Plant Profiler

Eyebright (Euphrasia officinalis)


Eyebright (Euphrasia officinalis) Image
Synonyms / Common Names / Related Terms
Adhib, ambrosia, augentrost, Augentrostkraut (German), Augstenzieger, briselunettes (French), casse-lunette (French), clary, clary wort, clear eye, eufragia, eufrasia (Italian), Euphraise, Euphraisiaeherba, Euphraisiae herbal (eyebright herb), Euphrasia, Euphrasia mollis, Euphrasia rostkoviana, Euphrasia sibirica, euphrasy, ewfras, frasia, herbed euphraise, herbe d'euphraise officinale, hirnkraut, laegeojentrost (Danish), luminella, meadow eyebright, muscatel sage, red eyebright, sage, salvia sclarea, schabab, Scrophulariaceae, see bright, weisses ruhrkraut, wiesenaugetrost, zwang-kraut.



Mechanism of Action

Pharmacology:

  • Constituents: Eyebright contains iridoid glycosides including aucubin2,3, flavonoids, including quercetin, apigenin, and tannins. The most studied constituent of eyebright is aucubin and its aglycone, aucubigenin. However, a mechanism of therapeutic action is not known at this time.
  • Anti-inflammatory effects: In an animal study of inflammation, an oral dose of aucubin (100mg/kg) demonstrated an anti-inflammatory effect comparable to indomethacin.4 A more recent in vitro study suggested that iriod glycosides might act through inhibition of thromboxane-synthase enzyme.5
  • Anti-microbial effects: Aucubigenin, the aglycone of aucubin has been shown in vitro to possess antibacterial effects against S. aureus, P. mirabilis, and B. subtilis, antifungal activity against C. albicans and P. italicum6,7, as well as anti-hepatitis B virus activity8.
  • Hepatoprotective effects: Aucubigenin, the aglycone of aucubin, inhibited hepatic RNA polymerase and protein synthesis in vivo and in vitro.9,10 In a study conducted on rat livers, aucubin inhibited the cytochrome P450 enzyme system through a glutaraldehyde-like protein cross-linking mechanism.1 Such mechanisms may mediate hepatoprotective properties against liver toxins such as carbon tetrachloride and alpha-amanitin.11

Pharmacodynamics/Kinetics:

  • Bioavailability: Aucubin, a constituent of eyebright, has shown linear pharmacokinetic behavior when administered intravenously to rats at doses of 40-400mg/kg.12 The half-life of aucubin in the post-distributive phase was 42.5 minutes, total body clearance was 7.2mL/min/kg and the volume of distribution was 346.9mL/kg at a given dose of 40mg/kg.12 When 100mg/kg of aucubin was administered orally, intraperitoneally, and hepatoportally to rats, bioavailability was 19.3%, 76.8% and 83.5% respectively, with a low plasma protein binding of 9%.12
  • Metabolism: Both fecal flora and bacterial strains isolated from human feces transformed aucubin, to aucubigenin, aucubinine A and aucubinine B.13 Aucubin is thought to be initially hydrolyzed to aucubigenin and glucose by bacterial β-glucosidase. Aucubigenin may then react with an ammonia model to form a base, which may be further subjected to reduction of the double bond and the hydroymethyl group, oxidation of the hydroxyl group and aromatization of the nitrogen containing ring, to give aucubinines A and B. It is not known whether these compounds are pharmacologically active.

References

  1. Bartholomaeus A and Ahokas J. Inhibtion of P-450 by aucubin: is the biological activity of aucubin due to its glutaraldehyde-like aglycone? Toxicol Lett 1995;80(1-3):75-83.
  2. Salama O and Sticher O. Iridoid glucosides from Euphrasia rostkoviana. Part 4. Glycosides from Euphrasia species. Planta Med 1983;47:90-94.
  3. Ersoz, T., Berkman, M. Z., Tasdemir, D., Ireland, C. M., and Calis, I. An iridoid glucoside from Euphrasia pectinata. J Nat Prod 2000;63(10):1449-1450. 11076577
  4. Recio, M. C., Giner, R. M., Manez, S., and Rios, J. L. Structural considerations on the iridoids as anti-inflammatory agents. Planta Med 1994;60(3):232-234. 8073089
  5. Bermejo, Benito P., Diaz Lanza, A. M., Silvan Sen, A. M., De Santos, Galindez J., Fernandez, Matellano L., Sanz, Gomez A., and Abad Martinez, M. J. Effects of some iridoids from plant origin on arachidonic acid metabolism in cellular systems. Planta Med 2000;66(4):324-328. 10865447
  6. Rombouts JE and Links J. The chemical nature of the antibacterial substance present in Aucuba japonica Thunbg. Experientia 1956;12(2):78-80.
  7. Ulubelen, A., Topcu, G., Eris, C., Sonmez, U., Kartal, M., Kurucu, S., and Bozok-Johansson, C. Terpenoids from Salvia sclarea. Phytochemistry 1994;36(4):971-974. 7765213
  8. Chang, I. M. Liver-protective activities of aucubin derived from traditional oriental medicine. Res Commun Mol Pathol Pharmacol 1998;102(2):189-204. 10100510
  9. Chang, I. M., Ryu, J. C., Park, Y. C., Yun, H. S., and Yang, K. H. Protective activities of aucubin against carbon tetrachloride-induced liver damage in mice. Drug Chem Toxicol  1983;6(5):443-453. 6194953
  10. Lee, D. H., Cho, I. G., Park, M. S., Kim, K. N., Chang, I. M., and Mar, W. Studies on the possible mechanisms of protective activity against alpha- amanitin poisoning by aucubin. Arch Pharm Res 2001;24(1):55-63. 11235813
  11. Chang I and Yamaura Y. Aucubin: a new antidote for poisonous amanita mushrooms. Phytother Res 1993;7:53-56.
  12. Suh, N. J., Shim, C. K., Lee, M. H., Kim, S. K., and Chang, I. M. Pharmacokinetic study of an iridoid glucoside: aucubin. Pharm Res 1991;8(8):1059-1063. 1924160
  13. Hattori M, Kawata Y, Inoue K, and et al. Transformation of aucubin to new pyridine monoterpene alkaloids, aucubinines A and B, by human intestinal bacteria. Phytother Res 1990;4(2):66-70.




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