Pharmaceuticals hemicellulose

For thousands of years, nature has provided humankind with a large variety of materials for the most diversified applications for its survival, such as food, energy, medicinal products, protection and defense tools, and others. The pharmaceutical industry has benefitted from such diversity of biomaterials and has exploited the use of natural products as sources of both drugs and excipients. One example of a promising biomaterial for pharmaceutical use is xylan, a hemicellulose largely found in nature, being considered the second most abundant polysaccharide after cellulose. 

Abstract Cellulose is the most important biopolymer in Nature and is used in preparation of new compounds. Molecular structure of cellulose is a repeating unit of p-D-glucopyranose molecules forming a linear chain that can have a crystallographic or an amorphous form. Cellulose is insoluble in water, but can dissolve in ionic liquids. Hemicelluloses are the second most abundant polysaccharides in Nature, in which xylan is one of the major constituents of this polymer. There are several sources of cellulose and hemicelluloses, but the most important source is wood. Typical chemical modifications are esterifications and etherifications of hydroxyl groups. TEMPO-mediated oxidation is a good method to promote oxidation of primary hydroxyl groups to aldehyde and carboxylic acids, selectively. Modified cellulose can be used in the pharmaceutical industry as a metal adsorbent. It is used in the preparation of cellulosic fibers and biocomposites such as nanofibrils and as biofuels. 

Produced from renewable resources, organic fibers and their derivatives have a wide range of functional applications. In the pharmaceutical and food industries, the presently best known cellulosic additive is microcrystalline cellulose (MCC). It is obtained from wood cellulose by acidic hydrolysis. The product does no longer contain lignins, hemicelluloses, or other impurities and is bleached to produce a high degree of brightness. 

Potential of hemicellulose in the pharmaceutical field could potentially be developed as drug formulation excipients such as binders, disintegrator, thickeners, and stabilizers. In addition, applications of hemicellulose have been done by making the derivatives that have pharmacological effects such as lowering cholesterol and inhibitors of HIV [26-28,41, 57]. 

Hemicellulose can be used as a source of raw material for several industrial processes. This polymer is applied in the biotechnology and pharmaceutical uses by formulation of various derivatives through a variety of chemical reactions [33, 34, 40]. 

Hemicellulose is a renewable natural resource and can be used for the needs of pharmaceutical raw materials both as a carrier and as a raw material for medicine. 

Wood The main compounds of wood are cellulose, hemicellulose, and lignin. Their share varies between hardwood and softwood as well as between single species. Table 4.4 shows the average shares of compounds in the cell wall of European hard- and softwood. Additionally, wood and bark contain a variety of extractives that are of interest for chemical and pharmaceutical applications. 

Garrett, E. R. Dvorchik, B.H. J. Pharmaceut. Sci. 1969. 58, 813-820. Vedernikov, N. Hemicelluloses Zinatne Riga, 1991,209-222 (in Russian). Vedernikov, N. Proc. lO" Intern. Symp. Wood and Pulping Chemistry, Yokohama, Japan, June 7-10,1999,3,468-470. 

Cellulose, the most abundant renewable and biodegradable polymer, is the promising feedstock for the production of chemicals for their appUcatimis in various industries. Annual production of cellulose in nature is estimated to be lO"—10 t in two forms, partially in a pure form, for example seed hairs of the cotton plant, but mostly as hemicelluloses in cell wall of woody plants (Klenun et al. 1998). The versatility of cellulose has been reevaluated as a useful structural and functional material. The environmental benefits of ceUulosics have become even more apparent (Hon 1996a). Cellulose is revered as a constmction material, mainly in the form of intact wood but also in the form of natural textile fibers like cotton or flax, or in the form of paper and board. The value of cellulose is also recognized as a versatile starting material for subsequent chemical transformation in production of artificial ceUulose-based threads and films as well as of a variety of cellulose derivatives for their utilization in several industries such as food, printing, cosmetic, oil well drilling, textile, pharmaceutical, etc. and domestic life. 

For biomedical purposes, considerable research has been done in the area of hemicelluloses due to the biocompatibility, biodegradability, and high stability of these compounds. Many hemicelluloses are already widely used in the pharmaceutical industry, while others are as yet relatively unexploited. More specialized drugs and methods of drug delivery will be necessary to fulfill requirements, as progress in the pharmaceutical industry leads to increased demands on materials for specific applications. Lots of hemicelluloses are already commonly used in this field, and other less investigated hemicelluloses may find application in the future. ... 

Keywords Agar, alginates, carrageenan, cellulose, chitin, chitosan, excipients, hemicelluloses, natural, pharmaceutical, polysaccharides, tragacanth... 

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