Insect's Venom Eyed For Cancer Defense

Camouflage is not the only trick Madagascar walkingsticks use to thwart their enemies. These insects also spray a defensive fluid, and a team of researchers hopes the fluid's key chemical, parectadial, will ward off a human enemy: cancer.

The team, led by biochemistry professor Arthur S. Edison of the University of Florida, details their discovery and characterization of parectadial along with their development of a synthetic route to this novel monoterpene (J. Nat. Prod., DOI: 10.1021/np070151g).

Studying an insect's defensive fluid is often a challenge because the sample size typically is minuscule. Edison's team overcame this obstacle by using microsample NMR technology aimed at analyzing natural products (C&EN, Sept. 25, 2006, page 15). Analysis of venom from the Madagascar walkingstick (Parectatosoma mocquerysi) revealed a monoterpene dialdehyde that Edison's team named parectadial.

"Parectadial is very similar to perillyl alcohol and perillaldehyde," Edison notes. Both of those plant-derived compounds have been investigated for anticancer activity, he adds. Perillyl alcohol is known to arrest tumor cells and has been the focus of a number of clinical trials conducted by the National Cancer Institute (NCI).

Parectadial's structural similarity to perillyl alcohol prompted Edison's team to study the dialdehyde's effectiveness against tumor cells. Preliminary unpublished results indicate that parectadial displays the same anticancer activity as perillyl alcohol. Results have been so promising that Edison's team filed for a patent on parectadial and aims to test it against approximately 60 cell lines at NCI. "If we are lucky, this new compound from an obscure Madagascar insect could be useful as a drug," Edison says.