Dextran degradation

R. R. Zohra, A. Aman, R.R. Zohra, A. Ansari, M. Ghani, and S.A.U. Qader, Dextranase Hyper production of dextran degrading enzyme from newly isolated strain of Bacillus licheniformis, Carbohydr. Polym., 92 (2), 2149-2153,2013. 

Fig. 63. Scission rate constant for the ultrasonic degradation of dextran as a function of molecular weight (M), in different solvents (according to Ref. [179]) ( ) formamide (a) 10% MgSQ4 ( ) water...

Degradation of Dextran by Ultrasonic Waves, M. Stacey, Research, 4 (1951) 48. 

Recently, Brich and coworkers (40) reported the synthesis of lactide/glycolide polymers branched with different polyols. Polyvinyl-alcohol and dextran acetate were used to afford polymers exhibiting degradation profiles significantly different from that of linear poly-lactides. The biphasic release profile often observed with the linear polyesters was smoothened somewhat to a monophasic profile. Further, the overall degradation rate is accelerated. It was speculated that these polymers can potentially afford more uniform drug release kinetics. This potential has not yet been fully demonstrated. 

Other important examples are blood and blood products, which are collected and processed in sterile containers, and plasma substitutes, for example dextrans and degraded gelatin. Dextrans, glucose polymers consisting essentially of (1 - 6) a-links, are produced as a result of the biochemical activities of certain bacteria of the genus Leuconostoc, e.g. L. mesenteroides (see Chapter 25). 

A second example is the colon-specific delivery of glucocorticoids linked to dextran via a succinic acid or glutaric acid spacer [256a]. Such conjugates resist hydrolysis in the upper gastrointestinal tract, but are rapidly degraded by bacteria in the colon and caecum where little drug absorption occurs. 

Fig. 5.11. Effect of irradiation time on the ultrasonic degradation of aqueous native dextran [2% w/v 60 W 30°C 20 kHz).

Fig. 5.14. The effect of the enthalpy of vaporisation on the degradation rate constant of dextran solutions. A - Water ...

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