Processing of natural products

Recovery of valuable bioactive compounds by nanofiltration, from natural products or streams resulting from the processing of natural products, is also gaining an increasing interest. Recent examples include the production of natural extracts from olive oil subproducts, which are rich in the most potent natural antioxidant compound identified so far (hydroxytyrosol) as well as the production of natural extracts from grape pomace residues, which are rich in a number of high-value compounds. 

Weatherley, L. R. (1996). Solvent extraction of fermentation broth. In Downstream Processing of Natural Products A Practical Handbook (M. S. Verrall, ed.), pp. 71-91. Wiley, New York. 

Verrall, M. S. (1996). Downstream Processing of Natural Products A Practical Handbook. Wiley, New York. 

Oxidative cleavage with hydrogen peroxide as oxidant is more important in oxidation processes of natural products. The use of a three-fold excess of hydrogen peroxide without further additives, except for the catalyst methyltrioxorhenium (MTO), enables the oxidation of certain natural products drawn from styrene... 

Verrall, M S. 1996) Downstream Processing of Natural Products Wiley, Chichester, U.K. Ikan, R. (1991) Natural Products A Laboratory Guide. Academic, San Diego, CA. Belter, P. A, Cussler, E L, and Hu, W. S. (1988) Bioseparations Wiley, New York... 

When operating isocratically, it is efficient to recycle that portion of the eluting solvent that is clean, that is, does not contain sample components. However, it IS often not possible to recycle the eluting solvent during preparative HPLC processing of natural product extracts because of the presence of a multitude of other components, which elute over a wide timespan. But, for certain isocratic separations where the sample contains predominantly the desired material(s), recycling a proportion of the eluent is a potentially useful option. 

This excellent and underexploited technique can be utilized as a primary clean-up process of natural products extracts or as a final purification step. CPTLC makes use of a rotor that is coated with a sorbent to form a circular plate that is then attached to a spindle and rotated using a motor. Solvent is then introduced into the middle of the circular plate by a pump to equilibrate the sorbent. Plates should be saturated with solvent and allowed to equilibrate at a given flow rate for 10 min. The sample mixture can then be introduced to... 

The last two decades have seen tremendous breakthroughs in each of these technologies as well as in information transfer. This chapter attempts to outline the scope of the dereplication problems and show how these technological advances, along with long-established methods, can be applied to these processes of natural product dereplication and partial identification. 

Natural products have provided leads to new pesticides. Knowledge of the biosynthetic processes of natural products and... 

Processing of natural products with supercritical fluids-based technologies has been an extensive area of research during the past two decades. In fact, since many valuable products occurring in natural compounds, such as vitamins, aromas, natural pigments or essential oils, are soluble in supercritical fluids, their extraction from natural materials is one of the most widely studied applications of supercritical fluids. To date, SFE technology is used at industrial levels in economically relevant processes such as decaffeination of both colTee and tea and extraction of hop constituents and spices [19]. 

Traditional Chinese medicines (TCMs) serve as a major source of a variety of drug lead compounds. In the process of natural products development, bioassay-guided isolation is a rapid and validated method for isolation of compounds with bioactivities. This chapter describes bioassay-guided separation and purification of compounds from the crude extracts of TCMs. Two approaches including size-exclusion chromatography (SEC) and high performance liquid chromatography (HPLC) are described in detail. 

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