Research uncovers unique anti-cancer properties in Tongan marine sponges

Research by Victoria University of Wellington PhD graduate Taitusi Taufa has found new medicinal properties in marine sponges collected from Tongan waters, including several unique anti-cancer compounds.

PhD graduate Taitusi Taufa, wearing a graduation cap and gowns, stands in front of a row of Victoria University of Wellington banners

Taitusi, who graduated this week from Victoria University with a PhD in Chemistry,  says while there is still a lot of work to be done in this area, his research could have applications for future medicines.

“Through my research I isolated several new natural products with unique and interesting anti-cancer properties, which could help us in the future to synthesise and design new anti-cancer drugs.”

He says his interest in the medicinal properties of natural marine products can be traced back to his childhood on Tongatapu, the main island of Tonga.

“As a child, my grandparents and mother often used plants and herbal remedies to treat us when we were sick. At that time, Western medicine was unpopular and many people did not trust it, so we relied heavily on their traditional knowledge and medicine made from the leaves and bark of plants.

“These traditional medicines always seemed to work, which prompted my curiosity about the chemical contents responsible for the healing process.

“When I did my undergraduate studies in Chemistry, I realised that many drugs used nowadays, such as aspirin and morphine, were either based on, or inspired by, traditional medicine.”

Taitusi says the active ingredients responsible for the medicinal properties of these traditional medicines are called ‘natural products’, and in the last few decades, researchers looking for new natural products with medicinal applications have shifted their focus from land-based sources to the untapped wealth of the marine environment.

“There was a lack of chemical investigation into this naturally rich environment, which presented an opportunity to explore the marine organisms from Tongan waters for potential drug discovery,” he says.

Taitusi’s research was not just bound to the laboratory, with several scuba diving expeditions in the waters of Tonga to collect organisms for analysis.

Back on dry land, Taitusi was able to isolate more than 40 known natural products and 18 new ones from the sponges he collected with his supervisors, Associate Professor Peter Northcote from the Ferrier Research Institute and Dr Robert Keyzers from the School of Chemical and Physical Sciences. He says several of the new natural products show interesting and unique anti-cancer properties.

If marine sponges seem an unlikely source for exciting new chemical compounds, Taitusi explains that it’s their sedentary nature that makes them such good sources for new drug discovery.

“Because sponges can’t move and lack physical defenses such as spines or protective shells, they are highly vulnerable to predators such as fish, turtles, and invertebrates. It’s not surprising then that sponges have developed a wide suite of defensive chemicals to deter predators. These chemical compounds can be isolated, identified and utilised for medicinal applications.”

While Taitusi and his supervisors undertook several dive collections in different geographical locations in Tonga, they discovered that the sponges collected from one particular island, ‘Eua, showed unique chemical properties.

“‘Eua is the most ancient island in Tonga and is geologically unrelated to the rest of the islands. It’s believed to be more than 30 million years old—one of the oldest islands in the South Pacific,” says Taitusi.

“Because of this, ‘Eua has a unique marine environment that can host organisms that produce interesting and novel chemistry.”

The high standard of Taitusi’s research was recognised by being selected for the Doctoral Dean's list—a formal record and public acknowledgement of doctoral graduates whose theses have been judged by their examiners to be of exceptional quality, and whose work makes an outstanding contribution to their field of research.

Dr Robert Keyzers, who co-supervised Taitusi’s PhD, says “Taitusi's research has again validated the marine environment as a rich source of new medicinal compounds. Moreover, his in-depth and detailed study of the chemistry of sponges from ‘Eua has shown us the value of exploring ancient island sites within the South Pacific for the discovery of new chemistry.

“Taitusi has proven himself time and again as a highly skilled and keen scientist through these discoveries, and through the sheer hard work and determination he has brought to his research.”

Taitusi says he’s elated to be graduating with a PhD.

“Happy is an understatement for the way I feel. I knew it wasn’t going to be an easy undertaking from the beginning, but it was a journey I was willing to take.”

Taitusi celebrated graduation with his family at a ceremony on Wednesday.