When Dulbecco's modified Eagle's medium (depleted of phenol red) was irradiated for up to 3 hr by 4-5 W/m2 black light, hydrogen peroxide (H2O2) was produced. Generation of H2O2 resulted from riboflavin-sensitized photooxidation of tryptophan and tyrosine. Reagent H2O2, or hydrogen peroxide generated in black light-exposed aqueous solutions containing riboflavin and tryptophan, induced 2 x 104 single-strand breaks per 1010 daltons of DNA in intact, physiologically viable human D98/AH2 cells. Concomitant with the single-strand breaks in the cells was loss of cellular reproductive viability. Two cases of photoproducts were identified: H2O2 and non-H2O2. The H2O2 component of the photoproducts was responsible for all the single-strand break induction but for only partial loss of reproductive viability. The non-H2O2 photoproducts, accountable for the remainder of cell lethality, caused no single-strand breaks.
All Science Journal Classification (ASJC) codes
- Radiology Nuclear Medicine and imaging