Design, synthesis, and pharmacological evaluation of heteroaryl thiol-linked kojic acid derivatives as a novel class of acetylcholinesterase inhibitors for Alzheimer's disease therapy.

Natural products have long served as versatile templates for discovering lead molecules against various targets of pharmacological interest. Kojic acid, a fungal metabolite epitomizes this versatility as it elicits broad-spectrum biological properties. Described herein is a series of heteroaryl thiol-linked kojic acid derivatives that demonstrate potent acetylcholinesterase (AChE) inhibition along with anti-amyloid-β (Aβ) aggregation activity and blood brain barrier (BBB) permeability highlighting their potential as a novel class of Anti-Alzheimer's therapeutics. Seventeen kojic acid derivatives, synthesized by incorporating three different heterocyclic thiols, were evaluated for in vitro AChE inhibition employing Ellman's method. The most potent analogs identified from the AChE inhibition studies were further evaluated for binding to the peripheral anionic site (PAS) of AChE using the propidium iodide (PI) displacement assay, anti-amyloid-β (Aβ) aggregation inhibition using the thioflavin T assay, and BBB permeability using the PAMPA-BBB assay. Obtained findings indicated that two compounds MS 21-05 and MS 21-11 bearing a 5-methoxybenzo[d]thiazol-2-yl)thio moiety and 5-phenyl-1,3,4-oxadiazol- 2-yl)thio moiety, respectively, elicited potent AChE inhibition (IC₅₀ < 5 µM), moderate anti-Aβ aggregation effects and good BBB permeability. The molecular docking studies of compound MS 21 - 11 along with its molecular dynamics simulations at peripheral anionic site (PAS) of enzyme AChE provided structural insights into the binding mode of these derivatives. Taken together, the findings of this study establish heteroaryl thiol-linked kojic acid derivatives as a valuable molecular framework for developing anti-Alzheimer's therapeutics that target both cholinergic dysfunction and amyloid-β aggregation.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-025-04295-5.