Geigeria poisoning in sheep, locally known as ‘vermeersiekte’, is an economically important
plant poisoning in southern Africa. The toxic principles contained by the toxic plants are
believed to be several sesquiterpene lactones, such as geigerin, vermeeric acid and vermeerin,
which cause striated muscle lesions in small stock. Because of ethical issues surrounding the
use of live animals in toxicity studies, there is currently a dire need to establish an in vitro
model that can be used to replace traditional animal experimentation. The objective of this
study was to determine the cytotoxicity of geigerin in a murine myoblast cell line (C2C12)
using methyl-thiazol-tetrazolium (MTT) and lactate dehydrogenase (LDH) assays, annexin V
and propidium iodide (PI) flow cytometry and transmission electron microscopy (TEM).
Mouse myoblasts were exposed to 2.0 mM, 2.5 mM and 5.0 mM geigerin for 24, 48 and 72 h.
A concentration-dependent cytotoxic response was observed. Apoptosis was detected by
means of annexin V flow cytometry during the first 24 h and apoptotic bodies were also visible
on TEM. According to the LDH and PI flow cytometry results, myoblast cell membranes were
not injured. We concluded that the murine myoblast cell line (C2C12) is a suitable model for
future studies planned to evaluate the cytotoxicity of other and combinations of sesquiterpene
lactones, with and without metabolic activation, implicated in ‘vermeersiekte’ and to elucidate
the subcellular effects of these myotoxins on cultured myoblasts.