Silymarin protects UVB-induced DNA damage and cell death in NER-proficient fibroblasts but not in NER-deficient fibroblasts.

<p><b>(A)</b>, NER-proficient and NER-deficient human fibroblasts were exposed to UVB (150 J/m²) with or without the treatment of silymarin (20 µg/mL) and cells were harvested 36 h later, cytospun, and subjected to cytostaining to detect CPD⁺ cells. CPD-positive cells are dark brown. CPD+ cells were not detectable in non-UVB-exposed cells. Magnification, x400. <b>(B),</b> The analysis of UVB-induced DNA damage in the form of CPDs was performed by dot-blot analysis. Genomic DNA from various treatment groups was subjected to dot-blot analysis using an antibody specific to CPDs. Results are shown from a single experiment and is representative of 3 independent experiments. <b>(C and D)</b>, UVB-induced cell death in NER-proficient and NER-deficient cells was detected by Cell Death Detection ELISA following manufacturer's protocol. Treatment protocol was same as reported in panels A and B. The amount of apoptotic cell death is reflected by increase of absorbance at 405 nm (optical density), as shown on the y-axis. ^*<i>P</i><0.001. ND = not detectable.