title: In vitro cytotoxicity of Gymnema montanum in human leukaemia HL-60 cells; induction of apoptosis by mitochondrial membrane potential collapse.
abstract: OBJECTIVE
  Gymnema montanum Hook, an Indian Ayurvedic medicinal plant, is used traditionally to treat a variety of ailments. Here, we report anti-cancer effects and molecular mechanisms of ethanolic extract of G. montanum (GLEt) on human leukaemia HL-60 cells, compared to peripheral blood mononuclear cells.
  
  
  METHODS
  HL-60 cells were treated with different concentrations of GLEt (10-50 μg/ml) and cytotoxicity was assessed by MTT assay. Levels of lipid peroxidation, antioxidants, mitochondrial membrane potential and caspase-3 were measured. Further, apoptosis was studied using annexin-V staining and the cell cycle was analyzed by flow cytometry.
  
  
  RESULTS
  GLEt had a potent cytotoxic effect on HL-60 cells (IC50 -20 μg/ml), yet was not toxic to normal peripheral blood mononuclear cells. Exposure of HL-60 cells to GLEt led to elevated levels of malonaldehyde formation, but to reduced glutathione, superoxide dismutase, catalase and glutathione peroxidase activities (P < 0.05). Induction of apoptosis was confirmed by observing annexin-V positive cells, associated with loss of mitochondrial membrane potential. Cell cycle arrest at G0/G1 was observed in GLEt-treated HL-60 cells, indicating its potential at inducing their apoptosis.
  
  
  CONCLUSIONS
  Findings of the present study suggest that G. montanum induced apoptosis in the human leukaemic cancer cells, mediated by collapse of mitochondrial membrane potential, generation of reactive oxygen species and depletion of intracellular antioxidant potential.
authors.affiliation: SRM Research Institute, SRM University, Kattankulathur, Tamil Nadu 603 203, India. ramkumar.km@res.srmuniv.ac.in
authors.forename: K M
authors.initials: KM
authors.lastname: Ramkumar
authors.forename: C
authors.initials: C
authors.lastname: Manjula
authors.forename: B
authors.initials: B
authors.lastname: Elango
authors.forename: K
authors.initials: K
authors.lastname: Krishnamurthi
authors.forename: S
authors.initials: S
authors.lastname: Saravana Devi
authors.forename: P
authors.initials: P
authors.lastname: Rajaguru
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D031103:Gymnema; D018922:HL-60 Cells; D006801:Humans; D007938:Leukemia / Q000188:drug therapy; D007963:Leukocytes, Mononuclear / Q000187:drug effects; D015227:Lipid Peroxidation / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017304:Annexin A5; D000972:Antineoplastic Agents, Phytogenic; D000975:Antioxidants; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D053148:Caspase 3