Ammi visnaga is a species of flowering plant in the carrot family known by many common names, including bisnaga, toothpickweed, and khella. It is native to Europe, Asia, and North Africa, but it can be found throughout the world as an introduced species. This is an annual or biennial herb growing from a taproot erect to a maximum height near 80 centimeters. Leaves are up to 20 centimeters long and generally oval to triangular in shape but dissected into many small linear to lance-shaped segments. The inflorescence is a compound umbel of white flowers similar to those of other Apiaceae species. The fruit is a compressed oval-shaped body less than 3 millimeters long. This and other Ammi species are sources of khellin, a diuretic extract. Khella was used in Ancient Egypt as a herbal remedy for renal colic.
The chemical visnagin, which is found in Ammi visnaga, has biological activity as a vasodilator and reduces blood pressure by inhibiting calcium influx into the cell. Traditionally A. visnaga tea has been used for kidney stones. Tests on rats have been promising. Ancient Egyptian and Indian writings describe vitiligo treated with psoralen-containing plants such as Ammi majus and exposed to sunlight. There have been a number of European research papers investigating this ancient folk use of the plant. Khellin, a chemical obtained from Ammi visnaga, was used as a smooth muscle relaxant, and the asthma drug cromolyn, which is used to prevent asthma attacks, is a synthetic derivative of it.  More importantly, the antiarrhythmic drug Amiodarone was isolated from khellin derived compounds in 1961 and eventually used to treat not only angina but heart rhythm diseases known as tachyarrhythmias
Fructus Ammi Visnagae WHO Monographs on Selected Medicinal Plants - Volume 3
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- ^ Vanachayangkul P., Chow N., Khan S.R., Butterweck V. "Prevention of renal crystal deposition by an extract of Ammi visnaga L. and its constituents khellin and visnagin in hyperoxaluric rats" Urological Research 2010 (1-7)
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- Khan, Z. A., et al. (2001) Inhibition of oxalate nephrolithiasis with Ammi visnaga (AI-Khillah). International Urology and Nephrology 33:4 605-8.