Sea sponges and rongoā

Rongoā is the Māori term for medicines produced from native flora and fauna. Rongoā are still used extensively today, and resources are carefully collected in a sustainable manner. But what happens when the potential medicine comes from a rare, endemic sea sponge that grows deep in the ocean off Fiordland? Hemi Cumming and his colleagues Peter Northcote and Paul Teesdale-Spittle are investigating.

Biodiscovery and marine sponges

Biodiscovery – finding chemicals within organisms that may have benefits for humans – is a high-risk high-reward research area. It is extremely expensive and takes years of research to create a new drug, but the financial and social pay-offs can be enormous.

Sea sponges are of particular interest to researchers. They have soft bodies and cannot move so they produce toxins to defend themselves. The marine sponge Mycale hentscheli produces several cytotoxins – substances that have toxic effects on certain cells – and have potential as cancer treatments. Peloruside A and B and pateamine are compounds that New Zealand scientists have isolated and are trying to develop as anti-cancer drugs.

One of the challenges for this research is getting enough sea sponges. The endemic Mycale hentscheli sponges are reasonably common, but only certain populations produce peloruside A and pateamine, so harvesting wild populations is not sustainable. Scientists either need to ‘farm’ the sea sponges or make the compounds in a laboratory. Both methods have their difficulties. Aquaculture trials were hampered by hungry sea slugs, and it can be difficult to synthesise complex chemical compounds found in nature.

Perhaps somewhere deep underwater or in the heart of the ngahere lie natural solutions to some of humanity’s most pressing problems.

Dr Ocean Mercier

Creating a simplified version of pateamine

Due to the scarcity of natural pateamine sources, Hemi Cumming is attempting to create a mimic of the natural compound. First, Hemi and his colleagues have to work out the compound’s complex chemical structure. Then they have to make it using simple chemical building blocks to recreate the large and chemically complex pateamine compound. To be commercially successful, the pateamine mimic must be able to be mass-produced and be able to reduce (inhibit) protein production in cancerous cells.

Dr Peter Northcote says, “Synthesis is more than just a science. You need to have the creativity to see new ways of making these compounds, and you also need to have persistence because you may get nine-tenths of the way only to find an unachievable target and then you have to go back and try a different way to get to the same place.”

Hemi has been able to make two of the key connections work, but the final connection is proving difficult. He says, “It’s a challenge, but you just have to be persistent and be quite determined because of the ultimate outcome and benefit that it potentially could have.”

For Hemi and the team, the drive to create an anti-cancer drug goes beyond the financial benefits. Most families have felt the effects of cancer – being able to find a treatment is an awesome goal.