Studies on South African cardiac glycosides. I. Isolation of toxic principles of Homeria glauca (W. & E.) N.E. Br. and observations on their chemical and pharmacological properties.

Abstract

NAUDE, T. W. & POTGIETER, D. ]. ]., 1971. Studies on South African cardiac glycosides. I. Isolation of toxic principles of Homeria glauca (W. & E .) N.E. Br. and observations on their chemical and pharmacological properties. Onderstepoort]. vet. Res. 38 (4), 255-278 (1971). The main toxic principle (1a, 2a-epoxyscillirosidin, a new bufadienolide cardiac aglycone) was iso­ lated by very mild isolation techniques constantly correlated with semi-quantitative toxicity determina­ tions in guinea-pigs. Extraction from plant material was effected at room temperature by suspending it in acetic acid solu­ tion and then extracting with chloroform. The residue was extracted with ethanolic citrate buffer and from this phase the toxic components were re-extracted with chloroform. The fin al separation was done by column chromatography on silica gel. The main toxic component (MTC) constituted 0,044% by mass of the dried plant material. The presence of several other related toxic components was indicated. Certain physical and chemical characteristics of the MTC were determined. The MTC had a subcutaneous LD 50 of 0,194 (0,183 to 0,203) mg/kg for guinea-pigs and 3,6 (2,9 to 4,46) mg/kg for mice. The clinical signs were nervous in nature: in guinea-pigs a generalized curare-like paralysis resulted in death from respiratory failure while in mice a convulsive syndrome was encountered. The MTC had potent local anaesthetic properties.