4,9-Anhydrotetrodotoxin (4,9-anhydro-TTX) is a derivative of TTX that selectively blocks inward sodium current through Nav1.6 voltage-activated sodium channels (IC50 = 7.8 nM in Xenopus oocytes). [1][2][3] It demonstrates IC50 values of 1.3, 0.34, 0.99, 78.5, 1.3, and >30 µM for Nav1.2, Nav1.3, Nav1.4, Nav1.5, Nav1.7, and Nav1.8, respectively.[1]
Mambalgin 1 TFA, a selective inhibitor of ASIC1a (with IC50 values of 192 nM for human ASIC1a and 72 nM for the ASIC1a/1b dimer), preferentially binds to the channel in its closed/inactive state. It demonstrates selectivity for ASIC1a over a range of other channels, including ASIC2a, ASIC3, TRPV1, P2X2, 5-HT3, Nav1.8, Cav3.2, and Kv1.2. In vivo, Mambalgin 1 TFA effectively prolongs the latency of the withdrawal response in mouse tail-flick and paw-flick tests.