Membrane of Usnic Acid in Solid Dispersion and Effectiveness in Burn Healing

Abstract

Usnic acid, a yellow crystalline of secondary metabolite of Usnea sp., has been known for its tremendous pharmacological activities including antibacterial and anti-inflammatory activities. The aim of this study was to prepare membrane containing usnic acid and evaluate its effectiveness for burns healing. Prior to the preparation of membrane, usnic acid was modified into solid dispersion (SD) system by freeze drying method using PVP K-30 (ratio usnic acid-PVP: 1:2 w/w). Then, usnic acid in solid dispersion with equivalent concentration of usnic acid at 0.5% (F1), 1% (F2), and 2% (F3) were formulated into membrane using poly-vinyl alcohol (PVA), glycerin and distilled water. The membranes were evaluated for the physical and mechanical properties including: appearance, thickness, tensile strength, percent of elongation, and Young's modulus. The effectiveness of burn healing activity was done on male white rabbits by creating superficial burns and evaluated the diameter of wound for 21 days. The appearance of each membrane was transparent but the color was different due to the concentration of usnic acid. The thickness of each membrane was less than 0.1 mm. F2 had the highest tensile strength, percent of elongation, and Young's modulus. Meanwhile, F3 showed a better result in burn healing compared to F2 and F1. The higher concentration of usnic acid solid dispersion in membrane increased effectiveness of burn healing significantly (p<0.05).