Sources of Drugs – Plants, Animals, Marine and Tissue Culture
- Natural Products
- Drugs obtained from Animal Sources
- Drugs obtained from Marine Sources
- Plant Tissue Culture
A natural product is a chemical compound or substance produced by a living organism – found in nature is that usually has a pharmacological or biological activity for use in pharmaceutical drug discovery and drug design. A natural product can be considered as such even if it can be prepared by total synthesis. Natural products may be extracted from tissues of terrestrial plants, marine organisms, or microorganism fermentation broths. A crude (untreated) extract from any one of these sources typically contains novel, structurally diverse chemical compounds, which the natural environment is a rich source of. The basic difference between active constituents and phytoconstituents is also important to identify the therapeutic active principles in the plants. Phytoconstituents are the whole chemical constituents that are present in the plants and active constituents are the specific chemical constituents that are therapeutically active or are responsible for the medicinal activity that is isolated from other extracted chemical constituents.
The most important things are to identify the natural origin plant sources like shrub, tree, creeper, and herbs that are the most basic criteria for authentication of the plant. Further traditional plants, complementary/alternative medicine, endangered plants, medicinal plants, aromatic plants, and natural products are also important terminologies that are quite similar, but an exact knowledge of these will provide good skill to the Pharmacognosists for research and to develop new drug molecules.
Shrub: A shrub is distinguished from a tree by its multiple stems and shorter height, usually under 6 m (20 ft) tall.
Tree: A tree is a perennial woody plant. It typically has many secondary branches supported clear of the ground by a single, self-supporting main stem or trunk.
Creeper: It is a prostate or trailing plant that spreads using stems that creep. These plants creep along the soil surface, though, unlike climbers, they have strong stems and a firm grip on the soil.
Herb: As per the botanists, an herb is a plant with no woody stem above ground distinguished from a tree or a shrub. In general terms, any part of the vegetable species that can be used for medicine, cosmetics, culinary or such purposes is known as an herb. The roots, leaves, bark, fruits, flowers, stems, or any part of the plant can be used for these purposes.
Traditional plant medicine: It is a system of plant-based on cultural beliefs from generation to generation and practices handed down to formulate the medicines for curing the diseases. Traditional medicine is the total of the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis, improvement, or treatment of physical and mental illness.
Complementary/alternative medicine (CAM): The terms “complementary medicine” or “alternative medicine” are used interchangeably with traditional medicine in some countries. They refer to a broad set of health care practices that are not part of that country’s tradition and are not integrated into the dominant health care system.
Endangered plant species: An endangered plant species is a population of plants that are facing a high risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters such as habitat destruction, climate change, or pressure from invasive species.
Medicinal plants: Medicinal herbs are plants or parts of plants used for therapeutic or medical benefit.
Aromatic plants: Plants that produce and exude aromatic substances (largely ether oils), which are used in making perfumes, in cooking, and in the food, pharmaceutical, and liquor industries.
Plant source is the old source of the drugs. Whole parts of the plants are used like leaves, stems, bark, fruits, roots, etc. Some important natural drugs that are procured from, plant sources are listed in table.1.
Table 1: Various sources of plant drugs
Drugs obtained from Animal Sources
The drugs that are procured from animal sources are depicted in table 2.
Table 2: Various sources of animal-based drugs
Drugs obtained from Marine Sources
There are more than 5 lakh species of marine organisms available in the seas and ocean. They are used for many important therapeutic activities. The enormous ecological resources of the sea and ocean have been exploited since ancient times and the use of marine animals like fish and preparations from algae are included as the sources of medicine. Oceans contain more than 80% of diverse plant and animal species. Such organisms like sponges, tunicates, fishes, soft corals, nudibranchs, sea hares, opisthobranch Molluscs, echinoderms, bryozoans, prawns, shells, sea slugs, and marine microorganisms are sources of bioactive compounds. The drugs that are procured from marine sources are depicted in tables 3 and 4.
Table 3: Marine anticancer natural products
Table 4: FDA approved drugs from marine sources
Many of the drugs from marine sources are in the clinical phase.
Plant Tissue Culture
It is in-vitro cultivation of plant cells, tissues, and organs in liquid or semi-solid nutrient media under an aseptic and controlled environment. In this method, primary and secondary plant metabolites are regenerated. The basic criteria for plant tissue culture are totipotency and plasticity. Totipotency is defined as the regeneration capacity of the selected plant parts whereas plasticity is the withstand capacity of plants in any stressful condition. The plant tissue culture technique is important because isolation of bioactive compounds from the medium is very easy, rare and endangered plant species are micropropagated and cultivated in mass scale, production of immobilized plant cells for future use, and even biochemical conversion is easy, etc.
- Mass scale production of plants.
- Conservation of endangered plant species.
- Cultivation of disease-resistant plants.
- Production of micropropagated plants.
- Some plants, which do not multiply by seeds, can be propagated through the plant tissue culture technique.
- More amounts of secondary metabolites are produced.
- A large number of plants can be produced in a short time.
- Chemicals that are used in the tissue culture increase the capacity of produced plants to resist biocidal chemicals, environmental stress, and compete to survive over weed.
- Isolation of constituents from the plant is easy.
- Mass propagation of plants is easy.
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