3.6. Determination of Elastase Inhibitory Activity

The elastase inhibitory assay was used with a slight modification of the method described by Chiocchio et al. [29]. Briefly, elastase from porcine pancreas (10 μg/mL, 10 μL) was mixed with Tris-HCl (0.2 M, 90 μL), STANA (2.5 mM, N-Succinyl-Ala-Ala-Ala-p-nitroanilide, 100 μL), and sample (50 μL) at 37 °C for 30 min. After completion of the reaction, the supernatant was centrifuged at 15,000 rpm for 10 min. The absorbance was measured at 405 nm using a microplate reader (Perkin Elmer, Waltham, MA, USA). Phosphoramidon was used as a positive control.