Inhibitory activity of phosphorylated chitooligosaccharides on the formation of calcium phosphate

Chitooligosaccharides (COSs) were successfully prepared using an ultrafiltration membrane bioreactor system, and named as COS-I (10-5 kDa), COS-II (5-3 kDa), COS-III (3-1 kDa), and COS-IV (below 1 kDa), respectively. In addition, their phosphorylated derivatives were prepared by a P2O5 in methanesulfonic acid solution, and inhibitory activity on the formation of insoluble calcium phosphate of phosphorylated chitooligosaccharides. Phosphorylated COS-IV exhibited the highest inhibitory activity of calcium phosphate precipitation among tested chitooligosaccharides. Its inhibitory activity, especially at the concentration more than 4 mg/ml, was similar to that of CPP, which is widely used as a calcium fortifying agent increasing calcium absorbability. Therefore, phosphorylated chitooligosaccharides may be potential inhibitors of calcium phosphate precipitation.