Thiolated pectin: Synthesis, characterization and evaluation as a mucoadhesive polymer

The objective of present study was to enhance mucoadhesive potential of pectin by thiolation. Thiolation of pectin was achieved with esterification with thioglycolic acid. Thiolated pectin was characterized by FTIR, DSC, XRD and SEM analysis. Thiolated pectin was determined to possess 0.60 ± 0.04 mmol of thiol groups/g of polymer by Ellman's method. Comparative evaluation of mucoadhesive property of metformin-loaded ionotropically gelled beads of pectin and thiolated pectin by wash off test using goat intestinal mucosa revealed higher ex vivo bioadhesion time of thiolated pectin as compared to pectin. Improved mucoadhesive property of thiolated pectin over the pectin can be attributed to the formation of disulfide bond between mucus and thiolated pectin. In vitro release study conducted using phosphate buffer (pH 6.8) revealed a similar release profile of metformin from pectin and thiolated pectin beads. In conclusion, thiolation of pectin improves its mucoadhesive property without affecting the release profile.