Utilization of the By-Product of Corn: Guided Identification of Bioactive Terpenoids from Stigma Maydis (Corn Silk).

Stigma maydis (corn silk) ( S. maydis ) is a food-based by-product of maize and possesses great nutritional and pharmaceutical value. This study aimed to explore bioactive components from S. maydis . By the guidance of bioactivity-guided approach and Global Natural Products Social (GNPS) molecular networking, 12 terpenoids were discovered from S. maydis . The structures of 11 undescribed compounds ( 1 - 11 ) were determined by detailed spectroscopic analyses, single-crystal X-ray diffraction analysis, specific rotation calculations, electronic circular dichroism (ECD) calculations, and NMR calculations. The neuroprotective and acetylcholinesterase (AChE) inhibitory effects of 1 - 12 were examined, and most of them showed significant or moderate activities. The underlying neuroprotective mechanism of 4 and 5 was revealed by Hoechst 33258, AO-EB, and JC-1 staining assays. This work illustrated the potential of S. maydis as a prospective natural source of bioactive compounds in food and pharmaceutical industries.