marine pharmaceuticals

marine pharmaceuticals are chemical substances derived from marine organisms that are effective in various types of medical treatment and research. To date most pharmaceuticals have been derived from terrestrial organisms, but with twice as many animal phyla in the oceans as on land, as well as a plethora of different micro-organisms, the chances of finding novel natural compounds useful for biomedical purposes are high. In the sea, seaweeds are an important source of iodine and are used for the treatment of patients with thyroid problems. Soft-bodied animals like sponges, sea-squirts (Tunicata), and soft corals that inhabit coral reefs both defend themselves from being eaten and wage territorial battles by producing noxious or distasteful chemicals, which are proving to be a treasure chest of useful chemicals. The dried remains of the seaweed Desmarestia is 18% sulphuric acid, strong enough to dissolve the limy shells of barnacles from rocks.

The chemicals produced by other organisms include terpenes, acetogenics, various alkaloids, and polyphenols. These have either proven or potential value that ranges from use as antibiotics, pain suppressors, and anti-inflammatory agents to sunscreens and anti-cancer agents. To give a few examples: neurotoxins (nerve poisons) like tetradotoxin —which renders pufferfish (Tetraodontidae) fatal to eat and is also the basis of the fatal bite of the Great Barrier Reef's blue-ringed octopus Hapalochlaena maculosa—block sodium channels in nerve endings and have considerable value in biomedical research; and some sponges produce a substance, Halichondrin B, which shows promise in the treatment of ovarian cancer, melanomas, and leukaemia. The larvae of a type of shrimp are covered with bacteria which, if removed, result in over 90% of the larvae dying. It turns out that these bacteria secrete a toxic chemical, isatin (2,3-indoledione), that protects the larva from fungal infections, and may give us similar protection. A sea mat (Bugula) produces Bryostatin, which has immuno-stimulating properties and is used in the treatment of leukaemia. The blood of the horseshoe crab (Limulus) has a single, very sensitive, clotting agent that is used to detect any impurities and endotoxins contaminating surgical instruments.

Numerous laboratories around the world are actively screening marine organisms for biological active substances that may have a variety of potential uses. A British company dedicated to marine drug discovery announced in 2003 that it had discovered a marine microbe that in laboratory tests has produced a toxin that kills methicillin-resistant staphylococcus aureas (MRSA), currently (2004) such a threat to anyone undergoing surgery.

Antarctica is of particular interest to biotech companies and one firm has patented the molecule responsible for producing ‘antifreeze’ in Antarctic fish which could be used commercially to protect frozen food. However, ‘bioprospecting’ in Antarctica could prove a problem as it could infringe the international Antarctic Treaty, which protects the area from commercial exploitation.

M. V. Angel