For centuries, the oceans have been a source of life, mystery, and endless novel discoveries. The relationship between humans and oceans has been shaped throughout the past in various ways, including nourishment by providing food sources, offering boundless resources such as minerals and many more.
Sri Lanka, like most of the islands in the world, is blessed by a tranquil ocean and recognised for its exceptional biological diversity, which attracts millions of tourists. The country’s marine ecosystems are unique and consist of coral reefs, seagrass beds, and many more, providing habitats for a large number of animal species. Sponges (or more scientifically, Poriferans) are abundant in almost all these habitats.
Marine sponges are usually not recognised as animals as they do not resemble animal-like features. They are simple, filter-feeding invertebrates (animals without a backbone) belonging to the phylum Porifera. They are considered the oldest multicellular animals on Earth, having evolved through millions of years in diverse marine environments from shallow coastal waters to deep-sea ecosystems.
Sponges play a crucial ecological role by filtering large volumes of water, which helps mix surface and deep water (Bentho-pelagic coupling), to maintain water quality and ecosystem balance. They provide essential habitats for various marine organisms, offer shelter and breeding grounds. Sponges contribute to the nutrient cycle by breaking down organic matter and releasing essential compounds into the environment. Some species also engage in symbiotic relationships with bacteria and algae, aiding in primary production and carbon cycling.
Dr. Varuni Gunathilake, Senior Lecturer at the Department of Zoology, Faculty of Applied Sciences, University of Sri Jayewardenepura, said, “We are all well familiar with the medicinal power of herbs and plants. But most of us do not know the medicinal power of marine organisms.”
Dr Gunathilake said, “Various marine organisms and even marine microorganisms can produce chemical compounds with medicinal properties. Marine sponges are ranked at the top of the hierarchy of these organisms. The potential of marine sponges to serve as excellent candidates for bioactive compounds was not recognised till the late 1960s. Marine sponges produce chemicals in their bodies naturally, and these chemicals protect them from predators, pathogens, and environmental stress. Many of these compounds have potential pharmaceutical applications, such as anticancer, antiviral, antibacterial, and many more.”
Sponge-produced compounds are scientifically identified as secondary metabolites. These metabolites include compounds such as alkaloids, terpenoids, saponins, flavonoids, and peptides, which are widely studied for their medicinal properties. These chemical compounds are sometimes produced by the microbial community, usually associated with the sponges.
The story of marine drugs dates back to the late 1960s, when a group of scientists accidentally discovered an anticancer compound named Ara-C from a Caribbean sponge. This discovery sparked interest in marine drug discovery, leading to much related research thereafter. Since then, advancements in science and technology have allowed for the identification and isolation of hundreds of marine-derived compounds, many of which have demonstrated potent medicinal properties.
Today, marine drug discovery is a rapidly growing field in many developed countries, even though marine sponges are not naturally available. Scientists work hard to isolate numerous compounds undergoing clinical trials, offering hope for new treatments for incurable diseases like cancer and antibiotic resistance. Sri Lankan coast is well-abundant with various species of marine sponges. Most of these sponges are not even properly identified. We, at the Department of Zoology, Faculty of Applied Science, University of Sri Jayewardenepura, started isolation of marine sponge-produced compounds with medicinal properties in 2017. As a result, a number of marine sponge species were studied for their ability to produce chemicals with medicinal properties.
“Our studies have investigated the bioactivities of various Sri Lankan marine sponge extracts, including Axinella sp., Luffariella herdmani, and Ircinia sp. We carry out this research from the very grassroots level, from identification to isolation of compounds. The identification of sponges is sometimes challenging, and we seek guidance from international experts for further clarification,” Dr. Gunathilake said.
The research team at the Department of Zoology, USJ, has been exploring the potential of marine sponges as a source of novel bioactive compounds with pharmaceutical applications. Over the past few years, they have worked with several sponge species, including Luffariella herdmani, Axinella, and Ircinia, which were collected from various coastal regions in Sri Lanka under the permission of the Department of Wildlife Conservation. These marine organisms, often overlooked, possess a unique chemical diversity that holds promise for drug discovery.
In laboratory studies, the sponge extracts were subjected to a series of in vitro bio assays to evaluate their antimicrobial, anticancer, and antioxidant properties. Some of these preliminary findings revealed the presence of biologically active compounds that have the potential to be developed into therapeutic agents. These experimental protocols were designed to minimise harm to animals, and the testing did not involve any live animal models.
“Instead, we focused on in vitro assays and biochemical analyses, aligning with modern scientific approaches that seek alternatives to traditional animal testing. These initial results have laid the foundation for more advanced research. With adequate funding and collaboration, we aim to isolate and characterise these compounds further and assess their mechanisms of action.”
“The long-term goal is to contribute to the development of safe and effective drugs derived from marine natural resources, while promoting sustainable use and conservation of marine biodiversity. This work not only highlights the untapped potential of marine sponges but also supports the global movement towards ethical and environmentally conscious research practices,” Dr. Gunathilake said.The research team working on the marine sponges includes Amila Wimarshana, Umasha Subasinghe and Sashini Kuruppuarachchi. The initial findings mark a promising beginning in the field of marine natural product research. As research progresses, there will be more compounds with diverse therapeutic properties, contributing valuable insights to biomedical science.
With continued support, advanced analytical techniques, and interdisciplinary collaboration, there will be scientifically significant and commercially viable outcomes. The potential for groundbreaking discoveries is vast, and the commitment remains strong in harnessing the wealth of marine biodiversity for the betterment of human health.
By: Dr. Varuni Gunathilake
Department of Zoology, Faculty of Applied Sciences, University of Sri Jayewardenepura
