Thiopyronine and 8-methoxypsoralen sensitized photodynamic effect on DNA synthesis in yeast.

The synthesis of DNA in growing yeast cells was investigated after photodynamic treatment of the cells with thiopyronine (TP) and visible light or with 8-methoxypsoralen (8-MOP) and UVA light. DNA synthesis was inhibited after photodynamic treatment with 8-MOP but not after photodynamic treatment with TP. This result is further evidence that the photodynamic effect with TP does not attack nuclear DNA in eucaryotic cells.