Elizabeth N. Kaweesa

The Cytotoxic Cardiac Glycoside (−)-Cryptanoside A from the Stems ofCryptolepis dubiaand Its Molecular Targets

A cardiac glycoside epoxide, (-)-cryptanoside A (

Exploration of Verticillins in High-Grade Serous Ovarian Cancer and Evaluation of Multiple Formulations in Preclinical In Vitro and In Vivo Models

Verticillins are epipolythiodioxopiperazine alkaloids isolated from a fungus with nanomolar anti-tumor activity in high-grade serous ovarian cancer (HGSOC). HGSOC is the fifth leading cause of death in women, and natural products continue to be an inspiration for new drug entities to help tackle chemoresistance. Verticillin D was recently found in a new fungal strain and compared to verticillin A. Both compounds exhibited nanomolar cytotoxic activity against OVCAR4 and OVCAR8 HGSOC cell lines, significantly reduced 2D foci and 3D spheroids, and induced apoptosis. In addition, verticillin A and verticillin D reduced tumor burden in vivo using OVCAR8 xenografts in the peritoneal space as a model. Unfortunately, mice treated with verticillin D displayed signs of liver toxicity. Tolerability studies to optimize verticillin A formulation for in vivo delivery were performed and compared to a semi-synthetic succinate version of verticillin A to monitor bioavailability in athymic nude females. Formulation of verticillins achieved tolerable drug delivery. Thus, formulation studies are effective at improving tolerability and demonstrating efficacy for verticillins.

Activity of Didesmethylrocaglamide in High Grade Serous Ovarian Cancer Using Preclinical In Vitro and In Vivo Models

High grade serous ovarian cancer (HGSOC) is the most lethal gynecological cause of death in women and requires new treatments to help tackle chemoresistance. Rocaglamides, a promising class of anticancer natural products, function as protein translation inhibitors and trigger apoptosis in other types of solid tumors. Didesmethylrocaglamide ((±)-DDR), a derivative of rocaglamide with potent antitumor activity, was synthesized, including three additional rocaglamide derivatives, (±)-DDR01, (±)-DDR03, and (±)-DDR04, to evaluate their cytotoxicity in HGSOC. Using in vitro models, it was determined that (±)-DDR induced cytotoxicity in ovarian cancer cell lines as early as 24 h after application and activated caspase-3, indicating pro-apoptotic activity. In addition, (±)-DDR was cytotoxic in the PE04 and MCF7-ADR (OVCAR8-RES) cell lines that are resistant to cisplatin and paclitaxel, respectively. Evaluation of each enantiomer revealed the minus enantiomer to be ∼18-fold more potent compared to the plus enantiomer in the OVCAR8 cell line. (-)-DDR was further evaluated using an OVCAR8 xenograft model in mice, and a reduction in tumor burden was observed. Its effective cytotoxicity in drug-sensitive and -resistant cell models suggests that (±)-DDR and its corresponding minus enantiomer may have potential as a new therapeutic strategy against HGSOC.