Ocean Sponge Source Of New Drug Discovery

Drs. Peter McCarthy and Amy Wright, senior research scientists in the Division of Biomedical Research, isolated compounds from the sponge Plakinistrella, commonly found in 25 feet of water in the seas off the Seychelles in the Indian Ocean.

The discovery comes after McCarthy and his staff screened 3,500 samples collected from the oceans and stored at Harbor Branch.

McCarthy called the discovery "exciting, to say the least."

"These are very unique chemical compounds, very unusual in nature," McCarthy said. "It only emphasizes what a treasure trove we have in the world's oceans, and the need to protect the oceans for what they offer."

The compounds comprise a completely new class of antifungal agents called cyclic peroxy acids, and in laboratory tests have been shown to kill two human pathogens; Candida albicans, which causes skin infections and thrush and can endanger the lives of AIDS patients, and Aspergillus fumigatus, which causes dangerous lung infections in people with weakened immune systems, such as cancer patients who are undergoing chemotherapy.

Amphotericin B, the current drug of choice for treating fungal infections, has toxic side effects. Other therapies are available but they are also toxic, or limited in activity.

Once Dr. McCarthy and his staff selected the 3,500 samples from the Harbor Branch inventory, the chemical extracts were sent to the Denver-based biotech company MycoLogics for analysis. MycoLogics has unique abilities to screen for antifungal agents. In all, MycoLogics identified 101 promising leads and Dr. McCarthy said he and his staff further narrowed that number further to identify the series of effective chemical compounds from the sponge Plakinistrella.

Fungi are all around us, and common examples include bread mold, and yeast. Dr. McCarthy points out that everyone has Candida albicans present in their bodies, but most people with healthy immune systems never have a problem.

He also points out that because more and more people are suffering from diseases of the immune system, or have their immune systems suppressed when undergoing treatment for other diseases, the need for antifungal agents is greater than ever before.

"We've only begun to realize the possibilities there are for new drug discoveries in the ocean. It's like the rain forests, where plants and animals that could hold the keys to new drugs are becoming extinct every day. We have the same potential in the oceans, the least-explored and understood environments in the world," McCarthy said.

He adds that the oceans "are potentially the richest source of new drugs to treat human disease."

It may not be obvious at first, but the way a sponge lives makes it logical that it would have chemicals to fight off predators. A sponge anchored to the ocean floor can't run away from predators or pathogens, so over time they've evolved home-made poisons they use to fight their enemies.

Dr. McCarthy and his team will continue to try to find and identify those chemicals for more and better drugs.

The current research was carried out with a grant from the Small Business Technology Transfer Program (STTR) of the National Institutes of Health. Phase I is complete and Phase II of the research is continuing. A patent on the new series of chemical compounds was applied for in July.

Harbor Branch Oceanographic Institution, Inc. is one of the world's leading nonprofit oceanographic research organizations dedicated to exploration of the earth's oceans, estuaries and coastal regions for the benefit of mankind.