A broad variety of oxygen-substituted diaryl ketones has been synthesized by solar energy-induced Friedel Crafts acylations of 1,4-benzo-and 1,4-naphthoquinones with benzaldehydes. The in vitro antiproliferative properties of the photoproducts were assessed on prostate (DU-145), bladder (T24) and breast (MCF7) human-derived tumor cell lines and compared to non-tumor mouse fibroblasts (Balb/3T3). Among the tested compounds, it was found that those containing a 3,4,5-trimethoxyphenyl A-ring, such as 12 and 22 are more active on DU-145, with EC 50 values of 1.2 and 5.9 μM, respectively. By comparing their effects on the three cancer cell lines, the analogue 22 has the best mean selective index (2.4).