Sea cucumbers yield effective cancer-fighting substance

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SOLVING A PICKLE Dennis Hall (centre) is flanked by fellow researchers Marlin Penner (left) and Vivek Rauniyar (right).

A team of researchers at the University of Alberta is hoping to reduce the harm done by melanoma with a treatment derived from sea cucumbers.

Melanoma accounts for only a small percentage of all skin cancer cases, but is responsible for over 75 per cent of skin cancer deaths. Some forms of melanoma can be removed through surgery and other invasive measures, but if the cancer grows to over one millimetre thick, the chances of survival are extremely small.

Dennis Hall, a professor in the Department of Chemistry, and his team, including Ludwig Kaspar, Marlin Penner, and Vivek Rauniyar, are working on a drug to lessen melanoma's impact. Palmerolide A is a potentially lifesaving compound that the team is hoping to synthesize into a marketable treatment of the condition.

“[This] is a small piece of bigger puzzle,” Hall said, though he's optimistic about the future of this compound, and its potential to improve melanoma treatment.

Palmerolide A was first isolated near a research station in the Antarctic for sea cucumbers. Hall explained that animals such as sea cucumbers have often evolutionarily developed toxins, designed to kill predators.

Groups of scientists at various locations around the world look for these types of compounds, and then test them against known cancers and other aliments to see if they have an effect. Palmerolide A was tested against 60 different types of cancers, and was found to kill melanoma cells with high selectivity, even when administered at low concentrations.

The biggest problem facing Palmerolide A is its size. This compound is too large, and more efficient methods of synthesis need to be designed before it can be administered, Hall explained.

The current process for synthesis devised by the team is a 21-step process, which is too time-consuming and costly to produce large quantities of the compound.

Palmerolide A is a very complex compound; there are 1,024 possible isomers (possible special orientations), and only one is suitably effective against melanoma. Therefore, the synthesis process needs to be very controlled and careful to only produce this particular compound. The ultimate goal is to design a process around 12 steps long.

The work done by Hall’s team has helped the chemical industry to better understand Palmerolide A, and has opened many doors for chemists to possibly shorten this process.

Hall explained that the discovery was a result of a competition, and he and his team were proud to be one of only three teams to have successfully synthesized Palmerolide A.

"There is a big reward for the first team to produce [a marketable drug], but the patient doesn’t care — they benefit anyway,” he said in October in an interview with the U of A monthly magazine /Folio/. “The potency of Palmerolide is exceptional and melanoma is a very aggressive cancer for which there is almost no chemotherapeutic recourse [...] Natural substances like Palmerolide offer real hope for such treatments."

But despite the promise the strategy has shown, it will likely be another 10 to 15 years before Palmerolide A is available for patients, Hall explained. This is due to the nature of drug manufacturing and the many steps involved before a drug can be marketed.