Antimutagenic activity of aqueous extracts of the South African
herbal teas, Aspalathus linearis (rooibos) and
Cyclopia spp. (honeybush) was compared with that of Camellia sinensis (black, oolong and
green) teas in the Salmonella mutagenicity assay using
aflatoxin B(1) (AFB(1)) and
2-acetylaminofluorene (2-AAF) as
mutagens. The present study presents the first investigation on antimutagenic properties of C. subternata, C. genistoides and C. sessiliflora. The
herbal teas demonstrated protection against both
mutagens in the presence of metabolic activation, with the exception of "unfermented" (green/unoxidised) C. genistoides against
2-AAF, which either protected or enhanced mutagenesis depending on the concentration. Antimutagenic activity of "fermented" (oxidised) rooibos was significantly (P<0.05) less than that of Camellia sinensis teas against AFB(1), while for
2-AAF it was less (P<0.05) than that of
black tea and similar (P>0.05) to that of oolong and
green teas. Antimutagenic activity of unfermented C. intermedia and C. subternata exhibited a similar protection as fermented rooibos against AFB(1). Against
2-AAF, fermented rooibos exhibited similar protective properties than unfermented C. intermedia and C. sessiliflora. Unfermented rooibos was less effective than the C. sinensis teas and fermented rooibos, but had similar (P>0.05) antimutagenicity to that of fermented C. sessiliflora against AFB(1) and fermented C. subternata against
2-AAF. Fermented C. intermedia and C. genistoides exhibited the lowest protective effect against
2-AAF, while fermented C. intermedia exhibited the lowest protection when utilising AFB(1) as
mutagen.
Aspalathin and
mangiferin, major
polyphenols in rooibos and
Cyclopia spp., respectively, exhibited weak to moderate protective effects when compared to the major
green tea catechin, (-)
epigallocatechin gallate (EGCG). Antimutagenic activity of selected
herbal tea phenolic compounds indicated that they contribute towards (i) observed antimutagenic activity of the aqueous extracts against both
mutagens and (ii) enhancement of the mutagenicity of
2-AAF by unfermented C. genistoides. Antimutagenic activity of the South African
herbal teas was
mutagen-specific, affected by fermentation and plant material, presumably due to changes and variation in phenolic composition.