Planet earth is covered with 70% of water; life was first seen in water bodies. There are large amount of flora and fauna in the sea and the coastal line. Marine ecosystem is rich source of both biological and chemical compounds which are widely being used in pharmaceutical, cosmetic, nutrition supplements, molecular probes, enzymes and agricultural chemicals.
In the past 30-40 years numerous compounds have been isolated from marine microbes they are biologically active and have a high value in drug development. In 1936 at Scripps institute a study based on antibiotic activity from marine microbes was found which was mainly focused to know "why sea water was bacteriostatic or bactericidal to non marine culture". It was seen 9 species of microbes had antibiotic property. This brought a great attention of many scientists to produce antibiotics from marine microbes. In 19th and 20th century cod liver oil was used as food supplement. In the middle of 20th century scientists began to use the oceans for pharmaceutical drugs. Thousands of marine microbes contain antibiotic substances but only some were used for pharmacological activity. Bacteria which produce bioactive substance in its surrounding habitat for protecting itself from predators have a high quality of antibiotic activity. The chemicals released exhibit antibacterial, antiviral, antitumor, anticoagulant and cardio active property when subjected to human conditions.
Not only microbial species even fishes are used for many of the product for human health and growth. The most well known paralytic shellfish toxin is Saxitoxin other than these there are other compounds like Neosaxitoxin. Due to potential health hazard of shell fish poisoning, monitoring program on protection of shellfish toxicity have been introduced in many countries. " Drug from the sea conference" was held in 1967 at university of Rhode Island (US) in which marine natural products was the main matter to be discussed. The rapid discovery and commercialization of new marine compound for free market. It took 30 years to all pharmaceutical company to derive compounds from marine and to perform final stage of clinical trials. The long and slow process was due to method of sample collection and expensive infrastructure to maintain these samples. Pharmaceutical companies had to hire young scientists from university for collection of samples and conduct experiments on the microbes. The optimum climate out of its natural ecosystem had to be established and constructed so that they produce the same quality of compounds and multiple. Mostly these marine microbes can only be found in the depth of sea at a limit of 30 -40 meters. Terrestrial fungi and actinomycetes have proven to be excellent sources for antibiotic activity.
All living organism produce metabolites, "Primary metabolites" are those compounds that are essential for growth, development and reproduction. The metabolic products that serve other function than these are called secondary metabolites. In some organism secondary metabolites is secreted out as waste product or stored in its body. In these cases the microbes in ecology affect the surrounding microbial colony. The waste produced from microbes can be attractive of defensive or aggressive function. For example cytotoxic prevents over growth and repel predator, antibiotic that kills microorganisms and stop their growth so that these microbes could grow and multiple.
The pharmaceutical potential of plant was discovered in early human history. The oldest example is Ayurveda and pharmaceutical records of Mesopotamian clay tablets in 2600BC which is still being used. Sponges similar to plants are sessile organism hence face various analogous ecological challenges. These get fixed on rock or coral and lose their efficient defense mechanism. Over 9000 known Sponges species represent a huge amount of natural products. More than 4000 new natural products are isolated from sponges. Many products showed pronounced biological activity. Some of the compounds are as follows
Vibarabine: - An antiviral drug, used against Herpes Simplex Encephalitic virus, anti cancer drug, which is a semi synthetic substance based on arabinosyl nucleosides. Isolated from sponge Tethya Crypta.
Halichondrin B: - Isolated from Halichondria Okadai. Compound had proven anti cancer activity, synthetic derivative E7389, currently in clinical trial against lung cancer.
Agelashins: - From Sponge Agelas mauritianus have proved antitumor and immune stimulatory property. Synthetic derivative used in clinical trial for cancer immunotherapy.
Psammaplin A: - A compound present in several species of the order Verongida, but was first found in Psammaplysilla sp. It was a lead structure for the synthetic anticancer compound NVP-LAQ824 and for the antibiotic against the bacterium Staphylococcus aureus.
Contignasterol: - Isolated from the sponge Petrosia contignata. Synthetic derivatives of this compound are in clinical trials against asthma and inflammation of the skin and eye.
Dideminins: - Cyclic depsipeptides isolated from Trididemnum species. Didemnins B being antiviral it shows pronounced antitumor activity. Avarol and Avarone are isolated from Disidea Avara, they inhibit the immunodeficiency virus, high therapeutic values induces and ability to cross blood through brain barrier.
Although large numbers of novel compounds have been isolated from marine organisms and many of these substances have pronounced biological activity, only very few have been marketed as pharmaceutical products. A few have also been valuable as 'lead' compounds, which have led to derivatives of them being marketed. Some compounds with cytotoxic properties both have been undergoing various phases of clinical trial and thus have the prospect of being new pharmaceutical products in the future. Despite major contributions to natural products the compounds extracted from marine organisms has been disappointing as the development of new medicinal agents is concerned.
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