Interestingly, some earlier studies revealed that ω-hydroxyemodin showed moderate activity against MRSA SK1 and mild activity against S. aureus ATCC 25923 with MIC values of 32 and 200 μg/mL, respectively , in addition to good anti-mycobacterial activity against M. tuberculosis H37Ra with MIC value of 12.5 μg/mL . It also showed potent cytotoxicity against the human oral epidermoid carcinoma KB cells with an IC50 value of 4.5 μg/mL, and weak cytotoxic activity against both human breast cancer cells, MCF7 and human lung carcinoma cells, NCI-H187 with IC50 values of 22 and 39 μg/mL, respectively . In contrast, penicillanthranin A (81) showed selective cytotoxicity to the KB cell lines with an IC50 value of 30 μg/mL .