Natural products extraction from

Flash chromatography is widely employed for the purification of crude products obtained by synthesis at a research laboratory scale (several grams) or isolated as extracts from natural products or fermentations. The solid support is based on silica gel, and the mobile phase is usually a mixture of a hydrocarbon, such as hexane or heptane, with an organic modifier, e.g. ethyl acetate, driven by low pressure air. (Recently the comparison of flash chromatography with countercurrent chromatography (CCC), a technique particularly adapted to preparative purposes, has been studied for the separation of nonchiral compounds [90].)... 

A great deal of interest has been shown in the mass spectral analysis of natural products. In most cases it is desirable to develop techniques incorporating g.l.c. to enable the separation of the components obtained in extracts from natural products. The volatility required for g.l.c. is... 

In API manufacture, whether via chemical synthesis, rDNA technology, or extraction from natural products, there are significant changes (physical and chemical) from the starting materials to the API. In the formulation process, however, the quality and specifications of the API are retained. The addition of excipients to produce the drug product in a finished dosage form does not present physical or chemical changes to the API. 

There are many publications and comprehensive handbooks on the thin-layer chromatography (TLC) of carbohydrates (e.g., Refs. 1 and 2). The reason is their great importance in life science and the great diversity of cases monosaccharide, disaccharide, trisaccharide, oligosaccharide, polysaccharide, aldose, ke-tose, triose, tetrose, pentose, hexose, as well as reducing and nonreducing sugars. In addition, when extracted from natural products or produced by fermentation, carbohydrates are accompanied by many impurities. That is why separation methods are used predominantly for their analysis. 

Diverse applications have been sought in the areas of monitoring quality, stability, and safety of pharmaceutical compounds, whether made synthetically, extracted from natural products, or produced by recombinant methods. Many of these applications are included throughout this book to afford ready reference to various methods. In addition, the reader may want to refer to the scientific literature where various applications of monitoring impurities are generally classified in the following categories 2... 

The non-pharmaceutical supplements are extracts from natural products such as seaweeds and sea shale, available in ancient mines and caves. Manufacturers claim... 

The concentrated sulfuric acid catalyses the reaction and binds the water formed. The reaction rate is increased by raising the temperature. However, the reaction mixture must be heated at reflux for several hours if large amounts of the ester are required. The reaction products are purified by distillation and characterised by means of modern analytical procedures. The esters are generally extracted from natural products by a careful. steam distillation, which is followed by separation of the components of the mixture. 

What is the source of the sample (chemical synthesis, fermentation, extraction from natural products, etc.) ... 

So far some very important aroma chemicals better known as flavor and fragrance chemicals used to be isolated and extracted from natural products such as essential oils, resinoids, extracts, etc. Solvent extraction, steam distillation or, more recently, supercritical fluid extraction using high pressure CO2 have been some of the important methods for isolation of the important flavor and fragrance chemicals. There is a wide range of aromatic chemicals both from natural sources or made by organic chemical synthesis which have been introduced in various finished products. They are never used in very pure form but are further formulated for specific... 

Traditionally, oxalic acid has been extracted from natural products by treating them with an alkaline solution, followed by crystallization of the acid. Sodium hydroxide is the alkaline material most commonly used for this procedure. Today, a number of methods are available for the commercial preparation of oxalic acid. In one procedure, carbon monoxide gas is bubbled through a concentrated solution of sodium hydroxide to produce oxalic acid. Alternatively, sodium formate (COONa) is heated in the presence of sodium hydroxide or sodium carbonate to obtain the acid. Another popular method of preparing oxalic acid involves the oxidation of sucrose (common table sugar) or more complex carbohydrates using nitric acid as a catalyst. The reaction results in the formation of oxalic acid and water as the primary products. 

In synthetic chemistry, SFE can be attractive as an alternative to conventional methods for purification of reaction products such as vitamins, pharmaceuticals and many other high-value products [4], Its technical use is currently mainly restricted to applications in food industry for extraction from natural products and in some cases for the fractionation of the products [5]. This chapter therefore focuses on these types of production and purification processes, but all the methodologies discussed may be readily adapted to synthetic applications. Equipment for carrying out separation processes of various sizes is available from coimnercial suppliers, and is described in more detail in Chapter 2.1 and elsewhere [1]. 

A recently developed industrial-scale application is a textbook example of the main advantages of supercritical carbon dioxide in extractions from natural products. The Diamond process, jointly developed by the Centre d Energie Atomique and the French company Sabate, [2] extracts the contaminant trichloroanisol (TCA) from cork stoppers for wine bottles. This contaminant is produced by fungi and is responsible for the infamous cork taint taste of wines, which has brought serious financial losses to the wine industry and damaged the image of cork as the ideal material for bottle stoppers. 

The third tool combines the rapid screening of combinatorial libraries or of a series of extracts from natural products to preparative-scale purification of biologically active compounds. The fractionation is controlled by the response of the compoimd of interest in the LC-MS. 

Nature has been a source of medicinal agents for thousands of years. Compounds extracted from natural products have been used either as a new drug or a lead molecule to synthesize modem therapeutic agents in the treatment of variety of diseases for centuries. Pharmacologic activities have been found in different kinds of secondary metabolites such as alkaloids, terpenoids, coumarins, flavonoids, and lignans, all firstly isolated from plants. 

The determination of riboflavine in most pharmaceutical materials does not require the complicated procedure necessary for its extraction from natural products (where the extraction is the cause of most error). A microbiological method is, however, necessary for yeast preparations and is official for vitamin capsules. 

LC-MS finds wide application in the analysis of compounds that are not amenable to GC-MS, i.e. compounds that are highly polar, ionic and thermo-labile, as well as (bio)macromolecules. In environmental applications, LC-MS is applied, often in combination with off-line or on-line solid-phase extraction, to identify pesticides, herbicides, surfactants and other environmental contaminants. LC-MS plays a role in the confirmation of the presence of antibiotic residues in meat, milk and other food products. Furthermore, there is a substantial role for LC-MS in the detection and identification of new compounds in extracts from natural products and the process control of fermentation broths for industrial production of such compounds, e.g. for medicinal use. LC-MS technology is also widely applied in the characterization of peptides and proteins, e.g. rapid molecular-mass determination, peptide mapping, peptide sequencing and the study of protein conformation and noncovalent interactions of drugs, peptides and other compounds with proteins and DNA. However, the most important application area... 

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