title: In vitro inhibition of human leukemia THP-1 cells by Origanum syriacum L. and Thymus vulgaris L. extracts.
abstract: BACKGROUND
  Natural products including, traditional medicinal plants have emerged as a tempting alternative to conventional chemotherapeutic protocols of leukemia because of their minimum side effects and less documented drug resistance.
  
  
  METHODS
  Ethanol extracts were prepared from Thymus vulgaris L. and Origanum syriacum L. plants and investigated against the THP-1 leukemia cell line and freshly isolated peripheral blood mononuclear cells (PBMCs). The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay and the lactate dehydrogenase (LDH) assay were respectively used to determine the cellular viability and cytotoxicity in response to treatment with increasing extract concentrations.
  
  
  RESULTS
  Both extracts exhibited a concentration dependent reduction in viability of the THP-1 cells (IC50 = 2.126 mg/mL for O. syriacum, and 0.1569 mg/mL for T. vulgaris). O. syriacum was more potent against the PBMCs (IC50 = 0.4247 mg/mL), while T. vulgaris was moderately selective (IC50 = 0.3345 mg/mL with PBMCs and SI = 2.1). Only in O. syriacum the reduction in cells viability was caused by cytotoxic effect against leukemic cells (LC50 = of 9.646 mg/mL).
  
  
  CONCLUSIONS
  T. vulgaris and O. syriacum are both antileukemic in vitro. T. vulgaris represents a potential selective cytostatic and safe target for future anticancer agents' development. O. syriacum on the other hand is cytotoxic against the leukemia cell line THP-1.
authors.forename: Basim M
authors.initials: BM
authors.lastname: Ayesh
authors.forename: Abdalla A
authors.initials: AA
authors.lastname: Abed
authors.affiliation: European Gaza Hospital Laboratory, Ministry of Health, Gaza, Palestine. d_fariss@yahoo.com.
authors.forename: Doa'a M
authors.initials: DM
authors.lastname: Faris
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000737:chemistry; D006801:Humans; D020128:Inhibitory Concentration 50; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007938:Leukemia / Q000201:enzymology / Q000473:pathology*; D031341:Origanum / Q000737:chemistry; D008517:Phytotherapy; D035261:Plant Components, Aerial; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010946:Plants, Medicinal; D012997:Solvents / Q000737:chemistry; D046930:Thymus Plant / Q000737:chemistry
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D010936:Plant Extracts; D012997:Solvents; D000431:Ethanol; D007770:L-Lactate Dehydrogenase