MASP-2-IN-1 (Compound 77) is the inhibitor for mannan-binding lectin-associated serine protease ( MASP ), that inhibits MASP2 and MASP3 with IC 50 of 11.4 nM and 13.2 µM. MASP-2-IN-1 exhibits a weak inhibitory activity against hERG with an IC 50 of 175 µM. MASP-2-IN-1 reveals a poor stability in mouse plasma with a half-life of 4.4 hours.