Carbohydrates, stabilizing agents

Several polyols (i.e. molecules displaying multiple hydroxyl groups) have found application as polypeptide stabilizing agents. Polyols include substances such as glycerol, mannitol, sorbitol and PEG, as well as inositol (Table 6.9 and Figure 6.22). A subset of polyols is the carbohydrates, which are listed separately (and thus somewhat artificially) from polyols in Table 6.9. Various polyols have been found to stabilize proteins in solution directly, and carbohydrates in particular are also often added to biopharmaceutical products prior to freeze-drying in order to provide physical bulk to the freeze-dried cake. 

They contain hydrophilic colloidal particles such as proteins, carbohydrates and phospholipids which act as stabilizing agents. 

Liquids. Liquid enzyme formulations usually contain a significant amount of stabilizing agents, such as carbohydrates, polyols and inactive (filler) proteins. In addition, side-products from the fermentation may be present. In general, they tend to stabilise enzymes and thus their removal (e.g., by dialysis) is not recommended. The same apphes to dilution, as concentrated protein solutions are usually more stable. Liquid formulations should be stored in the cold (0 to +4°C), but avoid freezing If long-term storage is required, two options are possible (if in doubt, test both methods on a sample first and check for any loss of activity) ... 

The incorporation of Ag-NP into biodegradable polymers for their potential applications in biotechnology has been a great interest topic in the last years (Huang et al. 2004 Narayanan and El-Sayed 2005 Mumgadoss and Chattopadhyay 2008 Sanpui et al. 2008 Rhim et al. 2013 Cheviron et al. 2014). The carbohydrates can act as a reducing and/or stabilizer agent, and also have the possibility to carry Ag-NP with excellent antibacterial activity. The formed nanocomposites result safe, biocompatible, nontoxic, and environmentally friendly (Rhim et al. 2013). 

Chemically, GA is a complex mixture of macromolecules of different size and composition (mainly carbohydrates and proteins). Today, the properties and features of GA have been widely explored and developed and it is being used in a wide range of industrial sectors such as textiles, ceramics, lithography, cosmetics and pharmaceuticals, encapsulation, food, etc. Regarding food industry, it is used as a stabilizer, a thickener and/or an emulsifier agent (e.g., soft drink syrup, gummy candies and creams) (Verbeken et al., 2003). 

The increase in pulp yield may reach 8% on dry wood basis, but requires high pressures (> 1000 kPa) and a large excess of hydrogen sulfide (ca. 10% of wood). Only a fraction of the hydrogen sulfide (1 -2% of wood) is consumed and the rest is recoverable. Table 7-7 illustrates the influence of some oxidizing and reducing agents on the carbohydrate yield of kraft pulp. Stabilization with anthraquinone is dealt with in Section 7.3.7. 

One of the critical factors in excipient selection and concentration is the effect on preferential hydration of the biopharmaceutical product [53, 54], Preferential hydration refers to the hydration layers on the outer surface of the protein and can be utilized to thermodynamically explain both stability enhancement and denatur-ation. Typical excipients used in protein formulations include albumin, amino acids, carbohydrates, chelating and reducing agents, cyclodextrins, polyhydric alcohols, polyethylene glycol, salts, and surfactants. Several of these excipients increase the preferential hydration of the protein and thus enhance its stability. Cosolvents need to be added in a concentration that will ensure their exclusion from the protein surface and enhance stability [54], A more comprehensive review of excipients utilized for biopharmaceutical drug products is available elsewhere [48],... 

---