Rhein (molecule)

For other uses, see Rhein (disambiguation).
Rhein
Chemical structure of rhein
Names
IUPAC name
4,5-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid
Other names
Rhubarb Yellow
Monorhein
Cassic acid
Rheic acid
Chrysazin-3-carboxylic acid
Identifiers
478-43-3 YesY=
ChEMBL ChEMBL418068 N
ChemSpider 9762 N
Jmol interactive 3D Image
MeSH Rhein
PubChem 10168
Properties
C15H8O6
Molar mass 284.22 g/mol
Appearance Orange crystals[1]
Density 1.687 g/cm3
Melting point 350 to 352 °C (662 to 666 °F; 623 to 625 K)[1]
Boiling point 597.8 °C (1,108.0 °F; 870.9 K) at 760 mmHg
Insoluble in water
Hazards
Main hazards Irritant
Xi
R-phrases R36/R37/R38
S-phrases S26-37/S39
Flash point 329.4 °C (624.9 °F; 602.5 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Rhein, also known as cassic acid, is a substance in the anthraquinone group obtained from rhubarb.[2] Like all such substances, rhein is a cathartic. Rhein is commonly found as a glycoside such as rhein-8-glucoside or glucorhein.[2] Rhein was first isolated in 1895.[3] It is found in rhubarb species like Rheum undulatum[4] and Rheum palmatum[5] as well as in Cassia reticulata.[6]

Originally the rhubarb plant which contains rhein was used as a laxative. It was believed that rhein along with other anthraquinone glycosides imparted this activity.[2]

Rhein has been reevaluated as an antibacterial agent against Staphylococcus aureus in 2008.[7] Synergy or partial synergy has been demonstrated between rhein and the antibiotics oxacillin and ampicillin.[8]

The pharmacokinetics of rhein have not been intensively studied in humans, but at least one study in healthy male volunteers found that rhein was better absorbed from oral administration of rhubarb than from a retention enema.[9] Rhein (at an oral dose of 50 mg twice per day) was shown to be safe when administered for five days to elderly patients with chronic congestive heart failure.[10]

See also

References

  1. 1 2 Cassic acid on www.naturestandard.com
  2. 1 2 3 Pharmacognosy of Rhubarb | Chemical Constituents
  3. ↑ Hesse O (1895). Pharm J 1: 325. Missing or empty |title= (help)
  4. ↑ Lee JH, Kim JM, Kim CS (2003). "Pharmacokinetic analysis of rhein in Rheum undulatum L.". J Ethnopharmacol 84 (1): 5–9. doi:10.1016/S0378-8741(02)00222-2. PMID 12499069.
  5. ↑ Hoerhammer L, Wagner H, Koehler I (1959). "New investigations on the components of Rheum palmatum L. Part 1: On the analysis of rhein". Arch Pharm 292 (64): 591–601. PMID 14402302.
  6. ↑ Anchel M (1949). "Identification of the antibiotic substance from Cassia reticulata as 4,5-Dihydroxyanthraquinone-2-carboxylic acid" (PDF). J Biol Chem 177 (1): 169–177. PMID 18123056.
  7. ↑ Yu L, Xiang H, Fan J, et al. (2008). "Global transcriptional response of Staphylococcus aureus to rhein, a natural plant product". J Biotechnol 135 (3): 304–308. doi:10.1016/j.jbiotec.2008.04.010. PMID 18514345.
  8. ↑ Joung DK, Joung H, Yang DW, et al. (2012). "Synergistic effect of rhein in combination with ampicillin or oxacillin against methicillin-resistant Staphylococcus aureus". Exp Ther Med 3 (4): 608–612. doi:10.3892/etm.2012.459. PMC 3438619. PMID 22969937.
  9. ↑ Zhu W, Wang XM, Zhang L, Li XY, Wang BX. (2005). "Pharmacokinetic of rhein in healthy male volunteers following oral and retention enema administration of rhubarb extract: a single dose study". Am J Chin Med 33 (6): 839–850. doi:10.1142/S0192415X05003508. PMID 16355440.
  10. ↑ La Villa G, Marra F, Laffi G, et al. (1989). "Effects of rhein on renal arachidonic acid metabolism and renal function in patients with congestive heart failure". Eur J Clin Pharmacol 37 (1): 1–5. doi:10.1007/bf00609415. PMID 2512175.


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