Antioxidant and Anti-inflammatory Activities of the Siamese Crocodile (Crocodylus siamensis) Hemoglobin Hydrolysate Derived from Trypsin and Papain Hydrolysis

Crocodylus siamensis hemoglobin hydrolysates (CHHs) were obtained by trypsin and papain digestion at different incubation times (2, 4, 6 and 8 h) at 37 degrees C and subjected to antioxidant and anti-inflammatory activity assessment. DPPH scavenging activity of CHH derived from trypsin was similar to intact Hb. CHH derived from papain hydrolysis by 8-h hydrolysis (8h-CHHp) showed the highest DPPH scavenging activity at 56.86% antioxidant inhibition with IC50 value of 31 mu g/ml. CHH derived from papain hydrolysis by 2-h hydrolysis (2h-CHHp) showed the highest reducing power activity at 0.99 mM Trolox equivalent and 4h-CHHt showed reducing activity at 0.16 mM Trolox equivalent (at concentration of 500 mu g/ml). The linoleic peroxidation activity of CHH derived from papain hydrolysis by 6-h hydrolysis (6h-CHHp) and CHH derived from trypsin hydrolysis by 8-h hydrolysis (8h-CHHt) was increased in a dose-dependent manner with IC50 value of 5 mu g/ml. The strongest anti-inflammatory activity was found for 2h-CHHp, which displayed a high efficacy in decreasing NO production of macrophage RAW 264.7 cells (46.86%) with no toxicity and significantly reduced pro-inflammatory cytokines interleukin-6 (IL-6) production to about 25.73 pg/ml. Taken collectively, the results of this work demonstrate that CHHs derived from papain hydrolysis possesses antioxidant and anti-inflammatory activities, which provides support for the application against inflammation and oxidative stress-related disorders.