Fungi from Saudi Arabia, including Penicillium, Fusarium, and Aspergillus species, produced powerful compounds that slowed or killed cancer cells. Some were as potent as standard drugs, like emodin from Penicillium sp. (IC50 ~2 µM, similar to paclitaxel) and Fusarium venenatum extract (IC50 0.38 µg/mL, on par with mitoxantrone).