Inhibition of tumour promotion in mouse skin by extracts of rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia), unique South African herbal teas.
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.
Marnewick
Jeanine
J
PROMEC Unit, Medical Research Council, P.O. Box 19070, Tygerberg 7505, South Africa. jeanine.marnewick@mrc.ac.za
Joubert
Elizabeth
E
Joseph
Shamiel
S
Swanevelder
Sonja
S
Swart
Pieter
P
Gelderblom
Wentzel
W
D000818:Animals; D036903:Aspalathus / Q000737:chemistry*; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D018890:Chemoprevention; D007887:Fabaceae / Q000737:chemistry*; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D010703:Phorbol Esters / Q000008:administration & dosage / Q000633:toxicity; D010936:Plant Extracts / Q000494:pharmacology*; D012878:Skin Neoplasms / Q000517:prevention & control* / Q000662:veterinary; D012995:Solubility; D013662:Tea
D010703:Phorbol Esters; D010936:Plant Extracts; D013662:Tea