Ac. Beekman et al., CYTOTOXICITY OF ARTEMISININ, A DIMER OF DIHYDROARTEMISININ, ARTEMISITENE AND EUPATORIOPICRIN AS EVALUATED BY THE MTT AND CLONOGENIC-ASSAY, PTR. Phytotherapy research, 10(2), 1996, pp. 140-144
Artemisinin and its derivatives possess an endoperoxide bridge, which
is thought to lead to the production of free-radical species, The cyto
toxicity of some of these agents to a murine Ehrlich ascites (EN19) an
d a human HeLa S3 cancer cell line was determined using the MTT and th
e clonogenic assay, The MTT assay cannot distinguish between growth in
hibition and cell killing, while the clonogenic assay detects actual c
ell death. The use of both assays to test a certain drug may give info
rmation on the mode of its cytotoxicity (i.e. growth inhibition versus
cell killing). The endoperoxides artemisinin and the dimer of dihydro
artemisinin showed much higher cytotoxicity in the MTT assay compared
with the clonogenic assay, Thus these drugs mainly induced growth inhi
bition, For artemisitene and eupatoriopicrin, which possess an exocycl
ic methylene with alkylating properties, both tests yielded comparable
results. For these compounds the MTT assay merely determined cell kil
ling, For the reference drugs cisplatin and doxorubicin the MTT assay
showed lower cytotoxicity than the clonogenic assay, This may be expla
ined by the metabolic activity of cells that were clonogenically dead,
Moreover, our experiments have shown that the MTT assay may lead to m
isinterpretations concerning the mode of action of certain drugs, when
it is used as a substitute for the clonogenic assay.