Photodynamic therapy (PDT) has shown promise as an effective treatment modality for cancers and other localized diseases, such as age-related macular degeneration and actinic keratosis. PDT relies on light, photosensitizer and oxygen as elements in its mechanism of action. BODIPY photosensitizers that have been under extensive study over the past decade have been demonstrated as a new class of photosensitizers. In this review, we attempt to summarize the decade-long study of BODIPY-based photosensitizers. We provide an overview of the superior photophysical properties possessed by BODIPY-based agents and the various synthetic strategies employed that have led to improved and selective and/or targeted photosensitizers.

Podophyllotoxin is an antimitotic natural product. Its inhibitory activity on cell growth led to the development of the clinically valuable anticancer agents, etoposide, teniposide and the water-soluble prodrug, etoposide phosphate. The cytotoxic mechanism of these drugs is the inhibition of topoisomerase II, unlike the lead compound which inhibits mitosis. Through extensive structure-activity relationship studies, several potential drug candidates were synthesized such as GL-331, TOP 53, NK611, and azatoxin. Recently, more complex and diverse analogues have been synthesized either to get more potent compounds or to overcome drug resistance. At the same time, a number of prodrug approaches have been tried to enhance the tumor selectivity or to increase the aqueous solubility. The prodrugs can release cytotoxic etoposide through the actions of hydrolysis, enzymes or catalytic antibodies. More sophisticated prodrug strategies have been applied in etoposide and these produced some interesting results. In this review, the current research trends in the design of new derivatives will be covered with a brief introduction of podophyllotoxin and related analogues.