Bitter Leaf Crude Extracts-Loaded Alginate Films as Potential Wound Dressings

Abstract

The bitter leaf (BL), a tropical herbal plant which possess antioxidant activity and several pharmacological properties, was extracted using water, ethanol, and ethyl acetate as solvents. The yield of BL crude extract from water (BL/W) was the highest, followed by those from ethanol (BL/E), and ethyl acetate (BL/EA), respectively. The BL/W and the BL/E exhibited the antioxidant activity as determined by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assay and slightly antibacterial activity against Staphylococcus aureus and Escherichia coli as determined by agar disc diffusion method. The alginate films containing 20% w/w of either the BL/W or the BL/E were fabricated from the solvent-casting technique. The release characteristics of the BL extracts therefrom were investigated by the total immersion method and the transdermal diffusion through a pigskin method in either the acetate buffer (pH 5.5) or the phosphate buffer (pH 7.4) solutions during 0-48 h, at the temperatures of 32° or 37°C, respectively. For total immersion method, the maximum released amounts of the BL/W were higher than those of the BL/E. Inversely, the maximum released amounts of the BL/E were higher than those of the BL/W in the case of the transdermal diffusion method. For both the total immersion and the transdermal diffusion methods, the released amounts of both BL/W and BL/E in the phosphate buffer were greater than those in the acetate buffer solutions. Both types of alginate films containing either BL/W or BL/E exhibited the antioxidant and antibacterial activities which showed the potential for use as topical transdermal and wound dressing materials.