Inhibition of tumour promotion in mouse skin by extracts of rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia), unique South African herbal teas

Cancer Lett. 2005 Jun 28;224(2):193-202. doi: 10.1016/j.canlet.2004.11.014. Epub 2004 Dec 10.


The modulating effect of ethanol/acetone (E/A) soluble fractions, prepared from methanolic extracts of processed and unprocessed rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia) as well as green (Camellia sinensis) teas was established in a two-stage mouse skin carcinogenesis assay. Topical application of the tea fractions prior to the tumour promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), on ICR mouse skin initiated with 7,12-dimethylbenz[a]anthracene (DMBA) suppressed skin tumorigenesis significantly (P<0.001) with the green tea E/A fraction exhibiting a 100% inhibition, unprocessed honeybush 90%, processed honeybush 84.2%, processed rooibos 75% and unprocessed rooibos 60%. The green tea fraction, with the highest flavanol/proanthocyanidin content, also exhibited the highest protective activity (99%) against hepatic microsomal lipid peroxidation, and completely inhibited skin tumour formation. Differences in the flavanol/proanthocyanidin and flavonol/flavone composition and/or non polyphenolic constituents are likely to be important determinants in the inhibition of tumour promotion by the herbal tea E/A fractions in mouse skin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aspalathus / chemistry*
  • Cell Transformation, Neoplastic / drug effects
  • Chemoprevention
  • Fabaceae / chemistry*
  • Female
  • Mice
  • Mice, Inbred ICR
  • Phorbol Esters / administration & dosage
  • Phorbol Esters / toxicity
  • Plant Extracts / pharmacology*
  • Skin Neoplasms / prevention & control*
  • Skin Neoplasms / veterinary
  • Solubility
  • Tea*


  • Phorbol Esters
  • Plant Extracts
  • Tea