Podophyllotoxin: Current Perspectives

Podophyllotoxin is a naturally occurring lignan with important antineoplastic and antiviral properties and supported by detailed understanding of their mechanism of action, and facilitated by chemical manipulations that have amplified their bioactivity, the podophyllotoxin analogues have advanced to the forefront of several areas of therapeutic and developmental chemotherapy. Additive and synergistic laboratory interactions with other cytotoxic drugs have been exploited to allow development of podophyllotoxin-based multidrug regimens, which are showing important activity in several malignancies, and many of its related analogues will complement conventional pharmaceuticals in treatment, prevention and diaganosis of disease, while at the same time adding value to agriculture. Additive and synergistic laboratory interactions with other cytotoxic drugs have been exploited to allow development of etoposide-based multidrug regimens, which are showing important activity in several malignancies. Extensive structural modifications of podophyllotoxin have been performed in order to obtain more potent and less toxic antitumour agents, which resulted in the widespread clinical introduction of two semisynthetic glucoconjugate analogues of etoposide and teniposide and newer agents with promising preclinical activity are in various stages of clinical assessment. As knowledge of molecular and biochemical mechanisms of action and resistance continues to expand, newer and better podophyllotoxin-based strategies for treatment of malignant disease are likely to evolve. This review provides a detailed discussion of research advances in the synthetic and medicinal chemistry of podophyllotoxin, and addresses the short history and pharmacological action of these compounds and further outlines the preclinical development and clinical trials of drugs in the pipeline and marketing approval. Finally, a systemic evaluation of novel and important analogues of podophyllotoxin and their contribution to the current structure-activity profile are considered. It is hoped that this review will be able to address the contributions of podophyllotoxin-related research to overall drug discovery and development and the role that this field will play in future. Keywords: Reviews, podophyllotoxin, short chronology, biological activity, medicinal application, mechanism of actions, chemical modification, structure-activity relationships.