title: Tea phenols in bulk and nanoparticle form modify DNA damage in human lymphocytes from colon cancer patients and healthy individuals treated in vitro with platinum-based chemotherapeutic drugs.
abstract: BACKGROUND
  Tea catechin epigallocatechin-3-gallate (EGCG) and other polyphenols, such as theaflavins (TFs), are increasingly proving useful as chemopreventives in a number of human cancers. They can also affect normal cells. The polyphenols in tea are known to have antioxidant properties that can quench free radical species, and pro-oxidant activities that appear to be responsible for the induction of apoptosis in tumor cells. The bioavailability of these natural compounds is an important factor that determines their efficacy. Nanoparticle (NP)-mediated delivery techniques of EGCG and TFs have been found to improve their bioavailability to a level that could benefit their effectiveness as chemopreventives.
  
  
  OBJECTIVE
  The present study was conducted to compare the effects of TFs and EGCG, when used in the bulk form and in the polymer (poly[lactic-co-glycolic acid])-based NP form, in oxaliplatin- and satraplatin-treated lymphocytes as surrogate cells from colorectal cancer patients and healthy volunteers.
  
  
  METHODS
  NPs were examined for their size distribution, surface morphology, entrapment efficiency and release profile. Lymphocytes were treated in the Comet assay with oxaliplatin and satraplatin, washed and treated with bulk or NP forms of tea phenols, washed and then treated with hydrogen peroxide to determine single-strand breaks after crosslinking.
  
  
  RESULTS
  The results of DNA damage measurements by the Comet assay revealed opposite trends in bulk and NP forms of TFs, as well as EGCG. Both the compounds in the bulk form produced statistically significant concentration-dependent reductions in DNA damage in oxaliplatin- or satraplatin-treated lymphocytes. In contrast, when used in the NP form both TFs and EGCG, although initially causing a reduction, produced a concentration-dependent statistically significant increase in DNA damage in the lymphocytes.
  
  
  CONCLUSIONS
  These observations support the notion that TFs and EGCG act as both antioxidants and pro-oxidants, depending on the form in which they are administered under the conditions of investigation.
authors.affiliation: Division of Medical Sciences, University of Bradford, Richmond Road, Bradford, West Yorkshire, BD7 1DP, UK.
authors.forename: Amal
authors.initials: A
authors.lastname: Alotaibi
authors.forename: Priyanka
authors.initials: P
authors.lastname: Bhatnagar
authors.forename: Mojgan
authors.initials: M
authors.lastname: Najafzadeh
authors.forename: Kailash C
authors.initials: KC
authors.lastname: Gupta
authors.forename: Diana
authors.initials: D
authors.lastname: Anderson
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000009:adverse effects; D000975:Antioxidants / Q000008:administration & dosage / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D018890:Chemoprevention; D002945:Cisplatin / Q000008:administration & dosage / Q000009:adverse effects; D003110:Colonic Neoplasms / Q000097:blood* / Q000188:drug therapy; D004249:DNA Damage / Q000187:drug effects*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects*; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry*; D010316:Particle Size; D011108:Polymers / Q000008:administration & dosage / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000494:pharmacology; D013662:Tea / Q000737:chemistry
chemical_list: D000970:Antineoplastic Agents; D000975:Antioxidants; D005419:Flavonoids; D011108:Polymers; D017382:Reactive Oxygen Species; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate; D002945:Cisplatin