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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 ...
A Soxhlet extractor has three main sections: a percolator (boiler and reflux) which circulates the solvent, a thimble (usually made of thick filter paper) which retains the solid to be extracted, and a siphon mechanism, which periodically empties the condensed solvent from the thimble back into the percolator.
Prior to the 1950s, every pharmacy student learned about crude drugs in pharmacognosy class. Pharmacognosy is the study of the proper horticulture, harvesting and uses of the raw medications found in nature. Raising, harvesting and selling crude drugs was how many large pharmaceutical companies started out.
Laboratory-scale liquid-liquid extraction. Photograph of a separatory funnel in a laboratory scale extraction of 2 immiscible liquids: liquids are a diethyl ether upper phase, and a lower aqueous phase. Soxhlet extractor. Extraction in chemistry is a separation process consisting of the separation of a substance from a matrix. The distribution ...
In the acidic extraction, the raw plant material is processed by a weak acidic solution (e.g., acetic acid in water, ethanol, or methanol). A base is then added to convert alkaloids to basic forms that are extracted with organic solvent (if the extraction was performed with alcohol, it is removed first, and the remainder is dissolved in water).
While HTS is a commonly used method for novel drug discovery, it is not the only method. It is often possible to start from a molecule which already has some of the desired properties. Such a molecule might be extracted from a natural product or even be a drug on the market which could be improved upon (so-called "me too" drugs).
In brewing, decoction mashing is the traditional method where a portion of the mash is removed to a separate vessel, boiled for a time and then returned to the main mash, raising the mash to the next temperature step. [citation needed] In herbalism, decoctions are usually made to extract fluids from hard plant materials such as roots and bark. [2]
Steam distillation once was a popular laboratory method for purification of organic compounds, but it has been replaced in many such uses by vacuum distillation and supercritical fluid extraction. It is however much simpler and economical than those alternatives, and remains important in certain industrial sectors.