The collagen was extracted from the outer skin waste according to the method of Nagai and Suzuki [1] with suitable modification. All the experiments were performed at 4 ◦C unless otherwise indicated. Briefly, the outer skin was removed,
cut into small pieces and defatted with 10 percent n-butyl alcohol (1:8) for 48 h, and washed with distilled water. Further, the skin was treated with 0.1 M NaOH to remove non-collagenous proteins for 3 days, washed with distilled water and lyophilized.