Cantharidin, a natural toxicant of blister beetles, is a strong inhibitor of protein phosphatases types 1 (PP1) and 2A (PP2A), and is a novel and potent multidrug resistance (MDR) reversal agent. Cantharidin has anti-tumor activity, it causes oxidative stress that provokes DNA damage and p53-dependent apoptosis, it impairs cell migration and invasion by suppressing MMP-2 and -9 through PI3K/NF-κB signaling pathways. Cantharidin is a monoterpenoid with an epoxy-bridged cyclic dicarboxylic anhydride structure secreted by many species of blister beetle, and most notably by the Spanish fly, Lytta vesicatoria. Natural toxin inhibitor of protein phosphatases 1 and 2A. It has a role as a herbicide and an EC 3.1.3.16 (phosphoprotein phosphatase) inhibitor. It is a monoterpenoid and a cyclic dicarboxylic anhydride.

Ingenol mebutate is a tetracyclic diterpenoid ester obtained by formal condensation of the carboxy group of (2Z)-2-methylbut-2-enoic (angelic) acid with the 3-hydroxy group of ingenol. Used for the topical treatment of actinic keratosis. It has a role as an antineoplastic agent. It is a carboxylic ester, a cyclic terpene ketone and a tetracyclic diterpenoid. It is functionally related to an angelic acid and an ingenol. Ingenol derivatives inhibit proliferation and induce apoptosis in breast cancer cell lines, formulating novel derivatives from Ingenol esters may be an innovative approach to develop new lead compounds to reactivate latent HIV. Ingenol mebutate is an effective treatment for actinic keratosis.

Podophyllotoxin is an organic heterotetracyclic compound that has a furonaphthodioxole skeleton bearing a 3,4,5-trimethoxyphenyl substituent. It is found in the roots and rhizomes of Podophyllum species and is used for the topical treatment of genital warts. It has a role as an antineoplastic agent, a keratolytic drug, a tubulin modulator, a microtubule-destabilising agent, an antimitotic and a plant metabolite. It is a lignan, an organic heterotetracyclic compound and a furonaphthodioxole. Podophyllotoxin(Podofilox ) is a potent inhibitor of microtubule assembly and DNA topoisomerase II. Podophyllotoxin has antitumor and antiviral properties, but it also shows cytotoxicity for normal cells and hence side effects derived from its lack of selectivity against tumoral cells.