Abstract
The seeds and stems of Leonurus sibiricus L. or I-Mu-Tsao (meaning “grass to benefit the mother” in Chinese) are widely used in China for post-partum hemorrhages and menstrual disorders. 1 Peckolt-Rio 2 states that the juice of the leaves is good for hemoptysis, and an infusion for hysteria and menstrual troubles. The same author succeeded in isolating a crystalline substance from the leaves which he called leonurin. No chemical or pharmacological study was made with this substance.
Our study is pharmaco-chemical in nature. An intravenous injection in dogs of 2 to 5 cc. of a 10 per cent decoction (i. e., each 10 gm. of material to 100 cc. of water), made from the leaves and stem, resulted in a brief fall of blood pressure, decrease in kidney volume, contraction of uterus, and stimulation of intestinal peristalsis. An attempt was then made to isolate any active principle by percolating the powdered leaves and stems with alcohol, distilling off the latter from the percolate under reduced pressure, and removing the ordinary plant constituents (resins, pigments, etc.) by lead acetate, the excess of which was precipitated with dilute sulphuric acid. When the filtrate is concentrated, a crystalline mass is obtained, which upon purification with alcohol produces the same physiological effects as the decoction. Half of a gram of this substance kills an anesthetized dog of 7.7 kilos by circulatory collapse. Qualitative chemical analyses show that these crystals are mostly potassium sulphate and potassium chloride, and that the parts of the plant under investigation contain no alkaloids. If the lead acetate in the percolate is removed by hydrogen sulphide instead of sulphuric acid, and the filtrate upon concentration is shaken with ether continuously for 15 hours, the ether extract after evaporation gives rise to a residue containing needle-like crystals.
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