A Promising New Pharma-Sea

Since shedding the primordial slime, we humans have turned our backs on the cool waters we once crawled out of. However, recent investigations show that the underwater world our primordial ancestors left behind is a shimmering expanse of pharmaceutical opportunity. The ocean is, undoubtedly, one of the biggest troves of biological treasure, not just in terms of biodiversity, but also in the abundance of unique chemical compounds with applications in drug development.

The Seven Seas are vast and dynamic — bubbling with activity from highly specialised, diverse groups of species. Marine organisms must adapt to regular fluctuations in water temperature, salt concentration, brightness, pressure, and acidity. They juggle this with their role in complex food webs and aquatic hierarchies — sourcing nutrients, evading predators, and finding mates. Over time, sea creatures have evolved diverse methods to survive rough conditions, most notably the production of secondary metabolites. 

Secondary metabolites are chemical compounds produced by organisms inhabiting harsh environments which aid survival or reproduction. Because of their value in the natural world, many scientists have spent years isolating, characterising, and recreating these chemicals for applications in treating human diseases.

One of the most recent successes in this area of research has come from the lab of Professor Seth Herzon at Yale University’s Department of Chemistry. Herzon, and his team of graduate students, have synthesised eight, potentially anti-cancer, compounds found in marine invertebrates that chemists have been trying to recreate for the past three decades.

These invertebrates belong to the Bryozoa — a group of tiny, simplistic marine animals, native to the North Sea, which live in colonies and feed on algae dispersed through the water. Bryozoans provide a unique source of securines and securamines — families of compounds consisting of large, complex molecules containing elements which are rarely found in organisms on land. Securines and securamines are highly active and have previously been shown to kill cancer cell lines. The synthesis of these molecules in the past has been challenging due to their intricate structure and high reactivity — even in this breakthrough, the yields of the final compounds were relatively low.

Illustration: Isabelle Holloway

Of nearly 2,000 drugs that have been approved for clinical use between 1981 and 2019, half of them have been sourced or derived from chemical compounds present in nature. The vast majority of these were discovered in terrestrial habitats — even though the likelihood of successful drug discovery is four times greater when testing natural products from marine environments. Despite oceans covering 71 per cent of the Earth’s surface, humanity has (quite literally) barely dipped its foot in the water, with 95 per cent of our oceans yet to be explored.

Scientists who have dared to explore the shadowy caverns of the midnight zone — the depths of the ocean at which light cannot infiltrate — have uncovered the answers to various biological dilemmas. Take the PCR tests which were so commonly used during the covid years, for example. PCR, or Polymerase Chain Reaction, is a technique used to amplify strands of DNA and relies on a heat-tolerant enzyme called Taq polymerase which was originally isolated from microorganisms inhabiting underwater geysers. Because of the scalding temperatures these microorganisms were forced to endure, over time they evolved heat-resistant Taq polymerase to stay alive. Another marine-reliant breakthrough, which won the 2008 Nobel Prize in Chemistry, was the discovery of Green Fluorescent Protein (GFP) in luminescent Crystal Jellyfish. GFP is regularly used to study the structure and function of important genes and proteins.

Nevertheless, something is calling for us in that vast navy blue. Not a siren, nor a serpent, but something tiny and hardy and rare. While others search the seas for sunken ships or lost artefacts, the scientists among us search for an altogether different treasure. The secret to the next breakthrough in treating human disease — the most priceless pearl you’ll ever find in the ocean.