Bioactivity-Guided Identification of Ethyl Gallate from Pecan (Carya illinoinensis) and Its Protective Effects Against Oxidative Stress and Amyloid-β-Induced Cognitive Impairment.

Pecan (Carya illinoinensis) is an edible nut rich in phytochemicals with potential health-promoting properties; however, the bioactive constituents responsible for its neuroprotective effects remain insufficiently characterized. This study aimed to identify bioactive constituents from pecan through bioactivity-guided fractionation and to evaluate the protective effects of pecan extract and the identified compound against oxidative stress and amyloid beta (Aβ)1-42-induced cognitive impairment. Pecan ethanolic extract exhibited antioxidant and cytoprotective activities in PC12 cells exposed to hydrogen peroxide-induced oxidative stress. Sequential liquid-liquid fractionation, silica gel open-column chromatography, and preparative thin-layer chromatography, coupled with repeated bioactivity screening, progressively tracked the active fractions and led to the identification of ethyl gallate as a bioactive constituent of pecan extract by high-performance liquid chromatography and gas chromatography-mass spectrometry. The biological relevance of these findings was further evaluated in Aβ1-42-injected male mice. Dietary administration of pecan extract significantly improved spontaneous alternation performance in the Y-maze test, whereas ethyl gallate improved Y-maze performance and memory retention in the passive avoidance test, without apparent systemic toxicity under the experimental conditions. Although brain malondialdehyde levels showed a numerical decrease following ethyl gallate administration, the differences were not statistically significant. Collectively, these findings demonstrate the bioactivity-guided linkage of ethyl gallate to an active pecan fraction and provide preclinical evidence supporting further investigation of pecan-derived bioactives as food-derived functional ingredients relevant to cognitive health.