*3.4. Cytotoxicity Assay*

A resazurin-based colorimetric (alamarBlue) assay was used for evaluating the cytotoxic activity of metabolites **1**–**10** against androgen-sensitive human prostate adenocarcinoma (LNCaP), metastatic human prostate adenocarcinoma (PC-3M), human breast (MCF-7), human non-small cell lung (NCI-H460), and human CNS glioma (SF-268) cancer cell lines and normal human lung fibroblast (WI-38) cells as described previously [32]. Doxorubicin and DMSO were used as positive and negative controls, respectively.
