Rhein Chemical Properties

Melting point:

≥300 °C (lit.)

Boiling point:

346.72°C (rough estimate)

Density 

1.3269 (rough estimate)

refractive index 

1.4413 (estimate)

storage temp. 

2-8°C

solubility 

DMSO (Slightly), Methanol (Slightly)

form 

Solid

pka

3.17±0.20(Predicted)

color 

Yellow to Dark Orange

Water Solubility 

<0.1 g/100 mL at 17 ºC

λmax

432nm(MeOH)(lit.)

Merck 

14,8176

BRN 

2222155

Stability:

Hygroscopic

InChIKey

FCDLCPWAQCPTKC-UHFFFAOYSA-N

LogP

4.290 (est)

CAS DataBase Reference

478-43-3(CAS DataBase Reference)

EPA Substance Registry System

2-Anthracenecarboxylic acid, 9,10-dihydro-4,5-dihydroxy-9,10-dioxo- (478-43-3)

Safety Information

Hazard Codes 

Xi

Risk Statements 

36/37/38

Safety Statements 

26-37/39

WGK Germany 

2

RTECS 

CA9516000

HS Code 

29189900

MSDS

• Language:English Provider:1,8-Dihydroxy-3-carboxyanthraquinone
• Language:English Provider:SigmaAldrich
• Language:English Provider:ACROS

Rhein Usage And Synthesis

Physical and Chemical Properties

The chemical name of Rhein is 1,8-dihydroxy anthraquinone-3-carboxylic acid, with the molecular formula C15H8O6 and the molecular weight of 284.21. It becomes yellow acicular crystal after sublimation, with the melting point 321~322 ℃ and decomposition temperature 330 ℃ and UVλmax (methanol) 229, 258, 435nm. It is soluble in alkali and pyridine, and slightly soluble in alcohol, ether, benzene, chloroform, petroleum ether, and insoluble in water. It can form red sylvine and pink sodium salt, and form a red precipitate with calcium hydroxide and barium hydroxide.
Production Method: being acquired from the hydrolysis of Rhein diacetic ester.
diethyl acetate. Uses: Current clinical treatment of rheumatic drugs often contain Rhein.
Rhein is extracted from the root of the plant Rheum palmatum L. in Polygonaceae family, which is a anthraquinones and has the functions of antibacterial, anti-cancer, cathartic, and diuretic. The contents of rhein, aloe-emodin and rheum emodin in rhubarb are listed in the following table:

Table 1. The contents of rhein, aloe-emodin and rheum emodin in rhubarb (n=2%).

Pharmacological effects

There are chemical compounds chrysophanic acid, rhein, aloe-emodin, rheum emodin, aloe emodin, and Sennoside in rhubarb.
Both the rhein and rheum emodin have the anti-tumor effect, especially a strong inhibitory effect for melanoma and they have certain inhibition on breast cancer and ehrlich’s ascites carcinoma. When rhein was applied to intratumoral administration in mice with breast cancer, there was a significant damaging in the cancer tissue. The inhibition rate of 5mg/kg rhein and rheum emodin on murine melanoma was 76% and 73%, respectively. Rheum emodin has significant competitive inhibition on tyrosinase, and this inhibition may be one of the mechanisms why rhubarb has the anti-melanoma effect. At the concentration of 10μg/ml, Rheum emodin significantly inhibited the cell division and DNA biosynthesis of human lung cancer A-549 cells. After the subcutaneous injection of crude extracts of rhubarb, an inhibition of mouse sarcoma S37 was found. The inhibition rate of Rhein on ehrlich’s ascites carcinoma and sarcoma S180 in mice was 15% and 21%, respectively. The inhibition rate of hot water extracts of Rhubarb on sarcoma S180 in mice was 48.8%.
Rhein has inhibition effect on mouse leukemia P388. Rhein, aloe-emodin and rheum emodin are extracted from rhubarb and these three anthraquinone derivatives could minimize the amount of ascites and the number of cancer cells in different extent in mice with tumors, among which the effect of rhein was most obvious and the effect of aloe-emodin was poorer, with a almost parallel relationship with prolonged survival time. The inhibition of rhein and rheum emodin on biosynthesis of DNA, RNA and protein was stronger, whereas the inhibition of aloe-emodin was weaker.

Uses

Medical intermediate;raw materials of health food.

Chemical Properties

Yellowish Brown Solid

Uses

Found in the free state and as glucoside in Rheum spp, Polygonaceae (rhubarb) and in Senna leaves. A potential antioxidant resource: endophytic fungi from medicinal plants.

Uses

Rhein is used to inhibit growth factor beta-1 induced plasminogen activator inhibitor-1 in endothelial cells. It acts as an antibacterial agent against Staphylococcus aureus. It is also used as a laxative. Further, it is employed as a pharmaceutical intermediate.

Uses

Rhein was used to induce necrosis-apoptosis switch in injured pancreatic acinar cells.

Definition

ChEBI: Rhein is a dihydroxyanthraquinone.

General Description

Yellow needles (from methanol) or yellow-brown powder.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

Rhein forms a red potassium salt and a pink sodium salt.

Hazard

Low toxicity by ingestion.

Fire Hazard

Flash point data for Rhein are not available; however, Rhein is probably combustible.

Biochem/physiol Actions

Constituent that is enriched in rhubarb with anti-inflammatory, anti-osteoarthritic, and anti-cancer activity. It reduces IL-1β production and secretion, caspase-3 activity, inducible nitric oxide synthase activity, and phosphorylation of c-Jun and c-Jun NH2-terminal kinase (JNK).

Safety Profile

A poison by intravenous route. Low toxicity by ingestion. When heated to decomposition it emits acrid smoke and irritating vapors.

Synthesis

Bisacodyl ryanin (150 g, 0.41 mol) was used as a starting material, which was dissolved in 10% (w/w) Na2CO3 solution (4 L) and stirred until it was completely dissolved to form a red mixture. The reaction mixture was stirred at room temperature overnight. Subsequently, it was slowly acidified to pH 2 with 5 M HCl solution, at which time a yellow precipitate precipitated. The precipitate was collected by filtration and dried in a vacuum oven at 50 °C to afford the product 4,5-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid (168 g, yield >100%). The structure of the product was confirmed by 1H NMR (400 MHz, DMSO): δ 7.40 (1H, d, J = 8 Hz), 7.71-7.76 (2H, m), 7.82 (1H, t, J = 8 Hz), 8.11 (1H, d, J = 1.6 Hz).

storage

Store at -20°C

References

[1] Bioorganic and Medicinal Chemistry Letters, 1997, vol. 7, # 7, p. 817 - 822
[2] Patent: WO2005/85170, 2005, A1. Location in patent: Page/Page column 9-10
[3] Bioorganic and Medicinal Chemistry Letters, 2012, vol. 22, # 24, p. 7582 - 7587
[4] Journal of the Chemical Society, 1909, vol. 95, p. 1088
[5] Patent: US5480873, 1996, A

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