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Pharmacognosy is the study of crude drugs obtained from medicinal plants, animals, fungi, and other natural sources. [1] The American Society of Pharmacognosy defines pharmacognosy as "the study of the physical, chemical, biochemical , and biological properties of drugs, drug substances, or potential drugs or drug substances of natural origin ...
Plant extracts may interact with conventional drugs, both because they may provide an increased dose of similar compounds, and because some phytochemicals interfere with the body's systems that metabolise drugs in the liver including the cytochrome P450 system, making the drugs last longer in the body and have a cumulative effect. [125]
Complexation with phospholipids has been applied to a number of popular herbal extracts and active molecules including Ginkgo biloba extract, [4] bilobalide isolated from Ginkgo biloba, [5] silybin isolated from milk thistle (Silybum marianum), [6] curcumin isolated from turmeric, [7] and green tea extract (Camellia sinensis).
Although many consumers believe that herbal medicines are safe because they are natural, herbal medicines and synthetic drugs may interact, causing toxicity to the consumer. Herbal remedies can also be dangerously contaminated, and herbal medicines without established efficacy, may unknowingly be used to replace prescription medicines. [38]
Secondary metabolites and pigments may have therapeutic actions in humans, and can be refined to produce drugs; examples are quinine from the cinchona, morphine and codeine from the poppy, and digoxin from the foxglove. [1] In Europe, apothecaries stocked herbal ingredients as traditional medicines.
Because Ayurveda is often used by practitioners to supplement conventional modern medicine, the interactive effects of Ayurvedic treatments can medically significant. For instance, medicinal plant remedies can interfere with the cytochrome enzyme system (CYP), a network of liver enzymes extremely important in drug metabolism.
The drug must be found to be effective against the disease for which it is seeking approval (where 'effective' means only that the drug performed better than placebo or competitors in at least two trials). The drug must meet safety criteria by being subject to animal and controlled human testing. Gaining FDA approval usually takes several years.
Native American traditional herbal medicine introduced cures for malaria, dysentery, scurvy, non-venereal syphilis, and goiter problems. [20] Many of these herbal and folk remedies continued on through the 19th and into the 20th century, [ 21 ] with some plant medicines forming the basis for modern pharmacology.