Fern spore extracts can damage DNA

The carcinogenicity of the vegetative tissues of bracken fern (Pteridium) h as long been established. More recently, the carcinogenic effects of the sp ores of bracken have also been recognized, Both vegetative tissues and spor es of bracken can induce adducts in DNA in animal tissues, but the possible genotoxic or carcinogenic effects of spores from fern species other than b racken are unknown. The single-cell gel electrophoresis ('comet') assay was used to investigate whether fern spores can cause DNA damage in vitro. Ext racts of spores from six fern species were administered to cultured human p remyeloid leukaemia (K562) cells. Spore extracts of five fern species: Anem ia phyllitidis, Dicksonia antarctica, Pteridium aquilinum, Pieris vittata a nd Sadleria pallida, induced significantly more DNA strand breaks than thos e in the control groups. Only in one species, Osmunda regalis, was the effe ct no different from that in the control groups. Using extracts from A, phy llitidis and P. vittata, the extent of DNA damage was increased by increasi ng the original dose 10 times, whereas an experiment in which exposure time s were varied suggested that the highest levels of strand breaks appear aft er 2 h exposure. Simultaneous incubation with human S9 liver enzyme mix abl ated the damaging effect of the extracts. Our data show that fern spore ext racts can cause DNA damage in human cells in vitro. Considering the strong correlation between DNA damage and carcinogenic events, the observations ma de in this report may well have some implications for human health. (C) 200 0 Cancer Research Campaign.