Seasonal variation in cotyledoside concentration of Tylecodon wallichii (Harv.) Tolken subsp wallichii sampled in a krimpsiekte-prevalent region

Krimpsiekte, an economically important neuromuscular affliction of small st ock, follows upon ingestion of certain members of the Crassulaceae (plakkie s) containing cumulative neurotoxic bufadienolides. Tylecodon wallichii (Ha rv.) Tolken subsp. wallichii is probably the most important species of the group of plants causing krimpsiekte. The growing tip of the stem and variou s other plant parts of T: wallichii, when available, were collected monthly . The seasonal variation in cotyledoside content of the plant was measured. Cotyledoside concentration was determined by high performance liquid chrom atographic-electrospray mass spectrometry analysis (HPLC-ESMS). The cotyled oside concentration in the plant stems fluctuated substantially during the year, but tended to be higher in the cold winter months and increased again in the spring and early summer. Elevated plant stem concentrations corresp onded with natural field outbreaks of krimpsiekte, which usually occur duri ng the winter to early summer. The highest cotyledoside concentrations were detected in the flowering stalk. Cotyledoside was not the only component o f this type in the plant, as mass spectrometry revealed the presence of oth er, possibly related, compounds.