Inhibition of acetylcholinesterase by Cenostigma pyramidale leaf extract: Chemical composition, antioxidant potential, and in vitro-in silico insights.

Cenostigma pyramidale, a species native to the Brazilian Caatinga and traditionally used to treat respiratory and gastrointestinal disorders, was investigated for its neuropharmacological potential related to Alzheimer's disease (AD). The ethanolic leaf extract was evaluated as a natural acetylcholinesterase (AChE) inhibitor through in vitro and in silico approaches. The quantification of total phenolic compounds in the ethanolic extract showed 414.70 ± 21.48 mg GAE g-1 of extract, and the flavonoid content was estimated at 41.42 ± 0.41 mg QE g-1 of extract. The extract exhibited strong AChE inhibitory activity, with an IC₅₀ of 7.04 ± 0.04 µg mL-1. Remarkable antioxidant performance was also recorded, with IC₅₀ values of 12.64 ± 0.11 µg mL-1 in the DPPH● assay, 12.38 ± 0.09 µg mL-1 in ABTS+●, and 7.95 ± 0.08 µg mL-1 in the β-carotene test. Chromatographic analysis indicated seven main constituents: gallic acid, geraniin, rutin, ellagic acid, isoquercitrin, quercetin, and agathisflavone. Molecular docking revealed favorable interactions between these compounds and AChE, particularly for geranin, rutin, and agathisflavone, mainly at allosteric regions of the enzyme. These findings suggest that C. pyramidale may be a promising source of multifunctional compounds with cholinesterase inhibitory and antioxidant properties, supporting its potential for AD therapeutics.