8.5.1.4　Chitosan and its derivatives

Chitosan are a group of cationic polysaccharides consisting of β-（1-4）-linked Dglucosamine and N-acetyl-D-glucosamine that are randomly distributed along the main chain.Among them，only relatively low molecular weight chitosan can increase the permeability of the skin，such as promoting the penetration of baicalin（an anti-tumor drug）into mouse skin.Nuclear magnetic resonance（NMR）spectroscopy shows that chitosan have no electrostatic interaction with keratin or glycoprotein in the stratum corneum，so the increased permeability of the stratum corneum may be ascribed to the dipole-dipole and van der Waals interaction between chitosan and lipid biomolecules.Other chitosan derivatives with penetration promoting effect include N-trimethyl chitosan，N-arginine chitosan and so on.(https://www.daowen.com)