Design, Synthesis, and Biological Evaluation of N ‐Acyl Pregnane Alkaloid Ester Derivatives as Acetylcholinesterase and α ‐Glucosidase Inhibitors

ABSTRACT

To discover novel potential enzyme inhibitors based on natural products, a series of N ‐acyl pregnane alkaloid ester derivatives were designed, synthesized, and evaluated for their inhibitory activity against acetylcholinesterase (AChE) and α ‐glucosidase. The bioassay test results revealed that the target compounds generally showed more potent inhibition against α ‐glucosidase than against AChE. Notably, compounds 6e and 6i demonstrated significant α ‐glucosidase inhibitory activity, with IC ₅₀ values of 29.85 µM and 38.11 µM (acarbose IC ₅₀ : 16.49 µM), respectively, and exhibited low cytotoxicity toward Thle‐2 cells, with IC ₅₀ values of 112.70 µM and 73.65 µM, respectively. Structure‐activity relationship (SAR) analysis indicated that derivatives bearing an N ‐tigloyl group and nitro or pyridine substituents at the C‐20 position contributed to enhanced α ‐glucosidase inhibition. Enzyme kinetics confirmed that 6e and 6i function as reversible, noncompetitive inhibitors of α ‐glucosidase. Molecular docking studies further illustrated that both compounds bind to the lateral surface of the α ‑glucosidase through hydrogen bonds and hydrophobic interactions, rather than occupying the catalytic active site. These findings highlight that 6e and 6i exhibit certain inhibitory activity, providing a basis for the design of subsequent derivatives.