Chemical studies upon the vermeerbos, Geigeria aspera, Harv. II. Isolation of the active principle "vermeeric acid"

Abstract

1. The toxic principle of the Vermeerbos, Geigeria aspera, has been isolated. It is a dibasic acid C₁₈H₂₈O₇ and has been named “Vermeeric acid”. On standing in the air, Vermeeric acid gradually loses two molecules of water forming the crystalline dilactone "Vermeerin" C₁₈H₂₁O₅. 2. Vermeerin has M.P. 143° but Vermeeric acid is optically inactive. 3. Both substances, like Geigerin, give a colour reaction with hydrochloric acid but the colour is browner, and in the case of Vermeerin it is of very slight intensity. An absorption band at 546.5 mμ could be distinguished and two other bands were faintly discernible. 4. Vermeeric acid forms a 2:4 dinitrophenylhydrazone soluble in sodium carbonate and reprecipitated by acids. This derivative appears to contain H₂O less than that expected upon the assumption of a simple reaction and it is thought probable that closure of one lactone ring simultaneously occurs. Vermeerin when treated with hot Brady's reagent reacts to such a very slight extent that the absence of any ketonic or keto-enolic function is inferred in the undecomposed substance. 5. Vermeeric acid decolorises potassium permanganate in the cold. By oxidation with this reagent in alkaline solution at the boiling temperature there was obtained an acid crystallising in small prismatic needles M.P. 229-30° and a substance which when treated with cold dilute acid immediately liberated acetaldehyde, the 2:4 dinitrophenylhydrazone of which was prepared for identification. 6. Accompanying Vermeeric acid in the plant were found two flavone-like substances, the one with M.P. 269-71° being, in all probability C₁₇H₁₂O₆(CH₃O)₂, the other, M.P. 243-4°, having the formula C₁₉H₁₈O₇ (methoxyl not determined). 7. Vermeeric acid drenched to sheep in doses of 10 to 15 gm. causes death from acute vermeersiekte within 6 to 48 hours.