title: The natural triterpene 3β,6β,16β-trihydroxy-lup-20(29)-ene obtained from the flowers of Combretum leprosum induces apoptosis in MCF-7 breast cancer cells.
abstract: BACKGROUND
  The 3β, 6β, 16β-trihydroxylup-20(29)-ene (TTHL) is a pentacyclic triterpene obtained from the medicinal plant Combretum leprosum Mart. In folk medicine, this plant is popularly known as mofumbo, cipoaba or mufumbo, and is used to treat several diseases associated with inflammation and pain.
  
  
  METHODS
  We investigated the antitumor efficacy of TTHL isolated from C. leprosum. The TTHL cytotoxic effect was investigated in MRC5, MCF-7, HepG2, T24, HCT116, HT29, and CACO-2 cells after 24, 48, 72 and 120 h of treatment. The mechanisms of cell death and DNA damage induction were investigated by flow cytometry and comet assay, respectively.
  
  
  RESULTS
  The results indicated that TTHL induced a time- and concentration-dependent growth inhibition in all human cancer cell lines. The cytotoxicity was more pronounced in MCF-7 breast cancer cells, with an IC50 of 0.30 μg/mL at 120 h. We therefore evaluated the cell death mechanism induced by TTHL (IC20, IC50, and IC80) in MCF-7 cells at 24 h. We found that the treatment with IC50 and IC80 TTHL for 24 h induced apoptosis in 14% (IC50) and 52% (IC80) of MCF-7 cells. The apoptosis induced by TTHL was accompanied by increased levels of both cleaved caspase-9 and intracellular ROS. In order to further understand the biological mechanism of TTHL-induced cytotoxicity, we have also investigated its effect on different Saccharomyces cerevisiae yeast strains. The mutant strains sod1Δ, sod2Δ, and sod1Δsod2Δ, which are deficient in superoxide dismutase antioxidant defenses, were hypersensitive to TTHL, suggesting that its capacity to disturb cellular redox balance plays a role in drug toxicity. Moreover, TTHL induced mutagenicity in the yeast strain XV185-14c.
  
  
  CONCLUSIONS
  Taken together, the results suggest that TTHL forms covalent adducts with cellular macromolecules, potentially disrupting cellular function and triggering apoptosis.
authors.forename: Cassiana Macagnan
authors.initials: CM
authors.lastname: Viau
authors.forename: Dinara Jaqueline
authors.initials: DJ
authors.lastname: Moura
authors.forename: Valdir Alves
authors.initials: VA
authors.lastname: Facundo
authors.affiliation: Department of Basic Health Sciences, Laboratory of Genetic Toxicology - UFCSPA, Porto Alegre, RS, Brazil. jenifers@ufcspa.edu.br.
authors.forename: Jenifer
authors.initials: J
authors.lastname: Saffi
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D029765:Combretum / Q000737:chemistry*; D005260:Female; D035264:Flowers / Q000737:chemistry; D045325:HCT116 Cells; D019073:HT29 Cells; D056945:Hep G2 Cells; D006801:Humans; D061986:MCF-7 Cells; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D014315:Triterpenes / Q000737:chemistry / Q000494:pharmacology*
chemical_list: C510987:3beta,6beta,16beta-trihidroxilup-20(29)-ene; D000970:Antineoplastic Agents; D010936:Plant Extracts; D014315:Triterpenes
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