I'll hop on the sea cucumbers bandwagon along with Sheril of The Intersection, Coturnix on Blog Around the Clock, and Benny of Zooillogix (be sure to check out the boffo cartoon in Benny's article).

In that netherworld between undergrad and graduate school, I thought to become a marine natural products chemist. One of the faculty of my undergrad alma mater's organic chemistry department had a keen interest in compounds from marine critters and plants. To this end, he and his coterie of post-docs and grad students (at least those with scuba diving certifications) traveled to locales like the Sea of Cortez (Baja California) and cruised on the western Caribbean (Belize and such) in search of samples. They carried along a trusty, near-indestructible gas chromatograph (not on their backs, but in a van or on the boat) to analyze specimens on the spot. It was my job, back in the lab on the land-locked prairie, to screen extracts of the collections against in vitro RNA and DNA polymerase activity as well as protein biosynthesis - a real bugger, that, if the RNA template wasn't perfect.

Among the specimens were sea cucumbers. Not only do sea cucumbers harbor the ability to regenerate, but they also make compounds called triterpene glycosides as chemical defense against predation and bacterial colonization. Triterpene glycosides have cytotoxic properties and might have utility against cancer. Not only did I test the extracts, I made them, too. I ground up up frozen sea cucumber along with organic solvents in an industrial strength blender. Let me tell you, those sea cucumbers were tough fuckers. Rovco's Super Bass-o-Matic '76 would never have survived the onslaught of a frozen Holothuria cocktail.

We did see some activity from the extracts, but with more interesting and active compounds from tunicates, the sea cuke extracts fell by the wayside. Additionally, like many natural products with a gazillion chiral centers (1), the triterpene glycosides are quite complex (see below), and perhaps not so amenable to scale-up in a pharma-industrial setting.

The image above is from Sea Cucumber:Food and Medicine by S. Dharmananda of the Institute for Traditional Medicine, Portland, Oregon.

(1) Here's the Wiki entry for chiral centers. A goodly number of these in a molecule make for a synthetic challenge since racemates (a mix of optical isomers) are often formed.