Phytochemical Composition and Bioactivity of Acanthus dioscoridis var. perringii: An Integrated Analysis of Antioxidant Activity, Enzyme Inhibition, and Phenolic–Bioactivity Correlations

<b>Objectives:</b> Plant organs often allocate phenolic metabolites unevenly, resulting in organ-specific bioactivities. This study aimed to characterize the organ-specific phenolic profile of <i>Acanthus dioscoridis</i> var. <i>perringii</i> and determine how this chemical segregation is associated with antioxidant capacity and enzyme inhibitory activities. <b>Materials and Methods:</b> Organ-specific extracts (roots, stems, leaves, bracts, and flowers) were evaluated for total phenolic and flavonoid contents, targeted LC-MS analysis of individual phenolics, antioxidant activity by multiple assays, enzyme inhibition [acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase, and α-glucosidase], and the relationships between phenolic composition and biological activities. Antioxidant performance was also assessed using the Relative Antioxidant Capacity Index (RACI). <b>Results and Discussion:</b> Roots showed the highest total phenolic content, whereas bracts had the highest total flavonoid level. Verbascoside was the dominant compound in all organs, with the highest levels in leaves, roots, and bracts. Roots exhibited the strongest reducing and radical-scavenging activities, while flowers showed the best metal-chelating capacity. Enzyme inhibition was organ-dependent and generally moderate, with stems showing the strongest cholinesterase inhibition, leaves the strongest α-amylase inhibition, and bracts together with roots the strongest α-glucosidase inhibition. Statistical analysis revealed close associations between phenolic richness, antioxidant responses, and cholinesterase inhibition. <b>Conclusions:</b> These findings demonstrate a clear organ-dependent distribution of phenolic compounds in <i>A. dioscoridis</i> var. <i>perringii</i>, reflected in distinct antioxidant and enzyme inhibitory profiles. Overall, the study provides a biochemical and bioactivity-based characterization of the species at the organ level.