is official in Indian Pharmacopeia
Species: Rheum emodi
Occurrence and Distribution
It is native to central Asia and widely distributed in China, Nepal, Bhutan and India. The plant is endemic to the western and central Himalayan regions. In China, R. emodi is mainly distributed to the west of the line from the Daxinganling Mountains, Taihang Mountains, Qinling Mountains, and Dabashan Mountains to Yunnan-Guizhou Plateau. In India, it is distributed in the temperate and subtropical region from Kashmir to Sikkim at an altitude of 2800-3000 m. It grows well in exposed or partially shaded habitats, rocky, well-drained, porous and humus-rich soil of alpine and sub-alpine areas of the Himalayas.
The discovery of Rheum emodi’s medicinal properties can be traced back to ancient civilizations in the Himalayan region, where traditional healers and practitioners used various parts of the plant to treat a wide range of ailments. Over the centuries, its reputation as a potent medicinal herb spread to neighbouring regions, and in more recent times, it has garnered the attention of the scientific community, leading to extensive research on its chemical composition and therapeutic potential.
1. Rheum emodi Wall. ex Meissn. belonging to the family Polygonaceae is a 3.0 m tall leafy perennial herb. Rewand chini is a perennial stout herb, 1.5–3.0 m tall.
2. Roots are very stout and thick. Roots and rhizomes are the main parts used as drugs and are collected from October to November. The root of Indian Rhubarb is darker, inferior in aroma, coarser and untrimmed, and is not decorticated. The fresh rhizome is 6 to 12 inches long, and the freshly fractured surface is dull orange to yellowish brown
3. Stem is very hard and greenish with brown streaks. Inflorescence is 0.6 – 0.9 m long panicle, pubescent, upright branched and leafy with erect stern branches.
4. Leaves are radical, orbicular, or broadly ovate, very large, and 30–45 cm in diameter with long petioles.
5. Flowers are small, dark purple or pale red in axillary panicles.
6. The plant has three to five years of juvenile phase, followed by the reproductive phase.
7. Flowers are minute with a 3 mm diameter, pale to reddish. Flowering occurs in June–July.
8. Fruits are 1-2 cm long, ovoid – oblong, winged, purple with cordiform base and erose apex.
9. Seeds are also winged. Roots are very thick, strong, dark brown with long rough texture. Rhizomes (16 – 12 inches long) are dull orange to yellowish brown.
10. Seeds are collected in late August–September when they turn dark brown. Seed production potential varies from 300 seeds to 950 seeds per plant.
Rheum emodi possess several phytoconstituents and these are: anthraquinones, anthrones, stilbenes, oxanthrone ethers and esters, flavonoids, lignans, phenols, carbohydrate and oxalic acid. The most common constituents of Rheum emodi are anthraquinone and stilbene. Anthraquinones include rhein, chrysophanol, aloe-emodin, emodin, physcion (emodinmonomethyl ether), chrysophanein and emodin glycoside. Stilbene includes picetannol, resveratrol and their glycosides . Different derivatives of oxanthrone include oxanthrone ether (revandchinone-4), oxanthrone esters (revandchinone-1 and revandchinone-2), and revandchinone-3 . Other complex compounds have also been reported, including torachrysone 8-O-b-D-glucoside, sulfated anthraquinone glycoside sulfemodin 8-O-b-Dglucoside b-asarone and rhein 11-O-b-D-glucoside . Tannins are also present in rhubarb which includes hydrolysable tannins, containing ester or glycosidic bonds composed of gallic acid, glucose and other monosaccharides and condensed tannins, derived primarily from the flavone derivatives catechin and leucocyanidin
Rheum emodi has a long history of use in traditional medicine systems, particularly in Ayurveda and Tibetan medicine. Its rhizomes are primarily utilized for their laxative, anti-inflammatory, and antipyretic properties. The plant is employed to alleviate constipation, promote digestion, and relieve inflammatory conditions. Additionally, Rheum emodi is considered useful in managing fever, supporting liver health, and treating certain skin disorders.
Beyond its traditional applications, modern research has also uncovered potential uses for Rheum emodi in the pharmaceutical industry. Its bioactive compounds are being investigated for their anti-cancer, antioxidant, and antimicrobial properties, opening up new avenues for drug development and therapeutic interventions.
Rheum emodi (Gol chotial) stands as a remarkable plant with a rich heritage in traditional medicine. Its scientific classification, origin, and description provide a foundation for understanding its significance, while the exploration of its phytochemistry and diverse uses offer a glimpse into the potential benefits it holds for human health. As research continues, the value of this Himalayan herb in both traditional and modern medicine is likely to be further appreciated, reaffirming its status as a valuable natural resource
Recent studies have shown that Rheum emodi possess anticancer, antioxidant, antidiabetic, antifungal, and antiulcer along with hepatoprotective and nephroprotective properties and these actions are due to several compounds isolated from it.
Rajkumar et al tested the methanolic and aqueous extracts of the Rheum emodi rhizome in human breast carcinoma (MDAMB- 435S) and liver carcinoma (Hep3B) cell lines for cytotoxicity. They found that the extracts exhibited extensive concentration-dependent cytotoxicity in tested cells
Ethanolic extract of Rheum emodi showed an antidyslipidemic effect in a study conducted by Mishra et al. Chrysophanol, emodin, chrysophanol 8-O-β-D-glucopyranoside and emodin 8-O-β-D glucopyranoside were active constituents and has significant effect in triton-induced rats by reducing plasma lipids levels. Emodin showed significant lipid-lowering activity in the high-fed diet model.
Rhein, physcion, aloe-emodin and chrysophanol isolated from Rheum emodi rhizomes exhibited antifungal activity against Candida albicans, Cryptococcus neoformans, Trichophytonmentagrophytes and Aspergillusfumigatus (MIC 25- 250µg/ml) responsible for skin diseases in India. In a different experiment, three compounds isolated from the Rheum emodi rhizome (revandchinone-1, 3 and 4) exhibited antifungal activity against Aspergillusniger and Rhizopus oryzae, with inhibition zone diameters of 8-9 and 9-11 mm for the 100 and 150 g/ml test concentrations, respectively.
Chauhan et al. studied the anti-inflammatory activity of the methanol extract of the rhizome (500 mg/kg). The anti-inflammatory activity was evaluated by using carrageenan-induced paw oedema. It was found that the degree of inhibition of oedema increased with time, reaching maximum inhibition after 5 h. This inhibitory activity was comparable to the control drug Ibuprofen (50 mg/kg body weight).
The antimicrobial activity compound of Rheum emodi was investigated by Babu et al. Compounds were tested against gram-positive (Bacillus subtilis, Bacillus sphaericus and Staphylococcus aureus) and gram-negative (Klebsiellaaerogenes, Chromobacteriumviolaceum and Pseudomonas aeruginosa) bacteria. Revandchinone-1 and 3 had lower degrees of antibacterial activity (inhibition zone diameters of 7–9 mm for the 30 and 100 g/ml test concentrations) than didrevandchinone-4 (inhibition zone diameter of 12–14 mm at both the 30 and 100 g/ml test concentrations).
The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging activities, inhibitory effects on lipid per oxidation (LPI) and Fe3+ reducing antioxidant properties of methanolic/aqueous extracts of the Rheum emodi rhizome were studied. Furthermore, the extracts proved to contain a high number of phenolic compounds, which were found to have a strongly significant positive correlation with free radicals (DPPH and OH) scavenging efficacies, percentages of LPI and Fe3+ reductions.
Antiplatelet and Anticoagulant Activities
Seo EJ et al. investigated the effects of anthraquinone derivatives isolated from rhubarb on platelet activity. Of the four anthraquinone derivatives isolated from rhubarb examined, chrysophanol-8-O-glucoside (CP- 8-O-glc) was found to have the most potent inhibitory effect on collagen- and thrombin-induced platelet aggregation. CP-8-O-glc–treated mice showed significantly prolonged bleeding times. Furthermore, CP-8-Oglc was found to have a significant inhibitory effect on rat platelet aggregation ex vivo and on thromboxane A2 formation in vitro.
The anti-ulcer effect of ethanolic extract of rhizome of Rheum emodi was investigated on pyloric ligation-induced ulcers in rats by Amandeep et al. It was found that there is a reduction in ulcer index along with a reduction in volume and total acidity and an increase in the pH of gastric fluid. He put protective Activity The hepato-protective activity of the ethanolic extracts of Rheum emodi rhizome against CCl4-induced liver damage in Wister rats has been evaluated by Ibrahim et al. Carbon tetrachloride administration caused a significant increase in the serum activities of AST, ALT and ALP and a similar increase in the total bilirubin. Oral administration of Rheum emodi at 3.0 g/kg significantly decreased the above-elevated parameters, and the normal structure of the liver pattern was restored. Another similar study by Akhtar et al. has confirmed the hepato-protective effect of an aqueous extract of Rheum emodi against liver damage induced by paracetamol in albino rats.
Konsar F et al. studied the immune-enhancing activity from ethyl acetate rhizome extract of Rheum emodi on the cell lines and it was found to have an immune-enhancing effect through the release of various cytokines. There is a dose-dependent increase in the release of NO (Nitric Oxide) and cytokines TNF-α, IL-12, and a decrease in IL-10 by RAW 264.7 in macrophages cell line in the presence of extract alone.
The renal effects of water-soluble (W-S) and water-insoluble (W-INS) portions of the alcoholic extract of Rheum emodi were investigated on cadmium chloride, mercuric chloride, potassium dichromate and gentamicin-induced nephrotoxicity in rats and normal rats by monitoring the levels of urea nitrogen and creatinine in serum. W-S fraction has a nephroprotective effect on all the proximal tubule segments (S1, S2 and S3) possibly through the antioxidant action of the tannins present in the fraction