Drowning Out Disease: Are Coral Reefs the Link?

When most people think of coral reefs, what comes to mind are vibrant scenes of enormous coral colonies surrounded by an immensely colorful array of organisms that would put rainbows to shame. And while these images are often visually astounding, they fail to convey the underlying significance of coral reefs. In addition to providing shelter and sustenance for a plethora of oceanic organisms, coral reefs are an important source of food and income for many tropical communities. However, one of the lesser known but incredibly important uses of coral reefs is in the pharmaceutical industry. In this series of blog posts, I plan to discuss some recent medical developments from coral reefs as well as give you yet another reason why we need to protect coral reefs worldwide.

In 2004, Boston native, Arden O’Connor, was diagnosed with leukemia, a form of cancer, and was subsequently told she likely had less than a year to live. When she was interviewed in 2012 about being cancer-free eight years after her initial diagnosis, she attributed everything to Ara-C (Figure 1), a chemotherapy medication derived from sponges common to coral reefs.¹ For many others with leukemia, Ara-C has proven to be a widely effective treatment when other treatment plans have been exhausted.

Figure 1: Chemical structure of Ara-C, also known as Cytarabine. (Wikimedia Commons)

After reading about O’Connor’s story, I assumed that these medical-reef discoveries began at the turn of the century, but to my surprise, there is over thirty years of research in the topic. In one article, Japanese scientists were cited as using the sea sponge Halichondria okadai to isolate the antitumor molecule halichondrin B back in 1986.² More than 20 years of research and numerous clinical trials later, a form of halichondrin B called eribulin is commercially available for treating breast cancer patients.

Figure 2: Halaven is commercially available for treatment of breast cancer patients. Eribulin, the active ingredient in Halaven, is a chemical derivative of halichondrin B, the antitumor molecule found in the sea sponge Halichondria okadai. (Medscape)

However, pharmaceuticals produced via coral reefs apply well beyond only cancer treatment. The Nature Conservancy, an organization dedicated to worldwide conservation, released a list of some of the most significant medical treatments made available from coral reefs.³ One of the most promising treatments that it lists is secosteroids, a subclass of organic molecules called steroids. Corals utilize secosteroids as protection from certain diseases; however, research into secosteroids (Figure 3) produced by coral in the genus Sinularia has revealed anti-inflammatory properties when used in humans.4,5  These molecules may have the potential to treat many chronic inflammatory diseases like arthritis.

Figure 3: Two secosteroids examined for anti-inflammatory properties (Huang et al., 2012)

Coral reefs have been in the news recently and not for good reasons; massive bleaching events and theories about the “end of the Great Barrier Reef” have plagued the media, leading people to believe the battle to save global reefs has been lost. Rather, we need to be emphasizing the importance of reefs, both to marine ecosystem and to us as humans. If we can effectively do that, then maybe we can mitigate any future damage done to reefs.

¹Caron, C. (2012, April 20). Doctors develop life-saving drugs from coral reefs. NBC News. Retrieved from http://dailynightly.nbcnews.com/_news/2012/04/20/11308813-doctors-develop-life-saving-drugs-from-coral-reefs?lite

²Menis, J., & Twelves, C. (2011). Eribulin (Halaven): a new, effective treatment for women with heavily pretreated metastatic breast cancer. Breast Cancer: Targets and Therapy, 3, 101. Retrieved from http://s3.amazonaws.com/academia.edu.documents/41054948/BCTT-21741-eribulin–halaven—a-new–effective-treatment-for-women-wit_082511.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1487668408&Signature=k49qNvnPotZaBDSY8weixAtksiM%3D&response-content-disposition=inline%3B%20filename%3DEribulin_Halaven_a_new_effective_treatme.pdf

³Levins, N. (2017). Coral Reefs: Nature’s Medicine Cabinet. The Nature Conservancy. Retrieved from http://www.nature.org/ourinitiatives/habitats/oceanscoasts/explore/coral-reefs-and-medicine.xml

4Huang, C. Y., Su, J. H., Duh, C. Y., Chen, B. W., Wen, Z. H., Kuo, Y. H., & Sheu, J. H. (2012). A new 9, 11-secosterol from the soft coral Sinularia granosa. Bioorganic & medicinal chemistry letters, 22(13), 4373-4376. Retrieved from http://www.sciencedirect.com.ezproxy.rice.edu/science/article/pii/S0960894X12005914

5 Tseng, Y. J., Wang, S. K., & Duh, C. Y. (2013). Secosteroids and norcembranoids from the soft coral Sinularia nanolobata. Marine drugs, 11(9), 3288-3296. Retrieved from http://www.mdpi.com/1660-3397/11/9/3288/htm

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