Dykellic acid

Small molecule inhibitors of apoptosis hold considerable promise for the treatment of a host of diseases, including neurodegeneration, myocardial infarction, and stroke. Many compounds that delay or prevent apoptotic death either reduce the amount of cellular reactive oxygen species (ROS) or are direct inhibitors of caspases. With the goal of using small molecules to identify novel antiapoptotic targets, we have investigated the cytoprotective activity of the natural product dykellic acid. Described herein is the first total synthesis of dykellic acid, the synthesis of several dykellic acid derivatives, and the evaluation of these compounds in assays related to cell death. We have found that dykellic acid protects cells from death as induced by etoposide and rotenone. Further experiments strongly suggest that dykellic acid does not scavenge ROS or directly inhibit caspase enzymes, and analysis of synthetic derivatives establishes key functional groups of the molecule that are essential for its cytoprotective activity.

Dykellic acid, a novel factor initially identified from the culture broth of Westerdykella multispora F50733, has been shown to inhibit matrix metalloprotease 9 activity, caspase-3 activity, B cell proliferation and LPS-induced IgM production, suggesting that this factor may have anti-cancer effects. In an effort to further address the possible anti-tumoral effects of dykellic acid, we used wound healing, invasion and RhoA-GTP assays to examine the effects of dykellic acid on cell migration, invasion and angiogenesis. Our results revealed that dykellic acid dose-dependently inhibits B16 cell migration and motility, and inhibits HUVEC tube formation. Western blot analysis of the active form of RhoA (RhoA-GTP) showed that dykellic acid treatment decreased the levels of RhoA-GTP. These findings collectively suggest that dykellic acid may have both anti-metastatic and anti-angiogenic acitivites, and provides the first evidence for the involvement of RhoA in dykellic acid-induced effects.

Dykellic acid is a novel microbial metabolite isolated from the broth of Westerdykella multispora F50733. Investigations on the molecular function of dykellic acid revealed that this compound partially inhibits calcium influx, resulting in a decrease in Ca(2+)-dependent endonuclease activation and DNA fragmentation induced by camptothecin. In our experiments, active caspase-3-like protease cleavage of procaspase-3, PARP, and cytosolic cytochrome c was inhibited by dykellic acid in a concentration-dependent manner when the apoptosis was induced by camptothecin as well as doxorubicin. We confirmed that dykellic acid did not bind to camptothecin using surface plasmon resonance analysis. These results suggest that dykellic acid inhibits drug-induced apoptosis via a caspase-3-like protease-suppressing mechanism. Our data provide important information on the mechanism of action of dykellic acid and indicate that this compound may be employed in the treatment of specific caspase-3-like protease-mediated diseases.