Novel drug delivery systems: Chitosan conjugates covalently attached to steroids with potential anticancer and agrochemical activity

Chitosan (CS) was linked to diosgenin monoesters with potential anticancer and agrochemical activity employing several methods (i.e. solid phase microwave assisted synthesis with carbodiimides activation, acyl chloride approach and homogeneous reaction with carbodiimides activation in aqueous solution). The steroid contents found by elemental analysis were between 5 and 33% (w/w) and was dependent on the nature of the employed linker and the steroid-CS conjugates preparation method. Linking was confirmed by FTIR spectroscopy. Differential scanning calorimetry studies are presented. In vitro release studies performed in water at different pH indicated a drug release dependence on the dicarboxylic acid employed as linker, the steroid content and the acidity of the solution. The obtained conjugates can be potentially applied as films, microspheres or gels for delivery of plant growth regulators in agriculture and anticancer drugs. (C) 2010 Elsevier Ltd. All rights reserved.