A library of benzimidazole derivatives
1–
20 were synthesized, and studied for their α-
chymotrypsin (α-CT)
inhibitory
activity in vitro. Kinetics and molecular docking studies were performed to identify the type of inhibition. Compound
1 was found to be a good
inhibitor of α-
chymotrypsin enzyme (IC
50 = 14.8 ± 0.1 μM,
Ki = 16.4 μM), when compared with standard chymostatin (IC
50 = 5.7 ± 0.13 μM). Compounds
2–
8,
15,
17, and
18 showed significant
inhibitory activities. All the
inhibitors were found to be competitive
inhibitors, except compound
17, which was a mixed type
inhibitor. The substituents (
R) in
para and
ortho positions of phenyl ring B, apparently played a key role in the
inhibitory potential of the series. Compounds
1–
20 were also studied for their cytotoxicity profile by using 3T3 mouse fibroblast cells and compounds
3,
5,
6,
8,
12–
14,
16,
17,
19, and
20 were found to be cytotoxic. Molecular docking was performed on the most active members of the series in comparison to the standard compound, chymostatin, to identify the most likely binding modes. The compounds reported here can serve as templates for further studies for new
inhibitors of α-
chymotrypsin and other
chymotrypsin-like serine proteases enzymes.