title: Antitumor activity of thevetoside in vitro.
abstract: OBJECTIVE
  To study the effects of thevetoside (TS), a cardiac glycoside, and an inhibitor of Na+, K(+)-ATPase, on tumor cells cultured in vitro.
  
  
  METHODS
  The cytotoxic effects of TS on tumor cells were determined by trypan blue dye exclusion, neutral red vital staining and clonogenic assay. The time-effect relationship and growth inhibition of tumor cells by TS were assayed with trypan blue exclusion method.
  
  
  RESULTS
  TS at low doses (0.005-0.1 mg.L-1), with dose dependence, was able to kill SMMC-7721, SGC-7901 and HeLa cells. IC50 values for SMMC-7721, SGC-7901 and HeLa cells were 0.007, 0.011 and 0.018 mg.L-1 by trypan blue dye exclusion test and 0.016, 0.055 and 0.078 mg.L-1 by neutral red vital staining test. TS inhibited the clonal forming rate of SMMC-7721 and SGC-7901 significantly with IC50 values of 0.021 and 0.036 mg.L-1, respectively. Only when the cells were continuously treated with TS for more than 8 hours, the drug-induced cell lethality could be displayed and strengthened quickly. The growth of tumor cells was notably inhibited after they were exposed to 0.1 microgram/ml of TS for 12 hours. All the experimental results of antitumor activity in vitro showed that SMMC-7721 was most sensitive to TS among the three kinds of tumor cells.
  
  
  CONCLUSIONS
  TS has cytotoxic action on tumor cells cultured in vitro and this lethal effect must have an action process, in which tumor cells are not dead but suffer from deadly injury and lost the capability of unlimited proliferation.
authors.affiliation: Department of Pharmacology, Fujian Medical College, Fuzhou, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: Z
authors.initials: Z
authors.lastname: Huang
authors.forename: C
authors.initials: C
authors.lastname: Li
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D002301:Cardiac Glycosides / Q000302:isolation & purification / Q000494:pharmacology*; D004365:Drugs, Chinese Herbal / Q000737:chemistry*; D006367:HeLa Cells / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013274:Stomach Neoplasms / Q000473:pathology; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D002301:Cardiac Glycosides; D004365:Drugs, Chinese Herbal; C016139:thevetoside; D000254:Sodium-Potassium-Exchanging ATPase