Lupine protein hydrolysates inhibit enzymes involved in the inflammatory pathway

Lupine protein hydrolysates (LPHs) were obtained from a lupine protein isolate (LPI) by enzymatic hydrolysis using two proteases, Izyme AL and Alcalase 2.4 L, and their potential anti-inflammatory capacities were studied by determining their in vitro inhibition of the following enzymes that are involved in the inflammatory process: phospholipase A2 (PLA(2)). cyclooxygenase 2 (COX-2), thrombin, and transglutaminase (TG). The strongest inhibitory activities toward PLA(2) and TG were found in the hydrolysates obtained by hydrolysis with Izyme and subsequently with Alcalase, with more than 70% inhibition obtained in some cases. All of the hydrolysates tested inhibited more than 60% of the COX-2 activity. In no case did the percentage of thrombin activity inhibition exceed 40%. The best inhibitory activities were found in the LPH obtained after 15 min of hydrolysis with Alcalase and in the LPH obtained after 60 min of hydrolysis with Izyme followed by 15 min of hydrolysis with Alcalase. Enzyme kinetic analyses were conducted to determine the K-m and V-max parameters of these two hydrolysates using the Lineweaver-Burk equation. Both hydrolysates competitively inhibited the thrombin and PLA(2) activities. In the case of COX-2 and TG, the inhibition appeared to be the mixed type. (C) 2013 Elsevier Ltd. All rights reserved.