Natural Cytotoxic Diterpenoids, a Potential Source of Drug Leads for Melanoma Therapy

Diterpenes present complex structure and due to their unique carbon skeleton and interesting biological activities, have been the focus of continuous studies for the development of new anticancer agents. Phorbol esters have been known for their activity against skin malignancies since ancient times. Taxol was first studied in melanoma cells, and recently, ingenol mebutate has been approved for the chemoprevention of melanoma in actinic keratosis patients. Therefore, there is a scope for research on this class of compounds. We here aim to review the relevant original research reporting on isolated diterpenes with cytotoxic and/or antitumoral activities upon melanoma cells. By collating and discussing the implications of past and current developments on diterpenes, we hope to steer further interest on this field and facilitate the drug discovery activities of the scientific community towards finding potential alternatives to current melanoma chemotherapy.