Larger amounts of the substance have been sought for 25 years and now researchers have found a coral that produces the substance and can tell us how it does it.
In the 1990s, scientists made a promising discovery. Near Australia they came across a rare coral that produced a compound called eleutherobin that inhibited the growth of cancer cells. “Those early studies were great and excellent,” said Eric Schmidt, a professor at the University of Utah. “They showed that eleutherobin was just as potent against cancer as paclitaxel (which is used in chemotherapy, ed.) and could probably also be used against types of cancer in which paclitaxel does not work.” But while those initial studies were promising, they soon had to be shut down. “There was not enough eleutherobin available.”
Quest
Encouraged by the good results of that first early research, there has been a lot of effort in recent years for larger amounts of eleutherobin. Without result. “The dedication of many scientists did lead to finding corals that could make eleutherobin,” explains Schmidt. “But it was never enough for the pharmacological evaluation that had to take place before we could move forward with this compound.”
Breakthrough
But finally – after 25 years of searching – there is good news. Because in the leaf Nature Chemical Biology Schmidt and colleagues announce they’ve discovered an easy-to-find, soft coral that spawns the stuff. And then they immediately went a step further: they also looked up the instructions for the production of eleutherobin in the genome of the coral. It was not easy, because the researchers had no idea what those instructions looked like. And then just look to find them in the DNA code. “It’s like looking in the dark for an answer to a question you don’t know,” notes Schmidt.
That sounds like an impossible task, but the researchers came up with a solution. They looked for pieces of DNA that resembled the genetic instructions that other coral species rely on to produce comparable substances. And it worked: the researchers found some of the instructions. And they immediately tried it out. To do this, they used bacteria that were programmed to follow the instructions. And those micro-organisms subsequently turned out to be able to take at least the first steps that must be taken to produce eleutherobin. The challenge now is to track down the remaining part of the instructions and then find a way to produce the substance – using those instructions – in larger quantities.
Coral
The eleutherobin-producing coral was discovered off the coast of Florida. What the coral uses eleutherobin for is not entirely clear. “One hypothesis is that the substance protects the coral from predators,” Schmidt said.
Potency
At least as interesting is of course what the good stuff can do for us. Although the studies from the 1990s give an idea of this, more research into the potential of the substance is desperately needed. “Of the substances discovered to date in the ocean, it is one of those with a lot of potential,” says Schmidt. “And although there are still a lot of experiments to be done, it is promising stuff.” But it is now important for scientists to continue where they were forced to stop in the 1990s. “By now having access to the genes that help make eleutherobin, we hope to increase their supply so that eleutherobin can be further evaluated and how promising (or not) the drug is in the fight against cancer.”
But even if eleutherobin doesn’t have as much potential as it seemed in the 1990s, the hard work of Schmidt and colleagues has not been in vain. For example, Schmidt explains that the methods his research group has now developed and used can at least be used in the future to evaluate other (promising) substances produced by animals. “For a long time science has focused on plants and microbes and the way they made potential drug-like substances (…) What we’re showing now is that animals are capable of the same thing, and they are—certainly compared to plants. and microbes – hardly researched yet. Given that there may be 10 million animal species on Earth, it is likely that methods similar to ours could be used to reveal new types of pharmaceuticals.”
Source material:
†Scientists find sea corals are source of sought-after “anti-cancer” compound– University of Utah Health
Interview with Eric Schmidt
Image at the top of this article: Bailey Miller