Serine protease inhibitor that specifically inhibits trypsin (Ki=73.8-78 nM) and chymotrypsin (Ki=993 nM) (PubMed:17886436, PubMed:17288251, PubMed:33802055). In vitro, it shows cytoprotective activity in the oxidative stress agent 6-hydroxydopamine (6-OHDA)-induced neurotoxicity model (PubMed:33802055). In this model, it decreases reactive oxygen species (ROS) level, and increases cell viability in a correlated manner (PubMed:33802055). It is possible that the observed effect is due to the ability of this peptides to act as free-radical scavenger (PubMed:33802055). Does not inhibit potassium channels (Kv1.1/KCNA1, Kv1.2/KCNA2, Kv1.3/KCNA3, Kv1.4/KCNA4, Kv1.5/KCNA5, Kv1.6/KCNA6, Shaker, Kv2.1/KCNB1, Kv3.1/KCNC1, Kv4.2/KCND2, Kv4.3/KCND3, hERG/KCNH2) and TRPV1, the capsaicin receptors (PubMed:22851925). Does not inhibit the serine proteases plasmin, thrombin, kallikrein, the cysteine proteinase papain, and the aspartic protease pepsin (PubMed:22851925, PubMed:17886436). Belongs to the venom Kunitz-type family. Sea anemone type 2 potassium channel toxin subfamily.