Leptomycin B (LMB) an antibiotic originally isolated from Streptomyces, is a specific inhibitor of CRM1 (exportin 1), an evolutionarily conserved receptor for the nuclear export signal of proteins. It binds covalently to cysteine 528 in the nuclear export signal binding region of CRM1 leading to the inhibition of protein nuclear export. It was shown, that LMB possessed the ability to augment the effect of the tumor suppressor p53 in esophageal squamous cancer cell lines and thus LMB could be a promising component in p53 gene therapy. Recently was conducted experiments, which revealed, that LMB at a very low concentration (0.5 nM) combined with gefitinib have shown synergistic therapeutic effects and have ameliorated the development of gefitinib-induced resistance in lung cancer cells.

Hypocrellin B (HB), a natural perylenequinone pigment, has been successfully employed in the photodynamic therapy (PDT) in a variety of human cancer cells due to its high singlet oxygen yield. Hypocrellin B exhibits antibacterial, anti-metastatic, and anticancer chemotherapeutic activities. Hypocrellin B inhibits proliferation of Staphylococcus by increasing ROS levels and damaging cell walls. In ovarian cancer cells, this compound induces apoptosis and inhibits cell migration and adhesion under photodynamic stimulation; it also induces tumor regression in animal models of lymphoma. In vitro, hypocrellin B induces DNA strand breakage.