A natural product is a chemical substance produced by a living organism. It is found in nature and has biological effects that can be studied in order to support drug discovery and drug design. A substance is considered a natural product even if it can be prepared by total synthesis. 
Sources of natural products are plants, bacteria, marine environments, and animal venoms.
Coprophiles are organisms that specifically thrive in animal dung. These territorial species spit out toxic chemicals to its neighboring fungi. Scientists and researchers allocate this information and specifically search for chemicals that are rather poisonous to some fungi and can be potentially dangerous to people that are infected.
Cyanobacteria, or blue-green algae, are plant-like organisms that live in both wet and damp environmental conditions. Cyanobacteria are photosynthetic organisms that can create energy from sunlight. These microorganisms can be found in colonies called algal bloom, and have dated back to the oldest fossils on earth. They make up one of the largest groups of bacteria in the world, and are linked to many human and animal diseases. Blooms will form when there is extravagant growth of the bacteria within a few days time. These algal blooms will cause clear water to become cloudy looking. Cyanobacterial blooms are dangerous because they can use up all of the oxygen present in the water they grow in, which will kill the other plants and animals living there. Some cyanobacteria even produce some of the most powerful natural poisons known, with no antidotes.
However, these species have been proven to become sources of cancer and bacterial cell killers. For example, the compound cryptophycin-8 can tear apart the scaffolding in a spectrum of tumors. Another molecule called majusculamide C focuses in on fungi, potentially allowing it to be used to treat fungi-related diseases in humans.
Filter feeders are organisms that stick to rocks and coral. These species compete with others for food and other natural resources. Filter feeders use an aquatic feeding method for getting their food. Scientists and researchers have discovered that some of the potent chemicals found in filter feeders can be used in the long run to treat cancer and other fatal diseases.
Filter feeders include the sea sponge, which is the simplest of multi-cellular animals. Sea sponges produce a great array of toxins, which they either release into the water or show on their surfaces. These toxins will ward off any predators that would feed on the sponges. Symptoms of being in contact with these toxins include: redness at the site of contact, pain, tingling, itching, swelling, bumps, nausea, or even fainting.
Despite their toxicity, sea sponges have proved to show great promise in the area of fighting infectious diseases and cancers. Scientists have been able to extract anti-viral, anti-cancer, and anti-neoplastic compounds from sea sponges to create many drugs. For example, in the 1950's chemists used sponge compounds to create a drug for treating Herpes called Acyclovir (Zovirax), and a drug to treat non-Hodgkin's lymphoma called Cytarabine (Cytosar). 
Ultimately, all of these natural products have been scientifically utilized to create both a wanted and an unwanted effect. In short, many of these chemicals show a promising future in the field of medicine.
Tunicates lie under the category of filter feeders that are greatly contributing to the medicinal research of cancer drugs. Also known as sea squirts, tunicates look merely like little colorful blobs but offer much to the pharmaceutical world than one would expect. For example, in the West Indie coral reefs, a tunicate named Ecteinascidia turbinata contributes to the fight of cancer. This marine animal, as discovered by Ken Rinehart from the University of Illinois, harbors the natural substance ecteinascidin used to make the cancer drug named Yondelis™. Although this medicine is still in its preliminary stage and further research needs to be done, lab tests have already confirmed that it can kill cancer cells and is suitable for human intake.
Recently, Elias J. Corey from Harvard University has discovered the way to synthesize ecteinascidin in the labs. This is important because to produce one gram of medicine, more than one ton of tunicates need to be harvested; a clearly ineffective process. With the ability to synthesize the natural product of interest, scientists are catalyzing the advancement of utilizing natural products to produce effective medications to cure diseases. 
HEALTH AND HUMAN SERVICES, </ref>]] Taxol is a drug used in the treatment of cancer. It is derived from the bark and needles of a tree called the Pacific Yew (Taxus brevifolia), which dies when taxol is extracted. On the downside, although it is one of the most useful drugs in fighting cancer, a small sample of taxol is produced from a large quantity of Yew barks (about 1200 kg of bark produces 10 g of pure taxol). Because of the negative impact the production of this drug has on the environment, the creation of taxol raises concerns over the ecological effects on the yew population.
Taxol works by preventing cancer cells from replicating. It does so by binding to the microtubules during cell division by preventing them from breaking down. Because in microtubules are normally disassembled after the cell divides, the presence of microtubules prevents the cell from dividing into daughter cells. 
Epibatidine is a molecule found on the skin of a species of Ecuadorian frog (Epipedobates tricolor) that has an analgesic effect, meaning that it is an effective painkiller. Although studies have proven Epibatidine to be a more effective painkiller than morphine, Epibatidine is poisonous and small doses of it can kill a large organism. Because of this, Epibatidine is unlikely to be available for the medicine market.
Epibatidine works by binding the nicotinic acetylcholine receptor (nAChR) binding sites. When nicotinic acetylcholine receptors are bound by neurotransmitters, it releases dopamine and norepinephrine, which causes the organism to be insensitive to pain. 
Clostridium botulinum is a bacterium that produces a type of toxins called neurotoxins, which are responsible for food poisoning. In the late 1960s, scientist Alan Scott tested botulinum toxin type A (BTX-A) in monkeys and discovered that BTX-A can be used to treat strabismus (a condition which the eyes are not aligned with one another).
A more well-known use for the botulinum toxin is its ability to reduce wrinkles and frown lines when injected into the skin. Many celebrities undergo botox (short term for botulinum toxin) to smooth out their facial skin. 
- Davis, Alison, Ph.D., (2006), Medicines By Design: Drugs from Nature, Then and Now: Ocean Medicines (NIH Publication No. 06-474): U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES,