Poly (Methacrylic Acid)-Grafted-Okra Gum: Synthesis, Characterization and Evaluation as Mucoadhesive

Abstract

Recently, worldwide extensive attention is being paid in exploration and exploitation of pharmaceutical excipients from natural resource. Various natural polysaccharides have been significantly reported as prospective drug delivery carriers. These natural gums are preferred over synthetic polymers because of their biocompatibility, low cost, free availability and biodegradability. But due to variable chemical composition, microbial load, microbial growth and change in viscosity upon aging, acceptability is low compared to commercial synthetic products. Tailoring or modification may be an approach to make them smart as drug carriers specially in order to modulate the site of drug release and it’s kinetic. The chemical modification of okra gum (OG) was the main objective of the present study in order to make it potential mucoadhesive for the application in mucoadhesive drug delivery. In this study, methacrylic acid was grafted onto okra gum. At first, okra gum has been isolated from the fruits of Hibiscus esculentus. Poly (methacrylic acid)-grafted-okra gum (PMAc-g-OG) was synthesised employing a microwave-promoted and redox-initiated method. Potassium persulphate was used as free- radical-initiator. Methacrylic acid was mixed to 1% solution of OG and then 30 ml of potassium persulphate aqueous solution was added to the previous mixture along with continuous stirring. The mixture was exposed to microwave in a domestic micro-oven. The mixture was kept overnight and the copolymer was collected and purified using acetone and aqueous methanol (30% v/v) subsequently. The copolymer was charateized by elemental analysis, FTIR, DSC-TGA, and ¹³C NMR study. Ex-vivo mucoadhesion test was performed using goat stomach. A highest % grafting of 448.32% was found in the synthetic procedure employed in the study. The characterization studies also substantiate the successful grafting. Ex-vivo mucoadhesion study also showed excellent mucoadhesive capacity over a period of 16 hours. The study exhibited that the method employed was very simple, less time consuming, one-pot and without N₂ atmosphere.  The copolymer also exhibited excellent mucoadhesivity which might be applied in different mucoadhesive drug delivery systems such as prolonged release gastroretentives, buccal gels, etc.