DNA damage induced by hypocrellin-A photosensitization.

Hypocrellin-A (HC-A) isolated from Hypocrellia bambusae Sacc., is a new and effective photosensitizer. Illumination of sarcoma 180 cells with visible light in the presence of HC-A leads to a decrease in cell viability and 3H-TdR incorporation, causes DNA strand breakage, and results in the selective destruction of guanine moieties in DNA. HC-A photosensitization causes an increase in the theta 260/theta 280 ratio in the circular dichroism spectra of DNA in vitro. Of the four usual 2'-deoxynucleotides illuminated in the presence of HC-A only 2'-deoxyguanylic acid was destroyed.