Tylecodon

Abstract: lNTRODUCfiON The plant families Iridaceae, Liliaceae, Melianthaceae and Crassulaceae contain many plants with bufadieno­ lides (cardiac glycosides) as their active toxic principles. Members of the genera Cotyledon, Tylecodon and Kalanchoe (Crassulaceae), however, also cause krimp­ siekte, a neurological syndrome differing from typical cardiac glycoside intoxication, which is brought about by repeated ingestion of small quantities of the plants (Naude, 1977; Vahrmeijer, 1981). Affected animals lag behind the flock . When forced to move, they tire quickly and either lie down or stand with muscles trembling. The neck may be held in a peculiar twisted way (torticollis) and the head often dangles loosely as the animal walks. Animal that recover can suffer from torticollis for months (Henning, 1926). Steyn ( 1949) concluded that Kalanchoe paniculata Harv., K. rotundifolia Harv. and K. thyrsiflora Harv., contain a toxin that causes krimpsiekte. Subsequently, K. lanceolata Forsk. was also suspected of being poison­ ous, but this suspicion was never confirmed. A bufadie­ nolide ( coty ledoside) from Tylecodon wallichii (Harv.) Toelken, subsp. wallichii (=Cotyledon wallichii Harv., Toelken, 1978) was isolated by Van Rooyen & Pieterse (1968) and characterized by Van Wyk (1975). Krimp­ siekte was manifested in sheep given intravenously repeated small doses of cotyledoside, while typical car­ diac glycoside poisoning symptoms occurred after a single high dose (Naude & Schultz, 1982). To date, however, bufadienolides have never been isolated from members of the Kalanchoe genus. MATERIALS AND METHODS Plant material Kalanchoe lanceolata Forsk. (Vahrmeijer, 1981) plants for extraction and dosing were collected during spring to autumn in the W aterberg district. Sometimes dead or senescent plants that had overwintered in the veld were given to sheep, while in other instances freshly picked plants, dried in the shade before being milled, were dosed (Table 2). Isolation of the toxic principles The fresh plants (120 kg) were minced and extracted 3 times in a Waring blender with ethyl acetate and the solvent evaporated under reduced pressure. The resultant syrup was partitioned between 95% methanol (3,5 f) and petroleum ether. Both extracts were evaporated to dry­ ness and the residues tested for toxicity. Only the residue obtained from the methanol extract (88 g) was toxic.