Cytotoxicity of Citrinin Heated at Temperatures above 100°C.

The toxicity of citrinin heated at various temperatures was examined with HeLa cell and judged from the cell proliferation. Citrinin or heated citrinin (0.1, 1.0 or 2.5μg) was added to 3 x 10(3) cells/100μl of medium, and the cell proliferation was monitored for 72 hr. Lethal toxicity was clearly indicated by the addition of 2.5μg of citrinin, while the addition of 0.1 or 1.0μg of citrinin only slightly repressed the cell proliferation. Heating above 160°C was required to detoxify under dry conditions, whereas heating at 100°C reduced toxicity to some extent under aqueous conditions. Consequently, the lower the moisture, the higher was the temperature needed to detoxify citrinin. However, under the aqueous conditions, strong toxicity was observed in the citrinin heated at 140°C, this cytotoxicity becoming weaker by heating at higher or lower temperatures than 140°C and disappearing completely by heating at 170°C.