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Khella (Ammi visnaga)


Khella (Ammi visnaga) Image
Synonyms / Common Names / Related Terms
Ammi, Ammi daucoides, Ammi visnaga, Bischofskrautfruchte, bishop's weed, bishop's weed fruit, daucus visagna, false Queen Anne's lace, fruits de khella, germakellin, honeyplant, khellin, picktooth, Spanish toothpick, toothpick plant, visnaga, visnagae, Visnagafruchte, visnagin.





Mechanism of Action

Pharmacology:

  • Constituents: Khella contains khellin (0.3-1.2%), visnagin, khellol, khellenin (also known as khellolglucoside), khellinol, ammiol and visammiol, samidin and dihydrosamidin.
  • Antispasmodic effects: It has been proposed that the antispasmodic activity may be partially due to a calcium antagonist effect. Khellin has a spasmolytic effect on the coronary arteries, bronchi, gastrointestinal tract, gall ducts and the lower urinary tract.1 According to present knowledge, the effects are due to direct action on smooth muscle.
  • Hematologic effects: Khella seems to improve blood supply to the myocardium and makes myocardial metabolism more efficient. It may dilate the coronary vessels, whereby increasing the capacity of the heart without increasing the heart rate or affecting blood pressure. A decrease in lactate, pyruvate and sugar levels in venous blood with a simultaneous increase in free fatty acids after visnadin medication suggests a favorable effect on the heart's energy metabolism.3 It was also shown that the minor constituents khellenin, khellol and ammiol have useful effects on serum lipoprotein and total cholesterol counts and atherosclerotic vessel changes.2
  • Dermatological effects: Khellin, a funochromone with a chemical structure closely resembling psoralen, is reported to treat vitiligo when combined with ultraviolet A irradiation.4 Photobiological activity on yeast is found to be much lower than that of bifunctional psoralens such as 5-methoxypsoralen. In vitro experiments reveal that khellin is a poor photosensitizer. It behaves as a monofunctional agent with respect to DNA photoaddition. It does not photoinduce cross-links in DNA in vitro or in Chinese hamster cells in vivo. This behavior may explain the low photogenotoxicity in yeast and the lack of phototoxic erythemal response when treating vitiligo with khellin.5

Pharmacodynamics/Kinetics:

  • Absorption of khellin after oral intake occurs slowly. Owing to low water solubility, large discrepancies must be expected, depending on how the khellin is administered (by infusion, tincture, fluid extract or tablet). However, precise data on the relationship between absorption quotients and administration methods are not available. When administered repeatedly, khellin seems to accumulate in organs and tissues; it is excreted slowly via the liver and the bile. No precise data are available on the bioavailability and pharmacokinetics of visnadin.3

References

  1. Trease GE, Evans WC. Pharmacognosy 11th ed. ed. London: Baillière Tindall, 1978.
  2. Stevens TJ, Jones BW, Vidmar TJ, et al. Hypocholesterolemic effect of khellin and khelloside in female cynomolgus monkeys. Arzneimittelforschung 1985;35(8):1257-1260. 3865654
  3. Hänsel R, Haas H. Therapie mit Phytopharmaka 1983
  4. de Leeuw J, van der BN, Maierhofer G, et al. A case study to evaluate the treatment of vitiligo with khellin encapsulated in L-phenylalanin stabilized phosphatidylcholine liposomes in combination with ultraviolet light therapy. Eur J Dermatol 2003;13(5):474-477. 14693493
  5. Morliere P, Honigsmann H, Averbeck D, et al. Phototherapeutic, photobiologic, and photosensitizing properties of khellin. J Invest Dermatol 1988;90(5):720-724. 3283251




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