2.1. Materials The gum Prunus cerasoides D. Don was collected from Aizawl, Mizoram, India (during the month of May-July). Diclofenac sodium was obtained from Kowsik Pharmaceuticals, Chennai, India. Calcium chloride and sodium alginate were purchased from SD Fine Chemicals Limited, Mumbai, India. All the chemicals and reagents used were of analytical grade.
2.2. Purification of Prunus cerasoides gum The purification of the gum was carried out as previously described by our group . Briefly, the crude gum powder was boiled with 80% ethanol solution to deactivate enzymes and dissolve out low molecular weight carbohydrates with coloring matters. Thereafter, it was dispensed in deionized water and gently stirred overnight in a magnetic stirrer. The gum solution was allowed to stand for 12 h at room temperature to detach any undissolved matters. The gum solution was then filtered by triple folded muslin cloth and evaporated up to one third of the original volume using a rotary vacuum evaporator (Heidolph, Germany), cooled, precipitated with isopropanol and air dried. The end product was passed via sieve (no. 85) and stored in desiccators until use.
2.3. Preparation of DS loaded mucoadhesive beads PC-SA [F0], DS-SA [F1] and DS-PC-SA [F2-F6] beads were prepared by the ionotropic gelation method and the compositions are summarized in Table 1. Initially, PC gum was dissolved in distilled water and boiled for 10 min, cooled and stirred for 24 h at