Marine Pharmacognosy - Marine Organisms As Sources of Natural Products

Marine Organisms As Sources of Natural Products

Over 70% of the earth's surface is covered by oceans which contain 95% of the earth's biosphere. It was over 3500 million years ago that organisms first appeared in the sea. Over time, they have evolved many different mechanisms to survive the various harsh environments which include extreme temperatures, salinity, pressure,different levels of aeration and radiation, overcoming effects of mutation, and combating infection, fouling and overgrowth by other organisms. Adaptations to survive the different environments could be by physical or chemical adaptation. Organisms with no apparent physical defense, like sessile organisms, are believed to have evolved chemical defenses to protect themselves. It is also believed that the compounds would have to be extremely potent due to the dilution effect of seawater. This has been described to be analogues to pheromones but with the purpose of repelling instead of attracting. As well, predators have evolved chemical weapons in order to paralyze or kill prey. Conus magus is an example of a cone snail that has a poisoned harpoon-like projectile which it uses to paralyze prey like small fish. Some organisms, like the Viperfish, are believed to attract small fish or prey by using its photophore.

Many different marine organisms have been explored for bioactive compounds. Some vertebrate animals include fish, sharks and snakes. Some examples of invertebrates are sponges, coelenterates, tunicates, echinoderms, corals, algae, molluscs and bryozoans. Some microorganisms include bacteria, fungi and cyanobacteria.