Marine Organisms as Biomedical Resources Enrich Quality of Life

The Ocean, called the ‘mother of origin of life’, is a rich source of biological and chemical diversity. Marine floras include microflora (bacteria, actinobacteria, cyanobacteria and fungi), microalgae, macroalgae (seaweeds), and flowering plants (mangroves and other halophytes). Marine organisms have unique properties as they are exposed to extreme marine environmental conditions. This vast marine floral resource offer a great way for discovery of new drugs which can fight deadly diseases like cancer, acquired immune deficiency syndrome (AIDS), arthritis, etc. Sea has got plenty of metabolites and other resources in living or dead form. Thermo-stable proteases, lipases, esterases, and starch and xylan degrading enzymes have been actively sought from bacterial and archaeal hyperthermophilic marine microorganisms. Marine cyanobacteria appear to be potential sources for production of vitamins such as B complex group and vitamin-E. The carotenoids and phycobiliprotein pigments of cyanobacteria have commercial value as natural food colouring agents, as feed additives, as enhancers of the color of egg yolks, to improve the health and fertility of cattle, as drugs and in the cosmetic industries. Some anti-HIV activity has been observed with the compounds extracted from Lyngbya lagerhaimanii and Phormidium tenue. Thus an attempt to review few marine derived biomedical resources was done emphasizing that with the advent of modern technologies it is anticipated that the marine environment will become an invaluable source of novel compounds in the future.


Introduction
Although more than 30 000 diseases have been clinically described, less than one-third of these can be treated symptomatically and only a few can be cured. New therapeutic agents are urgently needed to treat medical needs that are currently unmet. Natural products once played a major role in drug discovery [1,2]. The marine environment covers more than 70% of the world's surface.

Ocean Habitats
In Ocean Habitats, there are two major marine provinces: the benthic (bottom) and the pelagic (water column). The benthic environment is divided by depth into the: Intertidal zone, Sublittoral zone, Bathyal zone, Abyssal zone, and the Hadal zone. The pelagic environment is divided into the Neritic Zone and the Oceanic Zone.
The five major kingdoms in the ocean are: Monera, Protista, Fungi, Metaphyta and Metazoa (Animalia). Monera are the bacteria and blue-green algae. Protista are singlecelled organisms with a nucleus. Fungi are abundant in the intertidal zone and are important in decomposition. Metaphyta are the plants that grow attached to the sea floor. Metazoa include all multicellular animals in the ocean.

Marine Organisms as Biomedical Resources
Since the beginning of mankind nature has been contributing considerably to drug discovery for human beings by providing remedial treatments. One of nature's treasures is the marine biotope, which occupies almost three quarters of the earth's surface. Marine natural products play an increasingly important role in biomedical research and drug development [1]. Marine derived bioactive compounds help in the treatment of many diseases such as cancer, AIDS, inflammatory conditions, and a large variety of viral, bacterial and fungal diseases. Majority of the marine natural products have been isolated from sponges, coelenterates, tunicates, opisthobranch molluscs, echinoderms, bryozoans and a wide variety of marine microorganisms in their tissues [2].

Marine Algae
Microalgae, the most primary and simply-organized members of marine plant life, are rich sources of food ingredients, such as β-carotene, Vitamins C, A, E, H, B1, B2, B6 and B12, astaxanthin, polysaccharides and polyunsaturated fatty acids [3]. Toxins from dinoflagellates. are useful tools to investigate the structure and function of ion channels on cell membranes or to elucidate the mechanism of tumor promotion based on their specific inhibitory action against protein phosphatases.

Marine Invertebrates
Marine Sponges, the most primitive multicellular invertebrates, considered as a gold mine for isolation of promising bioactive compounds for human welfare. Interestingly, cytarabine (Cytostar-U) also known as Ara-C, a compound isolated from the Caribbean sponge Cryptotheca crypta currently being used with other anticancer drugs in the treatment of acute myelocytic leukaemia (AML) [4]. In addition to potential anticancer applications, the bioactive compounds of sponges have a myriad of activities ranging from antibiotic activity including anticoagulant, antithrombin, anti-inflammatory HIV-protease inhibitory, HIV reverse transcriptase inhibitory, as well as imunomodulatory activities [5].

Molluscs, Echinoderms and Crustaceans
Bioactive peptides obtained from the fermented blue mussel and oyster sauces significantly decrease hypertension whilst ground abalone and its shells are used for treating eye diseases [6]. The Pacific oyster contains a substance which may help diabetics by promoting the secretion of insulin.

Marine Fish
The nutritional benefits of fish consumption are due to the presence of proteins, unsaturated essential fatty acids, minerals (for example, calcium, iron, selenium and zinc), and vitamins, namely Vitamin A, B3, B6, B12, E and D.
Research has also shown that peptides derived from fermented fish following enzymatic treatment may be useful therapeutics for the treatment of many common acute and chronic diseases such as viral infections, hypertension, cancer and Alzheimer's disease [7]. Fish collagen may also be used in bone treatment as an alternative to mammalian collagen which is known to be immunogenic [8].

Technology in Exracting Marine Bioactive Compounds
Sample collection is the first and important step which is much more difficult in the marine environment than if working with terrestrial organisms. Selective extractions, separations, and purification procedures are followed. If the pure compound shows really interesting activity, further pharmacological assays (in vitro, in vivo, toxicity, tolerated dose, and so on) and chemical work (structure modification, preparation of analog, structure-activity relationship, total synthesis, cultivation, etc.) should be carried out in order to enter the development step. After biomass extraction with an adequate solvent system, the fist step in the isolation of a natural compound from the main extract or broth usually consists of a sequential gradient partition with solvents. Next the fractions of low or medium polarity contain lipophilic organic compounds that can usually be separated by standard normal or reverse phase column chromatography (CC) and/or MPLC and finally HPLC to get the individual components. The high-polarity fractions are chromatographed on Sephadex, and the individual components of the active fraction are further separated by countercurrent chromatography (i.e., DCCC) and/or HPLC on the appropriate column packing (C18, amino, cyano, etc.). Once the individual components are isolated in a pure form, efforts should be focused on the disclosure of their structure. This is carried out by spectroscopic methods, mainly MS and NMR (1D and 2D). Potent therapeutic agents are isolated from marine organisms using a conventional culturing method. Examples include AraC (the drug name of which is cytarabine) a clinically useful anticancer agent and bryostatin.

Metagenomics
Metagenomics affords an efficient and inexpensive method to capture this chemical diversity. Metagenomics is providing renewed insights into what chemical diversity means and how it originates in the ocean.

Bioactive Compounds Derived from Marine Organisms
Bioactive compounds derived from marine organisms has been reviewed in results. Anti-cancer agents have been isolated from algae, sponges, jellyfish, corals, shark cartilage and shellfish which are also summarised at one point. Commercially available marine by products have also been searched from the literature.  [9,10,11,12].

Category
Bioactive molecule Major marine source Health perspectives

Cold renneting milk and fish feed digestion aid Serine and cysteine Proteases
Crustaceans, mollusks and short-finned squid Preventing unwanted color changes in food products, meat tenderizing, curing of Herring, squid fermentation

Vitamins and Minerals
Fat and water soluble vitamins, iron, iodine, manganese and zinc Almost all marine sources. Seaweeds are rich sources of vitamins and minerals Vitamins and minerals perform many essential functions in the body, for example, they provide transport inside cells and also serve as cofactors during metabolic processes Table 2. Antitumor agents from marine sources [13].

Adaptations of Marine Organisms
Marine organisms show more adaptations compared to human (Figure 4)

Drugs from the Sea
Drugs from marine animals was compared with other terrestrial animals, terrestrial plants, marine plants and micro organisms and it found to be comparatively very high. Brown algae proved a rich biomedical resource. Chemical diversity clearly shows varied applications in medical field.

Discussion
Marine life constitutes almost 80% of the world biota with thousands of bioactive compounds and secondary metabolites derived from marine invertebrates such as tunicates, sponges, molluscs, bryozoans, sea slugs and many other marine organisms. These bioactive molecules and secondary metabolites possess antibiotic, antiparasitic, antiviral, anti inflammatory, antifibrotic and anticancer activities. They are also inhibitors or activators of critical enzymes and transcription factors, competitors of transporters and sequestrants that modulate various physiological pathways. The sources of new leads for treatment of many diseases such as cancer, AIDS, inflammatory conditions, and a large variety of viral, bacterial and fungal diseases. Metagenomics affords an efficient and inexpensive method to capture this chemical diversity.
Bioremediation speeds the natural degradation process. It is being used to clean up sewage, sludge, seafood wastes, and toxins in marine areas. By using genetically modified marine organisms, scientists are able to clean up or contain oil spills. For example, this approach achieved great success after the oil spill from the Exxon Valdez in Alaska. Research done on the Eastern Oyster has also produced the discovery of Polyaspartic Acid, which helps plants take in more nutrients from the soil without using as much fertilizer. This is helping to stimulate agriculture even further.

Conclusion
The marine environment provides a broad range of diverse habitats from which novel sources of natural products can be derived. Studies from around the world have shown that marine organisms produce a diverse array of metabolites with pharmaceutical properties used in the treatment of many diseases such as cancer, AIDS, inflammatory conditions, and a large variety of viral, bacterial and fungal diseases. Still there is a lot to unravel regarding the richness of marine environment. Thus an attempt to review few marine derived biomedical resources was done emphasizing that with the advent of modern technologies it is anticipated that the marine environment will become an invaluable source of novel compounds in the future. Still there is a lot to unravel regarding the richness of marine environment.
Need methods of recognizing species. Morphology has limited use.
Genetic markers (e.g., DNA sequences, length fragment polymorphisms in mitochondrial DNA) allow identification of populations With the advent of modern technologies it is anticipated that the marine environment will become an invaluable source of novel compounds in the future.