Rat Poison From White Squill

Abstract

It is generally known that white squill contains little, if any, rat poison (for literature, see Gold, Modell, Catell, Benton, and Cotlove, 1947). However, as early as 1938, Dr. J. 0. Pinkston, former chairman of this department, discovered that, whereas white squill bulbs collected from the coastal areas were inactive, those from the Lebanon mountains showed such activity that he used white squill powder to exterminate wild rats in and around the campus of the University. We have later obtained white squill from another part of the Lebanon mountains which occasionally showed as much activity as red squill. In general, however, the bulbs we have used yielded a dry squill powder that was lethal to male rats in an oral dose of 1.5-2 g./kg. body weight.Attempts to isolate the active principle from white squill were begun in 1942. In 1944 a small quantity of crystalline material was obtained with an oral MLD in male rats of about 1.5 mg./kg. Owing to the war, the isolation of scilliroside from red squill by Stoll and Renz (1942) became known to us only in 1945. Although the two methods of preparation had nothing in common, the products appeared to be identical, judged by the results of elementary analysis, crystal form, solubility, and the Liebermann colour reaction.In 1950 the Sandoz firm in Basle kindly supplied us with a sample of crystalline scilliroside, and a new batch of white squill was used to prepare material for comparison. It was soon found that the 1944 success had been dependent on the use of a brand of Merck (Darmstadt) charcoal which had stood in the laboratory for many years. The active substance was quantitatively adsorbed by the old charcoal and was eluted in a relatively pure form by treatment with 50% isopropyl alcohol. The available specimens of charcoal-Darco G 60, Mallinckrodt, and a new specimen from Merck-adsorbed the substance so tenaciously that it could not be eluted by 50 % isopropyl alcohol, and the procedure had therefore to be modified from that step onwards. An amorphous colourless product, 30-35 % as toxic to rats as Stoll's scilliroside, was obtained, and proved to be a mixture of scilliroside and a closely related product. This paper describes the properties of both compounds. MATERIALS AND METHODSPreparation of Rat Poison From White Squill.-The squill bulbs were collected during the months of June and July from a spot in Southern Lebanon ca. 1,800 ft. above sea level and about 15 miles from the Mediterranean coast. Activity was not lost if the bulbs were stored for a few months in a cool and shady place. Six kg. of intact scales was treated with 18 1. of a solution made by diluting 11.4 1. of 95% alcohol with 6.6 1. of water and kept standing at room temperature for a week. This solution contained maximum activity and a minimum of residue. The filtered solution was treated with lead subacetate until no more turbidity was produced on further addition. It was allowed to stand for not more than five hours, when the upper clear layer was siphoned off and the residue centrifuged. The...