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copied from Drug discovery

Until the Renaissance, the vast majority of drugs in Western medicine were plant-derived extracts. This has resulted in a pool of information about the potential of plant species as an important source of starting material for drug discovery. A different set of metabolites is sometimes produced in the different anatomical parts of the plant (e.g. root, leaves and flower), and botanical knowledge is crucial also for the correct identification of bioactive plant materials.

Many secondary metabolites produced by plants have potential therapeutic medicinal properties. These secondary metabolites contain bind to and modify the function of proteins (receptors, enzymes, etc.). Consequently, plant derived natural products have often been used as the starting point for drug discovery.

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Until the Renaissance, the vast majority of drugs in Western medicine were plant-derived extracts. This has resulted in a pool of information about the potential of plant species for drug discovery. Botanical knowledge about different metabolites and hormones that are produced in different anatomical parts of the plant (i.e. roots, leaves, and flowers) are crucial for correctly identifying bioactive and pharmacological plant properties. Identifying new drugs and getting them approved for market is a stringent process due to regulations set by the Food and Drug Administration (FDA). However, with new diseases emerging, novel methods and approaches are being sought to increase the capacity in which phytochemical compounds can be applicable to treatment of human diseases. Phytotherapy, a more scientific approach, to botanical medicine is being implemented to pass regulations set by the FDA.

Many secondary metabolites and plant hormones have potential therapeutic medicinal properties. These secondary metabolites contain many functional groups that allow them to bind to and modify protein functions (i.e. receptors, enzymes, etc.). Consequently, plant derived natural products have often been used as the starting point for drug discovery. The activity of these products are being exploited to develop drugs with many properties, such as anti-cancer and anti-inflammatory drugs. Two important plant hormone families, jasmonates and salicylates, have been identified to provoke human cell responses.

Jasmonates

Chemical structure of methyl jasmonate (JA).

Jasmonates are important in responses to injury and intracellular signals. They induce apoptosis and signaling cascades via proteinase inhibitors, have defense functions, and regulate plant responses to different biotic and abiotic stresses. Jasmonates also have the ability to directly act on mitochondrial membranes by inducing membrane depolarization via release of metabolites. They stimulate the release of cytochrome c into the cytosol which induces apoptosis. When jasmonates are appropriately activated, there is a lower ratio of leukemic cells remaining in cancer patients. Furthermore, methyl jasmonate (JA) activates apoptosis only against tumor cells and initiates cellular senescence, a tumor suppression mechanism. While there is still ongoing research on the effectiveness of jasmonates in treating cancer, it has very promising medicinal uses according to scientists.

Jasmonate derivatives (JAD) are also important in wound response and tissue regeneration in plant cells. They have been identified to have anti-aging effects on the human epidermal layer. It is suspected that they interact with proteoglycans (PG) and glycosaminoglycan (GAG) polysaccharides, components important for remodeling of the extracellular matrix (ECM). The discovery of JADs on skin repair has introduced newfound interest in the effects of these plant hormones in therapeutic medicinal application.

Salicylates

Salicylic acid (SA), a phytohormone, was initially derived from willow bark and has since been identified in many plant species. It is an important player in plant immunity, although its role is still not fully understood by scientists. For salicylates to effectively respond against threats to plants, they must bind to salicylic acid binding proteins (SABPs). When multiple SABPs with high binding affinities were identified in animal tissue, the usage of salicylates was exploited for management of disease and immune responses in mammals. The first discovered medicinal properties of SA were involved in pain and fever management. It was later uncovered that they also play an active role in the suppression of cell proliferation and induce death in lymphoblastic leukemia and other human cancer cells. One of the most common drugs derived from salicylates is aspirin, also known as acetylsalicylic acid, with anti-inflammatory and anti-pyretic properties. This synthetic compound has a similar mechanism to the natural plant-derived salicylates. They both target enzymes such as COX1 and COX2 (cyclooxygenases) which convert arachidonic acid to prostaglandins. Prostaglandins are lipid molecules that have hormone-like functions in almost all animal tissue; they foster inflammatory responses and increase pain sensitivity. When salicylates bind to cyclooxygenases, these enzymes are inhibited, effectively decreasing prostaglandin concentrations. The principal difference between the synthetic and natural form of salicylates is that aspirin is extremely fast-acting relative to the natural extracts.